Science and Conservation of Vernal Pools in Northeastern North America: Ecology and Conservation of Seasonal Wetlands in Northeastern North America

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Science and Conservation of Vernal Pools in Northeastern North America

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Science and Conservation of Vernal Pools in Northeastern North America Edited by

Aram J.K. Calhoun Phillip G. deMaynadier

Boca Raton London New York

CRC Press is an imprint of the Taylor & Francis Group, an informa business

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Cover photographs courtesy of Megan K. Gahl (spine wood frog and vernal pool), Leo P. Kenney (fingernail clam), and Patrick Zephyr (marbled salamander). CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2008 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed in the United States of America on acid-free paper 10 9 8 7 6 5 4 3 2 1 International Standard Book Number-13: 978-0-8493-3675-1 (Hardcover) This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. No part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www. copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC) 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data Calhoun, Aram J. K. Science and conservation of vernal pools in northeastern North America / Aram J.K. Calhoun and Phillip G. deMaynadier. p. cm. Includes bibliographical references and index. ISBN-13: 978-0-8493-3675-1 (alk. paper) ISBN-10: 0-8493-3675-9 (alk. paper) 1. Vernal pool ecology--Northeastern States. 2. Vernal pool ecology--Canada, Eastern. 3. Vernal pools--Northeastern States. 4. Vernal pools--Canada, Eastern. I. deMaynadier, Phillip G. II. Title. QH541.5.P63C35 2007 577.63’6--dc22 Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com

2007003505

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Dedication

To my beloved partner in conservation and exploring the wild, Mac Hunter A.J.K.C. To my parents – Suzanne and Franklin, Alain and Elisabeth P.G.D.

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Table of Contents Foreword ...................................................................................................................xi Preface......................................................................................................................xv Acknowledgments...................................................................................................xxi About the Editors..................................................................................................xxiii Contributors ...........................................................................................................xxv Chapter 1 Valuing and Conserving Vernal Pools as Small-Scale Ecosystems .........................1 Malcolm L. Hunter, Jr.

SECTION I Physical Setting: Classification, Hydrology, and Identification Chapter 2 Classification of Vernal Pools: Geomorphic Setting and Distribution ...................11 Richard D. Rheinhardt and Garrett G. Hollands Chapter 3 Hydrology and Landscape Connectivity of Vernal Pools.......................................31 Scott G. Leibowitz and Robert T. Brooks Chapter 4 Remote and Field Identification of Vernal Pools....................................................55 Matthew R. Burne and Richard G. Lathrop, Jr.

SECTION II Biological Setting: Principal Flora and Fauna Chapter 5 Flora of Northeastern Vernal Pools .........................................................................71 Andrew Cutko and Thomas J. Rawinski

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Chapter 6 Diversity and Ecology of Vernal Pool Invertebrates.............................................105 Elizabeth A. Colburn, Stephen C. Weeks, and Sadie K. Reed Chapter 7 Ecology and Conservation of Pool-Breeding Amphibians ...................................127 Raymond D. Semlitsch and David K. Skelly Chapter 8 Population and Genetic Linkages of Vernal Pool-Associated Amphibians .........149 James P. Gibbs and J. Michael Reed Chapter 9 The Importance of Vernal Pools to Reptiles, Birds, and Mammals.....................169 Joseph C. Mitchell, Peter W.C. Paton, and Christopher J. Raithel

SECTION III Conserving Vernal Pools in HumanModified Landscapes Chapter 10 Vernal Pool Conservation Policy: The Federal, State, and Local Context ..........193 Wende S. Mahaney and Michael W. Klemens Chapter 11 Chemical Contamination of Vernal Pools .............................................................213 Michelle D. Boone and Bruce D. Pauli Chapter 12 Conserving Vernal Pool Wildlife in Urbanizing Landscapes ...............................233 Bryan Windmiller and Aram J.K. Calhoun Chapter 13 Conserving Vernal Pool Amphibians in Managed Forests ...................................253 Phillip G. deMaynadier and Jeffrey E. Houlahan Chapter 14 Spatial Tools for Conserving Pool-Breeding Amphibians: An Application of the Landscape Species Approach ...........................................281 Robert F. Baldwin, Kathleen P. Bell, and Eric W. Sanderson

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Chapter 15 Vernal Pools as Outdoor Laboratories for Educators and Students .....................299 Hank J. Gruner and Richard D. Haley Chapter 16 Conserving Vernal Pool Habitat through Community Based Conservation ........319 Aram J.K. Calhoun and Patti Reilly

SECTION IV Index Index ......................................................................................................................345

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Foreword Having studied wetland ecosystems for over 30 years and tromped through thousands of wetlands of all different sizes, shapes, and types, I can honestly say that vernal pools are among my favorites. My life’s work has focused on mapping wetlands, and their plant life has been a major attraction, but the vernal pools I am most familiar with — those in eastern forests — are not especially unique in their vegetation composition. So what’s the attraction? Well, it’s their sounds that are so captivating to me. As you will learn from this book, vernal pools are the breeding grounds for many species of amphibians, and when breeding, male frogs of various types chorus to attract females. In the woods surrounding my house, the raucous, quack-like call of male wood frogs is a harbinger of spring, followed by the highpitched, almost deafening chorus of spring peepers and later by the melodious, birdlike calls of individual gray tree frogs perched high in the treetops. Vernal pools are, in fact, one of the few wetlands that can be identified by sound if you take a walk in the woods at the right time of year. More importantly, vernal pool music is a sign of productivity and underscores the critical role these wetlands play in the life cycle of pool-breeding amphibians, invertebrates, and myriad forest predators. Of course, not all seasonal pool species are musically inclined; salamanders are the silent type, yet they, too, require vernal pools for breeding and larval development, whereas the adults of many species spend their time virtually underground in surrounding forests. The staggered use of vernal pools for breeding is also fascinating — first by blue-spotted and spotted salamanders, then wood frogs, spring peepers, and gray tree frogs, and finally in the fall by marbled salamanders — the ultimate in cooperative living. I am confident that after reading more about vernal pools in this book, you, too, will be captivated by these unique ecosystems. Some of the best known wetlands are marshes, swamps, and bogs — ecosystems that are at least periodically flooded or waterlogged. Long viewed as wastelands by industrialized civilizations, wetlands are now largely recognized as one of our most valuable natural resources, providing such benefits as floodwater storage, water quality renovation, shoreline stabilization, wildlife habitat, timber and other natural products. Vernal pools are a unique wetland type that may be unfamiliar to most people. In the northeastern U.S. and Canada, vernal pool settings range from ephemeral ponds imbedded in an upland forest matrix to pools within large forested wetland complexes, to seasonal swales between sand dunes, to temporary pools in abandoned sand and gravel pits. The term “vernal pool” initially evokes an image of a small ephemeral pond holding water in the spring but drying up later in the year since “vernal” means

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“pertaining to spring” and “pool” suggests a small body of water. Although the hydrology is more complicated than this simple summation, seasonal wetness is typical of the hydrology of many wetlands. In temperate and boreal regions, this amounts to high water tables from winter, spring, and early summer with a buildup of water in the soil from a combination of precipitation (including snow melt), spring runoff, and groundwater discharge, followed by a gradual drawdown of the water tables in summer with increased evaporation and plant growth, and finally by a gradual renewal of the cycle in autumn, with a rise in the water table as air temperatures cool, plants become dormant, and precipitation continues. This “seasonal” change in wetness is obvious to anyone who has visited a vernal pool during each of our four seasons, and in some cases has led to local names like “Lost Pond.” Most importantly, this unique hydrology drives the ecology of seasonal wetlands. The fluctuating water level is the lifeblood that creates the foundation for the biological structure of vernal pools and sustains their ecological functions. As most amphibians breed in water, the availability of a breeding pool permits these animals to live mainly in terrestrial habitats (often hundreds of meters from the breeding pool) while allowing each new generation to retrace its evolutionary pathway from water to land. Many aquatic invertebrates have evolved a different pathway; they are most active when water is present and develop eggs or aestivating stages that can withstand periods of drought and are ready to hatch when seasonal waters return. Vernal pools are often geographically isolated wetlands, separated from other wetlands and waters by terrestrial habitat. This condition, combined with their relatively small size and patchy distribution across the landscape, offers unique opportunities to support local wildlife, while also making it difficult to formulate effective strategies for their conservation. These vernal pool landscape properties provide further support for the adage, “the whole is greater than the sum of its parts.” This phrase might be translated to “the value of the collection of vernal pools on the landscape is greater than the sum of the value of each pool individually” when considering regional wildlife diversity and the viability of local invertebrate and amphibian populations. The distribution and variety of pools in our region provide “stepping stones” for amphibians migrating across local landscapes as well as moist refugia (even when seemingly dry) for survival during periods of drought. In the Northeast, the linkage between forests and vernal pools is critical for vernal pool ecology as forests largely produce the organic matter that feeds the detritus-based food chain of vernal pools, help moderate water temperatures, and provide habitat for juveniles and adults of pool-breeding species. Some may even consider vernal pools as keystone habitats where terrestrial wildlife can obtain water, food, refuge, and other critical resources not available in the surrounding terrestrial landscape. Since the mid-1960s, U.S. federal environmental laws (especially the Clean Water Act) and wetland protection laws in most northeastern states have greatly reduced the indiscriminate filling of wetlands. Canada has adopted federal and provincial wetland policies that promote stewardship of wetlands on both private and public lands but, for the most part, alterations of privately owned wetlands are not regulated. Even under the best of circumstances, wetlands remain under siege as they become the last parcels of undeveloped real estate in many locales. The survival of vernal pool wildlife is further hampered by the fact that: (1) many vernal

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pools are geographically isolated wetlands and may be not be protected by current laws, and (2) many pool-breeding animals depend not only on wetlands but also on adjacent upland forests where they live as juveniles and adults; alteration of these forests is generally not subject to government regulation. At current rates of residential development in northeastern forests, it is more important than ever that scientists, educators, environmentalists, and concerned members of the public get more involved in bringing vernal pool science to bear in land-use policy decisions. The objective is not to prevent development from occurring but to guide it in ways that minimize adverse impacts on the environment. Ultimately, the fate of vernal pool wildlife in the Northeast depends largely on whether private land managers and landowners recognize the value of these threatened wetland systems. As such, increased awareness is essential, and this book is poised to fill an important role as one of only a few resources available on the subject of vernal pool conservation. This volume is designed to appeal to a wide audience, from scientists to the general public interested in learning more about the environment in which they live. You will learn much about the biology of vernal pools, their ecological significance, the links between pools, forest, and wildlife, and strategies to conserve these critical habitats. Furthermore, the book is filled with valuable references to other publications for those wishing to further expand their knowledge. After reading this contribution, you will have gained a broader understanding of why ecologists are increasingly concerned about the fate of these special wetlands and, hopefully, you will be motivated to join the ranks of those working to save these “wicked big puddles.” Ralph W. Tiner Wetland Ecologist U.S. Fish and Wildlife Service Northeast Region Hadley, Massachusetts

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Preface STILL HERE Softened by a glass or two of Cabernet, I left my neighbors’ crowded table, our bursts of laughter, and dour conversation about man and his dangerous antics in our only world, and went to the kitchen for more bread. There, through the window, a sweep of damp air and wild spring calls of peepers and wood frogs rushed in like the Holy Ghost and made me pause. Their piercing chorus of voices mixed into such a deep soup of sound that one frog was indistinguishable from another. And for one long moment I was held there in the world’s big hands, and everything that mattered was evening with its early, scattered stars, the fragile smell of daffodils and boggy water, and the mating calls of a population of those finely-tuned, permeable animals (indicators of the Earth’s well-being) so much older than we are, that have survived ice ages and the shifting of continental plates, but are now disappearing — though still here thriving in woods beyond my neighbor’s lawn in this hollow where we are all clinging to the slippery edge of wildness, where I was allowed a rush of such sweetness and grief, those fraternal twins who are born in us again and again, though perhaps not forever, singing whether or not we listen. Elizabeth Tibbetts (First published in the Beloit Poetry Journal)

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Fairies that are actually shrimp, frogs sporting bandit’s masks, and seemingly unnatural, yellow polka-dotted salamanders. How could an ecosystem that attracts such a motley crew of characters not capture the imagination of poets and artists? And yet, why has it taken so long to capture the interest of the general public? Imagine if Big Night — the first warm, rainy spring evening when salamanders and wood frogs move en masse from leafy retreats to vernal pools to breed — featured the same number of large mammals, say, moose and bear? Hundreds or thousands of bear and moose crossing a country road in one night to descend upon a single, small woodland hollow — now that would be a spectacle that could not be ignored. Is the spotted salamander courtship dance any less amazing than that of the familiar woodcock or ruffed grouse? Certainly not to anyone who has witnessed it! Perhaps the small, ephemeral nature of pools and the secretive life style of their specialized fauna have limited public appreciation of this uniquely spectacular ecosystem. After all, amphibian breeding lasts only a few weeks before the animals disappear into the surrounding forest until the following spring. It is our intent in this book to take the mystery (not the magic) out of vernal pool ecosystems and their inhabitants and to make them loom large in the minds of our readers. Cultivating an increasingly vernalpool-literate public, both lay and professional, is critical if we are to conserve one of North America’s most threatened wetland ecosystems.

DEFINITION OF VERNAL POOL Our group of authors, from diverse backgrounds and experiences (geologists, hydrologists, biologists, educators), engaged in many lively discussions regarding what to call the ecosystem we were all writing about and, indeed, how to define these small bodies of water. We decided to call them “vernal pools.” The reasoning was that this term is familiar to many practitioners, it is well-established in the literature, and it is often the term used in wetland regulations. Furthermore, we designed our book to complement the contribution recently published by Elizabeth Colburn, Vernal Pools: Natural History and Conservation (2004). We acknowledge that vernal pools are also commonly referred to as seasonal forest pools, seasonal pools, seasonal ponds, ephemeral ponds, woodland pools, isolated wetlands, and so on. In this book, we focus on the key ecological function of vernal pools as a potential breeding habitat for biota adapted to life in temporary waters. Nature is not divided into neat, textbook description units, and our broad definition allows for viewing vernal pools as dynamic systems defined by ecological functions, rather than by specific wetland type or landscape setting. The 16 chapters in this text were written with the goal of advancing the conservation of small, seasonal wetlands and their unique fauna. We call the pool and its associated terrestrial forest vernal pool habitat. The pool and surrounding forests provide habitat for a specialized biota including, most notably, pool-breeding amphibians, reptiles, and invertebrates, and it is our goal to link the two in the minds of resource managers and citizens who shape land-use policy. Although plants can be closely associated with pools as well, most of our chapters focus on wildlife, especially amphibians, as these animals clearly link the terrestrial and aquatic realms we seek to conserve and, in so doing, conserve key habitats for other taxa as well.

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TABLE 1 A Summary of Vernal Pool Characteristics in Northeastern North America Feature Geographic scope Size Hydroperiod Physical setting

Inlets and outlets Presence of fish Better known indicator species

Vernal Pool Attributes Region dominated by forests in glaciated northeastern North America No size limit, most under 1 ha (2.47 ac) Temporary to semi-permanent (drying partially in all years and completely in drought years) Not limited to any hydrogeomorphic setting. Range from isolated, upland depressions, to floodplain depressions, to pools associated with larger wetland complexes If present, they are ephemeral Lack resident, predatory fish populations Fairy shrimp, ambystomatid salamanders, wood frogs, and spadefoot toads

OUR WORKING DEFINITION Vernal pools are temporary to semi-permanent pools occurring in shallow depressions that typically fill during the spring or fall and may dry during the summer or in drought years. These pools are usually associated with forested landscapes in glaciated northeastern North America. They may have intermittent inlets or outlets, but are not otherwise hydrologically connected through surface waters to permanent bodies of water that support predatory fish. Vernal pools occur in a diversity of landscape settings including isolated upland depressions, depressions in floodplains, as part of headwater streams and seepage systems (pools “strung” like pearls on a temporally intermittent chain), or embedded in larger wetland complexes (e.g., shrub or forested swamps, peatland laggs). Vernal pools provide the primary breeding habitat for wood frogs, spadefoot toads, ambystomatid salamanders, and numerous invertebrate taxa adapted to temporary, fishless waters. They also provide an important secondary habitat for other biota, including several of the region’s rare and endangered species.

SCOPE OF THE BOOK: GLACIATED NORTHEASTERN NORTH AMERICA The combination of geologically recent, glacially formed, surficial geology, and present climatic conditions that favor forest-dominated vegetation makes glaciated northeastern North America a coherent ecologic unit in which to group vernal pools. Therefore, the extent of the Wisconsin glaciation and the surficial geology that resulted define the region covered in this book (Figure 1). The terminal moraines of the eastern portion of the Late-Wisconsin glaciation define the eastern and southern boundaries of the study area. These moraines stretch from Nantucket, Massachusetts, New Jersey, and Long Island, New York, across northern Pennsylvania, through central Ohio, Indiana, Illinois, Iowa, and Minnesota. The western boundary

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FIGURE 1 The light gray shading covers the part of North America that was glaciated during the Pleistocene (the most recent period of extensive glaciation). The darker gray areas (A, B, and C) mark the extent of the Late-Wisconsin glaciation (35,000–11,000 years B.P.), an event responsible for most of the landforms we see today. This darker gray region also defines the scope of this book, referred to throughout the text as the glaciated Northeast. The terminal moraines of the eastern portion of the Late-Wisconsin glaciation delineate the eastern and southern boundaries of the study area. The western boundary of the study area coincides with the transitional boundary between prairie and forest, whereas the northern boundary is defined by the northern forest tree line. The glaciated region of northeastern North America can be divided into three general surficial geologic/geomorphic subregions based on dominant bedrock type and mode of glaciation and deglaciation. A discussion of the geologic significance of the subregions for vernal pool formation and landscape setting can be found in Chapter 2, Rheinhardt and Hollands. One subregion encompasses the Canadian Shield (A), which includes most of Quebec and Labrador, northern and western Ontario, northern Wisconsin, northern Minnesota, and northern Michigan. Another geomorphic subregion (B) occurs south of the Canadian Shield in the eastern portion of the Region. It includes southern Quebec and Atlantic Canada, New England, northern New Jersey, and eastern and northern New York. The third geomorphic subregion (C) consists of the western area south of the Canadian Shield. It includes central and western New York, northern and western Pennsylvania, central and northern Ohio, central and northern Indiana, northern Illinois, southern and central Wisconsin, and southern Minnesota. (Figure modified from Colburn [2004] Vernal Pools: Natural History and Conservation. McDonald & Woodward Publishing, VA. Used with permission.)

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of the study area coincides with the transition between prairie and forest, therefore excluding North Dakota and South Dakota. The northern limit of the study area is defined by the northern boundary of forest (tree line). The tree line for northern reaches of the study area in Canada is delineated on official province maps of Quebec and Ontario. Although acknowledging the formative role that geologic history has had in shaping the flora and fauna of vernal pool ecosystems in the Northeast, we also believe that many of the biological principles and management recommendations presented in this volume are pertinent to seasonal pool ecosystems throughout the world.

INTENDED AUDIENCE Environmental consultants, land use planners, natural resource managers, academics, agency regulators, environmental lawyers, educators, and amateur naturalists will all find useful information in this book. Quite simply, most everyone working in the natural resources field has to address wetland issues either directly or indirectly in the course of their career. The fact that vernal pools are among both the most widespread and the most at-risk wetland types in northeastern North America has led to an increasing demand by natural resource professionals and concerned members of the public for better information on their ecology and conservation. This book offers readers state-of-the-art knowledge on vernal pools and provides the scientific basis and tools for their conservation.

WHAT THE BOOK IS AND ISN’T The editors have worked as researchers and policy advocates on vernal pool issues in New England for over 15 years. In that time, the scientific community has made significant progress in understanding the life history needs of vernal pool-breeding amphibians and, to a lesser extent, other pool biota. Many questions remain, but it is our belief that enough sound, scientific data on pool breeding fauna exist for planners, regulators, and resource planners to guide responsible resource decisions. Our work with these professionals has convinced us of the need for science-based recommendations to help advance the conservation of vernal pools and other small wetlands. Our goal in this book is to mine the published literature, personal communications from professionals working in the field, unpublished reports and data, and other sources in an effort to present the latest information and practical application of this knowledge to the community responsible for making conservation decisions. This book is not intended as a comprehensive literature review targeted to herpetologists or scientists, and it by no means covers all aspects of vernal pool ecology. Rather, we have focused on topics that, in our opinion, address key issues needing consideration by conservation practitioners. We have also written our book as a complement to Vernal Pools: Natural History and Conservation (Colburn 2004). Elizabeth Colburn provides a thorough review of the natural history of vernal pool fauna, including notably, invertebrates and

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microorganisms. It is our goal to build on her contribution with an in-depth focus on the ecology of better-known groups of vernal pool flora and fauna that can be used, in turn, to inform land management recommendations helpful in conserving all vernal pool biota, both cryptic and charismatic.

ORGANIZATION Science and Conservation of Vernal Pools in Northeastern North America synthesizes decades of research on vernal pools and pool-dependent biota as a foundation for presenting tools for conserving these ecosystems. Contributions from experts throughout the region are divided into three sections. We introduce vernal pools as a keystone ecosystem in northeastern forests of North America. This landscape approach to understanding these aquatic systems and the forests with which they are ecologically linked is the common current flowing through most chapters that follow. Section I helps set the stage by reviewing the physical parameters — mainly geomorphic setting, hydrology, and tools for identification — that help us understand how vernal pools function differently from other wetland systems and where they are found on the landscape. Section II breathes life into vernal pools by reviewing our state of knowledge on the diversity and natural history of their unique biota with a focus on plants, invertebrates, amphibians, and other pool-associated vertebrates. Finally, Section III draws on the collective expertise of researchers, consultants, and agency personnel to synthesize the best-available science from both peer-reviewed and unpublished sources relevant to conserving vernal pools in human-dominated landscapes. We also recognize in this section the significant role that educators and citizens have in effecting local conservation, and in ensuring a permanent place on the landscape for these uniquely ephemeral wetlands. Aram J.K. Calhoun Phillip G. deMaynadier

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Acknowledgments We give special thanks to Elizabeth Colburn for supporting the publication of a contribution intended to complement her book Vernal Pools: Natural History and Conservation and for her willingness to coauthor a chapter and provide figures from her original work. Her collaboration and willingness to review our prospectus, as well as other contributed chapters, improved our final product. We also wish to acknowledge the anonymous reviewers who contributed to this work and, among others, Darold Batzer, Dana Bauer, Frederic Beaudry, Kathleen Bell, Tom Biebighauser, James Bogart, Jeff Borisko, Christine Bridges, Mark Brinson, Robert Brodman, Matthew Burne, Brian Butler, Rob Byran, Elizabeth Colburn, Andrew Cole, Marcel Darveau, Molly Docherty, Stanley Dodson, Felix Eigenbrod, Erica Fleishman, Megan Gahl, Lloyd Gambel, Frank Golet, Evan Grant, David Green, Al Hanson, Eliza Harper, David Hirth, Garry Hollands, William Hopkins, Malcolm Hunter, Scott Jackson, Jacques Jutras, Bruce Kingsbury, Larry Klotz, Ruth Ladd, Scott Leibowitz, Michael Lew-Smith, Jonathan Mays, Marc Mazerolle, R. Mckinney, Alberto Mimo, Terry Morley, Suzanne Nash, Peter Paton, David Patrick, Michael Reed, Andrew Reeve, Patti Reilly, Karen Rempell, D. Chris Rogers, Joshua Royte, Clay Rubec, Molly Schauffler, Paul Sievert, Marie Simovich, Ulrich Sinsch, Edmund Smith, Pam Snow, Dan Sperduto, Lisa St. Hilaire, Sally Stockwell, Beth Swartz, Liette Vasseur, Glenn Wiggins, Ralph Yulo, and Paul Zedler. Additionally, we greatly appreciate the patience and dedication of Gerry Jaffe, our project editor at CRC Press. Robert Baldwin also deserves special recognition for his enthusiasm and ideas during project conception; discussions with Rob helped advance the project from concept to reality. The senior editor (AC) expresses special thanks to Malcolm (Mac) Hunter and Sally Stockwell who introduced her to vernal pools, a wetland system that captured her heart upon witnessing the first quack of a wood frog and dance of a spotted salamander. Lastly, the second editor (PD) is deeply grateful for the patience and encouragement offered throughout the project by his wife, Molly Docherty, and children, Treva and Emmett. Financial support for this research was provided by the Maine Audubon Society, the University of Maine, and contributions to the Endangered and Nongame Wildlife Fund of the Maine Department of Inland Fisheries and Wildlife (Chickadee Checkoff and Conservation License Plate).

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About the Editors Aram J.K. Calhoun is an associate professor of wetland ecology at the University of Maine and a wetland scientist with Maine Audubon Society. Her research focuses on forested wetlands, vernal pools, amphibians, and aquatic invasive plants. Dr. Calhoun is active in working at the state and local levels on wetland policy and conservation issues. She received her doctorate from the University of Maine where her research focused on microbial ecology and aquatic plants. She is an avid naturalist who has visited every continent seeking new species and ecosystems while birding, hiking, canoeing, skiing, or scuba diving with her husband Mac.

Phillip deMaynadier is a wildlife biologist with the Maine Department of Inland Fisheries and Wildlife where his primary responsibilities include survey, research, and recovery programs for rare amphibians, reptiles, and invertebrates. Some of his current projects include facilitating statewide strategies for protecting high value vernal pools, researching the effects of road mortality on endangered turtles, and coordinating citizen-science atlasing efforts for herptiles, odonates, and butterflies. Dr. deMaynadier received his doctorate in wildlife ecology from the University of Maine, Orono, where his research focused on forestry–amphibian relationships. He enjoys hiking, hunting, naturalizing and spending time with his family.

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Contributors Robert F. Baldwin, Ph.D. Two Countries, One Forest Halifax, Nova Scotia Kathleen P. Bell, Ph.D. Department of Resource Economics and Policy University of Maine Orono, Maine Michelle D. Boone, Ph.D. Miami University Oxford, Ohio Robert T. Brooks, Ph.D. USDA Forest Service University of Massachusetts Amherst, Massachusetts Matthew R. Burne Vernal Pool Association, Inc. Peabody, Massachusetts Aram J.K. Calhoun, Ph.D. University of Maine Orono, Maine Elizabeth A. Colburn, Ph.D. Harvard Forest Petersham, Massachusetts Andrew Cutko NatureServe Bowdoinham, Maine

Phillip G. deMaynadier, Ph.D. Wildlife Resource Assessment Section Maine Department of Inland Fisheries and Wildlife Bangor, Maine James P. Gibbs, Ph.D. State University of New York–ESF Syracuse, New York Hank J. Gruner Science Center of Connecticut West Hartford, Connecticut Richard D. Haley Centers and Education Audubon New York Albany, New York Garrett G. Hollands ENSR International Westford, Massachusetts Jeffrey E. Houlahan, Ph.D. Department of Biology University of New Brunswick–Saint John Saint John, New Brunswick Malcolm L. Hunter, Jr., Ph.D. Department of Wildlife Ecology University of Maine Orono, Maine

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Science and Conservation of Vernal Pools in Northeastern North America

Michael W. Klemens, Ph.D. Metropolitan Conservation Alliance Rye, New York Richard G. Lathrop, Jr., Ph.D. Grant F. Walton Center for Remote Sensing and Spatial Analysis Cook College Rutgers University New Brunswick, New Jersey Scott G. Leibowitz, Ph.D. U.S. Environmental Protection Agency National Health and Environmental Effects Research Laboratory Western Ecology Division Corvallis, Oregon Wende S. Mahaney Ecological Services U.S. Fish and Wildlife Service Old Town, Maine Joseph C. Mitchell, Ph.D. Mitchell Ecological Research Service Richmond, Virginia Peter W.C. Paton, Ph.D. Coastal Institute at Kingston Department of Natural Resources Science University of Rhode Island Kingston, Rhode Island Bruce D. Pauli Canadian Wildlife Service National Wildlife Research Centre Carleton University Ottawa, Ontario Christopher J. Raithel State Division of Fish and Wildlife West Kingston, Rhode Island

Thomas J. Rawinski Durham Field Office Northeastern Area State and Private Forestry U.S. Forest Service Durham, New Hampshire J. Michael Reed, Ph.D. Department of Biology Tufts University Medford, Massachusetts Sadie K. Reed Department of Biology University of Akron Akron, Ohio Patti Reilly Seal Harbor, Maine Richard D. Rheinhardt, Ph.D. Department of Biology East Carolina University Greenville, North Carolina Eric W. Sanderson, Ph.D. Living Landscapes Program Wildlife Conservation Society Bronx, New York Raymond D. Semlitsch, Ph.D. Division of Biological Sciences University of Missouri Columbia, Missouri David K. Skelly, Ph.D. School of Forestry and Environmental Studies Yale University New Haven, Connecticut Stephen C. Weeks, Ph.D. Department of Biology University of Akron Akron, Ohio

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Contributors

Bryan Windmiller, Ph.D. Hyla Ecological Services Concord, Massachusetts

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Valuing and Conserving Vernal Pools as SmallScale Ecosystems Malcolm L. Hunter, Jr.

CONTENTS The Values of Vernal Pools .......................................................................................2 Biodiversity....................................................................................................2 Ecosystem Processes .....................................................................................3 Vernal Pools as Keystone Ecosystems ..........................................................4 Social Values..................................................................................................4 Conserving Vernal Pools as Ecosystems...................................................................5 Summary ....................................................................................................................7 References..................................................................................................................7

Consider some of the ways that science challenges our human-centered perspectives on time and space. If you are transfixed by your mortality it will be painful to view your entire life span as lasting less than 2 milliseconds scaled against the age of the Earth on a 24-h clock. Struggling up the side of Mt. Washington is not any easier if you realize that all that topography would vanish if the Earth were scaled to the size of a billiard ball, leaving a surface smoother than any human hand could craft by polishing. Shifting from macro to micro, it is difficult to grasp the world of a tardigrade (a.k.a. water bear) for which the film of water on a single moss leaf might be home for its life span of a few months. And then there is time and space as experienced by the bacteria living in a tardigrade’s digestive tract. The leap of perspective required to understand and conserve vernal pools is modest compared to these examples, but nevertheless it can be a challenge for conservationists. How do we conserve ecosystems measured in fractions of a hectare in an era when most conservationists have embraced the concepts of landscape ecology, which have substantially increased the scales at which we view ecosystems? Strictly speaking, ecosystems are a scaleless construct, but very small ecosystems are easily overlooked when ecologists routinely refer to huge expanses like the Gulf of Maine or the Acadian forest as an ecosystem. How do we engender public understanding and enthusiasm for conserving ecosystems that are only

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conspicuously vibrant for a brief period and then disappear to the untutored eye? Subsequent chapters will examine these and other questions in great detail. My goal here is to set the stage by addressing two major aspects of the larger context within which vernal pool conservation operates: the values of vernal pools and the foundation for undertaking vernal pool conservation at an appropriate scale.

THE VALUES OF VERNAL POOLS Are vernal pools really “jewels in the crown” of northeastern landscapes that dazzle us for a few months each year, or just a hydrologic aberration exploited by mosquitoes and a few other species? Wetland ecologists may be confident that vernal pools are much more than over-sized puddles that take too long to dry up, but let us examine this issue, starting with biodiversity at three levels — species, genes, and ecosystems.

BIODIVERSITY From a species perspective, the most important issue is whether any species are absolutely dependent on vernal pools, either for their entire life cycle (e.g., fairy shrimp) or a critical portion (e.g., wood frogs, Rana sylvatica, for reproduction.). Chapter 6 and Chapter 7 (Colburn et al.; Semlitsch and Skelly) describe a number of invertebrates and amphibians, respectively, that are obligate vernal pool species, and there are likely to be additional invertebrate species that await description or understanding. Chapter 5 (Cutko and Rawinski) lists one plant species for the region, featherfoil (Hottonia inflata), that is also an obligate. A vagrant individual of a vernal pool obligate species may occasionally be found in another environment; the key issue is whether populations of the species could persist in the absence of vernal pools. Most taxonomic groups that occur in vernal pools, especially plants, reptiles, birds, and mammals, are dominated by facultative users that can survive without vernal pools because of their significant use of other types of ecosystems (Chapter 5, Cutko and Rawinski and Chapter 9, Mitchell et al.). These facultative users span a continuum from species that are largely dependent on vernal pools, such as various species of Ptilostomus caddisfly, to those that are only occasionally found there, such as moose (Alces alces). Evaluating the importance of vernal pools to species that only use them infrequently is difficult; for example, to an aquatic species dispersing overland a vernal pool may just be a convenient place to rest, or it may be a critical stepping stone where they must rehydrate or die. Collectively, these obligate and facultative species may give vernal pools high species richness per unit area relative to the overall landscape, but this is speculation because comprehensive surveys of species richness are extremely uncommon. (Indeed, truly comprehensive surveys are virtually impossible given the limited understanding of microbial taxonomy.) Of course many ecosystems have both obligate and facultative species; the high species richness of vernal pools is probably due to their structural complexity (wet pools, dry hummocks, potentially multiple layers of vegetation) and their dynamism as they shift seasonally from being predominantly aquatic to predominantly terrestrial environments. Beyond the high

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species richness of an individual pool (what ecologists call alpha diversity) a set of vernal pools may collectively have high species richness (beta diversity) because of variations in the species composition of different pools. Species composition at a given pool depends on environmental parameters (especially hydroperiod, size, and surrounding landscape context) and more or less random factors such as which species happened to colonize a new pool first. There may be some tendency for larger pools or pools with longer hydroperiods to “subsume” the biota of smaller, more temporary pools, but there are many exceptions that strongly argue for conservation of a broad range of pools (Oertli et al. 2002; Williams et al. 2003; Baber et al. 2004). Vernal pools may also be important to the genetic component of biodiversity. Here a key issue is how the spatial distribution of vernal pools interfaces with the population structure of various species. If a species (e.g., a relatively sedentary species like fingernail clams) exhibits very low rates of dispersal among pools then one would expect this isolation to lead to genetically distinct populations in different pools. Surprisingly, research on pool zooplankton suggests there is strong genetic differentiation even when dispersal is frequent, perhaps due to profound adaptations among the first colonists to reach a pool (DeMeester et al. 2002). Conversely, to the extent that vernal pool networks facilitate dispersal of organisms among pools, other wetlands, lakes, and rivers, then their distribution will increase genetic exchange. In particular, by providing widely distributed patches of aquatic habitat vernal pools may allow aquatic organisms to exist as a single large population or as a metapopulation, i.e., a group of subpopulations that are connected to one another by modest levels of dispersal (Chapter 8, Gibbs and Reed). Finally, it has been speculated that species that have populations living in both temporary and permanent pools have relatively high genetic diversity and thus a better ability to evolve in the face of environmental changes (Williams 1997). Evaluating the ecosystem level of biodiversity rests upon ecosystem classification schemes that may or may not have wide acceptance. In other words, whether or not vernal pools have value as an entity, independent of their constituent species, depends in large part on whether or not they are classified as a distinct type of ecosystem. Clearly, this entire book is premised on the idea that vernal pools are distinct enough to warrant the attention of ecologists and conservationists, and as we will see in the next section, vernal pools are quite distinct from an ecosystem processes perspective.

ECOSYSTEM PROCESSES When ecologists focus on the values of ecosystems they often emphasize three major processes: productivity, biogeochemical cycling, and hydrology. I am not aware of research on the primary productivity of ephemeral pools in any region, but one might surmise that primary production is modest in pools shaded by surrounding forest, as is typical of pools in northeastern North America. The input of organic matter from the forest may, however, be the basis of a robust detritus-based food web leading to high secondary production (Battle and Golladay 2001). Observations of large numbers of insects and juvenile amphibians emerging from vernal pools would

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support this idea (e.g., Vasconcelos and Calhoun 2004), but documentation is largely absent (Regester et al. 2006). The alternating wet and dry stages of a vernal pool generate biogeochemical processes that are quite different from those that typify an upland forest soil or the substrate of a permanently flooded water body. In simple terms, warmth, moisture, and oxygen are necessary for high levels of organic matter decomposition and mineralization, and vernal pools may have a more favorable combination of these factors than either permanently flooded wetlands (where anaerobic conditions prevail) or many forests (which are often too dry for optimal decomposition, especially during warm seasons) (Barlocher et al. 1977; Battle and Golladay 2001). The hydrologic role of vernal pools (e.g., recharging aquifers and storing water) has not been well studied, but given their diverse locations in the landscape, that role is probably greater than one would predict on the basis of the total area occupied by vernal pools (Chapter 2, Rheinhardt and Hollands and Chapter 3, Leibowitz and Brooks). Additionally, vernal pools may play a role in improving water quality because they are often located at the base of small watersheds where they receive and filter surface runoff.

VERNAL POOLS

AS

KEYSTONE ECOSYSTEMS

Ecologists often use the metaphor of keystones (a single stone that is critical to the integrity of an arch) to describe species that have both an important ecological role and a role that is significantly greater than you would predict from their abundance or biomass (Power et al. 1996). The ecological engineering of beavers (Castor canadensis) makes them a classic example from this region. Similarly, deMaynadier and Hunter (1997) argue that one could identify keystone ecosystems whose effect on the surrounding landscape is important and greater than one would predict based on their area (e.g., a spring in an arid landscape). By this definition, might vernal pools function as keystone ecosystems in northeastern forested landscapes? Their high species richness, roles as stepping stones for dispersing individuals, and substantial export of secondary production (mainly as amphibian and insect biomass) all argue “yes,” but it would be difficult to demonstrate this in a scientifically rigorous manner. One would need to undertake a draconian experiment: remove the vernal pools from several replicated landscapes while leaving all other features intact and then measure whether significant changes occur in the structure, composition, or function of the manipulated landscapes. Furthermore, the results of such an experiment could easily be muddled by landscape context; that is, vernal pools may be keystone ecosystems in some situations but not in others.

SOCIAL VALUES While the small size of vernal pools makes them easy to overlook, there are some advantages to being a compact and easy-to-grasp ecosystem. From an educational perspective, vernal pools are easy for a group of students, whether first-graders or university undergraduates, to conceptualize as an ecosystem, to visit, and to study (Chapter 15, Gruner and Haley). For adults, the charismatic biota of these ecosystems

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can be a catalyst for curiosity and concern about the natural world that exists in their town, perhaps literally in their backyard. In many cases, this curiosity and concern has encouraged people to become involved in local conservation efforts (Chapter 16, Calhoun and Reilly). The modest size of vernal pools also has some advantages for researchers who may require many replicates for statistical power or who may want to measure some characteristics of an entire ecosystem (e.g., with an encircling drift fence) rather than extrapolating from limited sampling (De Meester et al. 2005). Similarly, their sensitive relationship to climate and hydrology and small size may make vernal pools important sentinels of environmental change that are relatively easy for scientists or citizens to monitor (Chapter 11, Boone and Pauli; De Meester et al. 2005).

CONSERVING VERNAL POOLS AS ECOSYSTEMS If we accept the idea that vernal pools are small, distinct ecosystems, not just habitat for a handful of target species, then it is logical to organize conservation around this construct. In terms of one common biodiversity conservation paradigm this means focusing on a coarse-filter (ecosystem-centric) strategy rather than its complement, a fine-filter (species-centric) strategy (Hunter 1990; Groves 2003). The idea behind the filter metaphor is that conservation of ecosystems will be analogous to a coarse filter that efficiently captures habitat for large numbers of constituent species, but because the filter is coarse, some species will probably fall through the pores and require additional, fine-filter efforts attuned to their needs. For example, a vernal pool-dependent turtle species may fall through a pore in the filter designed to conserve the ecosystems that constitute its habitat because it also requires protection from collection for the pet trade. Conceptually, ecosystem-focused and species-focused approaches complement each other well, but in practical terms issues of scale can leave a fairly large gap between them. Usually ecosystem conservation has entailed identifying, delineating, and setting aside reserves that protect a large ecosystem, or a landscape comprising many ecosystems, at conventional scales, typically hundreds or thousands of hectares, large enough to be readily delineated on a 1:24,000 scale map. Conveniently, this scale is also roughly consistent with the scale at which organizations and individuals own property in rural areas. Ideally, establishing an ecosystem reserve at this scale will protect a high density of small, embedded ecological features such as vernal pools, springs, riparian zones, and rock outcrops. This is desirable because, as described above for vernal pools, the ecological influence of these features, especially as habitat for myriad invertebrates, fungi, mosses, and more, is greater than would be predicted from the size of the feature alone (i.e., your filter will capture far more species than if it did not contain these features). Whether we consider these features to be small ecosystems in their own right or ecological elements within larger ecosystems, their small size creates an interesting opportunity: they can be conserved in places where it is impractical to set aside conventional reserves that cover tens of hectares, usually more. In particular, their conservation can easily be integrated into the management of forests where timber

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extraction is a dominant goal as illustrated in Chapter 13 (deMaynadier and Houlahan). With sufficient foresight, these features can even be conserved in landscapes where residential development is the primary land use as discussed in Chapter 12, Chapter 14, and Chapter 16 (Windmiller and Calhoun, Baldwin et al., Calhoun and Reilly). Of course to accomplish this one cannot view vernal pools and other small features in isolation. As explained in many chapters vernal pools are intimately tied to their surrounding landscapes and their conservation should be undertaken in this context. Note that I define “landscape” as a set of interacting ecosystems, and thus, like “ecosystem,” landscape is a scaleless construct. Therefore, it is reasonable to discuss a landscape comprising a vernal pool and nearby forest and other wetlands, even though the term is conventionally used to describe much larger spatial extents. The idea that conserving small ecosystems and landscapes could be an important tool for maintaining biodiversity, especially with respect to the large majority of species that have small home ranges (e.g., most insects, nematodes, and fungi) catalyzed the idea of “mesofilter conservation” (Hunter 2005). The core objective of mesofilter conservation is to maintain small ecological features, such as decomposing logs and vernal pools, that are disproportionately important to many species, because such features are so small that a typical “delineate and set aside reserves” coarse-filter strategy may prove very inefficient. These features may even be too small to conserve using a “designate and regulate” paradigm given that they are often difficult to identify on aerial photographs or satellite images (Chapter 4, Burne and Lathrop), and furthermore, regulatory approaches to conservation can lead to inefficient confrontations (Chapter 10, Mahaney and Klemens). One of the principal advantages of mesofilter conservation is that it opens the door to collaborative biodiversity conservation in places where such protection must be integrated with other activities such as timber management, livestock grazing, or even building habitat for humans. If we can organize conservation of these miniature ecosystems in the context of other land uses then we can hope to avert some crises before they happen. Conservation biologists are too often in a pitched battle saving a species from the brink of global extinction like the northern right whales (Eubalaena glacialis) or black rhinos (Diceros bicornis). Some vernal pools species may be approaching global extinction now (Chapter 7 and Chapter 8), but in most cases we can conserve species before they are teetering on the edge of total oblivion. This situation is analogous to the efficiencies of public health medicine vs. emergency room surgery. Our actions to conserve vernal pools are more akin to measles vaccinations than to the emergency “heart bypass surgery” we are employing to save the northern right whale and Atlantic salmon (Salmo salar). Finally, a mesofilter perspective also reminds us that in focusing on vernal pools as we see them in the glaciated northeast of North America, we risk overlooking ephemeral wetlands at other scales that might merit our attention. We can be confident that we have not overlooked any ephemeral wetlands as large as North Lake Eyre, a body of water that intermittently covers over 8,000 km2 in central Australia. But what about extremely small wetlands? In many tropical forests a tree cavity containing a liter or two of water may support amphibian reproduction; are there any invertebrates tied to analogous environments in our region that merit conservation

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attention? If so, how would we conceptualize conservation of these environments? Would it be a very small example of the mesofilter approach? Would we think of them as very small wetlands or special trees? Similarly, are there very short duration wetlands that may be important to some creatures like tardigrades or fungi, which we usually overlook? In short, while it is impossible to completely shed our humanscaled view of the world, we need to approach conservation from many different scales of space and time if our efforts are to be comprehensive and efficient. Efficiency dictates that we focus on coarse filter approaches strongly complemented by mesofilter strategies. Comprehensiveness will require fine filter strategies for the species that fall through the pores of coarse and meso filters.

SUMMARY Vernal pools are valuable ecosystems whose role in northeastern landscapes is greater than one might predict, given their small size and ephemeral nature. From a biodiversity perspective they support a rich biota of both obligate species, chiefly certain invertebrates and amphibians, and many facultative species that use them to varying degrees, perhaps as moist refugia, productive foraging areas, or as stepping stones while moving among larger wetlands. In terms of ecosystem processes they are also rather unusual, probably supporting a detritus-based food web with high secondary production, high rates of nutrient cycling due to decomposition in alternating dry and saturated soil, and also playing a role in determining water quantity and quality. Their small size makes them attractive resources for ecological education and research, and they often occur close to high densities of people where they can inspire conservation action. Conserving vernal pools as small ecosystems can be construed as “mesofilter” conservation that fits between fine filter conservation directed at individual species and coarse filter conservation that often leads to the establishment of ecosystem reserves at conventionally large scales. At the intermediate or meso-scale it is feasible to integrate vernal pool conservation with other major land uses such as timber management and residential development.

REFERENCES Baber, M.J., Fleishman, E., Babbitt, K.J., and Tarr, T.L. (2004). The relationship between wetland hydroperiod and nestedness patterns in assemblages of larval amphibians and predatory macroinvertebrates. Oikos 107: 16–27. Barlocher, F., Mackay, R.J., Wiggins, G.B. (1977). Detritus processing in a temporary vernal pool in southern Ontario. Archiv fur Hydrobiologie 81: 269–295. Battle, J.M. and Golladay, S.W. (2001). Hydroperiod influence on breakdown of leaf litter in cypress-gum wetlands. American Midland Naturalist 146: 128–145. deMaynadier, P.G. and Hunter, M.L., Jr. (1997). The role of keystone ecosystems in landscapes. In Haney, A. and Boyce, M. (Ed.). Ecosystem Management. Yale University Press, New Haven, CT, pp. 68–76.

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De Meester, L., Gómez, A., Okamura, B., and Schwenk, K. (2002). The Monopolization Hypothesis and the dispersal–gene flow paradox in aquatic organisms. Acta Oecologica 23: 121–135. De Meester, L., Declerck, S., Stoks, R., Louette, G., Van De Meutter, F., De Bie, T., Michels, E. and Brendonck, L. (2005). Ponds and pools as model systems in conservation biology, ecology and evolutionary biology. Aquatic Conservation: Marine and Freshwater Ecosystems 15: 715–725. Groves, C. (2003). Drafting a Conservation Blueprint. Island Press, Washington, D.C. Hunter, M.L., Jr. (1990). Coping with ignorance: the coarse-filter strategy for maintaining biological diversity. In Kohm, K. (Ed.). Balancing on the Brink of Extinction. Island Press, Washington, D.C., pp. 266–281. Hunter, M.L., Jr. (2005). A mesofilter complement to coarse and fine filters. Conservation Biology 19: 1025–1029. Oertli, B., Auderset, J.D., Castella, E., Juge, R., Cambin, D., and Lachavanne, J.B. (2002). Does size matter? The relationship between pond area and biodiversity. Biological Conservation 104: 59–70. Power, M.E., Tilman, D., Estes, J.A., Menge, B.A., Bond, W.J., Mills, L.S., Daily, G., Castilla, J.C., Lubchenco, J., and Paine, R.T. (1996). Challenges in the quest for keystones. Bioscience 46: 609–620. Regester, K.J., Lips, K.R., and Whiles, M.R. (2006). Energy flow and subsidies associated with the complex life cycle of ambystomatid salamanders in ponds and adjacent forest in southern Illinois. Oecologia 147: 303–314. Vasconcelos, D. and Calhoun, A.J.K. (2004). Movement patterns of adult and juvenile wood frogs (Rana sylvatica) and spotted salamanders (Ambystoma maculatum) in three restored vernal pools. Journal of Herpetology 38: 551–561. Williams, D.D. (1997). Temporary ponds and their invertebrate communities. Aquatic Conservation: Marine and Freshwater Ecosystems 7: 105–117. Williams, P., Whitfield, M., Biggs, J., Bray, S., Fox, G., Nicolet, P., and Sear, D. (2003). Comparative biodiversity of rivers, streams, ditches and ponds in an agricultural landscape in Southern England. Biological Conservation 115: 329–341.

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Section I Physical Setting: Classification, Hydrology, and Identification

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Classification of Vernal Pools: Geomorphic Setting and Distribution Richard D. Rheinhardt and Garrett G. Hollands

CONTENTS Geologic History......................................................................................................12 Regional Variations in Surficial Geology................................................................13 Hydrogeomorphic Basis for Classifying Vernal Pools ...........................................14 Vernal Pool Classification by Hydrogeomorphic Setting .......................................18 Geomorphic Settings (Classes) ...................................................................20 Depressions ........................................................................................20 Slope...................................................................................................23 Flat......................................................................................................23 Riverine ..............................................................................................24 Anthropogenic ....................................................................................25 Conservation Implications .......................................................................................25 Summary ..................................................................................................................26 Acknowledgments....................................................................................................27 References................................................................................................................27

To conservationists, vernal pools are special wetland habitats that have unique biological characteristics as a result of hydrologic conditions. To the person wishing to develop their land, vernal pools may seem to be everywhere and occur in all shapes and sizes, from mud puddles to ponds. As vernal pools are increasingly being regulated and conserved, people want to know more about where vernal pools occur, if there are ways to predict where they are in the landscape, and whether a nearby development might adversely affect them. Although it is true that vernal pools vary widely in shape and size and occur broadly across the landscape, they do not occur everywhere. Rather, they occur in a repeatable pattern based on landscape geomorphology (defined as the shape, size, and topographic position of landforms derived from geologic evolution). For example, the geomorphology of a vernal pool influences its connection to surficial aquifers, which in turn affects both flooding depth and hydroperiod. Thus, a classification

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system based on geomorphology should provide answers to the questions posed above. This chapter provides a framework for classifying vernal pools in glaciated northeastern and Midwestern North America by geomorphic setting, which lends insight into their habitat and hydrologic functions. A critical component of developing a classification system is to identify the underlying environmental factors that are responsible for common patterns, such as differences in surficial geology, soil type, or disturbance history (Swanson et al. 1988). These differences can then be used to characterize and define the major structural attributes that influence functioning. We provide background on the geologic origins of vernal pools, how surficial geology and geomorphology control hydrological regime, and how repeatable patterns of surficial geology and geomorphology provide a framework for classifying vernal pools. Many of our statements on how pools function hydrologically and where they are likely to occur in each subregion are not based on specific vernal pool research, but follow from our knowledge of hydrological patterns in these settings. This framework provides a basis for a classification system that can be used to infer hydrological and habitat functioning and likely responses to human alterations to these functions. The final section examines how hydrogeomorphic information can be used to help conserve vernal pool habitat.

GEOLOGIC HISTORY Knowledge of the geologic history of a landscape is crucial in understanding how surficial geology influences the hydrologic regime of vernal pools and, in turn, their potential to support specialized pool-breeding fauna. In glaciated regions such as northeastern North America, surficial geology is primarily the product of geologic processes related to glaciation, deglaciation (complete retreat), and periglacial deformations (changes in landform near glaciers in response to extremely cold temperatures). The glacial processes of erosion and deposition created a distinct suite of landforms (Flint 1971) with which wetlands are associated (Jorden 1978; Koteff and Pessel 1981; Hollands 1987). Sediments deposited by glacial deposition are referred to as glacial drift. Drift is divided into two general types: till and stratified deposits (Flint 1971). Till is deposited under flowing glaciers and so is neither stratified nor sorted, leading to low permeability. Stratified drift is deposited by flowing melt water which sorts sediments and deposits it in layers as gravel, sand, and silt, which generally have moderate to high permeability. Vernal pools associated with till deposits generally have water balances driven by precipitation, whereas those associated with stratified drift are likely to have water balances driven by ground water. Changes to the landscape caused both by the advance and retreat of glaciers over the past 35,000 years and by recent geologic processes have formed a variety of hydrogeomorphic conditions that vernal pool specialists use as breeding habitat. Most of the natural landforms we see today are the products of the last glaciation (Benn and Evans 1998) known as the Late-Wisconsin glaciation (35,000–11,000 years BP). Following the complete retreat (deglaciation) of the Late-Wisconsin glacier, North America experienced approximately 2,000 years of periglacial climate,

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in which freezing and thawing of ice further modified the landscape (Pielou 1991). During the periglacial period, strong, cold winds blowing south off the retreating ice sheet transported and deposited a layer of fine sand and silt (loess) over the landscape (French 1996). This loess accumulated in low portions of the landscape, providing low permeability deposits that helped impede water flow and facilitated the formation of wetlands, including ephemerally flooded wetlands that provide potential vernal pool breeding habitat.

REGIONAL VARIATIONS IN SURFICIAL GEOLOGY The glaciated region of northeastern North America can be divided into three general surficial geologic/geomorphic subregions based on dominant bedrock type and mode of glaciation and deglaciation (Veregin 2005), which in turn affect the types of vernal pools that are likely to be encountered locally. One subregion encompasses the Canadian Shield, which includes most of Quebec, northern and western Ontario, Newfoundland, northern Wisconsin, northern Minnesota and northern Michigan (see Figure 1 in Preface). The Canadian Shield consists of Pre-Cambrian igneous and metamorphic rocks that have been tectonically stable since their formation more than 600 million years BP. It has been scoured repeatedly by a series of flowing ice sheets during the Pleistocene Epoch, creating little regional relief but complex local topography (Veregin 2005). Some northern areas of this geomorphic subregion still experience discontinuous permafrost (i.e., permanently frozen ground interspersed with unfrozen ground) and periglacial climatic conditions. Vernal pools in this subregion usually occur in local topographic depressions over granite outcrops and in blanket bogs. Scouring and differential erosion of the bedrock of the Canadian Shield by repeated glaciations created abundant, large and small bedrock depressions. The larger basins are occupied by lakes while some of the small basins contain vernal pools (personal observation). Another geomorphic subregion occurs south of the Canadian Shield in the eastern portion of the region. It includes southern Quebec, New England, northern New Jersey, and eastern and northern New York (see Figure 1 in Preface). This subregion consists predominantly of hard igneous and metamorphic Paleozoic rocks of the Appalachian Mountains and associated valleys. During deglaciation, irregular topography broke the retreating ice into many stagnant ice blocks. Zones of ice stagnation formed as the ice front retreated northward (Flint 1929; Koteff and Pessel 1981; Larson 1982). In central and eastern Maine, the ice front retreated across seawater into which low permeability glaciomarine silt and clay was deposited. Erosion of the hard igneous and metamorphic rocks of both the Canadian Shield and New England subregion created sandy till of low to moderate permeability and gravel outwash deposits of high permeability (Koteff and Pessel 1981). Melt-water streams deposited deltas of silt and gravel in numerous lakes formed by the damming action of moraines and ice during the retreat of melting glaciers. These deposits were subjected to approximately 2,000 years of periglacial climate in which little vegetation grew (Pielou 1991). During this time, cold winds flowing off the glacier deposited layers of wind blown fine sand and silt (loess) over the region’s landscape. Vernal pools are generally found in till and bedrock deposits at higher elevations on

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valley sides and in stratified, melt-water deposits found primarily in valley bottoms (e.g., kames, kame terraces, outwash plains, and deltas). The third general geomorphic subregion consists of the western area south of the Canadian Shield. It includes central and western New York, northern and western Pennsylvania, central and northern Ohio, central and northern Indiana, northern Illinois, southern and central Wisconsin, and southern Minnesota (Figure 2.1). In this subregion, the ice front retreated as a well-defined front, with occasional zones of stagnant ice, leaving behind many well-defined end moraines (Flint 1971). This subregion is primarily underlain by siltstone, shale, sandstone, and limestone, all soft sedimentary rocks formed in shallow seas during the Paleozoic Era. The relatively soft sedimentary rocks were easily eroded by the flowing glacier, creating a streamlined topography covered with dense, low permeability, clay-rich till. However, more permeable glacio fluvial deposits of sand and gravel were also deposited in valley bottoms. Other sand and gravel deposits were associated with deltas of pro-glacial lakes. Fine-grained lacustrine silt and clay deposits were formed in numerous lakes and in the basins of the ancestral Great Lakes (Flint 1971). In this subregion, vernal pools are primarily found associated with kettles in ground moraine or end moraines, or as shallow pools imbedded in large wetlands associated with low permeability lake bottom sediments (G. Hollands, personal observation).

HYDROGEOMORPHIC BASIS FOR CLASSIFYING VERNAL POOLS A geomorphological classification approach has not been developed for vernal pools. Past approaches have been based on fauna and flora in concert with substrate characteristics (Holland and Jain 1988; Bjork 1997; Barbour et al. 2003; Colburn 2004; Mitchell 2005; Skidds and Golet 2005). Although all these compositionally based classification systems may reflect long-term hydrologic characteristics, they are not particularly useful for explaining hydrologic flow paths or water budgets (Chapter 3, Leibowitz and Brooks, Figure 3.1). As such, these approaches cannot predict whether a proposed alteration might affect a pool’s hydrologic functioning or why a particular alteration has degraded it. In contrast, a geomorphic approach to classification recognizes vernal pools in the context of the landscape in which they occur and the hydrodynamics of their watersheds, rather than as isolated units (Leibowitz and Vining 2003; sensu Winter and LaBaugh 2003). By understanding the geomorphic context in which a vernal pool occurs, one should be able to predict not only the source and fate of water in a vernal pool, but how habitat functions of a pool might degrade in response to human alterations to the pool or to its watershed. In any classification system, it may be difficult to assign some natural systems to a predefined class, but most can be confidently assigned if the classification system is based on some recognizable and repeatable pattern (Thornberg 1965, 1969; Huggett 2002), for example, regional wetland types based on hydrogeomorphology and climate (Brinson 1993). The most robust classification systems also have explanatory power; that is, one can infer certain attributes about an ecosystem based on its class. For vernal pools, an explanatory classification system should be able to predict

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(a)

COARSE-GRAINED GLACIOFLUVIAL

(b)

FIGURE 2.1(A)–(B) (a) Idealized plan and cross-section of a precipitation-driven, depressional vernal pool with no inlet or outlet. The pool occurs in glacial till of low permeability over a fractured bedrock basement. (b) Idealized plan and cross-section of a groundwaterdriven, depressional vernal pool with a semi-permanent flooding regime and intermittent outlet, occurring on highly permeable, course-grained sand and gravel deposits.

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(c)

(d)

FIGURE 2.1(C)–(D) (c) Idealized plan and cross-section of a slope vernal pool on a thin layer of till of low permeability over a bedrock basement. Hydrologic regime is driven by shallow groundwater flow that occurs soon after precipitation events. (d) Idealized plan and cross-section of a slope vernal pool driven by groundwater discharge at the contact between permeable, fractured bedrock and glaciomarine silt and clay of low permeability.

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(e)

(f )

FIGURE 2.1(E)–(F) (e) Idealized plan and cross-section of riverine vernal pools (headwater complex) of an intermittent stream occurring in glacial till of low permeability over a bedrock basement. The stream stops flowing during the growing season, and so the pools are flooded seasonally. (f) Idealized plan and cross-section of a riverine floodplain vernal pool in a meander scroll of a perennially flowing river. The pool occurs in the 1-yr. floodplain on highly permeable, alluvial sand. Its hydrologic regime is driven by seasonal overbank flooding with some input from groundwater.

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parameters that explain hydrologic functioning, because appropriate hydroperiod is critical to maintaining vernal pool breeding habitat. The hydrodynamics of unaltered vernal pools and associated wetlands are partially determined by geomorphic position and surficial geology. Surficial geology determines the hydraulic conductivity (the ease with which water can move through pore spaces or fractures) of the near surface substrate, which in turn determines the relative capacity of the sediments to provide a conduit for groundwater flow. Thus, hydrogeomorphic position determines the potential sources and fate of water that can flow to a vernal pool because geomorphic position ultimately controls what is possible from a hydrologic perspective (Chapter 3, Leibowitz and Brooks). Due to the overwhelming importance of geomorphology to the functioning of vernal pools, hydrogeomorphic status should be the top level of any hierarchical classification of vernal pools. Geomorphology has been successfully used to classify wetlands to partition functional attributes (Noviski 1979; Brinson 1993; Cole et al. 1997; Rheinhardt et al. 1999). It has been used as a basis for developing a proposed classification system for wetlands globally (Semeniuk and Semeniuk 1997) and as part of a hydrogeomorphic (HGM) approach for developing wetland functional assessment procedures in the U.S. (Brinson et al. 1995; Smith et al. 1995; Brinson and Rheinhardt 1996; also see (http://el.erdc.usace.army.mil/wetlands/hgmhp.html). The HGM classification divides wetlands into seven basic geomorphic types: depressional, riverine, slope, flat (organic soil flat and mineral soil), and fringe (lacustrine and estuarine), based on landscape geomorphic position (Brinson et al. 1995; Smith et al. 1995). In the subject region, vernal pools occur in all of these geomorphic landscape positions. However, they are rarely associated with lakes (lacustrine fringe) and are not associated with salt or brackish marshes (estuarine fringe).

VERNAL POOL CLASSIFICATION BY HYDROGEOMORPHIC SETTING At a local scale, all vernal pools are depressions (basins that can hold water). They occur within all geomorphic settings, except those with marine or estuarine influences (Table 2.1), and vary widely in surficial geology. Vernal pools occur as small pools at the bottom of larger depressions, on slopes, in flats, within headwater riparian reaches, and on floodplains of mid- to higher order creeks and rivers. Some vernal pools are surrounded by uplands (the “classic” isolated vernal pool: sensu Leibowitz and Nadeau 2003), others are parts of larger wetland complexes. Classic vernal pools have received the most scientific attention (Colburn 2004). Although local and regional geologic conditions are extremely important in determining how groundwater and surface water interact at a specific location (Winter 1999; Whigham and Jordan 2003; Brooks 2004), relatively few studies have focused on vernal pools that are part of a larger wetland complex (but see Egan and Paton 2004). Vernal pools vary widely in size, whether they are surrounded entirely by uplands or are a part of a larger wetland complex. Pools affiliated with larger wetlands with high water tables (e.g., riverine floodplains) are often associated with small-scale

a

Wetland complex Upland or wetland complex

Groundwater dominated Variable

complex complex complex complex complex complex

Wetland complex Upland or wetland comlex

Uplanda Upland or wetland Upland or wetland Upland or wetland Upland or wetland Upland or wetland Upland or wetland Wetland complex

Surrounding Landscape

Bedrock Low permeability High permeability Bedrock Low permeability High permeability Low permeability Headwater Floodplain Overbank flow dominated Precipitation dominated

Subclasses Based on Surficial Geologic Conditions

Vernal pools surrounded by uplands fit the “classic” vernal pool profile.

Anthropogenic

Flat Riverine

Slope

Depression

Geomorphic Setting

Fluvial sand and gravel Fine silt and clay over sand and gravel Fluvial sand and gravel Variable

Overbank flow Precipitation Groundwater Variable

Granite Loess Glaciofluvial sand and gravel Granite Glacio-marine silt and clay Glaciofluvial sand and gravel Glacio-lacustrine silt and clay Glacial till, bedrock

Examples of Surficial Material

Precipitation Precipitation Groundwater Precipitation Precipitation Groundwater Precipitation Groundwater

Principle Source of Water

None None

2.1e 2.1e

None None 2.1a None 2.1b 2.1c None 2.1d

Reference to Figures

TABLE 2.1 Types of Vernal Pools in Northeastern North America, Classified by Geomorphic Setting and Surficial Geology

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disturbances, such as small basins created by root wad tip-ups, which occurs when trees are blown over. However, larger pools also occur within wetland complexes. Examples would be an abandoned oxbow within a wetland portion of a floodplain or a series of connected basins in a larger wetland shallow basin or flat. The following section provides a general overview of the vernal pool geomorphic classes that occur in northeastern North America and their associated hydrological characteristics. Leibowitz and Brooks (Chapter 3) provide a review of vernal pool hydrology, but they cover only a subset of the types known to occur in northeastern North America because there is limited information on the hydrology of diverse pool hydrogeologic settings. In fact, much of the information provided below on hydrodynamics is based on what we generally know about the hydrodynamics of the geomorphic settings in which pools occur and is not derived from specific studies of vernal pools in those settings.

GEOMORPHIC SETTINGS (CLASSES) Identifying a vernal pool according to its geomorphic class requires basic information on its topographic position and surficial geology. This information can be obtained from topographic maps, surficial geologic maps (if available), and soil maps. In most cases, U.S. Geological Survey (USGS) topographic maps are adequate for determining geomorphic position. State geologic maps (if available) and soil surveys are often adequate for determining surficial geology. One could also use these maps to locate and inventory potential vernal pool habitat on a regional scale to improve landscape-level management of vernal pool species (Grant 2005). We recognize five major geomorphic settings in which vernal pools occur: depressions, slopes, flats, riverine, and anthropogenic. All but anthropogenic include several subclasses based on surficial geology or source of water. Depressions Depressions are concave landforms, which include basins, hollows, and similar low places in a landscape surrounded by higher elevation. Although technically all vernal pools occur as depressions, this class encompasses vernal pools associated with larger scale depressional landforms, at a scale larger than any individual vernal pool. Vernal pools in depressional landforms often occur as a wetland in the bottom of the depressional landform and may or may not be surrounded by uplands. In vernal pools surrounded by uplands, wetlands are only associated with the vernal pool itself while vernal pools in wetland complexes occur as scattered pools throughout a more extensive wetland. Vernal pools in depressional landforms are associated with a number of surficial geologic settings: bedrock basins, till deposits of low permeability, and till deposits of high permeability. These settings can be used to subdivide pools into functionally distinct subclasses, each with distinctly different hydrodynamics. Outcrops of igneous and metamorphic rocks occur in scattered localities throughout southern Canada, the Maritime Provinces, New England, eastern and northern New York, New Jersey, northern Michigan, Northern Wisconsin and Minnesota. In all these locations,

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bedrock basins were formed by glacial erosion (Flint 1971). Because bedrock is generally impermeable to water infiltration, the source of water to most bedrock basins is precipitation and surface runoff, whereas loss is to evapotranspiration (ET). However, sand or permeable till deposits overlying the bedrock usually provide a conduit for groundwater to seep into the pool. In the Canadian Shield region, glaciers eroded previously existing soil and scraped the land surface to bedrock. Shallow depressions were left in the bedrock. Due to perpetually cold, wet, or saturated conditions, wetland plants only partially decompose, thus forming thick layers of peat that accumulated slowly over time to eventually produce extensive bogs in which the highest elevation is in the middle of the wetland, e.g., domed bogs (Damman and French 1987). In some bogs, groundwater is discharged at their edges from adjacent uplands. Vernal pools in bogs commonly consist of linear pools associated with a moat that occurs at the contact between the bog’s peat soils and the adjacent upland’s mineral soil, so their soils may be either organic or mineral. Depressional vernal pools associated with bogs are generally very low in nutrients and have low pH, but some may be minerotrophic due to the input of mineral-rich groundwater. Pools associated with bogs typically have a dependable source of water from year to year and so are less influenced by drought than pools that rely on precipitation. In more central portions of the region, vernal pools commonly occur on ground moraines (till layers) deposited by flowing glaciers, particularly in the Midwestern states and southern Ontario. The tills of New York, southern Ontario, and the Midwestern states contain a high clay content of low hydraulic conductivity (Flint 1971). Vernal pools underlain with this relatively impermeable substrate are usually precipitation driven. Fine substrate impedes the infiltration of water and so water from precipitation and overland flow to the pool remains mounded above the local water table until it evaporates or is transpired by plants (Figure 2.1a). Therefore, the hydrologic regime of depressional vernal pools with impermeable substrate is strongly influenced by short-term fluctuations in seasonal precipitation. This means that during years of low rainfall, hydroperiod (length of time flooded) may be too short for successful reproduction of vernal pool species in many depressions. Conversely, many depressions that are normally incapable of providing vernal pool habitat may do so during unusually wet years (Chapter 3, Leibowitz and Brooks). In contrast to the relatively impermeable tills of the southwestern portion of the study area, depressional basins in New England, southern Quebec, and the Maritime Provinces commonly occur on moderately permeable till that is typically more sandy and less dense than tills in the Midwest (Hollands 1987). Vernal pools in these depressions are usually maintained by groundwater and so are typically in contact with the local water table (Figure 2.1b). As a result, the hydrologic regime of vernal pools with permeable substrate tend to hold water for longer periods than pools that rely on local precipitation. They are also most likely to be influenced by longer-term cycles of regional drought. Depressional vernal pools also commonly occur in kettle depressions (Figure 2.1b and Figure 2.2), which are basins created by ablation (melting) of buried ice in drift (Flint 1971). Kettles may be associated with till deposits of both high and low permeability (Hollands 1989). Kettle ponds and forested wetlands occur in

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FIGURE 2.2 Vernal pool in permeable glacial till on Cape Cod, Massachusetts. This kettle depression is located in the Buzzard’s Bay glaciotectonic end moraine (http://pubs.usgs. gov/gip/capecod/glacial.html).

highly permeable glacial till in former outwash plains in southeastern Massachusetts (Koteff and Pessel 1981) and in parts of Wisconsin and Minnesota (Novitski 1979). The extensive kettle forested wetlands in southeastern Massachusetts, dominated by red maple (Acer rubrum) or Atlantic white cedar (Chamaecyparis thyoides), are scattered throughout low areas in the regional landscape. The hydrology of these forested wetlands is probably influenced by a combination of regional water table fluctuations, groundwater discharge from surrounding areas of higher elevation, and by precipitation in the larger forested wetlands. One or more of these sources of water may predominate at any one location within a given wetland. However, none of the kettle wetlands remains flooded long enough to support fish. Microtopography within the red maple forested wetlands retain water long enough in the lowest places (basins) to provide potential vernal pool breeding habitat (authors’ personal observation). Kettle depressions probably provide the most dependable source of water for maintaining breeding habitat. Depressional settings are relatively low energy, sedimentary environments. As discussed above, vernal pools in depressional settings that rely on direct precipitation (bedrock basins and low permeable till) are likely to be particularly sensitive to alteration by anthropogenic activities such as land clearing and conversion to impervious surfaces. Vernal pools on more permeable substrates are less likely to be detrimentally affected by land-use changes in the contributing watershed, particularly

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if they are fed by regional groundwater. However, many groundwater depressions (e.g., kettle depressions) have a dependable source of water and may have been converted to commercial cranberry production. Abandoned cranberry bogs may be the easiest systems in which to restore hydrology and recreate vernal pool habitat. Slope Slopes occur on hillsides where down-slope, unidirectional flows dominate hydrodynamics. Vernal pools on slopes are less common than vernal pools occurring in other geomorphic settings because hill slopes are generally not conducive to the formation of basins. However, vernal pools do occur in hilly and mountainous areas throughout the region. Like vernal pools in depressional landscapes, vernal pools on slopes are either surrounded by uplands or are parts of larger wetland complexes. They commonly occur above headwater stream channels into which they may discharge or at the toe of a slope at the edge of large river floodplains, as well as far from streams on hillsides. Vernal pools associated with bedrock outcrops are extremely susceptible to vagaries of recent climatic conditions. Only the deepest pools would provide breeding habitat and then probably do so only in extremely wet years. On slopes underlain by till or low permeability deposits, water moves down slope to vernal pools as shallow groundwater flow (interflow) and surface runoff (Figure 2.1c). This type of vernal pool reacts quickly to precipitation events and snowmelt and so responds to short-term fluctuations in climate. This pool type is highly susceptible to changes in up-gradient land use, particularly to urbanization. If fractured bedrock supplies water from a more regional groundwater source, then vernal pools on slopes of low permeability may be capable of holding water longer due to their more reliable source of water (Figure 2.1d). On slopes with more permeable surficial substrate, groundwater discharge to vernal pools is via springs and seeps (Hollands and Mulica 1978), for example, slope wetlands (fens) of the Catskill Mountains and Anticosti Island, Quebec. Flat Flats are broad expanses of flat terrain, generally in low relief landscapes, such as the lake plains of the ancestral Great Lakes, the central Wisconsin Sand Plain, and numerous glacially formed lake beds, such as glacial Lake Hitchcock in the Connecticut Valley of New England. Flats also occur in Canada as extensive peatlands, in northern New England (usually dominated by spruce and fir), and in southern New England (as extensive red maple forested wetlands). Vernal pools of flats are commonly underlain by low permeability glacio-lacustrine silt and clay deposits which would allow some of them to retain water even after the local water table drops. The water table of vernal pools in flats fluctuate in response to precipitation and evapotranspiration (ET). Vernal pools will pond when water tables rise in the fall, winter, and early spring when ET is minimal. Snow melt in spring may contribute

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significantly to water storage, but pool water level generally drops quickly after leafout when ET begins in earnest. Organisms that succeed in precipitation-driven pools on flats are most likely those that have relatively short larval stages. Vernal pools on flats can be divided into two general types: those that primarily contain mineral soils and those primarily containing organic soils (histosols). In New England and the Canadian provinces, precipitation-driven peatlands (bogs) are very common and tend to support a high density of vernal pools. In contrast, vernal pools on flats in the Central subregion are rare because most have been drained and converted to agriculture. For example, a vast flat region in northwestern Ohio the size of Connecticut, known as the Black Swamp, was almost entirely drained by the early 1900s and converted to agriculture (Verduin 1969). The Black Swamp was undoubtedly full of vernal pools prior to its conversion. A flat is a low-energy environment where little erosion and sedimentation occurs and so would tend to persist for a long time if not altered. However, the rich soils of most flats are so conducive to agricultural production that most were cleared and drained long ago, thus extirpating most of the vernal pools within them (see Bauder and McMillan 1998). However, mineral soil vernal pools in flats are also probably some of the most easily restorable type (if not filled) simply by preventing drainage. In contrast, when vernal pools on organic soils are drained, their soils oxidize (burn off). This makes them extremely difficult to restore, even after artificial drainage is removed, because organic soils take hundreds to thousands of years to form. Riverine Vernal pools associated with riverine geomorphic settings occur in headwater reaches and in valleys on active floodplains of higher order streams and rivers. Headwater settings differ from slopes in that water flows through headwater systems in a defined channel, even if the channel is not continuous. Vernal pools in headwater reaches are associated with intermittent to first-order perennial streams. Some occur in small topographic basins connected in a step-like series with other pools by stream channels (Figure 2.1e). Most of these basins are probably formed by tree tip-ups, debris dams, and beaver dams, but some may have formed in response to years of frost heaving. Where channelized flow begins, a wet slope becomes an intermittent headwater stream, but this transition is often difficult to detect. From a functional perspective, it really does not matter how a vernal pool in a transition zone is classified, because in both cases, hydrologic functions are identical, i.e., the pool is likely being fed by groundwater discharge either directly or from intermittent stream flow fed by groundwater. Riverine floodplains differ from headwater reaches in that floodplains are highly complex sedimentary environments containing a variety of energy regimes and sources of water (Naiman and Décamps 1997). Most active floodplains in glaciated northeastern North America consist of highly conductive fluvial sand and gravel deposits that connect the local water table and the river by hyporheic flow (subsurface flow through gravels) during low-flow conditions (Stanford and Ward 1993) and by overbank flow during flooding events. Floodplains further from channels obtain

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water from precipitation or from groundwater discharge if they lie along the toe of slope at the edge of the floodplain. Vernal pools nearest the channel may derive their water largely from overbank flooding (Figure 2.1f). They often occur in abandoned channels, scour channels, or high-flow channels, and are usually a component of floodplain wetlands. However, these pools are the least geologically stable in that they eventually fill with sediments or get reconnected to channels following floods. They are also somewhat less likely to harbor vernal pool species because late-season floods may bring fish to the pools or wash egg masses downstream. However, they could potentially provide important vernal pool breeding habitat during prolonged periods of drought. Vernal pools located further from the channel receive overbank flow less frequently, especially if located on a higher elevation terrace (Figure 2.1f). In many cases, this part of the floodplain is often not considered to be jurisdictional wetlands. The rare flooding events that bring water to such pools also deposit fine sediments (silt and clay) in them. These fine sediments create a barrier to the infiltration of water, i.e., water in pools are perched above the local water table. Although rare flooding events may bring water to such pools, these pools usually receive most of their water from precipitation. Vernal pools on floodplains might fill over decades because sediments are occasionally deposited in them during flooding events. (If they are flooded infrequently, they may accumulate sediment.) However, the formation of new vernal pools is an ongoing process on floodplains: small depressions form where root wads are exposed when trees topple, and channels are periodically abandoned or reconnected. Research on floodplain pool hydroperiod and development is needed to understand their functions and potentially unique role in supporting wetland-dependent species associated with rivers. Anthropogenic Vernal pools created by human activities occur in all geomorphic settings. They occur where humans have inadvertently or purposely created areas that pond for long enough to allow vernal pool species to reproduce. They are sometimes purposely created as compensatory wetland mitigation sites but incidentally occur in abandoned borrow pits, quarries, drainage ditches, and behind blocked culverts. Some created pools may be extremely productive (see Chapter 12). Other created pools may be detrimental to local pool-breeding amphibian populations. For example, they sometimes occur in skidder ruts created when timber is harvested, but such ruts usually dry out quickly, except in unusually wet years (DiMauro and Hunter 2002). For this reason, skid trails are often responsible for high mortality and wasted gametic production (see Chapter 13).

CONSERVATION IMPLICATIONS Understanding how geomorphic setting and surficial geology interact to affect hydrodynamics in a given vernal pool should enable resource managers to predict the pool’s likely persistence of surface water, or hydroperiod, which is key to supporting

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the diversity of vernal pool biota. This information could also be used to infer the types of land use practices that would be especially detrimental to a pool’s habitat functions and to determine how to prioritize protection and restoration efforts at a regional scale. For example, one could not realistically control the water source of vernal pools in precipitation-driven flats, but one might be able to manage the upgradient landscape of vernal pools on slopes that receive water from shallow groundwater flow and surface runoff. Regional and landscape approaches to managing and restoring vernal pool resources are essential for the long-term viability of vernal pool species (Gibbs 1993, Semlitsch 2002, Calhoun et al. 2003, Baldwin et al. 2006), especially since migration corridors among vernal pools and other wetland types are required to facilitate gene flow in amphibian populations (Chapter 3, Leibowitz and Brooks; Chapter 8, Gibbs and Reed; Chapter 14, Baldwin et al.). A systematic survey of potential vernal pool habitat, by geomorphic setting and surficial geology, could be used to prioritize restoration on a regional scale. Locating such sites could be facilitated by determining the types of alterations that would be expected for the most common types of vernal pools in a region. For example, in southeastern Massachusetts many depressional basins were converted to cranberry bogs over the past century, but some have been recently abandoned. In many cases, temporary flooding regimes could be restored to abandoned cranberry bogs by plugging drainage ditches, thus providing breeding habitat for vernal pool biota. Likewise, vernal pool hydrology could be restored by eliminating artificial drainage in mineral soil basins located in areas of flat topography, such as the lake plains of the ancestral Great Lakes (Chapter 12, Windmiller and Calhoun). In all cases, relatively unaltered vernal pools could serve as templates for restoration if consideration is given to the geomorphic variation that exists in the landscape. For long-term conservation of vernal pool species, it is desirable to protect pools with a variety of hydroperiods (Semlitsch 2002). Conserving pools in a range of hydrogeomorphic settings on a landscape would be more tractable for managers than trying to predict a range of hydroperiods. This approach would be particularly advantageous in areas where many vernal pools are perched on silt and clay, as the hydroperiod of such pools rely on the vagaries of local precipitation.

SUMMARY Potential vernal pool breeding habitats occur in a variety of landforms and geologic settings in northeastern North America. Hydrological and habitat functions of these pools are best understood by recognizing how geomorphic setting and surficial geology combine to affect hydrological regime. We provided a geomorphically based classification approach that recognizes these functional differences. By classifying potential vernal pool breeding habitat by geomorphology, one can gain an understanding of how a vernal pool would be expected to function, what factors might disrupt its functions, and how to best manage and restore them. This classification approach can be used a framework for planning conservation and restoration on a local or regional scale. Protecting vernal pools belonging to a wide range of

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hydrogeomorphic settings within a region or local area will better insure long-term conservation of vernal pool species.

ACKNOWLEDGMENTS We thank Phillip deMaynadier, Frank Golet, Andrew Cole, Mark Brinson and, especially, Aram Calhoun for critical reviews of the manuscript. We also thank Bob Brooks, Scott Leibowitz, Aram Calhoun, and Phillip deMaynadier for lively discussions on classification while tromping around vernal pools in Maine.

REFERENCES Baldwin, R., Calhoun, A.J.K., and deMaynadier, P.G. (2006). Conservation planning for amphibian species with complex habitat requirements: a case study using movements and habitat selection of the wood frog (Rana sylvatica). Journal of Herpetology 40: 443–454. Barbour, M., Solomeshch, A., Witham, C., Holland, R., Macdonald, R., Cilliers, S., Molina, J.A., Buck, J., and Hillman, J. (2003). Vernal pool vegetation of California: variation within pools. Madrono 50: 129–146. Bauder, E.T. and McMillan, S. (1998). Current distribution and historical extent of vernal pools in southern California and northern Baja California, Mexico. In Witham, C.W., Bauder, E.T., Belk, D., Ferren, W.R., Jr., and Ornduff, R. (Eds.). Ecology, Conservation, and Management of Vernal Pool Ecosystems — Proceedings from a 1996 Conference. California Native Plant Society, Sacramento, CA, pp. 56–70. Benn, D.I. and Evans, D.J.A. (1998). Glaciers and Glaciation. Oxford University Press, Oxford. Bjork, C.R. (1997). Vernal pools of the Columbia Plateau of eastern Washington. Report to the Washington Field Office of The Nature Conservancy. Brinson, M. (1993). A hydrogeomorphic classification of wetlands. Wetland Research Program Technical Report, U.S. Army Corps of Engineers, Waterways Experiment Station, Vicksburg, MS. WRP-DE-4. Brinson, M.M. and Rheinhardt, R.D. (1996). The role of reference wetlands in functional assessment and mitigation. Ecological Applications 6: 69–76. Brinson, M.M., Hauer, F.R., Lee, L.C., Nutter, W.L., Rheinhardt, R.D., Smith, R.D., Whigham, D. (1995). A guidebook for application of hydrogeomorphic assessments to riverine wetlands. U.S. Army Corps of Engineers Waterways Experiment Station, Wetlands Research Program Technical Report, Vicksburg, MS. WRP-DE-11 (http://el.erdc. usace.army.mil/wetlands/guidebooks.html). Brooks, R.T. (2004). Weather-related effects on woodland vernal pool hydrology and hydroperiod. Wetlands 24: 104–114. Calhoun, A., Walls, T., Stockwell, S., McCollough, M. (2003). Evaluating vernal pools as a basis for conservation strategies. Wetlands 23: 70–81. Colburn, E.A. (2004). Vernal Pools: Natural History and Conservation. McDonald and Woodward, Granville, OH. Cole, C.A., Brooks, R.P., Wardrop, D.H. (1997). Wetland hydrology as a function of hydrogeomorphic (HGM) subclass. Wetlands 17: 456–467.

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Damman, A.W.H. and French, T.W. (1987). The Ecology of Peat Bogs of the Glaciated Northeastern United States. U.S. Fish and Wildlife Service, Office of Biological Services, Washington, D.C. Report 85 (7.16). DiMauro, D., Hunter, M.I., Jr. (2002). Reproduction of amphibians in natural and anthropogenic temporary pools in managed forests. Forest Science 48: 397–406. Egan, R.S. and Paton, P.W.C. (2004). Within-pond parameters affecting oviposition by wood frogs and spotted salamanders. Wetlands 24: 1–13. Flint, R.F. (1929). The stagnation and dissipation of the last ice sheet. Geographical Review 19: 256–289. Flint, R.F. (1971). Glacial and Quaternary Geology. Wiley and Sons, New York. French, H.M. (1996). The Periglacial Environment, Addison Wesley Longman, Harlow, New York. Gibbs, J.P. (1993). Importance of small wetlands for the persistence of local populations of wetland animals. Wetlands 13: 25–31. Grant, E.H. (2005). Correlates of vernal pool occurrence in the Massachusetts, USA landscape. Wetlands 25: 480–487. Holland, R.F., and Jain, S. (1988). Vernal pools. In Barbour, M.E. and Major, J. (Eds.) Terrestrial Vegetation of California. California Native Plant Society, Sacramento, CA. Special Publication Number 9. pp. 515–533. Hollands, G.G. (1989). Regional Analysis of the creation and restoration of kettle and pothole wetlands. In Kusler, J.A. and Kentula. M.E. (Eds.). Wetland Creation and Restoration: The Status of the Science. Vol. II. US EPA Environmental Lab, Corvallis, OR. USEPA/300/3-89/038. pp. 287–304. Hollands, G.G. (1987). Hydrogeologic classification of wetlands in glaciated regions. National Wetlands Newsletter 9: 6–9. Hollands, G.G. and Mulica, W.S. (1978). Application of the morphological sequence method of mapping surficial geologic deposits to water resource and wetland investigations in eastern Massachusetts. Geological Society of America Abstracts with Programs 10: 470. Huggett, R. (2002). Fundamentals of Geomorphology. MIT Press, Cambridge, MA. Jorden, R. (1978). Glacial Geology and Wetland Occurrence on the Tug Hill Plateau, New York. Ph.D. dissertation, Department of Geology, Syracuse University, Syracuse, New York. Koteff, C. and Pessel, F. (1981). Systematic ice retreat in New England. U.S. Geological Survey, Washington, D.C. Professional Paper 1179. Larson, G.H., (1982). Nonsynchronous retreat of ice lobes from southeastern Massachusetts. In Larson, G.H. and Stone, B.D. (Eds.). Late Wisconsinan Glaciation of New England. Kendall/Hunt Publishing, Dubuque, IA, pp. 101–114. Leibowitz, S.G. and Vining, K.C. (2003). Temporal connectivity in a prairie pothole complex. Wetlands 23: 13–15. Leibowitz, S.G. and Nadeau, T.L. (2003). Isolated wetlands: state-of-the-science and future directions. Wetlands 23: 663–684. Mitchell, J.C. (2005). Using plants as indicators of hydroperiod class and amphibian suitability in Rhode Island seasonal ponds. Master’s thesis, University of Rhode Island, Kingston, RI. Naiman, R.J. and Décamps, H. (1997). The Ecology of interfaces: riparian zones. Annual Review of Ecology and Systematics 28: 621–658.

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Novitski, R.P. (1979). Hydrologic characteristics of Wisconsin’s wetlands and their influence on floods, stream flow, and sediment. In Greeson, P.E., Clark, J.R., and Clark, J.E. (Eds.), Wetland Functions and Values: The State of Our Understanding. American Water Resources Association, Minneapolis, MN, pp. 337–388. Pielou, E.C. (1991). After the Ice Age: The Return of Life to Glaciated North America. University of Chicago Press, Chicago, IL. Rheinhardt, R., Rheinhardt, M., Brinson, M., and Faser, K. (1999). Application of reference data for assessing and restoring headwater ecosystems. Restoration Ecology 7: 241–251. Semeniuk, V. and Semeniuk, C.A. (1997). A geomorphic approach to global classification for natural wetlands and rationalization of the system used by the Ramsar Convention — a discussion. Wetlands Ecology and Management 5: 145–158. Semlitsch, R.D. (2002). Critical elements for biologically-based recovery plans for aquaticbreeding amphibians. Conservation Biology 16: 619–629. Skidds, D.E. and Golet, F.C. (2005). Estimating hydroperiod suitability for breeding amphibians in southern Rhode Island seasonal forest ponds. Wetlands Ecology and Management 13: 349–366. Smith, D., Ammann, A., Bartoldus, C., and Brinson, M. (1995). An approach for assessing wetland functions using hydrogeomorphic classification, reference wetlands, and functional indices. U.S. Army Corps of Engineers Waterways Experiment Station. Wetlands Research Program Technical Report WRP-DE-9. Vicksburg, MS. Stanford, J.A. and Ward, J.V. (1993). An ecosystem perspective of alluvial rivers: connectivity and the hyporheic corridor. Journal of the North American Benthological Society 12: 48–60. Swanson, F.J., Kratz, T.K., Caine, N., and Woodmansee, R.G. (1988). Landform effects on ecosystem patterns and processes. BioScience 38: 92–98. Thornberg, W.D. (1965). Regional Geomorphology of the United States. John Wiley and Sons, New York. Thornberg, W.D. (1969). Principles of Geomorphology. John Wiley and Sons, New York. Verduin, J. (1969). Man’s influence on Lake Erie. The Ohio Journal of Science 69: 65–70. Veregin, H. (Ed.). (2005). Goode’s Atlas of Physical Geography. 21st ed. Rand McNally, Hoboken, NJ. Whigham, D.F. and Jordan, T.E. (2003). Isolated wetlands and water quality. Wetlands 23: 541–549. Winter, T.C. (1999). Relation of streams, lakes, and wetlands to groundwater flow systems. Hydrogeology Journal 7: 28–45. Winter, T.C. and LaBaugh, J.W. (2003). Hydrologic considerations in defining isolated wetlands. Wetlands 23: 532–540.

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Hydrology and Landscape Connectivity of Vernal Pools Scott G. Leibowitz and Robert T. Brooks

CONTENTS Definitions................................................................................................................32 Vernal Pool Hydrology............................................................................................33 Hydrologic Budget ......................................................................................33 Precipitation .......................................................................................33 Groundwater.......................................................................................33 Surface Water .....................................................................................35 Evapotranspiration..............................................................................36 Basin and Catchment Morphology..............................................................37 Hydrologic Dynamics..................................................................................38 Hydrologic Connectivity .............................................................................39 Population Dynamics and Landscape Connectivity................................................42 Metapopulation Theory ...............................................................................42 Connectivity and Dispersal..........................................................................44 Wetland–Terrestrial Connectivity ................................................................46 Conservation Implications .......................................................................................47 Hydrologic Impacts .....................................................................................47 Timber Harvesting..............................................................................47 Land Development .............................................................................48 Climate Change..................................................................................49 Loss of Landscape Connectivity .................................................................49 Summary ..................................................................................................................50 Acknowledgments....................................................................................................50 References................................................................................................................51

Hydrology is fundamental to wetland establishment and maintenance of wetland processes (Cole et al. 2002). Hydrology has been shown to affect, if not control, 31

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many aspects of wetland ecology, including litter decomposition and the accumulation of organic matter and sediment (Bärlocher et al. 1978), the composition and productivity of pool fauna (Paton and Couch 2002), and amphibian diversity (Burne and Griffin 2005). Vernal pools are a type of wetland that normally experiences drawdowns and dry periods. Tiner (2003) notes that although alternating wet and dry periods occur in most wetlands, vernal pools experience extreme fluctuations in moisture conditions. This hydrologic variability, both within- and between-year, is a primary factor influencing species composition and productivity (Paton and Couch 2002). Vernal pool organisms have special life history strategies for completing their life cycle under fluctuating wet and dry conditions (Chapter 6, Colburn et al., Colburn 2004). Despite these strategies, a pool species can go locally extinct if hydrologic conditions are sufficiently harsh. In spite of this, the biotic diversity of vernal pools can be maintained over time if local extinctions are offset by recolonizations from surrounding sites. This can occur through passive or active dispersal of organisms between pools, either over the ground or through the air. Recolonization may also occur, to a more limited extent, through surface-water connections. Landscape connectivity between vernal pools can be a major factor that influences recolonization of unoccupied pools. This chapter examines the hydrology and landscape connectivity of vernal pools of glaciated northeastern North America. We begin by defining vernal pools and addressing their relationship to isolated wetlands. We then review the hydrology of northeastern pools, and population dynamics and landscape connectivity. The chapter concludes with a discussion of conservation implications.

DEFINITIONS Northeastern vernal pools are temporary to semipermanent bodies of water occurring in shallow depressions that typically fill during the spring or fall and may dry during the summer or in drought years. These systems are bounded on the drier end by ephemeral pools that do not normally contain standing water, and on the wetter end by semipermanent ponds that only rarely dry (see Preface, Calhoun and deMaynadier). This book focuses on vernal pools associated with forests in the glaciated northeast of North America. Distinguishing features of these pools include fluctuating hydrologic conditions, presence of seasonally standing water, and occurrence within the glaciated forest biome (see Figure 1, Preface). Vernal pools often occur as depressional wetlands surrounded by uplands. These pools conform to Tiner’s (2003: 495) definition of a geographically isolated wetland: “wetlands that are completely surrounded by upland at the local scale.” However, vernal pools are often embedded within larger wetlands, and they can also occur in floodplains (Preface, Calhoun and deMaynadier, and Chapter 2, Rheinhardt and Hollands). For example, Colburn (2004) reports that 7% of 48 vernal pools in the glaciated northeast were found in flood plain settings. Although they are often included as a type of isolated wetland (Tiner 2003), northeastern vernal pools do not have geographic isolation as a distinguishing feature.

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VERNAL POOL HYDROLOGY The hydrology of vernal pools is determined by patterns in precipitation and temperature, connections to ground- and surface-water resources, losses from evapotranspiration, and the physical and biotic features (including plant community composition and structure) of pool basins and catchments. Factors related to weather are external to the pools and vary with time; physical site characteristics are intrinsic to each pool, are essentially fixed, and vary spatially among pools. The hydrology of vernal pools is characterized by both hydroregime, which is the temporal pattern of inundation, drying, and water-level change, and hydroperiod, or the duration of inundation (a component of hydroregime). The physical attributes of pools determine the general length of pool hydroperiod, whereas annual patterns in precipitation and temperature-driven evapotranspiration determine the year-toyear variation in hydroregime and hydroperiod. In the following, we discuss the hydrologic budget of vernal pools, some of the physical characteristics of pools and their basins that affect pool hydrology, and their hydrologic dynamics and connectivity. As there are few published studies on the hydrology of northeastern vernal pools, we also draw on information from other ephemeral, ponded wetland systems.

HYDROLOGIC BUDGET The hydrology of vernal pools can be characterized by a simplified climate–water balance equation where the change in the amount of water in a pool is equal to the sum of inputs from precipitation, groundwater, and surface water, minus loss from evapotranspiration (Lide et al. 1995; Figure 3.1); note that groundwater or surface water inputs can be negative, representing net losses. Studies have shown that wetlands in different hydrogeologic and climatic settings vary considerably in the influence of these factors on the change in storage (Winter et al. 2001). Precipitation Precipitation is, almost by definition, a major source of water input to many types of wetlands such as vernal pools. Precipitation can enter a vernal pool directly at the pool surface or indirectly as surface runoff from the adjacent catchment during a rainfall event. In a 10-year study of geographically isolated pools in central Massachusetts, Brooks (2004) showed that amounts of weekly precipitation accounted for more than half the variation in the change in weekly pool depths. The importance of precipitation as a major water source has also been reported for some California vernal pools (Zedler 1987; Pyke 2004), Carolina bays (Lide et al. 1995), cypress pond–pine flatwood ecosystems (Mansell et al. 2000), Mississippi forest pools (Bonner et al. 1997), and prairie potholes (Hayashi et al. 1998). Groundwater Groundwater–surface water interactions occur in nearly all freshwater systems, including wetlands and vernal pools (Winter and LaBaugh 2003). The interactions

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Precipitation

Transpiration

Evaporation SW runoff SW spillage

Water table GW discharge

GW recharge Local flow system

Intermediate flow system

Confining layer

Regional flow system

FIGURE 3.1 Schematic diagram illustrating elements of a vernal pool water budget. Inputs can include precipitation, ground water discharge, and surface-water runoff. Ground water can originate from local, intermediate, or regional flow systems. Outputs can include evaporation, transpiration, ground water discharge, and intermittent surface-water spillage. Vernal pools in riverine settings can also have stream input and output (not shown). (Adapted from Sando, S.K. (1996). South Dakota wetland resources. In Fretwell, J.D., Williams, J.S., and Redman, P.J. [compilers] National Water Summary on Wetland Resources. U.S. Geological Survey, Reston, VA. Water-Supply Paper 2425, pp. 351–356.)

are affected by the positions of the pools relative to groundwater level or flow and the geologic, climatic, and edaphic (soil-related) settings of the pools (Chapter 3, Rheinhardt and Hollands). Groundwater flow can occur at scales ranging from regional to local (Winter and LaBaugh 2003; Figure 3.1). On a regional scale, topographically high locations function as recharge areas and topographic lows are discharge areas. Local groundwater flow, relative elevations, and site-specific hydrologic processes also need to be considered and may have greater influence (Rains et al. 2006). Changes in direction of groundwater flow, from recharge (outflow of pool water to groundwater) to discharge (inflow of groundwater to the pool), are determined by the relative elevations of a pool and local groundwater. These directional changes are mostly climate driven, as long-term weather patterns control groundwater levels. The hydraulic conductivity (rate of water movement through the soil) of pool basins and catchments depends on soil permeability and controls the exchange of pool water and groundwater (Winter and LaBaugh 2003). These authors suggest that a hydraulic conductivity of 0.3 m d–1 (1.0 ft d–1) separates permeable from nonpermeable soils. Vernal pools often occur because local soils have relatively low hydraulic conductivity or because topographic depressions have filled with impervious

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sediments. Gay (1998) found the till soils adjacent to vernal pools in central Massachusetts had hydraulic conductivities between 1.5 × 10–3 and 6.4 × 10–6 m d–1 (4.9 × 10–3 and 2.1 × 10–5 ft d–1), clearly indicating they occurred on low-permeability materials. Pools can also occur on highly permeable soils where the water table is high. On the outer Cape Cod, vernal pools occur on fine to coarse grain glacial outwash sediments with horizontal hydraulic conductivities of 100 m d–1 (328 ft d–1) (Sobczak et al. 2003). Water levels in these pools match regional groundwater levels during periods of high groundwater levels. During periods of low groundwater levels, pool levels are perched above the ground water with exchange restricted by relatively impervious peat mats. At these times, pool water levels are largely affected by frequency and intensity of precipitation events. Where it has been investigated, groundwater exchange appears to occur mostly at the pool margins, resulting in short groundwater flow paths (Phillips and Shedlock 1993). Loss of pool water to adjacent catchment groundwater seems to be driven mainly by transpiration from plants along the margins of the pools (Hayashi et al. 1998). In prairie potholes, lateral infiltration to shallow groundwater, driven by transpiration from adjacent catchment vegetation, was estimated to be up to 70% of total pool water loss in the summer months (Parsons et al. 2004). Pool water specific conductance measures that are in excess of precipitation conductance values indicate the contribution of groundwater, which has a greater mineral concentration than precipitation or surface runoff. Palik et al. (2001) suggested that conductance measurements above 100 µS cm–1 indicate groundwater contributions for seasonal pools in Minnesota forests. For 65 vernal pools in Rhode Island, pool water conductance measurements ranged between 19 and 376 µS cm–1, with a mean of 64 µS cm–1 (Skidds and Golet 2005). Surface Water Surface water can enter a pool through runoff or surface water inlets and exit through surface water outlets. There is no published quantification of surface water inputs to, or outflow from, geographically isolated vernal pools, and groundwater is assumed to be a more significant water source (Brooks 2005). However, surface runoff from the adjacent catchment should play a significant role during snow melt or rainfall events when soils are saturated (Chapter 2, Rheinhardt and Hollands, Colburn 2004). Small depressional wetlands that have low storage capacity, such as some vernal pools, are vulnerable to filling at these times, which can cause surfacewater overflow or spillage. Whether spillage will enter neighboring water bodies depends on the volume of outflow, the distance to the neighboring surface water, the permeability of the soils over which the flow travels, and the elevational difference between the water bodies (Leibowitz and Vining 2003; Winter and LaBaugh 2003). Low-volume surface outflows will generally infiltrate into the ground before reaching neighboring waters. However, intermittent connections between isolated wetlands and other waters have been reported (Leibowitz 2003; Leibowitz and Vining 2003). In addition, vernal pools that occur within riverine settings are not strictly isolated and can be connected by surface waters from ephemeral or intermittent streams or be inundated by flooding of larger streams and rivers. Thus, surface-water

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input from other vernal pools or other aquatic systems may occur during episodic events in these settings. Evapotranspiration Evapotranspiration includes evaporation of pool surface water and transpiration from pool and adjacent catchment vegetation, especially forest trees. Evapotranspiration is the principal pathway for water loss from geographically isolated pools (Brooks 2004, 2005). Many pools experience a drop in water after trees leaf out in the spring. Evapotranspiration has also been reported as the major source of water loss for other isolated, ponded wetlands including Carolina bays (Lide et al. 1995), cypress ponds (Mansell et al. 2000), prairie potholes (Hayashi et al. 1998), and California vernal pools (Pyke 2004). Evapotranspiration is principally a temperature-driven process. Annual temperature patterns are less variable in the Northeast than annual precipitation patterns. Brooks (2004) showed that weekly water level change was significantly related to potential evapotranspiration (PEt) but that the effect of precipitation was 2–5 times greater. PEt peaks in the late spring and summer months when forest trees are in full foliage. PEt losses typically exceed precipitation inputs from mid-June through mid-September (Figure 3.2). This period of water deficit coincides with the period of maximum vernal pool drying. Pools dried earlier in those years with larger cumulative water deficits, especially when early spring groundwater resources were below long-term means and late winter snowpack was reduced or absent. Ppt and PEt (cm) 16

Pool depth (cm) 60

14

50

12 40

10

30

8 6

20

4 10

2 0

Oct

Nov

Dec

Jan

Feb Ppt

Mar Apr Month PEt

May

Jun

Jul

Aug

Sep

0

503 1710

FIGURE 3.2 Thirty-year average (1971–2000) precipitation (Ppt) and potential evapotranspiration (PEt) for the Quabbin Reservoir watershed, central Massachusetts, and eight-year average monthly surface-water depths for two vernal pools (503, 1710) on the Quabbin.

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BASIN

AND

37

CATCHMENT MORPHOLOGY

The effects of precipitation inputs and evapotranspiration losses on vernal pool hydrology are dependent on the pool’s basin and catchment characteristics. Basin volume also determines storage capacity. In addition, the soil characteristics of the basin and catchment control permeability, which affects groundwater dynamics, groundwater storage, and surface runoff. Thus, basin and catchment characteristics are fundamental factors in the hydrologic budget of a vernal pool. Surprisingly little is known about the morphology of vernal pool basins and catchments, or their relationships to pool hydrology. What information is available has been reviewed by Brooks and Hayashi (2002) and Brooks (2005). Surface area is the most commonly reported morphological attribute of pool basins, probably as it is most easily determined (Brooks 2005). Limited empirical data show that 66% of 430 Massachusetts pools (Brooks et al. 1998) and about 75% of 304 Maine pools (Calhoun et al. 2003) are less than 500 m2 (0.12 ac) in maximum surface area. Longer hydroperiods generally occur in pools that exceed 1000 m2 (0.25 ac) (Brooks and Hayashi 2002). Pool size, either surface area or volume, affects the duration of standing water. Smaller or shallower pools have a larger perimeterto-area (or volume) ratio, and higher rates of water loss (relative to maximum pool volume). This is caused by either transpiration from forest trees along the perimeter or groundwater leakage (Millar 1973). For larger pools, water loss relative to available volume is so low that these pools may be permanent. Measures of basin volume, area, and depth are positively correlated (Brooks and Hayashi 2002). Larger pools typically have greater maximum depths, but this relationship is also dependent upon the basin profile. For pools of equal surface area, concave basins will have greater depths. Lastly, maximum pool volume is a mathematical function of maximum pool surface area, depth, and basin profile (Brooks and Hayashi 2002). We are unaware of any published studies on the extent and characteristics of vernal pool catchments and their effects on pool hydrology. However, an unpublished thesis by Gay (1998) concluded that differences in the hydrologic systems of two pairs of vernal pools were attributable to differences in bedrock beneath pool catchments, catchment morphologies, and transmissivities of catchment soils. The pair of pools with the longer hydroperiods occurred in catchments over bedrocks composed of gabbro, which weathers more easily than the gneiss underlying the shorter hydroperiod pools. The longer hydroperiod pools were located in bowl-shaped catchments, whereas the shorter hydroperiod pools were located on relatively flat terrain. Finally, hydraulic conductivities were one to two orders of magnitude lower in the shorter hydroperiod pools. Gay (1998) felt that these characteristics collectively resulted in greater surface-water/groundwater connections in the catchments of the longer hydroperiod pools. The shorter hydroperiod pools, with weaker groundwater connections, were more direct expressions of precipitation. The area that actually contributes surface water or groundwater to a pool may be different than the catchment area defined strictly by topography. Two studies that attempted to quantify the spatial extent of catchments of cypress ponds (Mansell et al. 2000) and karst ponds (O’Driscoll and Parizek 2003) determined that the area

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of potential surface-water and groundwater contributions to the pools was much smaller (i.e., an order of magnitude) than the catchment areas defined by surficial topography. Conversely, groundwater that originates outside a catchment may enter a pool if intermediate or regional groundwater flow discharges to the pool (Winter and LaBaugh 2003; Figure 3.1).

HYDROLOGIC DYNAMICS Hydroregime and hydroperiod vary among vernal pools and, over time, within any single pool. These important characteristics affect pool structure and habitat availability, which strongly influence the composition and reproductive success of pool biota. For example, vernal pool-breeding species are adapted to fluctuating water levels, whereas annual drying precludes organisms that require permanent standing water. Effects of hydrologic dynamics on pool biota are discussed by Colburn et al. (Chapter 6) and Semlitsch and Skelly (Chapter 7). Despite its importance, there has been little research on the hydrologic variability of vernal pools. The hydroperiods of ephemeral forest pools occur over a temporal gradient, from highly ephemeral rainwater pools to semipermanent water regimes (Colburn 2004). Historically, there has been very limited information on the occurrence and distribution of pools by hydroperiod. On a year-to-year basis, Brooks (2004) found that pool hydroperiods were shorter and pools dried earlier in years with less rainfall and larger cumulative water deficits. Hydroperiod can be correlated with pool depth and volume, but it is only moderately to poorly correlated with pool area (Brooks and Hayashi 2002; Skidds and Golet 2005). The hydroregime of vernal pools is best described by a repeating, annual pattern of inundation and drying. In central Massachusetts, this pattern is best captured by a hydrologic year that starts in October and ends the following September (Brooks 2004). Geographically isolated pools in this area are typically dry or at minimum depths by the first of October, fill partially with late fall rains after leaf fall, fill to capacity with spring rains and snow melt, and then dry through late spring and summer after full forest canopy development (Figure 3.2). This hydroregime pattern can differ dramatically for any single pool in any one year, e.g., a pool can be dry or full to overflowing in almost any month (Table 3.1). This pattern can also differ for pools in other locations and in other hydrogeomorphic settings. Colburn (2004) has proposed a hydrologic classification for vernal pools that considers the timing of annual drying and filling. Short-cycle, spring-filling pools are usually dry or mostly dry during the winter. They then fill and reach their maximum depth and volume in the spring due to snow melt and spring rains. These pools quickly shrink in size as inputs decline and evapotranspiration increases, drying by late June or early July. Short-cycle, fall-filling pools behave similarly, except they fill in late fall or early to mid winter. Short-cycle, spring-filling pools are typically flooded for three to four months per year, compared with seven to nine months for short-cycle, fall-filling pools. Long-cycle pools, in contrast, usually dry in mid to late summer or early fall. These pools are also divided into spring or fall filling. Long-cycle, spring-filling pools typically have water for five to eight months,

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TABLE 3.1 Thirteen-Year (1993–2005) Average Monthly Mean, Standard Deviation, Minimum, and Maximum Water Depths for Vernal Pool PR243, Quabbin Watershed, Central Massachusetts

Month October November December January February March April May June July August September

Average Monthly Mean 4.8 14.3 30.4 34.0 22.5 39.2 46.2 40.6 23.9 7.0 5.2 1.8

(1.9) (5.6) (12.0) (13.4) (8.9) (15.4) (18.2) (16.0) (9.4) (2.8) (2.0) (0.7)

Standard Deviation 12.0 18.6 21.3 21.6 31.8 13.7 6.7 11.2 17.2 14.8 13.1 6.6

(4.7) (7.3) (8.4) (8.5) (12.5) (5.4) (2.6) (4.4) (6.8) (5.8) (5.2) (2.6)

Minimum 0 0 0 0 0 16 26 3 0 0 0 0

(0) (0) (0) (0) (0) (6) (10) (1) (0) (0) (0) (0)

Maximum 51 51 51 51 45 51 51 51 51 50 50 33

(20) (20) (20) (20) (18) (20) (20) (20) (20) (20) (20) (13)

Number of Weekly Observations 48 43 31 5a 2a 9a 32 52 50 50 49 49

Note: Depths in cm (inches). Maximum depth before surface overflow is 51 cm (20 in.) for this pool. a

Pool is frozen during the winter season; accessibility is limited and few visits were made to the pool. Source: Brooks (unpublished data).

compared to nine to eleven months for long-cycle, fall-filling pools. Finally, semipermanent vernal pools contain water throughout the year, generally remaining flooded for several years at a time. Water levels in these pools also reach a maximum during the spring and then decrease during the summer. These five classes represent a continuum of increasing hydroperiod (Colburn 2004); however, hydroperiod also varies between years within classes. Given the lack of field data on hydrologic variability, a classification system such as Colburn’s may be useful for categorizing pools according to their hydrologic variability and for inferring possible effects on pool organisms.

HYDROLOGIC CONNECTIVITY A vernal pool can have hydrologic connections to other pools and water bodies through groundwater flow. In addition to local groundwater flows, this may also include connections between distant pools through regional flow systems (Winter and LaBaugh 2003; Figure 3.1). It is also possible that vernal pools can have permanent surfacewater connections to other bodies of water, as pools can occur in larger wetlands that have perennial inlets (Garret Hollands, personal communication). Permanent

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FIGURE 3.3 Examples of intermittent surface-water connections between vernal pools (dotted lines denote intermittent connections). (a) Geographically isolated pools connected through a swale zone by snow melt and spring runoff. (b) Depressional pools occurring within a larger, forested wetland merged during high water events. (c) Riverine pools within the floodplain of a permanent stream connected during floodplain inundation. (d) Riverine pools occurring as a headwater complex are connected when the intermittent or ephemeral stream is flowing.

surface-water connections would be expected to occur in a relatively small number of pools. However, a larger number of northeastern vernal pools may be connected by surface water intermittently. Such intermittent connections have been reported for California vernal pools (Zedler 1987), prairie potholes (Leibowitz and Vining 2003), and other wetland types (e.g., Snodgrass et al. 1996; Babbitt and Tanner 2000). Intermittent surface-water connections could occur between vernal pools during wetter conditions in various ways. For example: geographically isolated vernal pools could be connected to each other through swale zones during snow melt and spring runoff (Figure 3.3a); individual pools within a larger forested wetland can merge if conditions are wet enough to cause standing water in the larger wetland (Figure 3.3b); riverine vernal pools occurring in floodplains of permanent streams can connect to each other and to the stream during floodplain inundation (Figure 3.3c); and riverine vernal pools that occur as a headwater complex connect to each other during times of intermittent or ephemeral stream flow (Figure 3.3d). Intermittent surface-water connections should occur at a hierarchy of scales (Figure 3.4). There is also a temporal hierarchy of intermittent connections, though

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FIGURE 3.4 Spatial hierarchy of hydrologic interactions (dotted lines denote intermittent surface-water connections). (a) Micropools connect annually as water fills the entire pool. (b) Pools within a geographically isolated wetland connect during flood events (annual or less frequent) when the larger wetland fills. (c) Geographically isolated wetlands containing pools can connect during extreme flood events when the wetland spills over into an adjacent isolated wetland. Some hydrologic interactions may not fit in this hierarchy, e.g., connections between riverine pools or between geographically isolated pools.

this need not match the spatial pattern. For example, micropools, riverine pools in a 1-year floodplain, and vernal pools connected through swale zones will usually have annual intermittent connections, though the micropool connections should have the longest duration. At the other extreme, geographically isolated pools in areas with large relief and riverine pools in 100-year floodplains will rarely have intermittent surface-water connections. Thus, vernal pools occur within an isolationconnectivity continuum over time and space (Leibowitz and Vining 2003). Groundwater connections can serve as an important mechanism for transporting soluble materials between vernal pools and other waters. Surface-water connections can transport not only soluble compounds but also insoluble materials such as sediment, organisms, and reproductive propagules. While there have been some studies of groundwater interactions between vernal pools, surface-water interactions have received almost no attention. Thus, we are not able to say at this time how widespread or significant these connections are. Characterizing the frequency distribution of these surface-water connections (Leibowitz and Vining 2003) could promote a better understanding of the ecological functioning of these systems.

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POPULATION DYNAMICS AND LANDSCAPE CONNECTIVITY Vernal pools support a diversity of aquatic organisms. These organisms must survive in a stressful environment that experiences regular drying. Survival is made possible by a number of life-history strategies that allow organisms to successfully grow and reproduce in these systems (Colburn 2004). Eggs of pool-breeding organisms must hatch and develop while water is present, and populations must be able to withstand or avoid drought. Yet the timing and duration of water availability is highly variable, both spatially (among pools) and temporally (among years). Thus, in spite of adaptive life-history strategies, populations of a particular species may go locally extinct in pools that experience particularly harsh conditions. Classical ecological theory dealt with complete extirpation of a species over its entire range. More recently, metapopulation theory has been proposed to explain the dynamics of local extinctions and recolonizations over a group of individual sites (Hanski 1999). In the absence of field studies on these dynamics, metapopulation theory can provide an explanation of how a species might persist in the face of local extinctions, and the factors that could influence their persistence (Chapter 8, Gibbs and Reed).

METAPOPULATION THEORY Levins (1970) introduced the term metapopulation to refer to a population of local populations. His theory examines the long-term viability of a species in a landscape where various factors affect its ability to persist. Metapopulation dynamics are increasingly recognized as playing an important role in the long-term sustainability of certain wetland species (Gibbs 1993; Lehtinen et al. 1999). Metapopulation dynamics are a function of extinctions of local populations within distinct sites, due to random environmental and demographic variation, and recolonization from neighboring sites (Hanski 1999). Levins (1970) was able to demonstrate that the metapopulation could be maintained if the rate of recolonizations is greater than the rate of extinctions. According to this perspective, it is the metapopulation that can persist over time; local populations wink on and off in response to local extinction and recolonization events. If recolonizations do not offset local extinctions, the proportion of occupied sites will decrease over time, and the metapopulation will eventually go extinct. A species’ extinction rate is related to local population dynamics, community structure, and genetic change (Figure 3.5). For vernal pools, extreme hydrologic variability would be expected to have a major influence on the extinction rate. This could include direct effects on the population, such as increased mortality from desiccation and reduced reproduction because of delayed flooding, as well as indirect effects through lowered habitat quality. The recolonization rate of a species depends on the rate of emigration from occupied sites, which is a function of local population dynamics (for example, movement due to overcrowding) and behavior, e.g., emigration in response to poor conditions (Hanksi 1999). The recolonization rate also depends on the probability

FIGURE 3.5 Factors influencing metapopulation dynamics. The equilibrium number of occupied sites is a balance between the extinction and recolonization rates. Metapopulations can survive only if the recolonization rate is greater or equal to the extinction rate. A species’ behavior affects the distance it can disperse (d), whereas the distribution of distances between sites (D) is a function of the environment’s spatial pattern. (Adapted from Levins, R. (1970). Extinction. In Gerstenhaber, M. (Ed.) Some Mathematical Questions in Biology. American Mathematical Society, Providence, RI. pp. 75–107. With permission.)

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that these emigrants will successfully recolonize an empty site (Figure 3.5). This is affected by the emigrants’ ability to arrive at an unoccupied site and, once there, to become successfully established. In the original Levins (1970) model, extinction is random with an average rate that is constant across all sites. This would cause local populations to wink on and off independently of each other. However, local extinctions in vernal pools are likely to be clustered in time during harsh hydrologic conditions. In addition, some pools will have greater hydrologic variability than others and therefore experience higher rates of extinction. For example, pools that are shallow and totally dependent on precipitation would experience more frequent than average dry conditions. This would represent marginal habitat for a species requiring longer and more predictable wet periods, and so local extinctions would be relatively common. In contrast, deeper pools that receive groundwater would be less responsive to variations in precipitation, and would have a lower than average extinction rate for that species. These pools would remain wet during mild droughts, when other pools were dry. At such times the wet sites could function as source pools (Hanksi 1999), producing emigrants that could recolonize pools with marginal habitat (sinks) that experienced more frequent extinctions. However, pools may shift from being sources to sinks and vice versa, due to year-to-year variability within and between pools. This suggests that long-term maintenance of metapopulations may require a variety of pools having different hydrologic regimes to sustain local populations and serve as source areas under different conditions (Elizabeth Colburn, Harvard University, personal communication).

CONNECTIVITY

AND

DISPERSAL

We noted in the previous section that recolonization is dependent on the emigrants’ ability to arrive at an unoccupied site. The probability that an emigrant will successfully get to an unoccupied site depends on the dispersal distance of the species (a function of behavior) and the distribution of distances between sites, which is a function of the spatial pattern of the environment (Figure 3.5). For a given species with a fixed dispersal distance, the level of connectivity is higher in landscape settings with smaller distances between pools (Figure 3.6). Distances between sites are a function of pool density, which has been reported in the literature to range between 0–13.5 pools km–2 (0–35 pools mi–2) over the glaciated northeastern United States (Chapter 3 in Colburn 2004). This means that regions with higher pool densities should have greater recolonization rates and, consequently, sustain more species. Similarly, connectivity in a given landscape is greater for species with larger dispersal distances. For example, wood frogs are highly mobile, with first-time breeders able to disperse 1.1–1.2 km (0.68–0.75 mi) (Colburn 2004). Thus, these frogs should be able to readily move between pools. Colburn (2004), deMaynadier and Houlahan (Chapter 13), and Semlitsch and Skelly (Chapter 7) include dispersal distances for some vernal pool organisms. There are many different mechanisms by which species disperse between vernal pools. Dispersal can be active or passive, can happen during different life stages, and can occur over land or through the air. For example, adult frogs and salamanders

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45

(b)

(c)

Connections (#)

7000 6000 5000 4000 3000 2000 1000 0

6

5

3 2 4 Pool Density (# km–1)

1

0

(d)

FIGURE 3.6 Effect of reduced pool density on landscape connectivity. Pools were randomly generated in a 100 km2 (38.6 mi2) landscape and then randomly removed to simulate the effects of pool conversion. Initial pool density is based on a glacial collapse valley in Cape Cod, MA, and connections are for a species having a fixed dispersal distance of 1.15 km (0.7 mi), e.g., wood frog (Colburn 2004). (a) Density of 5.8 pools km–2 (15.0 pools mi–2). (b) Density of 3 pools km–2 (7.8 pools mi–2). (c) Density of 1 pool km–2 (2.6 pools mi–2). (d) Plot showing number of connections vs. pool density.

actively travel between pools over land, whereas birds and certain insects disperse through flight. For many other species, reproductive propagules or resting stages are passively dispersed between sites. As an example, plant seeds can be transported by wind, and fingernail clams and fairy shrimp can be carried on the feet or feathers of birds (Chapter 6, Colburn et al.). Although it has not received much attention, surface-water connections between wetlands — both permanent and intermittent — may also serve as corridors for movement (Leibowitz 2003). Dispersal of seeds by water (hydrochory) has been observed in southeastern swamp forests (Schneider and Sharitz 1988). Small-fruited spike-rush (Eleocharis microcarpa Torrey var. filiculmis), which can be abundant in vernal pools south of New England, may disperse through hydrochory (Hickler 2004). Thus, it is possible that certain animals, plant parts, and reproductive propagules disperse between northeastern vernal pools through surface-water connections. As few vernal pool animals have adaptations to disperse through flowing water (Elizabeth Colburn, personal communication), surface water is probably not a major dispersal mechanism. However, surface water could be important for particular

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taxa (e.g., crayfish) and for certain types of pools, such as those occurring in floodplains. Given these different modes of dispersal, interpreting distances between pools as straight line distances — as we implicitly did above — can be problematic. For example, an organism might require forest cover, moist habitat, or a hedgerow for movement. In this case, the effective distance between sites would need to reflect the length of the actual travel path — which would take into account the presence of corridors and barriers — rather than straight-line distance (Wiens 1997). The use of simple, straight-line distances can also be inappropriate for aquatic organisms and reproductive propagules that are carried between sites through permanent or intermittent surface-water connections. Another complication in this case is that downstream flow — either through swale zones (Figure 3.3a) or intermittent or ephemeral streams (Figure 3.3d) — adds directionality; e.g., passively transported organisms and propagules cannot travel upstream and actively transported organisms can move greater distances and expend less energy in the downstream direction. This would not be the case with bi-directional connections that occur when water surfaces merge (Figure 3.3b) or floodplains fill (Figure 3.3c). The temporal pattern of intermittent surface-water connections, both frequency and duration, must also be considered. Timing could be the more critical factor for organisms that disperse in this manner. For example, two riverine pools located 1 km (0.6 mi) apart within a 1-year floodplain would have greater hydrologic connectivity than two geographically isolated pools that are 0.1 km (0.06 mi) apart but, due to high relief, only merge during 10-year storm events.

WETLAND–TERRESTRIAL CONNECTIVITY The Levins metapopulation model conceptualizes the landscape as consisting of sites, or “pockets of suitable habitat” (Levins 1970: 80), embedded within surrounding unsuitable habitat. Up until this point, we have interpreted “site” as an individual vernal pool. This would be the case for obligate wetland species that live their entire lives within the confines of the pool basin. Such permanent residents include fingernail clams, nematodes, flatworms, fairy shrimp, spreadwing damselflies, and clam shrimp (Chapter 6, Colburn et al.). These organisms have different life-history strategies that allow them to feed and breed during wet conditions and survive dry periods. Permanent residents would also include plants adapted to vernal pool hydrology. Many other organisms, however, are migrants that use the pool for only a portion of their life. This includes nonbreeding migrants (e.g., some species of predaceous diving beetles, turtles, snakes, birds, and mammals) that feed but do not breed in vernal pools (Chapter 6, Colburn et al.; and Chapter 9, Mitchell et al.). Nonbreeding migrants can include both wetland obligate and facultative wetland (not requiring wetlands to survive) species. In contrast, migratory breeders use the vernal pool basins to breed (this may take place during wet or dry conditions, depending on the species) but then leave as the pool dries out. These species are pool-dependent, they breed most successfully in seasonal pools. Migratory breeders include mole

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salamanders (Ambystoma spp.), wood frogs, and certain dragonflies and caddisflies (Chapter 6, Colburn et al.; and Chapter 7, Semlitsch and Skelly). Migrants that are wetland obligates require vernal pools to complete their life cycle. However, they are only obligates during a particular life stage. These “stagespecific” wetland obligates also require core terrestrial habitat (Chapter 7, Semlitsch and Skelly). Gibbons (2003) argued eloquently that the strong focus on jurisdictional delineation and presence of hydric conditions for defining wetlands has caused wetland scientists to overlook how critical terrestrial habitat is for many wetland species. Thus, the term “site” needs to take on a different meaning for these migratory species; it does not represent a single, homogeneous habitat type, but rather a mixture of core habitats, including vernal pools, that fulfill the particular species’ life history requirements. The arrangement of these habitats is also important; e.g., amphibian migratory breeders require vernal pools and terrestrial forests to be located within their maximum adult migratory travel distance (Regosin et al. 2005; Baldwin et al. 2006). This means that the concept of landscape connectivity must be expanded to include not only movement between pools but also movement between vernal pools and other required habitat (Chapter 7, Semlitsch and Skelly; Chapter 8, Gibbs and Reed; and Chapter 12, Windmiller and Calhoun).

CONSERVATION IMPLICATIONS HYDROLOGIC IMPACTS Vernal pool organisms have numerous life history strategies for surviving, including different life stages for wet and dry conditions. These stages are tightly linked to the timing of flooding and drawdown. Although flooding and drawdown exhibit significant temporal variability from year-to-year, any impacts that have a long-term effect on the frequency, duration, magnitude, or variability of flooding will inevitably alter community composition. We discuss several potential impacts below. These range in scale from impacts to individual pools to large-scale effects throughout the entire glaciated northeast. Timber Harvesting The hydrologic effects of timber harvesting on forest pools are determined by the impacts of the harvesting on the sensitive components of the hydrologic budget, namely runoff, evapotranspiration, and soil permeability. The effects of timber harvesting and associated reductions in evapotranspiration on isolated ponds have been studied for various types of forest in the southeastern United States. This research has generally revealed elevated groundwater levels and an increase in runoff to ponds, resulting in longer hydroperiods (Sun et al. 2000). However, these effects are very ephemeral and become insignificant by the tenth year following harvesting, due to rapid regeneration and growth of other forest vegetation (Sun et al. 2000). Although relatively short-lived, these effects could still be significant for species requiring short hydroperiods if source populations are unavailable for recolonization.

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In contrast to the effects observed by Sun et al. (2000), no relationship was found in Minnesota between time since harvesting and forest pool hydroperiod (Palik et al. 2001). However, these researchers observed that the youngest stand in their study had been harvested seven years prior, so that hydrology may have already returned to preharvest conditions. Batzer et al. (2000) also were unable to find an effect of timber harvesting on pond hydrology, concluding that natural annual variation in hydroperiods overwhelmed any timber harvesting effect. Although informative, studies in other areas may not reflect the impact of timber harvesting on northeastern vernal pools. Based on a conceptual understanding of pool hydrology, any impacts that do occur should be greater in dry climates with low potential evapotranspiration than in wetter areas, and greater for geographically isolated pools vs. pools associated with other waters. Impacts should also be directly related to the intensity of the management. Recommended modifications of timber management practices for protecting vernal pools and their biota are discussed by deMaynadier and Houlahan (Chapter 13). Land Development Urbanization and development for associated land uses is a significant threat to vernal pools in many areas of the glaciated Northeast (McKinney 2002). Urbanization can cause hydrologic impacts through cumulative watershed modifications that alter hydrology (Richter and Azous 1995). Windmiller and Calhoun (Chapter 12) discuss best management practices for minimizing the impact of development on vernal pools. Wetland hydrology in urban areas is usually highly altered in amounts, sources, and flow rates. Urbanization can increase the area of impervious surfaces (e.g., buildings, roads, parking lots) and alter natural flow pathways (e.g., construction of storm drainage systems). These changes can be expected to alter the hydrology of urban wetlands so that they will have more frequent, rapid, and large (“flashy”) changes in water level and have a lower frequency of flooded and/or saturated conditions (Ehrenfeld et al. 2003). In a study of 21 wetlands in northeastern New Jersey, including four depressional wetlands, flashiness was significantly different among disturbance classes; sites with high levels of disturbance had larger fluctuations (Ehrenfeld et al. 2003). However, Rubbo and Kiesecker (2005) found that the modified hydrologic regimes of urbanized wetlands in central Pennsylvania tended to result in longer hydroperiods and a tendency towards permanence of standing water. Other land use changes can also impact vernal pool hydrology. Permanent clearing of forests for field crops or pastures could alter evapotranspiration rates and cause surface-water temperatures to rise (due to reduced shading). Farm machinery could also alter soil permeability. The impact of this change in land use can be regional in scope: according to Colburn (2004), up to 85% of most of southern and central New England and much of the Canadian Maritime Provinces were converted from forest to fields and pastures by the mid-1800s. However, much of this land subsequently reverted to forest cover.

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Climate Change The dominant effect of weather patterns on pool hydrology means that these systems will be affected by climate change (Sun et al. 2002). Furthermore, vernal pools and their biota are likely to be affected by climate change early on, due to their relative hydrologic isolation and location at the land/water interface (Root and Schneider 2002). Climate change predictions of more episodic precipitation and increased evapotranspiration would cause pools to dry earlier in the year and remain dry longer (Brooks 2004). In addition, climate change could increase the frequency of extreme rainfall events and cause more frequent and longer interevent droughts. This could increase the frequency of the drying and refilling cycle, compared with the slow, extended drying that now occurs (Brooks 2004). Increasing magnitude and variability of temperature could alter quantities and timing of snow melt. This could potentially affect many species, especially early spring migrants that deposit eggs around the time of snow melt. Finally, any of these hydrologic changes could affect stream flow, thereby impacting riverine pools.

LOSS

OF

LANDSCAPE CONNECTIVITY

According to metapopulation theory (Levins 1970), the distribution of pool species across a region represents a dynamic equilibrium between factors that cause local extinctions and those that affect recolonization. Any impacts that increase local extinctions or reduce recolonization will therefore decrease species distributions. One such impact is the conversion of pools to different land uses, which can cause the local extinctions of all the species dependent on those pools. Conversion can also indirectly affect populations in surrounding pools by lowering recolonization rates. This might occur because the converted pools are no longer able to serve as sources of emigrants. Conversion can also reduce recolonization because the cumulative loss of pools increases the average distance between remaining sites (Figure 3.6). Reduced landscape connectivity can be caused by other impacts besides direct conversion. Impacts that decrease pool flooding, such as climate change, would lower landscape connectivity by making intermittent surface-water connections less frequent or shorter in duration. In addition, roads in upland areas can act as barriers to dispersal by increasing mortality or changing behavior. Pool-dependent species can also be affected by impacts that alter the spatial relationship between pools and other core habitat areas. For example, deforestation can cause the direct loss of a semiaquatic pool species that also requires forested habitat if the distance between the pool and remaining forest exceeds its maximum migratory travel distance. Vernal pool conservation has historically focused on protecting pool habitat. Yet because pool species depend on landscape connectivity for long-term persistence, conservation programs must also preserve connectivity. In addition, conservation efforts should include the other core habitat types needed by some pool organisms. A landscape perspective that considers connectivity and supplemental habitat is necessary to conserve the rich biota associated with these seasonally flooded pools.

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SUMMARY Vernal pools are shaped by hydrologic processes which influence many aspects of pool function. The hydrologic budget of a pool can be summarized by a waterbalance equation that relates changes in the amount of water in the pool to precipitation, ground- and surface-water flows, and evapotranspiration. For many vernal pools, precipitation and evapotranspiration are the major determinants of the water cycle. However, groundwater can also be significant in specific settings and at particular times. Surface-water flows can be important for certain vernal pools, e.g., those in riverine settings. Basin and catchment characteristics influence the relative role of surface water and groundwater. A limited number of vernal pools may have permanent surface-water connections to other waters. Intermittent surface-water connections may also occur during episodic events, either annually or less frequently. It is suggested that these intermittent surface-water connections result in a spatial hierarchy of hydrologic interactions. There is also a temporal hierarchy of intermittent connections, though this need not match the spatial pattern. Thus, vernal pools occur within an isolation-connectivity continuum over time and space. Theory suggests that the persistence of a species across vernal pools represents a balance between factors that cause local extinctions and those that allow for unoccupied areas to be recolonized. Landscape connectivity makes it possible for species to disperse between vernal pools and recolonize pools that are unoccupied due to local extinctions. Connectivity is greater for species with larger dispersal distances and in landscape settings with greater pool densities. In addition to connections between pools, migratory species also require landscape connectivity between pools and other core habitat areas, such as forests. Any impacts to vernal pools that have a long-term effect on the frequency, duration, magnitude, or variability of flooding will inevitably alter community composition. These impacts, which range in scale from changes to individual pools to large-scale effects throughout the entire glaciated Northeast, include timber harvesting, land development, and climate change. A landscape perspective that considers connectivity and supplemental habitat is necessary to conserve the rich biota associated with these seasonally flooded pools.

ACKNOWLEDGMENTS Special thanks to E. Colburn, R. McKinney, P. Zedler, and an anonymous reviewer for their thoughtful comments on this manuscript. We also received useful suggestions from A. Calhoun, G. Hollands, and R. Rheinhardt. Thanks to D. White for helpful discussions on metapopulations and dispersal. The information in this document has been funded by the U.S. Environmental Protection Agency (EPA) and the U.S. Forest Service. This document has been subjected to EPA’s peer and administrative review, and it has been approved for publication as an EPA document. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

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Schneider, R.L. and Sharitz, R.R. (1988). Hydrochory and regeneration in a bald cypresswater tupelo swamp forest. Ecology 69: 1055–1063. Skidds, D.E. and Golet, F.C. (2005). Estimating hydroperiod suitability for breeding amphibians in southern Rhode Island seasonal forest ponds. Wetlands Ecology and Management 13: 349–366. Snodgrass, J.W., Bryan, A.L., Jr., Lide, R.F., and Smith, G.M. (1996). Factors affecting the occurrence and structure of fish assemblages in isolated wetlands of the upper coastal plain, U.S.A. Canadian Journal of Fisheries and Aquatic Sciences 53: 443–454. Sobczak, R.V., Cambareri, T.C., and Portnoy, J.W. (2003). Physical hydrology of selected vernal pools and kettle ponds in the Cape Cod National Seashore, Massachusetts: ground and surface water interactions. Cape Cod Commission, Water Resources Office, Barnstable, MA. Sun, G., McNulty, S.G., Amatya, D.M., Skaggs, R.W., Swift, L.W., Jr., Shepard, J.P., and Riekerk, H. (2002). A comparison of the watershed hydrology of coastal forested wetlands and the mountainous uplands in the southern U.S. Journal of Hydrology 263: 92–104. Sun, G., Riekerk, H., and Kornhak, L.V. (2000). Gound-water table rise after forest harvesting on cypress-pine flatwoods in Florida. Wetlands 20: 101–112. Tiner, R.W. (2003). Geographically isolated wetlands of the United States. Wetlands 23: 494–516. Wiens, J.A. (1997). Metapopulation dynamics and landscape ecology. In Hanski, I.A. and Gilpin, M.E. (Eds.) Metapopulation Biology: Ecology, Genetics, and Evolution. Academic Press, New York, pp. 43–62. Winter, T.C. and LaBaugh, J.W. (2003). Hydrologic considerations in defining isolated wetlands. Wetlands 23: 532–540. Winter, T.C., Rosenberry, D.O., Buso, D., and Merk, D.A. (2001). Water source to four U.S. wetlands: implications for wetland management. Wetlands 21: 462–473. Zedler, P.H. (1987). The ecology of southern California vernal pools: a community profile. U.S. Fish and Wildlife Service, Washington, D.C. Biological Report 85(7.11).

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Remote and Field Identification of Vernal Pools Matthew R. Burne and Richard G. Lathrop, Jr.

CONTENTS Vernal Pool Survey Techniques...............................................................................57 Remote Sensing ...........................................................................................57 Interpretation and Analysis Techniques ......................................................59 Discussion of Errors...........................................................................60 Field Identification.......................................................................................61 Field Survey Techniques....................................................................61 Conservation Recommendations .............................................................................65 Summary ..................................................................................................................66 Acknowledgments....................................................................................................67 References................................................................................................................67

Vernal pools have been underrepresented in wetland and natural resource inventories throughout their range. They are often small and ephemeral in nature, and they are typically geographically isolated from open-water wetlands. Due to these characteristics, vernal pools have not historically received regulatory protection nor have they been targeted in the land use planning process (Chapter 10, Mahaney and Klemens). In many respects, vernal pools have not been captured in regulatory safety nets (Tappan and Marchand 2004; Burne and Griffin 2005b) or by most governmental mapping programs. For example, in the U.S., the U.S. Fish and Wildlife Service has the primary responsibility for wetland mapping under the auspices of the National Wetland Inventory (NWI). Due to the inherent limitations of the aerial photography employed by the NWI, the minimum mapping unit for open water and emergent wetlands ranges from 0.4 ha (1 ac) within a deciduous forested matrix upwards to 1.2 ha (3 ac) in evergreen coniferous forest dominated landscapes (Tiner 1990). The majority of vernal pools in New England fall well below these minimum size thresholds (Brooks et al. 1998; Calhoun et al. 2003; Burne and Griffin 2005a), and consequently are not mapped under these existing nationwide wetland inventory programs. The Canadian Wetland Inventory, which relies heavily on the analysis of

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satellite imagery to classify and map wetland communities, has a minimum mapping unit of 1 ha (2.4 ac) (Milton et al. 2003). In recent years, heightened awareness and appreciation of the biodiversity value of vernal pools has led to an increase in demands for their conservation and protection (Section III, this volume). Location data on vernal pools are often collected by state or provincial agencies as part of routine wetland evaluations or species recovery plans, but not generally in a systematic or comprehensive fashion. In response, a number of states in the northeastern U.S. and Canadian provinces have initiated vernal pool identification and documentation programs to fill this information gap (Brown and Jung 2005). These efforts are often initiated as a means of preliminary data gathering on number and abundance (Burne 2001), but may also be directed at identifying high-value conservation targets, such as clusters that are likely to support metapopulation dynamics of particular species, or pools that have significant areas of undisturbed, terrestrial, nonbreeding habitat (Compton et al. 2003). Targeted vernal pool surveys generally consist of three steps: (1) identifying potential vernal pools, (2) geo-locating or mapping these potential pool locations, and (3) documenting or certifying that the identified feature is actually a vernal pool. The last step may be primarily a biological determination for triggering wildlife habitat protection components of regulations (as is the case in a number of New England states) or may be designed as a means of filtering false positives from remotely sensed datasets (see discussion of errors below). The initial identification and location stages may consist of the serendipitous discovery of vernal pool sites or, ideally, a more systematic inventory of a specific area. Although there are many examples of municipalities that have undertaken comprehensive surveys of vernal pools (Chapter 16, Calhoun and Reilly; Calhoun et al. 2003), surveys at a state or provincial level are uncommon. Two notable exceptions are Massachusetts and New Jersey, which have conducted ambitious statewide inventory programs to produce systematic comprehensive mapping of potential vernal pools. There is great value in exhaustive surveys. They facilitate proactive protection, provide consistent and equitable coverage that does not bias certain geographic locales or regions, provide some consistency in pool identification, and illustrate spatial patterns of occurrence. The objective of this chapter is to review remote and field-based approaches to vernal pool surveys and to provide practical advice on undertaking such surveys. We describe various techniques to locate and identify vernal pools using both ground surveys and remotely sensed image interpretation and mapping. We frame the discussion around key steps in undertaking pool surveys: (1) identifying potential vernal pools, (2) geo-locating or mapping the pools, and (3) quality control (checking for errors). Although the focus of our chapter is on the application of image interpretation to undertake systematic surveys of broad areas, we will evaluate several approaches. As with environmental data in general, there is a strong movement toward using geographic information systems (GIS) technology to map and distribute vernal pool data. In this context, we will discuss various methods to acquire accurate locational data on vernal pools that may be readily incorporated into a GIS.

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VERNAL POOL SURVEY TECHNIQUES REMOTE SENSING Vernal pool surveys can be ground-based, remote, or, ideally, some combination of the two. Several types of images are available for remote surveys. Photographs looking straight down at the Earth’s surface can be acquired by satellites or airplanes at various altitudes. When photographs are taken from directly overhead, a threedimensional perspective (if using paired, or stereo, photographs) is gained that allows the photo interpreter to see landscape features that might be difficult or impossible to distinguish from other vantage points. Although less effective for broad-scale mapping efforts, low-altitude oblique aerial views of the landscape can be very useful for interpreting potential vernal pools. The synoptic view of the landscape provided by overhead aerial photography and other remotely sensed imagery provides an excellent starting point for any vernal pool survey, whether the study area comprises only a single property or an entire province or state. Aerial photographic interpretation has been extensively used to map wetland habitats and formed the basis for the NWI (Tiner 1990, 1997). However, the 0.4–1.2 ha (1–3 ac) minimum mapping unit of the NWI is too large to effectively map most vernal pools. Stone (1992) first demonstrated the feasibility of using large-scale aerial photographic interpretation of vernal pools. These techniques were adapted for application across New England from Connecticut to Maine (Donahue 1997; Calhoun and deMaynadier 2004; Tappan and Marchand 2004). Massachusetts and New Jersey have employed a remote sensing approach to conduct their statewide inventory of vernal pools (Burne 2001; Lathrop et al. 2005). The advantage of a remote sensing approach is the ability to survey large areas for potential vernal pools in a time- and cost-effective manner. Pools are visually identified based on size, shape, color, and texture (or signature), topography, and other site cues. The ability to detect vernal pools, especially smaller ones, is greatly affected by the scale and spectral characteristics of the remotely sensed imagery. Aerial photography is available in different film emulsions such as color infrared (CIR), true color, and black and white (B&W) or panchromatic (Color Plate 1). Stone (1992) used 1:4,800 scale (1 in = 400 ft) B&W photography for her study in a western Massachusetts town. However, large-scale photography has small ground coverage. Although providing greater detail, large-scale photography may make inventories of large areas prohibitive due to greater numbers of individual photos, time to interpret, and cost. Brooks et al. (1998) showed that 1:12,000 scale (1 in = 1,000 ft) photography was a suitable compromise between image resolution and ground coverage. Massachusetts used 1:12,000 scale CIR stereo photography for its statewide survey (see Case Study, Text Box 4.2). The CIR imagery was preferred over B&W or color photography because standing water strongly absorbs near infrared wavelengths giving a dark signature that is more easily discriminated. With the easily scattered blue wavelengths filtered out of CIR imagery, the haze effect is minimized allowing for clear viewing of the terrain. Black and white, color, and CIR photography may be available through local boards, universities, and state/provincial, non-governmental organizations, and national agencies.

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In addition to traditional analog “hard-copy” aerial photography, digital remotely sensed imagery is increasingly available (Text Box 4.1). Digital imagery may be in the form of digital orthophotography or satellite imagery. Orthophoto maps combine the image characteristics of a photograph with the geometric qualities of a map in that the imagery is planimetrically correct with differences in terrain elevation removed. The U.S. Geological Survey (USGS 2005) is producing digital orthophoto quarter quadrangle (DOQQ) imagery as a standard geographic data product. Standard DOQQs are projected as Universal Transverse Mercator (UTM) with the North American Datum of 1983 (NAD83), though some U.S. states may have DOQQs in a state plane coordinate system. The scale of digital imagery is a function of the ground resolution cell (GRC) size, sometimes referred to as the pixel size. The 1m GRC size of a DOQQ approximates 1:12,000 scale aerial photography in the potential for detailed ground interpretation. New Jersey employed CIR DOQQs as the base imagery for its statewide survey (Lathrop et al. 2005).

TEXT BOX 4.1 Image Availability The majority of the continental U.S. is covered by the 1 meter DOQQs (digital ortho quarter quad) in either B&W or CIR, available from the USGS or USDA (USGS 2005, USDA 2005). The National Digital Orthophoto Program plans to update the existing DOQQ coverage with new and often higher resolution imagery (NDOP 2005). As USGSderived DOQQs are in the public domain, they can be acquired at a comparatively low cost and in many cases are available for free download via the Internet through state level data clearinghouses. Free images are also available through Internet services such as Google Earth (earth.google.com) and Terraserver (terraserver.microsoft.com), though resolution and image type varies widely. Digital aerial photographs are available in Canada through the National Air Photo Library (Natural Resources Canada 2005). High spatial resolution satellite remote sensing systems such as the DigitalGlobe Quickbird satellite can produce color or color-infrared imagery with a submeter GRC (ground resolution cell). As these satellites are in the private domain, imagery costs can be several orders of magnitude higher than the equivalent DOQQ coverage. Aerial videography presents an additional alternative to the use of still photography, as has been demonstrated in prairie pothole inventories (Strong and Cowardin 1995), though it is untested in forested regions.

The successful identification of potential vernal pools is highly dependent on the timing of imagery acquisition. Spring imagery is advantageous because (1) leafoff conditions provide a clearer view of the ground, especially where deciduous forest vegetation dominates; (2) there is a higher likelihood that pools will be flooded with standing water; and (3) snow- and ice-free conditions are preferred to provide a greater contrast between the dark, open water and surrounding matrix. Fortunately, the majority of aerial photography and digital orthophotography acquired by government mapping programs is spring-time, leaf-off.

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INTERPRETATION

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ANALYSIS TECHNIQUES

Computer-assisted interpretation methods exist and will continue to improve in identification of features such as vernal pools as techniques are developed for distinguishing between spectral characteristics of adjacent pixels. However, due to the tremendous variability in vegetation and setting of vernal pool habitats, there is difficulty in objectively defining vernal pool signatures on remotely sensed images. Visual interpretation by human image analysts is, therefore, still the method of choice. Analysts may interpret directly from hard-copy paper prints or diapositives or do on-screen interpretation of digital imagery (e.g., DOQQs). Each has advantages at the interpretation and data transfer steps. Final map form, in addition to availability and cost, may be an important consideration in deciding which image type to use. Hard-copy prints are particularly useful in aiding initial field reconnaissance and simple sketch mapping. Stereo viewing is a major advantage with hard-copy photos, providing a three-dimensional view of the terrain, which may help in the detection of the depressions associated with vernal pools (Pawlak 1998; Burne 2001). Once identified remotely, pool centroid point locations or outer boundaries must be transferred to a standard base map such as a topographic quad sheet or orthophoto map, or digitized into a GIS. The Massachusetts potential vernal pool survey was conducted on hard-copy aerial photographs which were then digitized onto B&W digital orthophotos in desktop GIS software (Burne 2001). Alternatively, one can reduce the need for cumbersome photo-to-map data transfer steps through the use of on-screen interpretation of digital orthophotography. Because the imagery is rectified (i.e., projected to a standard coordinate system), the pool centroid point location or outer boundaries can be digitized directly onscreen into a GIS thematic coverage, known as “heads-up digitizing.” This one-step direct capture may also provide greater accuracy of the geographic coordinate locations by eliminating possible errors introduced in transferring the pool locations from source interpretation to final map or GIS. In using on-screen interpretation, the digital imagery can be viewed across a range of scales. Lathrop et al. (2005) chose a map scale of 1:5,000 as a compromise between a high level of visible detail and the spatial extent displayed for any single image frame. One of the disadvantages of on-screen interpretation of digital orthophotography is the loss of stereo-viewing capability. However, these two methods can complement each other with stereoviewing of analog photos (if available) to identify potential vernal pools and onscreen digitizing serving as a data-capture tool. With either method, interpreters must go through an initial training process correlating the visual cues on the imagery with the field conditions. Field and map reconnaissance of vernal pools across the range of expected landscape conditions is highly advised. Referring to other wetlands maps (e.g., NWI maps in the U.S. or CWI maps in Canada), topographic, soil (e.g., NRCS county soil surveys) or surficial geology maps may aid in the interpretation process by helping to locate wetland or upland complexes that may contain vernal pools (Color Plate 2). For example, in using NWI maps, one should look for wetlands labeled as palustrine, unconsolidated bottom wetland (PUB or POW), headwater wetlands that may have an outlet stream, and palustrine emergent, shrub, or forested wetlands (PEM, PSS, or PFO,

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respectively) not connected to a stream or lake. For reviews of various map sources that may aid in locating vernal pools, consult Kenney (1994) or Calhoun and deMaynadier (2004). Although it may be desirable to collect additional spatial information beyond the pool centroid, such as the individual pool area, this requires mapping the pool boundaries. The interpretation and digitizing of the pool boundaries is significantly more time consuming, as well as subject to greater uncertainty, especially in the smaller size classes. Although on the ground it is often feasible to discern and measure the general outline of the vernal pool depression even when not flooded, the digitization of pool boundaries from remotely sensed imagery is highly dependent on the water level at the time of imagery acquisition. Discussion of Errors Remotely sensed vernal pool surveys have many advantages, but they also have limitations. The ability to discern a potential vernal pool on remotely sensed imagery is dependent upon the size and shape of an individual pool, and the contrast with its surroundings and the larger landscape context, as well as the inherent spatial and spectral characteristics of the remotely sensed imagery. Two types of mapping errors are common: (1) errors of commission (i.e., pools mapped from the remotely sensed imagery that were not pools; also known as false positives); and (2) errors of omission (i.e., pools that exist in the field but not mapped from the remotely sensed imagery; also know as false negatives). The only way to evaluate errors in remotely sensed data is through ground surveys. Errors of commission are either features that were not bodies of water, such as large tree shadows or cellar holes (Burne 2001), or features that were bodies of water but that did not meet the physical or biological definition of a vernal pool. Classification of water bodies in the latter category is entirely dependent on the goals of the survey and rules that govern the designation of a feature as a vernal pool. An example is official designation of vernal pool habitat for purposes of administering wetlands protection regulations. If specific indicator species are required to be present and they are not documented, the regulations do not provide protection for the pool. A single field visit to verify biological function — to detect presence of indicator species — can not be viewed as determinative if no indicators are detected. Yearly variation in water level, in breeding effort by resident species, timing of field surveys, and numbers of other factors (including observer skill and effects of weather), all affect the results. Brooks et al. (1998) reported that interpreter experience and image quality were the most important characteristics that affected rates of commission. It is therefore very difficult to generate conclusive data on the rates of commission and to design remote survey approaches that eliminate such errors. Errors of omission occur when features are inadvertently overlooked, falsely mistaken for another land cover feature and not mapped, or are too small to be discernable. The ability to discern vernal pools is enhanced by the use of spring-time leaf-off photography; optimal weather and precipitation conditions prior to image acquisition is needed to ensure that the vernal pools are flooded. Even under dry conditions, stereo viewing enhances the identification of depressions (i.e., potential

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pools) in areas of high relief. Interpretation and mapping of vernal pools is hampered in areas of evergreen vegetation and mixed forests where the forest floor is obscured (Tiner 1990; Calhoun et al. 2003). Other landscape and pool characteristics, such as low topographic relief or diffuse pool margins, can lead to errors of omission. Examples of omission errors can be seen in the Massachusetts potential vernal pool data (Color Plate 3). Using visual interpretation of 1:12,000 CIR stereo-pairs, Burne (2001) found that pools as small as 14 m (45 ft) or less in diameter could be identified, but 30 m (100 ft) was a more reliable limit of detection. Lathrop et al. (2005) found the median diameter of pools at the small size limit of detection to be on the order of 9 to 12 m (30 to 40 ft) using 1 meter resolution DOQQs.

FIELD IDENTIFICATION Remotely sensed approaches provide an initial screening tool to identify potential vernal pools. Often, land use planning and wildlife management decisions will require field verification of biological function or physical criteria. Before receiving conservation protection under governmental regulations (where they exist), potential vernal pools often must meet explicit biological criteria (Chapter 10, Mahaney and Klemens; Chapter 16, Calhoun and Reilly). When this is the case, extensive fieldchecking by ground-based survey is required. Field checking confirms the accuracy of the mapping and documents errors of commission, and to some extent, omission. One great advantage of ground-based surveying is the ability of the field observer to examine and weigh the biological as well as the physical evidence, and therefore have a higher degree of certainty about the habitat function of the vernal pool feature. Field confirmation efforts can be affected by a number of problems, including access to interpreted pools, seasonality of biological evidence, and metapopulation dynamics that function at the landscape-scale (for example, some pools may lack indicator species in some years and be recolonized in others). When conducting field verification of interpreted pools, it is important to plan surveys and evaluate results in the context of these factors. Field Survey Techniques Field-based surveys can function as stand-alone survey and mapping efforts, or as a companion to the remotely sensed approaches described above. Ground-based surveys may be conducted through spot-checking of probable locations based on prior information, such as remotely sensed data, or through systematic transect surveys. The latter approach is most feasible at smaller geographic scales, and should be directed by the goals and means of the organization attempting the survey. Spotchecking entails navigating to suspected vernal pool locations previously identified through remote sensing-based mapping effort, prior investigation of wetland, topographic, or soil maps, or spring-time road surveys during periods of high breeding and calling activity of vernal pool amphibian species. Ground-based spot checking can be an effective means of determining errors of commission, but it is not a good method for determining errors of omission. Evaluation of errors of omission requires an exhaustive survey of the study area. Surveys using parallel transects are

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recommended. The distance between adjacent transect lines is a compromise between efficiently covering the survey area and ensuring that vernal pools are not overlooked in the intratransect spaces. Distances between transects will vary with the ability of an observer to see through the forest (i.e., in open forests, transects may be farther apart). Obviously, such a systematic ground survey can be a timeand personnel-intensive proposition if a large area is to be inventoried. Systematic ground surveys can be targeted and made more time-effective if surficial geology or other biophysical characteristics are used to identify regions with high probability of containing vernal pools (Grant 2005; Chapter 2, Rheinhardt and Hollands). This approach is appropriate for small scale, parcel-based surveys or surveys of particular properties such as public parks, conservation holdings, or other management units. GIS can be used to do coarse landscape-scale evaluation of potential vernal pool density to help direct ground survey effort, and is also a very useful tool for overlaying protected open space data (where available) to help direct ground survey effort away from lands where access will be a significant constraint. Once a vernal pool has been located on the ground, its location should be recorded through sketch mapping onto a suitable base map (i.e., orthophoto map or topographic map) or preferably, with a global positioning system (GPS) receiver. GPS technology can be used to record the geographic coordinates (i.e., latitude and longitude or UTM easting and northing) of a feature’s location with much greater accuracy and precision than simple sketch mapping. GPS is an invaluable aid for both spot-checking and systematic transect surveying and complements GIS-based mapping efforts. For example, point locations or transect line coordinates can be easily uploaded to the GPS to support navigation in the field. Likewise, the coordinate location of vernal pools located in the field can be recorded by GPS and later downloaded for input to a GIS for mapping purposes. The spatial accuracy of the GPS coordinates depends on: (1) the configuration of the GPS satellites at the time of acquisition, (2) the number of individual satellite fixes, (3) whether the GPS is differentially corrected through postprocessing or is WAAS (wide area augmentation system) enabled, and (4) amount of obstructing forest cover or terrain. Higher spatial accuracy can be obtained by collecting multiple fixes and averaging the results and using a WAAS-enabled GPS or differentially correcting the data. WAAS-enabled GPS receivers can collect data on the order of +/– 5 m (16.4 ft) error while differentially corrected data is on the order of +/– 1 m (3.3 ft) spatial accuracy. For information on collecting GPS data and integrating the data into a GIS, consult a good textbook on the subject, such as Kennedy (2002). As GPS equipment decreases in price and complexity, it is being adopted by the outdoors-oriented public and can be easily incorporated into citizen-science pool mapping efforts. For example, as part of the New Jersey statewide vernal pool mapping effort, Rutgers University developed an interactive Internet mapping Web site to aid the citizen volunteer corps in field-checking the remotely sensed map of potential vernal pools (Lathrop et al. 2005). The Web map enables database querying, panning, and zooming to various scales and exhibits a number of geographic layers, including aerial photography and NWI maps. Volunteers can visually locate pools and query the map to get the pool’s unique ID code number and UTM coordinate (http://www.dbcrssa.rutgers.edu/ims/vernal/viewer.htm). The UTM

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coordinate location can be downloaded to a GPS receiver to aid navigation in the field. The pool’s ID number is directly linked to a survey form that can either be downloaded and printed or filled out and submitted online. In addition, locations of vernal pools observed in the field by citizen volunteers but omitted from the original mapping can be uploaded to add to the GIS database after a quality assurance review by state officials, in much the same way that the Massachusetts vernal pool certification process is conducted (Text Box 4.2).

TEXT BOX 4.2 Case Study: Vernal Pool Mapping in Massachusetts Massachusetts was the first state to conduct a comprehensive, statewide survey of vernal pools and to develop a large-scale database of vernal pool locations. Statewide salamander surveys conducted in the early 1980s awakened an interest in protecting habitat for amphibians, specifically spotted salamanders (Ambystoma maculatum). This interest has led to the inclusion of protection for vernal pools under the state Wetlands Protection Act and a vernal pool certification process (see Burne and Griffith 2005 for details). Between 1988 and 1998, 1,778 vernal pools had been officially certified in Massachusetts. However, it became apparent that the certification process was under-representing pool occurrences based on an assumption that pool distribution was likely to be relatively uniform across the state (Figure 4.1).

FIGURE 4.1 Certified vernal pools (2003 data) in Massachusetts (N = 3,097). Each point representing a certified vernal pool is projected at approximately 1600 m (5,240 ft) diameter.

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Based on the success of some researchers in using aerial photographs to identify vernal pools (Stone 1992, Brooks et al. 1998), the state undertook an effort to conduct a statewide survey to better assess the distribution of vernal pools, and to provide a database that advances protection of vernal pools. Pilot studies were conducted in 1998 and 1999, using existing Massachusetts Department of Environmental Protection (DEP) 1:12,000 scale leaf-off CIR stereo photographs. There were 100 photographs randomly selected and interpreted; 300 potential vernal pools were field checked. The studies showed very low errors of commission for features that were not water bodies (<3%) and commission rates of less than 15% for water bodies that could not be shown to provide breeding habitat based on a single spring field visit. It should be noted that this rate would be expected to go down if site visits were conducted on negative pools in multiple years. There was nonsignificant variation in errors of commission between different ecoregions across the state (NHESP unpublished data). No attempt was made to determine errors of omission in these studies because Stone had shown extreme variance in errors of omission due to highly nonrandom distribution of pools across the landscape. Approximately one third of the state had CIR photography at the initiation of the survey, which had been acquired by the state DEP for its Wetlands Conservancy Mapping program. The Natural Heritage and Endangered Species Program (NHESP) contracted a private firm to fly over two southeastern Massachusetts counties in spring 2000 and make a second flight of the remainder of the state in spring 2001 at a total photo acquisition cost (including free use of existing photography) of approximately $30,000. Aerials acquired in 2000 were quite late, and the first blush of deciduous canopy cover affected photo quality. Interpretation was done by one investigator, over the course of approximately three months, on to acetate overlays taped to the face of hard-copy stereo photo images. Digitization was conducted by three technicians over a three to four month period. Pool centroids were transferred by heads-up, on-screen digitizing onto B&W digital orthophotos in ArcView 3.1 software. The statewide survey of potential vernal pools was completed in 2001 (Burne 2001), resulting in the identification of approximately 29,600 potential vernal pools or approximately 1.1/km2 (2.8/mi2) (Figure 4.2). Pool distribution is fairly uniform across the landscape, but there are areas of high pool density in the north- and southeastern portions of the state, and lower densities around highly urbanized centers and in western regions of the state, including the Berkshire hills. This data provides an overview of the number and distribution of potential vernal pools in Massachusetts that was never possible prior to the survey. The survey and digitizing process resulted in a statewide data layer that is available as an ArcView shapefile from the Massachusetts office of Geographic Information Systems (MassGIS, www.mass.gov/gis). Data were also distributed through the NHESP on a stand-alone ArcView runtime data viewer with complete USGS topographic map coverage for the project area. Both survey methods (remote sensing and citizen-driven certification process) used by Massachusetts result in qualitatively different data; field-based approaches identify vernal pools that have had physical and biological criteria verified, and remotely sensedbased approaches identify pools that are likely to meet the physical and biological criteria based on their aerial signature. When developing survey or inventory strategies to protect vernal pools, the field-verified data resulting from the certification model is highly accurate, though extremely time-consuming, both in data collection and in data confirmation and management. In contrast, the aerial photo survey method of vernal pool

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FIGURE 4.2 Potential vernal pool density in Massachusetts is approximately 1.1/km2 (2.8/mi2). This 259 km2 (100 mi2) area in eastern Massachusetts contains 368 potential vernal pools (pvp), a density of 1.42 pvp/km2 (3.68 pvp/mi2). Each point representing a potential vernal pool is projected at approximately 130 m (426 ft) diameter.

inventory is an efficient approach for depicting numbers and distribution of vernal pools on the landscape developed in a relatively short period of time, but at the cost of far greater uncertainty.

CONSERVATION RECOMMENDATIONS Vernal pool surveys conducted by remote sensing are valuable at many scales, and can be accomplished for increasingly little expense as imaging becomes more widely available and accessible. We strongly recommend conducting field verification of data produced by remote sensing to calibrate image quality and characteristics to

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on-the-ground conditions prior to, or during interpretation, and also postproduction to ascertain rates of commission. This is a critical step in establishing the accuracy and quality of interpreted data. This can be done at fairly small geographic scales if image quality and time of capture is consistent across the study area. Large study areas, as in a statewide survey, are likely to result in geographic artifacts in error rates and should be considered in evaluating the results of field confirmation efforts. Surveys that result in comprehensive locational data for specific areas, at any scale, can be used as a baseline for long-term environmental monitoring. Imagery captured subsequent to the images used in the initial survey can easily be used to monitor loss of breeding habitat and the surrounding upland nonbreeding habitat matrix, or to evaluate number and distribution of pools prior to the survey (Kent and Mast 2005). Survey data can also be an extremely useful tool in evaluating landscape-scale parameters such as isolation of pools from nearest neighbors, clustering, and upland nonbreeding habitat availability (Baldwin et al. 2006). Incorporating vernal pool locational data generated either remotely or via ground survey into a GIS is an extremely valuable step and can then facilitate a vast array of landscape-scale analyses, assist in conservation planning, habitat monitoring, and threats analysis.

SUMMARY Remote and field identification of vernal pools provides an information base for understanding the distribution of these habitats at different landscape scales. Remotely sensed data can be used as the foundation of field-based surveys or for planning and conservation practices without extensive field checking if the techniques employed in the remote surveys have been confirmed to be accurate. The choice of vernal pool mapping technique should match the goals of the study. Strictly ground-based surveys may be sufficient for studies of small geographic areas. However, studies for areas larger than single properties will greatly benefit from the incorporation of remotely sensed imagery. Stereo-viewing of hardcopy aerial photographs and mapping onto standard base maps provides a low-tech approach that can be applied almost anywhere, and can then be digitized for incorporation into a GIS. With the increasing availability of CIR DOQQ imagery and desktop GIS mapping software, on-screen visual interpretation and digitization mapping techniques can easily be adopted to meet the information needs of individual towns to entire states (Chapter 14, Baldwin et al.). Remotely sensed and ground-based vernal survey techniques should be complementary. Regardless of the survey technique employed, it is important that the data be in a form that can be easily captured and input to a GIS. As GIS finds increasing application in land use planning and natural resources conservation at all levels of management jurisdiction, it is important that information concerning vernal pools be included in GIS databases so that vernal pools do not continue to fall through the regulatory and planning cracks. As the vernal pool mapping and certification process continues, this evolving database will become increasingly valuable in enhancing our understanding of the status of pool-dependent biota. The ultimate conservation potential for these data will be enormous as they are incorporated into

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larger landscape level wildlife protection efforts as well as other state and local land use planning and management activities.

ACKNOWLEDGMENTS We gratefully acknowledge Henry Woolsey, Patricia Huckery, Janice Stone, Betsy Colburn, Leo Kenney, Steve Meyer, and Jack Buckley for their contributions to the Massachusetts Potential Vernal Pool Survey, and Paul Montesano, John Bognar, Mike Mills, Eric Stiles, Jason Tesauro and Brian Zarate, who were all instrumental in implementing the New Jersey Vernal Pools Mapping Project. We would like to thank Paul Zedler and two anonymous reviewers for their constructive manuscript suggestions.

REFERENCES Baldwin, R., Calhoun, A.J.K., and deMaynadier, P.G. (2006). Conservation planning for amphibian species with complex habitat requirements: a case study using movements and habitat selection of the wood frog (Rana sylvatica). Journal of Herpetology 40: 443–454. Brooks, R.T., Stone, J., and Lyons, P. (1998). An inventory of seasonal forest ponds on the Quabbin reservoir watershed, MA. Northeast Naturalist 5(3): 219–230. Brown, L.J. and Jung, R.E. (2005). An introduction to Mid-Atlantic seasonal pools. U.S. Environmental Protection Agency, Fort Meade, MD. EPA/903/B-05/001. 92 pp. Burne, M.R. (2001). Massachusetts aerial photo survey of potential vernal pools. Massachusetts Division of Fisheries and Wildlife, Natural Heritage and Endangered Species Program, Westborough, MA. Burne, M.R. and Griffin, C.R. (2005a). Habitat associations of pool-breeding amphibians in eastern Massachusetts, USA. Wetlands Ecology and Management 13: 247–259. Burne, M.R. and Griffin, C.R. (2005b). Protecting vernal pools: a model from Massachusetts, USA. Wetlands Ecology and Management 13: 367–375. Calhoun, A.J.K. and deMaynadier, P. (2004). Forestry habitat management guidelines for vernal pool wildlife. MCA Technical Paper No. 6, Metropolitan Conservation Alliance, Wildlife Conservation Society, Bronx, New York. Calhoun, A.J.K., Walls, T., McCollough, M., and Stockwell, S. (2003). Developing conservation strategies for vernal pools: a Maine case study. Wetlands 23: 70–81. Compton, B.W., Cushman, S.A., and McGarigal, K. (2003). A model of vernal pool connectivity for amphibians in western Massachusetts. Tenth Annual Meeting of the Wildlife Society, Burlington, VT. Donahue, D.F. (1997). A guide to the identification and protection of vernal pool wetlands of Connecticut. Connecticut Forest Stewardship Program, West Hartford, CT. Grant, E.H.C. (2005). Correlates of vernal pool occurrence in the Massachusetts landscape. Wetlands 25: 480–487. Kennedy, M. (2002). The Global Positioning System and GIS: An Introduction. CRC Press, Boca Raton, FL. Kenney, L.P. (1994). Wicked big puddles: a guide to the study and certification of vernal pools. Vernal Pool Association. Peabody, MA. http://www.vernalpool.org.

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Kent, B.J. and Mast, J.N. (2005). Wetland change analysis of San Dieguito Lagoon, California, USA: 1928–1994. Wetlands 25(3): 780–787. Lathrop, R.G., Montesano, P., Tesauro, J., and Zarate, B. (2005). Statewide mapping and assessment of vernal pools: a New Jersey case study. Journal of Environmental Management 76: 230–238. http://www.dbcrssa.rutgers.edu/ims/vernal. Milton, R.G., Belanger, L., Crevier, Y., Helle, R., Hurley, J., and Kazmerik, B.H. (2003). Development of a remotely-sensed wetland inventory and classification system for Canada. Backscatter 14(1): 32–34. http://www.wetkit.net/modules/4/index.php. National Digital Orthophoto Program (NDOP). (2005). http://www.ndop.gov/index.html. Natural Resources Canada. (2005). National Air Photo Library. http://airphotos.nrcan.gc.ca/ index_e.php. Pawlak, E.M. (1998). Remote sensing and vernal pools. In Fellman, B. (Ed.) Our Hidden Wetland: The Proceedings of a Symposium on Vernal Pools in Connecticut. Yale University and the Connecticut Department of Environmental Protection. Hartford, CT, pp. 20–21. Stone, J.S. (1992). Vernal pools in Massachusetts: aerial photographic identification, biological and physiographic characteristics, and state certification criteria. M.S. thesis, University of Massachusetts, Amherst, MA. Strong, L.L. and Cowardin, L.M. (1995). Improving prairie pond counts with aerial video and global positioning systems. Journal of Wildlife Management 59(4): 708–719. Tappan, A. and Marchand, M. (2004). Identification and documentation of vernal pools in New Hampshire (second edition). New Hampshire Fish and Game Department, Nongame and Endangered Wildlife Program. Concord, NH. Tiner, R.W., Jr. (1990). Use of high-altitude aerial photography for inventorying forested wetlands in the United States. Forest Ecology and Management 33,34: 593–604. Tiner, R.W. (1997). NWI Maps: What they tell us. National Wetlands Newsletter, 19(2): 7–12. U.S. Department of Agriculture (USDA). (2005). http://datagateway.nrcs.usda.gov/GatewayHome.html. U.S. Geological Survey (USGS). (2005). http://edcw2ks51.cr.usgs.gov/Website/orthoimagery/.

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Section II Biological Setting: Principal Flora and Fauna

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Flora of Northeastern Vernal Pools Andrew Cutko and Thomas J. Rawinski

CONTENTS Characteristic Flora..................................................................................................73 Vegetation Types and Classification........................................................................73 Canadian National Vegetation Classification ..............................................75 U.S. National Wetlands Inventory (NWI) ...................................................75 National Vegetation Classification (NVC) ..................................................76 State Natural Heritage Classifications.........................................................76 Importance of Physical Factors and Biogeography on Vegetation Structure and Composition......................................................................................77 Biogeography...............................................................................................77 Hydroperiod .................................................................................................78 Basin Size and Canopy Closure..................................................................79 Substrate.......................................................................................................79 Surrounding Vegetation ...............................................................................80 Zonation .......................................................................................................80 Adaptations ..................................................................................................82 Floristic Diversity at Multiple Scales......................................................................82 Genetic Diversity .........................................................................................83 Conservation Implications .......................................................................................83 Rare Plants ...................................................................................................84 Rare Ecological Associations (Natural Communities) and Systems..........85 Relationship of Vegetation Type to Faunal Associates ...............................85 Vegetation in Disturbed Vernal Pools .........................................................86 Invasive Plant Species .................................................................................86 Summary ..................................................................................................................87 Acknowledgments....................................................................................................88 References................................................................................................................88

For many naturalists the term vernal pool brings to mind a spring chorus of frogs or a woodland puddle of wriggling tadpoles. Yet northeastern vernal pools support a wide variety of plant species and vegetation communities, representing a rich flora that reflects the full spectrum of broader wetland types in the region (Cutko 1997; 71

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FIGURE 5.1 The uncommon featherfoil (Hottonia inflata) is well adapted to the changing conditions of vernal pools because it has no attachment to the substrate and inflated fruiting stems that protrude out of the water. (Photo by Don Cameron.)

VT DEC 2003). This flora includes rarer vernal pool specialists, such as featherfoil (Hottonia inflata) and the colorful Plymouth gentian (Sabatia kennedyana), as well as hundreds of more cosmopolitan wetland species such as red maple (Acer rubrum) and royal fern (Osmunda regalis) (Figure 5.1). Vernal pools are commonly defined by their characteristic animal assemblages. Despite the fact that many vernal pool plant species have unique adaptations that reflect the complex ecological conditions and processes of these habitats, vernal pool vegetation has often been overlooked in research and conservation efforts. In one of the few studies attempting to associate vernal pool fauna with flora, Ray and Evans (2004) found no significant correspondence of faunal communities with vegetation types. They concluded that it is possible, if not likely, that vernal pool vegetation may be less important than the surrounding landscape in influencing vernal pool invertebrate communities. Furthermore, for the habitat needs of the broader suite of vernal pool-associated invertebrates and amphibians, it is likely that

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the structure and phenology (timing of flowering, fruiting, and growth) of vernal pool flora are more important (e.g., for the function of egg attachment) than the plant species composition per se. Nonetheless, in light of the broad floristic diversity of vernal pools and the rarity of some associated plant species, these vegetation communities are worthy of conservation attention in their own right. The purpose of this chapter is to provide an overview of the characteristic flora, vegetation-based classifications, abiotic and biogeographic relationships, and conservation implications of vegetation of northeastern vernal pools.

CHARACTERISTIC FLORA Wetlands meeting the various definitions of vernal pools used by regulators or scientists occur by the tens of thousands across the glaciated Northeast. With so many examples over such a large area, the total flora is quite large, consisting of hundreds of species. On a broad scale, vernal pool floras reflect the biogeographic region in which they occur. On a smaller scale, the plants reflect particular site conditions, surrounding landscapes, and disturbance histories. Many vernal pool plant species are quite rare (Table 5.1), as are some of the plant communities. For example, plant species such as Plymouth gentian, New Jersey rush (Juncus caesariensis), and narrow-leaved fragrant goldenrod (Euthamia tenuifolia) are restricted to sandy, ephemeral pools of the northeastern coastal plain and do not occur further inland. Vernal pool plants play an important role in pool ecology by providing structure for fauna (e.g., woody and herbaceous vegetation, downed woody debris), creating organic matter as substrate, and influencing evapotranspiration. Knowing the plant life of vernal pools is undeniably important in understanding the full biotic complexity of pools, and toward this end we have prepared a comprehensive list of plant species at least occasionally associated with vernal pools in northeastern landscapes (Appendix 5.1). This list is compiled from the literature, unpublished data, and our own professional field surveys throughout the region. It is important to note that no vernal pool obligate plant species (i.e., those restricted to vernal pools) have been documented. Consequently, all species listed in Appendix 5.1 occur in some or many other kinds of wetlands.

VEGETATION TYPES AND CLASSIFICATION In an effort to simplify the complexities of the natural world, ecologists impose structure or organization on dynamic living systems by classifying them into like groups. Multiple levels of living systems have been classified, ranging from cells to species, natural communities, landscapes, and biomes. In any classification system, it is necessary to portray shades of gray as black and white in order to satisfy our need for order. Numerous natural community and ecosystem classifications exist at international, national, state, and local scales (Grossman et al. 1998). Such classifications serve multiple purposes in conservation planning and help to ensure that the full range of

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TABLE 5.1 At-Risk Plant Species Associated with Seasonal Wetlands

Latin Name

Common Name

Global Rank1

Carex decomposita

Cypress-knee sedge

G3

Coreopsis rosea

Rose coreopsis

G3

Dicanthelium hirstii Eleocharis nitida

Hirst’s panic-grass Slender spikerush

G1 G3G4

Eleocharis wolfii

Wolf spikerush

G3G4

Euthamia galetorum

Narrow-leaf fragrant goldenrod Virginia sneezeweed Creeping St. John’s-wort

G3

Helenium virginicum Hypericum adpressum

Iris lacustris Dwarf lake iris Juncus caesariensis New Jersey rush Lycopodiella margueritiae Northern prostrate clubmoss Lycopodiella subappressa Northern appressed clubmoss Muhlenbergia torreyana Torrey’s dropseed Oligoneuron houghtonii Houghton’s goldenrod Platanthera leucophaea Eastern prairie-whitefringed orchid Rhexia aristosa Awned meadow beauty Sabatia kennedyana Plymouth gentian Sagittaria teres Slender arrowhead Schoenoplectus hallii Hall’s bulrush Northeastern bulrush Scirpus ancistrochaetus

Federal Status (U.S.)

Candidate

G2 G3

Threatened

G3 G2 G2

Threatened

G2 G3 G3 G3 G3 G3 G3 G2 G3

Distribution (Northeast U.S. and Adjacent Canada) IL, IN, MI, MO, NY, OH MA, NH, NY, PA, RI, NS NJ ME, MI, MN, NH, VT, WI, NF, NS, ON, PE, QC IA, IL, IN, MN, MO, OH, WI MA, NS MO CT, IL, IN, MA, MO, NJ, NY, PA, RI MI, WI, ON NJ, NS MI, PA IN, MI, OH

NJ MI, NY, ON ME, MI, NY, OH, PA, WI, ON NJ MA, RI, NS MA, NH, NH, NY, RI MA, MI, WI Endangered MA, NH, NY, PA, VT

Threatened Threatened

1

Global rank refers to the global rarity of the species, as assigned by the conservation organization NatureServe. G2 species are considered globally “imperiled” and G3 species are considered globally “vulnerable”. See www.natureserve.org for details.

global and regional habitats is conserved. For example, classification of vernal pools may be useful for conserving pools differing in hydrology, geologic setting, and vegetation type as well as for stratifying pools for research and monitoring purposes. Reflecting numerous studies, Colburn (2004) noted that “vernal pools defy simple classification,” and there remains no uniformly accepted vegetation classification for vernal pools. Nonetheless, there are often enough recurring commonalities among pools or differences between them that groupings may be assigned. Numerous

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classification systems have been suggested, based on a variety of characteristics, including geography, physical setting, hydrology (Chapter 2, Rheinhardt and Hollands; and Chapter 3, Leibowitz and Brooks), flora and fauna (Ray and Evans 2004), or combinations of biotic and abiotic characteristics. Like many other vernal pool classifications, Colburn’s proposed groups (2004) combine aspects of plant structure and composition, focusing on long-lived perennials. She suggested a vegetation classification of six pool types for the glaciated northeastern U.S. based on personal observation and literature review: mixed canopy pools, red maple swamps, coniferous swamp pools, shrub swamp pools, water willow (Decadon verticillatus) pools, and marsh pools. Similarly, Klotz and Falkenstein (2002) focused on plant physiognomy in recognizing four vegetation types in Pennsylvania pools: shrub swamp (chiefly buttonbush), marsh (chiefly graminoids), aquatic vegetation, and bare (unvegetated). However, some or all of these types may be present in any given pool, limiting the utility of this scheme for distinguishing among pools. Some classifications use landscape setting as a proxy for vegetation. In New Hampshire, for example, Dan Sperduto (New Hampshire Natural Heritage Inventory [NHI], personal communication) suggested just two vernal pool types: vernal woodland pool and vernal floodplain pool. He noted that whereas all examples in New Hampshire do not fit these types perfectly, the floristic differences between the types reflect opposite ends of a gradient that exists among isolated basin wetlands. In both types there is typically some fluctuation from year to year in terms of vegetative expression, but the cycle of wet and dry years converges around a set of distinctive zones that is described by characteristic vegetation forms. Other prominent vegetation classifications and their treatments of vernal pools are discussed below.

CANADIAN NATIONAL VEGETATION CLASSIFICATION The Canadian National Vegetation Classification (CNVC), a parallel effort to the U.S. National Vegetation Classification, remains in development but currently does not recognize vernal pool vegetation as a distinct association. Like many classification systems in the U.S., the CNVC assumes that vernal pools span a number of vegetation types (e.g., outwash plain ponds, basin marshes) or treats them merely as fine-scaled inclusions within broader upland types (Sean Basquil, Atlantic Canada Conservation Data Centre, personal communication).

U.S. NATIONAL WETLANDS INVENTORY (NWI) This hierarchical classification, developed by the U.S. Fish and Wildlife Service (Cowardin et al. 1979), is based primarily on vegetation structure. Colburn (2004) describes the NWI classes most often associated with vernal pools, including palustrine and riverine systems that cover a variety of nonvegetated, herbaceous, shrub–scrub, and forested types. While “seasonally flooded” is the most common hydrologic modifier for vernal pools, other pools may be classified as “intermittently flooded” or “semi-permanently flooded,” depending on the setting (Chapter 4, Burne and Lathrop).

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NATIONAL VEGETATION CLASSIFICATION (NVC) The U.S. National Vegetation Classification (Grossman et al. 1998; Jennings et al. 2003; NatureServe 2004) presents a hierarchical approach that currently includes more than 4500 vegetation types nationwide. This classification system has been adopted by the Federal Geographic Data Committee for use by all U.S. federal agencies. The NVC has several levels, but two are commonly used in conservation applications: finer scale plant “associations” and coarser-scaled ecological “systems.” Because vernal pools do not hold together neatly as definable, repeatable vegetation units, there are no vernal pool equivalents in either the NVC ecological association or system classifications. Comer et al. (2005) concluded that the high variability of vernal pools (hydrologic, substrate, floristic) from occurrence to occurrence makes vernal pool classification problematic. Consequently, in the NVC vernal pools are often considered small inclusions within broader associations or systems. However, a review of hundreds of NVC associations suggests that dozens of classifications, ranging from calcareous sinkholes to floodplain oxbows to peatland laggs, may include vernal pool functions for fauna (Comer et al. 2005).

STATE NATURAL HERITAGE CLASSIFICATIONS Many natural heritage programs in the northeastern U.S. have developed natural community classifications unique to their own states (e.g., Thompson and Sorensen 2000). These classifications are based primarily on vascular vegetation. Although state classifications are linked or “cross-walked” to the NVC, the scale of each state classification varies considerably, with some states assigning community associations that are broader than the NVC, and others using associations that are narrower. Treatment of vernal pools differs among state heritage classifications. The three northeastern states (Maine, Pennsylvania, and Vermont) that have attempted to classify vernal pool vegetation using plot data and quantitative methods agree with Comer et al. (2005) that pools are difficult to classify by vegetation type. For 18 pools in Pennsylvania, Ray and Evans (2004) found that no meaningful parsing of pools by vegetation type was noted by either cluster analysis or nonmetric multidimensional scaling. In assessing the vegetation of 33 pools in Maine, Cutko (1997) concluded that vernal pool vegetation is not substantially different from vegetation that occurs in other wetland types, although several selected wetland plants may be more likely than others to occur in vernal pools. Accordingly, in comparison with other wetland types, Maine vernal pool vegetation does not comprise a distinct natural community type. Among 28 pools in Vermont, there was extreme variability in both the plant species composition and the overall abundance of plants, with ordination attempts depicting few clear distinctions among pools (VT DEC 2003). Vermont researchers concluded that vascular plants and bryophytes were not effective in classifying either reference quality or disturbed seasonal pools. Several states (Pennsylvania, Vermont, Rhode Island, Massachusetts, and New York) list just one vernal pool community type, which aligns closely with an “upland isolated” vernal pool concept (Fike 1999; Thompson and Sorensen 2000; Edinger et al. 2002;

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VT DEC 2003; Enser and Lundgren 2005). Other states, such as New Hampshire, recognize only a few vernal pool variants: vernal woodland pool and vernal floodplain pool (Dan Sperduto, New Hampshire NHI, personal communication).

IMPORTANCE OF PHYSICAL FACTORS AND BIOGEOGRAPHY ON VEGETATION STRUCTURE AND COMPOSITION Floristic patterns in vernal pools reflect a number of related factors, including biogeography, hydrologic regime, basin size and canopy closure, substrate conditions, and surrounding vegetation. Although vernal pool vegetation varies considerably throughout the glaciated Northeast, these physical factors often result in repeated patterns or zones of vegetation in pools. Vegetation zones are defined by characteristic plant species adapted to the particular biotic and physical factors present in each zone. Each of the factors influencing vernal pool vegetation is discussed below.

BIOGEOGRAPHY The floristic differences among vernal pools over large geographic areas reflect the more general alignment of vegetation communities across broad biophysical regions (i.e., regions characterized by similar climate and physiography, such as the Allegheny Plateau or Lower New England regions). In fact, over large geographic areas, such as the glaciated Northeast, the biophysical region may be the dominant determinant of vernal pool vegetation, and even within relatively small regions, vernal pool vegetation may show strong influences of climatic and biophysical factors (Cutko 1997, Rawinski 1997). Upland isolated pools in Quebec, for example, might be distinguished by red maple, speckled alder (Alnus incana ssp. rugosa), and sensitive fern (Onoclea sensibilis), whereas upland isolated pools in Connecticut might be characterized by red maple, buttonbush (Cephalanthus occidentalis), and long sedge (Carex folliculata). Klotz and Falkenstein (2002) compared the floristic lists of central Pennsylvania pools with lists for similar ponds in western Maryland and eastern West Virginia (Bartgis 1992), the Shenendoah Valley of Virginia (Rawinski 1992), and Carolina bays (coastal plain ponds) of Delaware and Maryland (Bowman 2000). The percent of floristic similarity was directly correlated with geographic proximity and physiographic proximity; that is, pools closer to one another and at similar elevations tended to support similar plant species. This finding suggests that to capture the full variety of vernal pool vegetation types, it is important to conserve pools at multiple landscape positions and across multiple ecoregions. In Maine, an ordination of vernal pool vegetation in two study areas 320 km (173 mi) apart indicated that geographic separation accounted for 62% of the difference between the vascular floras (Cutko 1997). The two study areas shared fewer than one third of the plant species in common, with plants such as Massachusetts fern (Thelypteris palustris) occurring only in the southern study area where it is at its northern range limit. Moreover, the geographic differences in study areas were so strong that they obscured other sources of vegetation variation among pools,

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including pool physical setting. In Virginia, two vernal pool study areas separated by 210 km (113 mi) and 370 m (689 ft) in elevation contained only 23% of the species in common (Rawinski 1997). In both Maine and Virginia, the vegetation of vernal pools was a variable subset of the wetland vegetation characteristic of the biophysical region in which the pools were located.

HYDROPERIOD Hydrology is one of the most important influences on wetland formation and maintenance (Mitch and Gosselink 1992), and this is particularly true for the vegetation of vernal pools. Timing and duration of inundation, and frequency of flooding, will determine both faunal and vegetation communities (Chapter 2, Rheinhardt and Hollands; and Chapter 3, Leibowitz and Brooks). Pool depth and canopy cover correlate strongly with hydroperiod (timing and duration of inundation) in many areas, with deeper, open pools typically holding water until later in the spring (Skidds and Golet 2004). In a study of 65 Rhode Island pools over three years, Mitchell (2005) tested the utility of plants as indicators to predict pool hydroperiod. Mitchell’s underlying assumption was that, given the inherent hydrologic fluctuations in vernal pools, plants may serve as more stable, measurable, and efficient indicators of pool hydrology than measuring the water level itself. He assigned the 34 plant species encountered in these 65 pools to four different hydroperiods, based on the depth at which the plants were most often observed. He used the individual plant species and the overall vegetation communities to assign pools to one of four different hydroperiod classes that reflected the flooding duration of pools. His results yielded a 72% accuracy rate for predicting hydroperiod class. Not surprisingly, the aquatic plants occupying the deepest parts of the pool were the most effective plant indicators. However, some pools across multiple hydrologic gradients have no vascular vegetation at all (Skidds and Golet 2004), complicating efforts to associate plants with certain pool types. Mitchell (2005) found that pools visited several years in a row show considerable yearly variation in the vegetation, in large part reflecting annual variations in hydrology. Although he found little year-to-year variation in the vegetation of the deepest zone, the vegetation of other zones showed higher annual variability. In Virginia vernal pools, Rawinski (1997) found a mean of 31 plant species per pool in 1995 and only 23.7 in the same pools in 1996; 26 plant species (primarily annuals) documented in 1995 failed to appear a year later because prolonged high water levels likely impeded germination. In addition, the vast majority of tree seedlings observed in 1995 were killed by prolonged flooding in 1996. However, several of the herbaceous plants appeared again during drawdown in the fall of 1997, and others were found in 1997 that had not been seen in either of the two previous years. Klotz and Falkenstein (2002) found similar annual variability in Pennsylvania, where the final year of a four-year study yielded drier pools with much higher species abundance and species cover than previously observed. These findings suggest that some vernal pool species are able to persist in the seed bank and germinate profusely in years when favorable hydrologic conditions return. The sometimes dramatic annual

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variations in vernal pool flora are reflected in pools in other regions as well (Keeley and Zedler 1996). The response of individual plants to hydrological changes may have broader implications for the vernal pool vegetation community, based on interspecific relationships between species. Rawinski (1997), for example, documented a perennial, mat-forming creeping rush (Juncus repens) that appeared to preclude the establishment of certain annuals in 1995. Prolonged flooding in 1996 reduced the cover of this rush, and in 1997 the rush was nearly absent, which allowed colonization by annuals. Not all annuals, however, require dewatered conditions for germination and growth. The small beggar-ticks plant (Bidens discoidea) is able to establish itself on moss-covered stems of buttonbush and grow as an epiphyte (Hickler 1999). Collectively, these studies suggest that repeated visits to pools over multiple years are needed to document the full richness of plant species present. Moreover, these studies confirm that the life history strategies of some vernal pool plants are strongly linked to hydroperiod.

BASIN SIZE

AND

CANOPY CLOSURE

Because shade tolerance is such an important characteristic of plant species and plant communities, it is not surprising that vernal pool vegetation strongly reflects levels of pool shading. Vernal pools in the our region include closed-canopy pools, open canopy pools in glacial outwash plains, partially open shrub wetlands in floodplain oxbows, and many variants in between. For pools in forested settings, the amount of shade is often closely associated with pool size and shape, with larger, more circular pools typically receiving less shade than smaller, irregular ones (Skidds and Golet 2004). In Vermont, an ordination of 23 vernal pool attributes for 28 pools indicated that perimeter and canopy closure were inversely correlated, and both were among the strongest influences on the vernal pool vegetation community (VT DEC 2003). While few other studies have attempted to isolate the influences of shade from pool size and shape or relate these factors to pool vegetation, it is likely that shade-tolerant plants increase in relative dominance in the peripheral/shaded zones of open pools. Klotz and Falkensteins (2002) “overarch” zone of vegetation in Pennsylvania pools, for instance, suggests that the sparse flora within this zone is adapted to both the shade from overhanging trees and the low to intermediate level of inundation near the pool borders. The type of forest canopy may also be an important influence on vernal pool vegetation. The year-round shade from softwood trees such as eastern hemlock (Tsuga canadensis) and spruce (Picea spp.), particularly on the south side of pools in northern regions, may delay the germination or growth of plants in comparison to pools with hardwood canopies that allow greater sunlight to reach the forest floor, at least in the early spring (A. Cutko, personal observation).

SUBSTRATE Vernal pools in our region may exist in association with a variety of substrate conditions, including upland isolated pools with shallow bedrock depressions,

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compact basal till, lowland glacial marine sediments, organic soils, glacial outwash plains, and others (Chapter 2, Rheinhardt and Hollands). Furthermore, there is considerable variation in substrate depth, chemistry, and composition, all of which may influence vernal pool vegetation. Greater depth of organic substrate is expected to occur in pools with more permanent inundation, in part because of the lack of oxidation and decomposition of leaf litter (VT DEC 2003). In Pennsylvania, Klotz and Falkenstein (2002) found low nutrient availability and low pH across the entire moisture gradient of pools, whereas particle size analysis indicated high sand content in the upland forest and high clay, silt, or organic matter content in the basins. The deeper organic soils and fine-grained mineral soils in pool basins typically retain moisture once the pools dry out. As a result, these soil types may be more likely to support permanent wetland shrubs and perennial herbs. Likewise, in peaty settings (e.g., borders of bogs and fens, glacial kettleholes, portions of spruce flats overlaying glacial marine soils) pools may be dominated by Sphagnum spp. and acid-tolerant heath shrubs such as leatherleaf (Chamaedaphne calyculata), sheep laurel (Kalmia angustifolia), cranberries (Vaccinium spp.), or great laurel (Rhododendron maximum). In contrast, coarse-grained soils with low organic content and low nutrient availability are prone to desiccation and are more likely to support annual species. Vegetation in these latter pool types is likely to exhibit greater seasonal and annual variation and may be more influenced by hydroperiod.

SURROUNDING VEGETATION The distinctness of vernal pool vegetation from surrounding areas is likely to be dependent upon the pool setting. Upland-isolated pools are more likely to support different species than those embedded in broader wetland complexes, where wetland plants may occupy multiple niches. In 16 Pennsylvania pools Klotz and Falkenstein (2002) found that the tree and shrub species diversity of adjacent upland forests exceeded the tree diversity of pools, but the total vascular plant diversity was just the opposite; it was higher in the pools and lower in the uplands. This finding reflects the relatively low diversity of wetland woody plant species compared to wetland herbaceous diversity.

ZONATION The varying tolerance of plant species to inundation influences the partitioning of plants along a hydrological (elevational) gradient, with obligate wetland plants such as duckweeds (Lemna spp.) and pondweeds (Potamogeton spp.) occupying the wettest (deepest) parts of the pools and facultative wetland plants (i.e., plants adapted to both wetlands and uplands) such as New York fern (Thelypteris novae-boracensis) and beggars ticks (Bidens spp.) occupying the upland borders (A. Cutko and T. Rawinski, personal observation). These affiliations to specific elevations along the pool borders help to explain the pronounced zonation that occurs in many pools.

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Basin Size/ Amount of Sunlight

Long-stalked false pimpernell -

Buttonbush Swamp loosestrife Plume grass Maryland meadowsweet

Loblolly pine Willow oak Listera

Persimmon Panicgrass

Sweetgum Blackgum Cypress

Three-way sedge Ticklegrass-

Organic Soils

Un-vegetated/leaf litter

Water Permanence

FIGURE 5.2 Relationship of basin size, sunlight, and water permanence to typical vernal pool plant communities in the Mid-Atlantic United States. (T. Rawinski, personal observation.)

More generally, the combined factors of pool morphology, hydrology, and shading often result in distinct zones of pool vegetation, even if the plant communities are different from region to region. For example, in Pennsylvaina, Klotz and Falkenstein (2002) found a repeated pattern of three concentric zones: a central zone, an overarch zone, and basal area (perimeter) zone. The central open-canopy zone occurs in basins deep enough to impede tree germination and wide enough to prevent canopy closure over the pool; it is often smaller than the gap in tree cover. Similarly, Rawinski (1997) suggested a repeated pattern of vegetation zones in Virginia pools (Figure 5.2), reflecting both hydroperiod and physical setting. Whereas the vegetation types depicted in Figure 5.2 are specific to the region studied, the general pattern of zonation, influenced by basin size and water permanence holds true throughout the region. Zones may be particularly pronounced in pools with gradual basin morphologies, such as coastal plain ponds. However, the number of zones, their proportions, and their distinctness varies considerably among pool types; some uniformly shallow pools may lack the deep zone vegetation altogether, whereas steep-sided deep pools such as artificial borrow pits or farm ponds may feature aquatic vegetation as the dominant type and lack others. In deeper pools, the perimeter of trees that forms the transition to uplands may be the most distinct, reliable, and lasting vegetation zone. Tree roots are sensitive to prolonged inundation, and trees in the central part of a pool may not withstand multiple years of inundation (Skidds and Golet 2004). Of 39 deciduous tree species studied over an eight-year period in Tennessee pools (Hall and Smith 1955), none was able to survive if the root crown was inundated for more than half the growing season. Moreover, red maple can only withstand such prolonged flooding for a single growing season (Teskey and Hinckley 1978) and is unlikely to survive in the central part of deeper pools.

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ADAPTATIONS Many vernal pool plant species possess a number of adaptations that enable them to tolerate fluctuating water levels. Some species germinate during an initial wetting phase or during a subsequent inundation phase. Many of these are “R-selected” annual species whose reproductive strategy is to produce thousands of seeds when conditions are appropriate. As a result, the annual timing and duration of these reproductive phases may play key roles in determining community composition, particularly since some species may lie dormant for years until favorable conditions exist (Keeley and Zedler 1996). Numerous species that germinate during inundation (e.g., quillworts (Isoetes spp.) and related genera) are characterized by round, rigid leaves with well-developed airspaces. This growth form apparently enhances carbon assimilation (Keeley and Zedler 1996) and provides structural support for apical leaves to reach air or for reproducing stems to disperse seeds. When water level drops later in the season, some of these species undergo a metamorphosis whereby stout, cylindrical foliage is replaced with flat foliage; this change is often associated with flowering (Keeley and Zedler 1996). Other vernal pool plant species, such as mermaid weed (Proserpinaca palustris) and some pondweeds (Potamogeton spp.), have morphologically different submersed, floating, and emergent leaves that are all present at the same time. In contrast to the “R-selected” annuals noted above, vernal pools also support a number of “K-selected” (i.e., low reproductive capacity) perennial herbs and shrubs with well developed root systems able to tolerate periodic drought. Examples of the latter include highbush blueberry, winterberry, and buttonbush.

FLORISTIC DIVERSITY AT MULTIPLE SCALES Floristic diversity of vernal pools exists at multiple scales: diversity within a single pool, diversity among pools within a biophysical region, and diversity among groups of pools in different regions. Often, the diversity of plant species within a given pool (alpha diversity) is quite low in our region. Many pools studied in Maine and Vermont, for example, support only a few plant species, and some pools have no plants at all (Cutko 1997; VT DEC 2003). In contrast to alpha diversity, variation between pools within a biophysical region (beta diversity) may be much higher, reflecting the variation in physical pool settings. One method of gauging the beta diversity of pool floras is to divide the total number of vernal pool species encountered in a study area by the mean number of species per pool. The resulting quotient provides an indication of the number of pools needed to account for the full species richness of the study area. If all species occurred in each pool, the beta diversity would be 1 (the lowest possible quotient); a higher number indicates greater diversity. In a study of 35 Virginia pools, Rawinski (1997) found a total of 131 vascular plant species and a mean of 31.9 species per pool, yielding a beta diversity of 4.1. In other words, if each species were to occur in only one pool, it would take 4.1 pools to capture the full species diversity of the study area. Unfortunately, similar comparative measures are not available from other studies.

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Finally, in the Northeast there is substantial floristic variation among pools across different biophysical regions (gamma diversity). As discussed previously, this variation in vernal pool floras is a reflection of the broader differences between vegetation communities across biophysical regions.

GENETIC DIVERSITY Conceptually, reduced genetic variation among plants may decrease the potential for persistence in the face of long-term environmental change or short-term stresses such as herbivores or pathogens (Elam 1998). Consequently, if populations with higher levels of intra-population genetic diversity are more persistent, these populations may be especially important in conservation efforts. Similarly, if genetic variation is high among plant populations in different pools (i.e., interpopulation diversity), this diversity underscores the importance of conserving many types of pools. From an applied standpoint, it is often not practical to determine the level of genetic variation among plants in a study area, and we found no studies on this topic from the Northeast. In California studies, vernal pools exhibit many of the factors consistent with plant populations with low intrapopulation genetic diversity, including small and fluctuating population sizes (i.e., population bottlenecks), presence of inbreeding taxa, and geographic isolation (Elam 1998). In fact, dispersal between pools through insect pollination and seed dissemination both appear limited, with a maximum dispersal distance observed of 80 m (263 ft), and typical dispersal distances much smaller (Kesseli 1992, Elam 1998). California studies also indicate that vernal pool plants may exhibit intrapopulation differentiation over very short distances (2–5 m; 6.6–16.4 ft) from pool center to pool periphery (Linhart 1976). Maintenance of differences when these same plants are grown in uniform greenhouse conditions suggests that the observed variation is genetically based, at least in part. In natural conditions, this differentiation occurred over just a few meters, over which gene flow by seed and pollen undoubtedly takes place. These findings suggest that the gene flow may be overcome by strong selective effects of micro-habitat conditions (Elam 1998). In contrast, similar differentiation was not observed in selected plants from a disturbed California pool, where seed mixing was probably extensive (Linhart 1976). Although it is premature to make strong conclusions about genetic variation in plants of northeastern vernal pools, theoretical and empirical evidence from California pools suggests that vernal pool plant populations may have high variation both between pools (caused by limited dispersal) and even within the same pool (caused by gradients in abiotic conditions) (Linhart 1976; Elam 1998).

CONSERVATION IMPLICATIONS The conservation value of vernal pool flora has often been overlooked because of the focus on vernal pool fauna. However, vernal pools provide important habitat for numerous rare plants and natural communities throughout the Northeast and adjacent Canada, and many of the same conservation concerns facing reptiles, invertebrates, and amphibians are relevant to vernal pool flora.

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Chief among these concerns is the lack of uniform regulation and inconsistent enforcement for small, geographically isolated wetlands (Comer et al. 2005). In a report to the U.S. Environmental Protection Agency by NatureServe, Comer et al. (2005) assessed the biodiversity associated with “geographically isolated wetlands” to better gauge the potential effect of the 2001 Supreme Court decision to remove these wetlands from the jurisdiction of the Clean Water Act (Chapter 10, Mahaney and Klemens). Although the definition used in Comer et al. (2005) for isolated wetlands includes some permanently flooded wetland types and is thus somewhat broader than the definition for vernal pools used in this volume, the findings of this study highlight the importance and sensitivity of isolated wetlands. Among other conclusions, Comer et al. (2005) noted that 29% of the wetland types within the U.S. met the definition of geographically isolated and may therefore no longer be protected by the Clean Water Act. Other conservation issues specifically relevant to vernal pool flora are reviewed below, including the presence of rare plants, rare vegetation communities, relationships between flora and fauna, and threats from invasive plants.

RARE PLANTS There have been no systematic assessments of rare plants associated with vernal pools in our region. In assessing isolated wetlands, Comer et al. (2005) identified 241 at-risk plant species (i.e., considered “critically imperiled, imperiled, or rare”; that is, ranked G1–G3) as being closely associated with these wetland types. This list includes 73 plants recognized under the U.S Endangered Species Act (ESA). Nationally, 37 of the ESA listed plant species are obligate to isolated wetlands (Comer et al. 2005). Within our region, 20 at-risk species are closely associated with isolated wetlands, including five listed under the ESA (Comer et al. 2005) (Table 5.1). Within each state of this region, the percentage of at-risk plant species associated with isolated wetlands varies considerably and is highest in New Jersey, New York, and Massachusetts, with 14, eight, and eight species, respectively. In addition to documenting globally at-risk plants, many states and provinces track the status of state or provincially rare species (i.e., those ranked S1–S3 by natural heritage programs or conservation data centers). Although no rare plants in the Northeast are considered vernal pool obligates, hundreds are facultatively associated with vernal pools. In Pennsylvania, for instance, five state-rare plants are known to inhabit vernal pools, and in Maine four state-rare plants are closely associated with vernal pools and their borders. In southern Nova Scotia, vernal pools support a number of plant species, such as sweet pepperbush (Clethra alnifolia), smooth alder (Alnus serrulata), netted chain fern (Woodwardia aereolata), and threenerved joe-pye weed (Eupatorium dubium), which are geographic outliers well beyond their core range in the mid-Atlantic U.S. These species are all tracked as rare by the Atlantic Canada Conservation Data Centre (S. Basquil, Atlantic Conservation Data Centre, personal communication). Many states and provinces do not regulate the taking of state- or provincially-listed rare plants on private lands, so the protection of these species is the responsibility of the landowner.

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Rare plant populations associated with vernal pools endure many risk factors, including several that affect reptiles and amphibians, such as habitat loss and fragmentation (e.g., disruption of seed dispersal patterns), stochastic factors affecting small population sizes (e.g., poor seed years), predation (herbivory), and alteration of habitat by invasive plants. Although no northeastern studies have demonstrated the metapopulation pattern of interbreeding plants associated with vernal pool complexes, it is possible that proximal pools support some widely dispersing plant species that share genetic material through pollination and seed dispersal. The New England Wild Flower Society’s Plant Conservation Program has generated approximately 100 detailed, on-line conservation and research plans for the most imperiled plant species in the region. Several of these species occur in vernal pools, namely Barratt’s sedge (Carex barrattii), false hop sedge (Carex lupuliformis), dwarf burhead (Echinodorus tenellus), three-angled spikerush (Eleocharis tricostata), creeping St. John’s-wort (Hypericum adpressum), many fruited false-loosestrife (Ludwigia polycarpa), swamp cottonwood (Populus heterophylla), toothcup (Rotala ramosior), inundated beak-rush (Rhynchospora inundata), and slender marsh-pink (Sabatia campanulata). Each plan presents a clear conservation strategy including protection, monitoring, and management components, and the approach is worthy of being emulated in other regions.

RARE ECOLOGICAL ASSOCIATIONS (NATURAL COMMUNITIES)

AND

SYSTEMS

For the U.S. as a whole, Comer et al. (2005) described 279 globally at-risk vegetation associations (9% of all plant community types classified in the U.S. National Vegetation Classification (NVC) as being associated with “isolated wetlands”; 92 of these at-risk associations are in the glaciated Northeast. A similar analysis is currently not feasible for Canada because the Canadian National Vegetation Classification is still in development. Nationally, 81 ecological systems, or 13% of the systems that have been described for the U.S., meet the definition of geographically isolated wetlands; 24 of these systems are in the glaciated Northeast. As noted previously, NatureServe’s definition of isolated wetlands includes a broad variety of vegetation associations and system types, ranging from Acadian–Appalachian Conifer Seepage Forest (i.e., cedar seep) to Atlantic Coastal Plain Northern Pondshore (Comer et al. 2005). From a faunal perspective, only some of these vegetation associations and systems qualify as vernal pools. A closer inspection of the isolated wetland types indicates that roughly one in four may serve some important characteristic vernal pool wildlife functions. Nonetheless, extrapolating from this estimate, it is likely that dozens of the 92 at risk NVC associations and several ecological systems have close affinities to vernal pools.

RELATIONSHIP

OF

VEGETATION TYPE

TO

FAUNAL ASSOCIATES

Although certain groups of amphibians and invertebrates have been strongly associated with vernal pools in general, it is unclear whether vernal pool wildlife species show affinities for specific pool vegetation types. Nonetheless, there may be some cases in which rare or endangered animal species are associated with vegetation

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characteristic of specific pool types. Sphagnum-dominated vernal pools, for example, are often associated with four-toed salamanders (Hemidactylium scutatum) (Petranka 1998) and ringed-boghaunter dragonflies (Williamsonia lintneri) (deMaynadier and Carlson 1998; Lundgren 1999). Pools dominated by Atlantic white cedar (Chamaecyparis thyoides) in our region may host populations of the rare Hessel’s hairstreak butterfly (Callophrys hesseli). Further study of vernal pool animal–vegetation relationships is likely to be productive, especially among invertebrates that often require highly specialized microhabitat conditions.

VEGETATION

IN

DISTURBED VERNAL POOLS

As vernal pool vegetation is adapted to specific conditions of substrate, hydrology, and sunlight, it is logical that disturbances would alter the flora of a pool. In assessing the effects of anthropogenic degradation on a Pennsylvania pool, Klotz and Freese (2006) studied a pool that occasionally receives overflow from an abandoned iron ore pit. The resulting sedimentation has decreased the depth of the southern end of the pool and caused the soils to have a higher ratio of sand to clay and a lower percent of organic matter. As a result, plant species richness is slightly higher in the southern half of the pool than in the northern half and includes many species characteristic of more nutrient-rich wetland types, such as fresh marshes along creek margins, as well as two nonnative grass species: Agrostis stolonifera and A. gigantea. In Maine, artificial roadside “borrow pits” (that may provide limited vernal pool functions from a faunal standpoint) have sand and gravel substrates that tend to support a greater proportion of annual species than adjacent natural pools (A. Cutko, personal observation).

INVASIVE PLANT SPECIES Vernal pools are not free from the threat of nonnative plant species (and invasive natives), and like many other habitats, disturbance is often a key agent of introduction. Glossy buckthorn (Rhamnus frangula) and rusty willow (Salix cinerea ssp. oleifolia) have dramatically altered the structure, and perhaps function, of vernal pools in eastern Massachusetts (Rawinski, personal observation). In some pools, aggressive clonal species such as reed canary grass (Phalaris arundinacea), common reed (Phragmites australis), and cattails (Typha latifolia, T. angustifolia, T. glauca) grow densely to the exclusion of other species, potentially altering habitat for both plants and animals and altering pool hydrology through increased evapo-transpiration (T. Rawinski, personal observation; Vasconcelos and Calhoun 2006). These species are often associated with disturbance or occur in eutrophic habitats. Consequently, minimizing disturbance and preventing the influx of nutrients should be important considerations in conserving these vernal pools, particularly when there is a non-native species seed source in the vicinity (Table 5.2).

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TABLE 5.2 Frequent Nonnative Plants in Northeastern Vernal Pools Latin Name

Common Name

Bidens tripartita Erysimum cheiranthoides Frangula alnus Hydrocharis morsus-ranae Iris pseudacorus Lysimachia nummularia Lythrum salicaria Mentha arvensis Myosotis scorpioides Ranunculus repens Rhamnus cathartica Rorippa nasturtium-aquaticum Salix alba Salix cinerea spp. oleifolia Setaria glauca Solanum dulcamara

Leafy-bracted beggar-ticks Wormseed-mustard Glossy buckthorn Frog’s-bit Yellow iris Moneywort Purple loosestrife Field-mint True forget-me-not Creeping buttercup Common buckthorn Water-cress White willow Rusty willow Yellow foxtail Bittersweet nightshade

Invasiveness Moderate Low Moderate No No Low High Low Low Moderate Moderate Low Low Moderate Low High

Source: Adapted from Comer et al. 2005.

SUMMARY Although often overlooked, the floristic characteristics of vernal pools are just as complex, varied, and dynamic as the faunal and hydrologic components. Vernal pools in this region support hundreds of plant species adapted to fluctuating hydrologic conditions, multiple substrate types, and a range of shade conditions. Although none of these plant species are known to be obligate pool species, many have strong affinities for vernal pool settings. Numerous vernal pool plant species are aligned in recognizable zones radiating out from the pool center, ranging from aquatic macrophytes of the deepest pools to short-lived annuals that inhabit sandy pool perimeters. Aside from these in-pool zones, multiple attempts to classify vernal pools using vegetation have been complicated by the wide spectrum of vernal pool abiotic conditions and the broad differences in vernal pool flora across geographic regions (not to mention that some pools have no vegetation at all!). As a result, there is no uniformly accepted classification of vernal pools from a vegetation standpoint. Several states use their own classifications for vernal pools, including components of pool vegetation, physical setting, and hydrology. Despite the comparatively scant research on vernal pool vegetation in contrast to vernal pool fauna, there are compelling reasons to conserve vernal pool flora. Within our region, 23 at-risk (i.e., G1–G3) plant species are closely associated with

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isolated wetlands, including five plants listed under the U.S. Endangered Species Act (Comer et al. 2005). Moreover, 92 at-risk vegetation associations in the glaciated Northeast are associated with isolated wetlands (Comer et al. 2005). Many of the same threats that face vernal pool fauna, such as direct disturbance, habitat fragmentation, pollution, and invasive species, may significantly degrade the quality of vernal pool flora.

ACKNOWLEDGMENTS The authors would like to thank the numerous members of the natural heritage network and The Nature Conservancy who provided useful information and data on vernal pool vegetation. These contributors include Sean Basquill of the Atlantic Canada Conservation Data Centre, Don Cameron of the Maine Natural Areas Program, Greg Edinger of the New York Natural Heritage Program, Julie Lundgren of The Nature Conservancy, Eric Sorensen of the Vermont Non-game and Natural Heritage Program, Dan Sperduto of the New Hampshire Natural Heritage Inventory, Pat Swain of the Massachusetts Natural Heritage and Endangered Species Program, and Sally Ray and Ephraim Zimmerman of the Pennsylvania Natural Heritage Program. Lisa St. Hilaire provided a thorough and thoughtful review. In addition, editors Aram Calhoun and Phillip deMaynadier provided constructive guidance and direction throughout the process.

REFERENCES Bartgis, R.L. (1992). The endangered sedge Scirpus ancistrochaetus and the flora of sinkhole ponds in Maryland and West Virginia. Castanea 57: 46–51. Bowman, P. (2000). Draft natural community classification for Delaware. Unpublished manuscript. Delaware Natural Heritage Program, Department of Natural Resources and Environmental Control, Dover, DE. Colburn, E. (2004). Vernal Pools: Natural History and Conservation. The McDonald and Woodward Publishing Company, Blacksburg, VA. Comer, P., Goodin, K., Tomaino, A., Hammerson, G., Kittel, G., Minnard, S., Nordman, C., Pyne, M., Reid, M., Sneddon, L., and Snow, K. (2005). Biodiversity Values of Geographically Isolated Wetlands in the U.S. NatureServe, Arlington VA. Cowardin, L.M., Carter, V., Golet, F.C., and LaRoe, E.T. (1979). Classification of wetlands and deepwater habitats of the U.S. U.S. Fish and Wildlife Service, Washington, D.C. FWS/OBS-79/31. Cutko, A. (1997). A Botanical and Natural Community Assessment of Selected Vernal Pools in Maine. Maine Department of Inland Fisheries and Wildlife and Maine Natural Areas Program, Augusta, ME. deMaynadier, P. and Carlson, B. (1998). A survey and evaluation of habitat potential for Williamsonia lintneri in southern Maine, 1998. A report to the Maine Department of Inland Fisheries and Wildlife, Bangor, ME. Edinger, G.J., Evans, D.J., Gebauer, S., Howard, T.G., Hunt, D.M., and Olivero, A.M. (2002). Ecological Communities of New York State, second edition. New York Natural Heritage Program, NYS Department of Environmental Conservation, Latham, NY.

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Elam, D. (1998). Population genetics of vernal pool plants: theory, data, and conservation implications. In Witham, C.C. (Ed.) Ecology, Conservation and Management of Vernal Pool Ecosystems, California Native Plant Society, Sacramento, CA, pp. 180–189. Enser, R. and Lundgren, J.A. (2005). Natural communities of Rhode Island. Rhode Island Natural Heritage Program, Department of Environmental Management and The Nature Conservancy of Rhode Island, Providence, RI. Fike, J. (1999). Terrestrial and Palustrine Plant Communities of Pennsylvania. Pennsylvania Department of Conservation and Natural Resources, The Nature Conservancy, and Western Pennsylvania Conservancy, Harrisburg, PA. Grossman, D.H., Faber-Langenden, D., Weakley, A.S., Anderson, M., Bourgeron, P., Crawford, R., Goodin, K., Landaal, S., Metzler, K., Patterson, K.D., Pyne, M., Reid, M., and Sneddon, L. (1998). International classification of ecological communities; terrestrial vegetation of the U.S., Vol. I. The national vegetation classification system: development, status, and applications. The Nature Conservancy, Arlington, VA. Hall, T.F. and Smith, G.E. (1955). Effects of flooding on woody plants, West Sandy Dewatering Project, Kentucky Reservoir. Journal of Forestry 53: 281–285. Hickler, M.G. (1999). Notes on the habits and life-history of Bidens discoidea: an epiphyte in Massachusetts floodplain ponds. Rhodora 101: 298–299. Jennings, M., Loucks, O., Glenn-Lewin, D., Peet, R., Faber-Langendoen, D., Grossman, D., Damman, A., Barbour, M., Pfister, R., Walker, M., Talbot, S., Walker, J., Hartshorn, G., Waggoner, G., Abrams, M., Hill, A., Roberts, D., Tart, D. (2003). Guidelines for describing associations and alliances of the U.S. National Vegetation Classification. The Ecological Society of America Vegetation Classification Panel, Version 2.0. Keeley, J.E. and Zedler, P.H. (1996). Characterization and global distribution of vernal pools. In Witham, C.W., Boulder, E.T., Belk, D., Ferren, W.R., Jr., and Ornduff, R. (Eds.). Ecology, Conservation, and Management of Vernal Pool Ecosystems — Conference Proceedings. Native Plant Society, Sacramento, CA, pp. 1–4. Kesseli, R.V. (1992). Population biology and conservation of rare plants. In Jain, S.K. and Botsford, L.W. (Eds.) Applied Population Biology. Kluwer Academic Publishers, Boston, MA, pp. 69–90. Klotz, L. and Falkenstein. T. (2002). Vegetation of the southern part of the Mount Cydonia Ponds Natural Area, Michaux State Forest, Franklin County, Pennsylvania. Unpublished manuscript. Klotz, L. and Freese, D. (2006). Vegetation and soils of Thomson Hollow Pond, a disturbed seasonal wetland in Michaux State Forest, Cumberland County, Pennsylvania. Unpublished manuscript. Linhart, Y.B. (1976). Evolutionary studies of plant populations in vernal pools. In Jain, S.K. (Ed.). Vernal Pools: Their Ecology and Conservation. Institute of Ecology, University of California. Davis, CA, pp. 40–46. Lundgren, J. (1999). Characterization and Classification of Plant Communities Inhabited by the Ringed Boghaunter Dragonfly (Williamsonia lintneri). The Nature Conservancy Eastern Regional Office, Boston, MA. Mitch, W.J. and Gosselink, J.G. (1992). Wetlands. 2nd ed. Van Nostrand Reinhold, New York. Mitchell, J. 2005. Using Plants as Indicators of Hydroperiod Class and Amphibian Habitat Suitability in Rhode Island Seasonal Ponds. M.S. thesis, University of Rhode Island, Kingston, RI. NatureServe. (2004). A Working Classification of Terrestrial Ecological Systems in the Conterminous U.S. International Terrestrial Ecological Systems Classification. NatureServe, Arlington, VA.

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Petranka, J.W. (1998). Salamanders of the U.S. and Canada. Smithsonian Institution Press, Washington, D.C. Ray, E., and Evans, R. (2004). Refining the natural communities in Pennsylvania through zoological studies on State Lands: a study of vernal pool invertebrates in the Central Appalachian Ecoregion. Pennsylvania Natural Heritage Program, Middletown, PA. Rawinski, T.J. (1992). A classification of Virginia’s indigenous biotic communities: vegetated terrestrial, palustrine, and estuarine community classes. Natural Heritage Technical Report 92-21. Virginia Department of Conservation and Recreation, Division of Natural Heritage, Richmond, VA. Rawinski, T.J. (1997). Vegetation ecology of the Grafton Ponds, York County, Virginia, with notes on waterfowl use. Natural Heritage Technical Report 97-10. Virginia Department of Conservation and Recreation, Division of Natural Heritage, Richmond. Unpublished report submitted to the U.S. Environmental Protection Agency, Washington, D.C. Skidds, D.E. and Golet, F.C. (2004). Estimating hydroperiod suitability for breeding amphibians in southern Rhode Island seasonal forest ponds. Wetlands Ecology and Management 13: 349–366. Teskey, R.O. and Hinckley, T.M. (1978). Impact of water level changes on woody riparian and wetland communities. Eastern Deciduous Forest Region, Vol. 4. U.S. Fish and Wildlife Service, Office of Biological Services, Washington, D.C. FWS/OBS-78/87. Thompson, E.H. and Sorenson, E.R. (2000). Wetland, Woodland, Wildland: A Guide to the Natural Communities of Vermont. University Press of New England, Hanover, NH. Vasconcelos, D. and Calhoun, J.K. (2006). Monitoring created seasonal pools for functional success: a six-year case study of amphibian responses, Sears Island, Maine, USA. Wetlands 26: 992–1003. Vermont Department of Environmental Conservation (VT DEC) and Vermont Department of Wildlife Non-Game and Natural Heritage Program, (2003). Vermont Wetlands BioAssessment Program: An Evaluation of the Chemical, Physical, and Biological Characteristics of Seasonal Pools and Northern White Cedar Swamps, Waterbury, VT.

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APPENDIX 5.1 Plant Species Associated with Vernal Pools in Northeastern North America Scientific Name

Common Name

Abies balsamea

Balsam fir

Acalypha rhomboidea Acer rubrum Acer saccharinum

Broad three-seeded mercury Red maple Silver maple

Agalinis paupercula Agalinis purpurea Agalinis tenuifolia Agrostis hyemalis Agrostis perennans Agrostis scabra Agrostis stolonifera Alisma subcordatum Alnus incana spp. rugosa Alnus serrulata Alopecurus aequalis

Small-flowered gerardia Purple gerardia Slender gerardia Southern ticklegrass Upland bentgrass Northern ticklegrass Creeping bentgrass Water-plantain Speckled alder Smooth alder Short-awned foxtail

Ambrosia artemisiifolia Amelanchier canadensis Andropogon glomeratus Andropogon virginicus Apocynum cannabinum

Ragweed Thicket shadbush Bunched broom-sedge Broom-sedge Indian hemp

Argentina anserina

Silverweed

Arisaema dracontium

Green dragon

Arisaema triphyllum

Jack-in-the-pulpit

Asclepias incarnata Asclepias syriaca Atriplex patula Azolla caroliniana

Swamp milkweed Common milkweed Orache Mosquito-fern

Betula alleghaniensis

Yellow birch

Betula populifolia

Gray birch

Bidens Bidens Bidens Bidens Bidens

Nodding bur-marigold Swamp beggar-ticks Small beggar-ticks Devil’s pitchforks Smooth bur-marigold

cernua connata discoidea frondosa laevis

Habitat Comments Northern pools with peat/muck substrates1 Frequent annual plant species2 A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 Frequent annual plant species2 Atlantic coastal plain pools4 Frequent annual plant species2 A variety of pool habitats A variety of pool habitats A variety of pool habitats Inland saline pools5 A variety of pool habitats A variety of pool habitats Atlantic coastal plain pools4 Mesotrophic to eutrophic (nutrient rich) pools3 Frequent annual plant species2 A variety of pool habitats Atlantic coastal plain pools4 Atlantic coastal plain pools4 Mesotrophic to eutrophic (nutrient rich) pools3 Mesotrophic to eutrophic (nutrient rich) pools3 Mesotrophic to eutrophic (nutrient rich) pools3 Mesotrophic to eutrophic (nutrient rich) pools3 A variety of pool habitats A variety of pool habitats Inland saline pools5 Aquatic macrophytes and semi aquatic pool species6 Northern pools with peat/muck substrates1 Oligotrophic (nutrient poor) pools3 A variety of pool habitats Frequent annual plant species2 Frequent annual plant species2 A variety of pool habitats Frequent annual plant species2

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APPENDIX 5.1 (CONTINUED) Plant Species Associated with Vernal Pools in Northeastern North America Scientific Name

Common Name

Boehmeria cylindrica Boltonia asteroides Brasenia schreberi

False nettle Boltonia Water-shield

Bulboschoenus maritimus Bulbostylis capillaris Calamagrostis canadensis

Prairie bulrush Sand sedge Canada bluejoint

Calamagrostis coarctata Calamagrostis stricta

Reed bluejoint Slim-stem reedgrass

Calla palustris

Wild calla

Caltha palustris Cardamine pensylvanica Carex abscondita Carex albicans var. emmonsii Carex aquatilis Carex atlantica

Marsh-marigold Pennsylvania bittercress Concealed sedge Emmons’ sedge Water sedge Atlantic prickly sedge

Carex baileyi

Bailey’s sedge

Carex barrattii Carex bigelowii

Barratt’s sedge Bigelow’s sedge

Carex bromoides

Broomlike sedge

Carex brunnescens

Brownish sedge

Carex Carex Carex Carex Carex Carex

Button sedge Buxbaum’s sedge Silvery bog sedge Bristly sedge Awned sedge Crowded sedge

bullata buxbaumii canescens comosa crinita cumulata

Carex decomposita Carex disperma Carex echinata

Cypressknee sedge Two-seeded bog sedge Prickly sedge

Carex gracillima Carex grayi

Graceful drooping sedge Gray’s sedge

Carex gynandra

Northern awned sedge

Habitat Comments A variety of pool habitats A variety of pool habitats Aquatic macrophytes and semi aquatic pool species6 Inland saline pools5 Frequent annual plant species2 Oligotrophic (nutrient poor) pools3 Atlantic coastal plain pools4 Northern pools with peat/muck substrates1 Northern pools with peat/muck substrates1 A variety of pool habitats A variety of pool habitats Atlantic coastal plain pools4 Atlantic coastal plain pools4 A variety of pool habitats Oligotrophic (nutrient poor) pools3 Northern pools with peat/muck substrates1 Atlantic coastal plain pools4 Northern pools with peat/muck substrates1 Mesotrophic to eutrophic (nutrient rich) pools3 Northern pools with peat/muck substrates1 Atlantic coastal plain pools4 A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats Oligotrophic (nutrient poor) pools3 A variety of pool habitats A variety of pool habitats Oligotrophic (nutrient poor) pools3 A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 A variety of pool habitats

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APPENDIX 5.1 (CONTINUED) Plant Species Associated with Vernal Pools in Northeastern North America Scientific Name

Common Name

Carex hystericina

Porcupine sedge

Carex intumescens Carex lacustris

Swamp sedge Lakeside sedge

Carex lasiocarpa

Slender woolly-fruited sedge

Carex lenticularis

Shore sedge

Carex longii Carex lupuliformis

Long’s sedge False hop sedge

Carex lupulina Carex lurida Carex magellanica

Hop sedge Sallow sedge Pendant bog sedge

Carex michauxiana

Michaux’s sedge

Carex nigra Carex oligosperma

Black sedge Fewseed sedge

Carex pseudocyperus

Galingale sedge

Carex saxatilis

Russett sedge

Carex Carex Carex Carex Carex Carex

Broom sedge Awl-fruited sedge Walter’s sedge Tussock sedge Blunt broom sedge Three-seeded bog sedge

scoparia stipata striata var. brevis stricta tribuloides trisperma

Carex tuckermanii

Tuckerman’s sedge

Carex utriculata

Beaked sedge

Carex vesicaria Carex viridula

Inflated sedge Little green sedge

Carex vulpinoidea Cephalanthus occidentalis Chamaecyparis thyoides Chamaedaphne calyculata

Fox sedge Buttonbush Atlantic white cedar Leatherleaf

Habitat Comments Mesotrophic to eutrophic (nutrient rich) pools3 A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 Oligotrophic (nutrient poor) pools3 Northern pools with peat/muck substrates1 Atlantic coastal plain pools4 Mesotrophic to eutrophic (nutrient rich) pools3 A variety of pool habitats A variety of pool habitats Northern pools with peat/muck substrates1 Northern pools with peat/muck substrates1 Atlantic coastal plain pools4 Northern pools with peat/muck substrates1 Mesotrophic to eutrophic (nutrient rich) pools3 Northern pools with peat/muck substrates1 A variety of pool habitats A variety of pool habitats Atlantic coastal plain pools4 A variety of pool habitats A variety of pool habitats Northern pools with peat/muck substrates1 Northern pools with peat/muck substrates1 Oligotrophic (nutrient poor) pools3 A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 A variety of pool habitats A variety of pool habitats Atlantic coastal plain pools4 Oligotrophic (nutrient poor) pools3

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APPENDIX 5.1 (CONTINUED) Plant Species Associated with Vernal Pools in Northeastern North America Scientific Name

Common Name

Chamaesyce maculata Chenopodium rubrum Chrysosplenium americanum Cicuta bulbifera Cicuta maculata Cinna arundinacea Cinna latifolia

Milk-purslane Coast-blite Golden saxifrage Bulblet water-hemlock Water-hemlock Broad woodreed Drooping wood-reed

Cladium mariscoides

Twig-rush

Clethra alnifolia Conyza canadensis Coptis trifolia

Sweet pepperbush Horseweed Goldthread

Coreopsis rosea Cornus amomum Cornus sericea

Pink tickseed Silky dogwood Red osier

Cuscuta sp. Cyperus dentatus Cyperus diandrus Cyperus erythrorhizos

A dodder Pondshore flatsedge Red-edged flatsedge Redroot flatsedge

Cyperus esculentus

Yellow flatsedge

Cyperus squarrosus Cyperus strigosus Decodon verticillatus Dichanthelium acuminatum Dichanthelium boreale

Awned flatsedge Straw-colored flatsedge Swamp loosestrife Panic-grass Northern panic-grass

Dichanthelium clandestinum Dichanthelium spretum Digitaria filiformis Diodia teres Diospyros virginiana Drosera filiformis Drosera intermedia

Deer-tongue Smooth anic-grass Slender crabgrass Buttonweed Persimmon Thread-leaf sundew Spatulate-leaved sundew

Drosera rotundifolia

Round-leaved sundew

Dryopteris cristata Dulichium arundinaceum Echinochloa muricata

Crested wood-fern Threeway sedge Small-spiked cockspur

Habitat Comments Frequent annual plant species2 Inland saline pools5 A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats Northern pools with peat/muck substrates1 Oligotrophic (nutrient poor) pools3 Atlantic coastal plain pools4 Frequent annual plant species2 Northern pools with peat/muck substrates1 Atlantic coastal plain pools4 A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 Frequent annual plant species2 A variety of pool habitats Frequent annual plant species2 Mesotrophic to eutrophic (nutrient rich) pools3 Mesotrophic to eutrophic (nutrient rich) pools3 Frequent annual plant species2 A variety of pool habitats A variety of pool habitats A variety of pool habitats Northern pools with peat/muck substrates1 A variety of pool habitats Atlantic coastal plain pools4 Frequent annual plant species2 Frequent annual plant species2 A variety of pool habitats Atlantic coastal plain pools4 Oligotrophic (nutrient poor) pools3 Oligotrophic (nutrient poor) pools3 A variety of pool habitats A variety of pool habitats Frequent annual plant species2

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APPENDIX 5.1 (CONTINUED) Plant Species Associated with Vernal Pools in Northeastern North America Scientific Name

Common Name

Echinochloa walteri Eleocharis acicularis Eleocharis equisetoides Eleocharis melanocarpa Eleocharis microcarpa Eleocharis obtusa Eleocharis olivacea

Walter’s cockspur Little spike-rush Knotted spikerush Black-fruited spike-rush Small-fruit spikerush Soft-stemmed spike-rush Olive spike-rush

Eleocharis parvula Eleocharis quadrangulata Eleocharis robbinsii

Salt pond spike-rush Square-stem spikerush Robbins’ spike-rush

Eleocharis smallii Eleocharis tenuis Eleocharis tricostata Eleocharis tuberculosa Epilobium ciliatum Epilobium leptophyllum Equisetum arvense Equisetum fluviatile Eragrostis hypnoides Erechtites hieraciifolia Eriocaulon aquaticum

Small’s spike-rush Slender spike-rush Three-angled spikerush Tubercled spike-rush Glandular willow-herb Narrow-leaved willow-herb Common horsetail River horsetail Sandbar lovegrass Pilewort Pipewort

Eriophorum tenellum

Rough cotton-grass

Eriophorum virginicum

Tawny cotton-grass

Eupatorium capillifolium Eupatorium maculatum

Small bog-fennel Spotted Joe-pyeweed

Eupatorium perfoliatum Eupatorium pilosum Eurybia radula

Boneset Rough boneset Rough aster

Euthamia tenuifolia Fimbristylis autumnalis Fraxinus americana Fraxinus pennsylvanica

Coastal flat-topped goldenrod Northern fimbry White ash Green ash

Fuirena pumila Galium palustre Galium tinctorium

Annual umbrella-sedge Marsh bedstraw Stiff marsh bedstraw

Habitat Comments Atlantic coastal plain pools4 A variety of pool habitats Atlantic coastal plain pools4 Atlantic coastal plain pools4 Atlantic coastal plain pools4 A variety of pool habitats Oligotrophic (nutrient poor) pools3 Inland saline pools5 Atlantic coastal plain pools4 Oligotrophic (nutrient poor) pools3 A variety of pool habitats A variety of pool habitats Atlantic coastal plain pools4 Atlantic coastal plain pools4 A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats Frequent annual plant species2 Frequent annual plant species2 Oligotrophic (nutrient poor) pools3 Oligotrophic (nutrient poor) pools3 Oligotrophic (nutrient poor) pools3 Atlantic coastal plain pools4 Mesotrophic to eutrophic (nutrient rich) pools3 A variety of pool habitats Atlantic coastal plain pools4 Northern pools with peat/muck substrates1 Atlantic coastal plain pools4 Frequent annual plant species2 A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 Atlantic coastal plain pools4 A variety of pool habitats A variety of pool habitats

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APPENDIX 5.1 (CONTINUED) Plant Species Associated with Vernal Pools in Northeastern North America Scientific Name Gaultheria hispidula Gaylussacia baccata Gaylussacia frondosa Geranium robertianum Glyceria acutiflora Glyceria borealis Glyceria canadensis Glyceria grandis Glyceria obtusa Glyceria septentrionalis Glyceria striata Gnaphalium uliginosum Gratiola aurea Hemicarpha micrantha Hordeum jubatum Hottonia inflata Hydrocotyle americana Hydrocotyle umbellata Hypericum adpressum Hypericum boreale Hypericum canadense Hypericum ellipticum Hypericum gentianoides Hypericum majus Hypericum mutilum Hypericum stragulum Ilex glabra Ilex laevigata Ilex opaca Ilex verticillata Impatiens capensis Iris prismatica Iris versicolor Isoetes engelmannii Isoetes riparia

Common Name Creeping snowberry

Habitat Comments

Northern pools with peat/muck substrates1 Black huckleberry Oligotrophic (nutrient poor) pools3 Dangleberry Atlantic coastal plain pools4 Herb-Robert Mesotrophic to eutrophic (nutrient rich) pools3 Sharp-scaled mannagrass A variety of pool habitats Northern mannagrass Northern pools with peat/muck substrates1 Rattlesnake-grass Oligotrophic (nutrient poor) pools3 Tall mannagrass Mesotrophic to eutrophic (nutrient rich) pools3 Coastal mannagrass Atlantic coastal plain pools4 Eastern mannagrass A variety of pool habitats Fowl meadow-grass A variety of pool habitats Low cudweed Frequent annual plant species2 Golden pert A variety of pool habitats Lakeshore hemicarpha Atlantic coastal plain pools4 Squirrel-tail grass Inland saline pools5 Featherfoil Aquatic macrophytes and semi aquatic pool species6 Swamp pennywort A variety of pool habitats Water pennywort Atlantic coastal plain pools4 Creeping St. John’s-wort Atlantic coastal plain pools4 Nothern dwarf St. John’s-wort A variety of pool habitats Canadian St. John’s-wort A variety of pool habitats Pale St. John’s-wort A variety of pool habitats Orange grass Frequent annual plant species2 Larger Canadian St. John’s-wort A variety of pool habitats Dwarf St. John’s-wort A variety of pool habitats St. Andrew’s cross Atlantic coastal plain pools4 Inkberry Atlantic coastal plain pools4 Smooth winterberry Atlantic coastal plain pools4 American holly Atlantic coastal plain pools4 Winterberry A variety of pool habitats Spotted touch-me-not A variety of pool habitats Slender blue flag Atlantic coastal plain pools4 Northern blue flag A variety of pool habitats Engelmann’s quillwort Aquatic macrophytes and semi aquatic pool species6 Shore quillwort Aquatic macrophytes and semi aquatic pool species6

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APPENDIX 5.1 (CONTINUED) Plant Species Associated with Vernal Pools in Northeastern North America Scientific Name

Common Name

Juncus acuminatus Juncus brevicaudatus

Sharp-fruited rush Short-tailed rush

Juncus canadensis

Canada rush

Juncus Juncus Juncus Juncus

Leathery rush Weak rush Soft rush Thread rush

coriaceus debilis effuses filiformis

Juncus marginatus Juncus militaris Juncus pelocarpus

Grass-leaf rush Bayonet rush Pondshore rush

Kalmia angustifolia

Sheep laurel

Lachnanthes carolina Larix laricina

Redroot Tamarack

Ledum groenlandicum

Labrador tea

Leersia oryzoides Leersia virginica

Rice cut-grass Floodplain cut-grass

Lemna minor

Duckweed

Leptochloa fusca spp. fascicularis Saltpond grass Leucothoe racemosa Swamp fetterbush Lindera benzoin Spicebush Lindernia dubia Lindernia dubia var. anagallidea Liquidambar styraciflua Listera australis Ludwigia alternifolia Ludwigia palustris Ludwigia polycarpa

False pimpernel Long-stalked false pimpernel Sweet gum Southern twayblade Seedbox Water-purslane Many-fruited seedbox

Ludwigia sphaerocarpa Lycopus americanus Lycopus amplectens Lycopus uniflorus Lycopus virginicus Lygodium palmatum

Round-fruited seedbox American water-horehound Pondshore water-horehound Northern water-horehound Virginia water-horehound Climbing fern

Habitat Comments A variety of pool habitats Oligotrophic (nutrient poor) pools3 Oligotrophic (nutrient poor) pools3 Atlantic coastal plain pools4 Atlantic coastal plain pools4 A variety of pool habitats Northern pools with peat/muck substrates1 A variety of pool habitats Atlantic coastal plain pools4 Oligotrophic (nutrient poor) pools3 Oligotrophic (nutrient poor) pools3 Atlantic coastal plain pools4 Northern pools with peat/muck substrates1 Northern pools with peat/muck substrates1 A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 Aquatic macrophytes and semi aquatic pool species6 Inland saline pools5 Atlantic coastal plain pools4 Mesotrophic to eutrophic (nutrient rich) pools3 Frequent annual plant species2 Frequent annual plant species2 Atlantic coastal plain pools4 Atlantic coastal plain pools4 A variety of pool habitats A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 Atlantic coastal plain pools4 A variety of pool habitats Atlantic coastal plain pools4 A variety of pool habitats A variety of pool habitats A variety of pool habitats

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APPENDIX 5.1 (CONTINUED) Plant Species Associated with Vernal Pools in Northeastern North America Scientific Name

Common Name

Lyonia ligustrina Lysimachia hybrida Lysimachia terrestris Maianthemum trifolium

Maleberry Narrow-leaved loosestrife Swamp candles Three-leaved Solomon’s seal

Matteuccia struthiopteris

Ostrich fern

Menyanthes trifoliata

Buckbean

Muhlenbergia uniflora

Pondshore muhly

Myrica gale

Sweet gale

Myriophyllum humile

Lowly water-milfoil

Myriophyllum pinnatum

Pinnate water-milfoil

Najas flexilis

Common naiad

Najas gracillima

Slender naiad

Nemopanthus mucronatus

Common mountain-holly

Neobeckia aquatica

Lake-cress

Nuphar lutea spp. advena

Yellow pond-lily

Nuphar lutea spp. variegata

Variegated yellow water lily

Nymphaea odorata

Fragrant water lily

Nymphoides cordata

Floating heart

Nyssa sylvatica Oldenlandia uniflora Onoclea sensibilis Orontium aquaticum Osmunda cinnamomea Osmunda claytoniana Osmunda regalis Panicum capillare Panicum dichotomiflorum Panicum philadelphicum Panicum rigidulum

Black gum Clustered mille grains Sensitive fern Golden club Cinnamon fern Interrupted fern Royal fern Witch-grass Fall panic-grass Philadelphia panic-grass Flat-stemmed panic-grass

Habitat Comments A variety of pool habitats A variety of pool habitats A variety of pool habitats Northern pools with peat/muck substrates1 Mesotrophic to eutrophic (nutrient rich) pools3 Northern pools with peat/muck substrates1 Oligotrophic (nutrient poor) pools3 Oligotrophic (nutrient poor) pools3 Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 Northern pools with peat/muck substrates1 Mesotrophic to eutrophic (nutrient rich) pools3 Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 A variety of pool habitats Atlantic coastal plain pools4 A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats Frequent annual plant species2 Frequent annual plant species2 Frequent annual plant species2 A variety of pool habitats

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APPENDIX 5.1 (CONTINUED) Plant Species Associated with Vernal Pools in Northeastern North America Scientific Name

Common Name

Panicum rigidulum var. pubescens Redtop panic-grass Panicum verrucosum Warty panic-grass Peltandra virginica Arrow arum Penthorum sedoides Ditch stonecrop Phalaris arundinacea

Reed canary-grass

Photinia melanocarpa

Black chokeberry

Photinia pyrifolia

Red chokeberry

Phragmites australis Picea mariana

Common reed Black spruce

Picea rubens

Red spruce

Pilea pumila

Clearweed

Pinus rigida

Pitch pine

Pinus strobes Poa palustris Polygala cruciata Polygala sanguinea Polygonum amphibium

White pine Fowl-meadow grass Cross-leaved milkwort Common milkwort Water smartweed

Polygonum Polygonum Polygonum Polygonum Polygonum Polygonum Polygonum

Halberd-leaf tearthumb Carey’s smartweed Water-pepper False water-pepper Dock-leaf smartweed Pennsylvania smartweed Dotted smartweed

arifolium careyi hydropiper hydropiperoides lapathifolium pensylvanicum punctatum

Polygonum sagittatum Pontederia cordata

Arrow-leaf tearthumb Pickerel-weed

Populus deltoides

Cottonwood

Populus heterophylla

Swamp cottonwood

Populus tremuloides Potamogeton bicupulatus

Trembling aspen Hairlike pondweed

Habitat Comments Atlantic coastal plain pools4 Atlantic coastal plain pools4 A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 Mesotrophic to eutrophic (nutrient rich) pools3 Oligotrophic (nutrient poor) pools3 Oligotrophic (nutrient poor) pools3 Inland saline pools5 Northern pools with peat/muck substrates1 Northern pools with peat/muck substrates1 Mesotrophic to eutrophic (nutrient rich) pools3 Oligotrophic (nutrient poor) pools3 A variety of pool habitats A variety of pool habitats Atlantic coastal plain pools4 Frequent annual plant species2 Aquatic macrophytes and semi aquatic pool species6 A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 A variety of pool habitats Aquatic macrophytes and semi aquatic pool species6 Mesotrophic to eutrophic (nutrient rich) pools3 Mesotrophic to eutrophic (nutrient rich) pools3 A variety of pool habitats Aquatic macrophytes and semi aquatic pool species6

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APPENDIX 5.1 (CONTINUED) Plant Species Associated with Vernal Pools in Northeastern North America Scientific Name

Common Name

Potamogeton epihydrus

Ribbon-leaf pondweed

Potamogeton gramineus

Grass-leaf pondweed

Potamogeton oakesianus

Oakes’ pondweed

Potamogeton pulcher

Spotted pondweed

Potamogeton pusillus

Tiny pondweed

Proserpinaca palustris

Mermaid-weed

Proserpinaca pectinata Prunella vulgaris Quercus bicolor Quercus macrocarpa

Cut-leaved mermaid-weed Heal-all Swamp white oak Bur oak

Quercus palustris Quercus phellos Ranunculus flabellaris

Pin oak Willow oak Yellow water crowfoot

Ranunculus Ranunculus Ranunculus Ranunculus

Creeping spearwort Bristly buttercup Hooked buttercup Cursed crowfoot

flammula pensylvanicus recurvatus sceleratus

Rhexia virginica Rhododendron canadense

Northern meadow-beauty Rhodora

Rhododendron viscosum

Swamp azlea

Rhynchospora alba

White beaksedge

Rhynchospora capitellata

Brown beaksedge

Rhynchospora macrostachya Rhynchospora scirpoides Rhynchospora torreyana Rorippa palustris

Big-headed horned sedge Longbeak beaksedge Torrey’s beaksedge Marsh yellowcress

Rosa palustris Rotala ramosior Rubus hispidus Rubus pubescens

Swamp rose Tooth-cup Bristly dewberry Swamp dewberry

Habitat Comments Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 Atlantic coastal plain pools4 A variety of pool habitats A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 A variety of pool habitats Atlantic coastal plain pools4 Aquatic macrophytes and semi aquatic pool species6 A variety of pool habitats A variety of pool habitats A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 Atlantic coastal plain pools4 Northern pools with peat/muck substrates1 Oligotrophic (nutrient poor) pools3 Oligotrophic (nutrient poor) pools3 Oligotrophic (nutrient poor) pools3 Atlantic coastal plain pools4 Atlantic coastal plain pools4 Atlantic coastal plain pools4 Mesotrophic to eutrophic (nutrient rich) pools3 A variety of pool habitats Frequent annual plant species2 A variety of pool habitats A variety of pool habitats

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APPENDIX 5.1 (CONTINUED) Plant Species Associated with Vernal Pools in Northeastern North America Scientific Name

Common Name

Rubus setosus

Bog blackberry

Rumex verticillatus

Swamp-dock

Ruppia maritima Sabatia kennedyana Sagittaria cuneata

Ditch-grass Plymouth gentian Wapato arrowhead

Sagittaria engelmanniana Sagittaria graminea

Engelmann’s arrowhead Grass-leaf arrowhead

Sagittaria latifolia Sagittaria teres Salix bebbiana Salix discolor Salix nigra Salix petiolaris Salix sericea Sambucus canadensis Schoenoplectus pungens Schoenoplectus purshianus Schoenoplectus smithii Schoenoplectus subterminalis

Common arrowhead Terete arrowhead Bebb’s willow Large pussy willow Black willow Meadow willow Silky willow Common elderberry Common three-square Pursh’s bulrush Smith’s bulrush Water bulrush

Schoenoplectus tabernaemontani Schoenoplectus torreyi

Soft-stemmed bulrush Torrey’s bulrush

Scirpus ancistrochaetus

Northeastern bulrush

Scirpus atrocinctus

Dusky bulrush

Scirpus Scirpus Scirpus Scirpus Scirpus

Dark green bulrush Wool-grass Spreading bulrush Red-stemmed bulrush Stalked bulrush

atrovirens cyperinus expansus microcarpus pedicellatus

Scleria reticularis Scutellaria lateriflora Senecio pauperculus

Pondshore nut-rush Mad-dog skullcap Balsam ragwort

Sibbaldiopsis tridentata

Three-toothed cinquefoil

Habitat Comments Oligotrophic (nutrient poor) pools3 Mesotrophic to eutrophic (nutrient rich) pools3 Inland saline pools5 Atlantic coastal plain pools4 Mesotrophic to eutrophic (nutrient rich) pools3 Atlantic coastal plain pools4 Oligotrophic (nutrient poor) pools3 A variety of pool habitats Atlantic coastal plain pools4 A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats Frequent annual plant species2 Frequent annual plant species2 Northern pools with peat/muck substrates1 A variety of pool habitats Oligotrophic (nutrient poor) pools3 Oligotrophic (nutrient poor) pools3 Northern pools with peat/muck substrates1 A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats Oligotrophic (nutrient poor) pools3 Atlantic coastal plain pools4 A variety of pool habitats Northern pools with peat/muck substrates1 Northern pools with peat/muck substrates1

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APPENDIX 5.1 (CONTINUED) Plant Species Associated with Vernal Pools in Northeastern North America Scientific Name

Common Name

Sium suave

Water-parsnip

Smilax glauca Smilax rotundifolia Solidago gigantea

White-leaf greenbrier Common greenbrier Late goldenrod

Solidago latissimifolia Solidago patula

Elliott’s goldenrod Rough-leaved goldenrod

Solidago rugosa Solidago simplex spp. randii

Rough goldenrod Rand’s goldenrod

Solidago uliginosa

Swamp goldenrod

Sparganium Sparganium Sparganium Sparganium

Common bur-reed Shining bur-reed Narrow-leaved bur-reed Giant bur-reed

americanum androcladum angustifolium eurycarpum

Sparganium natans

Small bur-reed

Spartina pectinata Spergularia marina Spiraea alba var. latifolia Spiraea tomentosa

Prairie cord-grass Saltmarsh sand-spurrey Meadowsweet Steeple-bush

Stachys hyssopifolia Symphyotrichum lanceolatum Symphyotrichum lateriflorum Symphyotrichum novi-belgii Symphyotrichum prenanthoides

Hyssop hedge-nettle Panicled aster Calico aster New York aster Crooked-stemmed aster

Symplocarpus foetidus Thalictrum pubescens Thelypteris noveboracensis Thelypteris palustris Thelypteris simulata

Skunk-cabbage Tall meadow-rue New York fern Marsh fern Massachusetts fern

Thuja occidentalis

Northern white cedar

Torreyochloa pallida Pale false mannagrass Torreyochloa pallida var. fernaldii Fernald’s false mannagrass Toxicodendron radicans Poison-ivy Triadenum fraseri Northern marsh St. John’s-wort

Habitat Comments Mesotrophic to eutrophic (nutrient rich) pools3 Atlantic coastal plain pools4 Atlantic coastal plain pools4 Mesotrophic to eutrophic (nutrient rich) pools3 Atlantic coastal plain pools4 Mesotrophic to eutrophic (nutrient rich) pools3 A variety of pool habitats Northern pools with peat/muck substrates1 Oligotrophic (nutrient poor) pools3 A variety of pool habitats A variety of pool habitats A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 Northern pools with peat/muck substrates1 Inland saline pools5 Inland saline pools5 A variety of pool habitats Oligotrophic (nutrient poor) pools3 Atlantic coastal plain pools4 A variety of pool habitats A variety of pool habitats A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats Oligotrophic (nutrient poor) pools3 Northern pools with peat/muck substrates1 A variety of pool habitats A variety of pool habitats A variety of pool habitats A variety of pool habitats

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APPENDIX 5.1 (CONTINUED) Plant Species Associated with Vernal Pools in Northeastern North America Scientific Name

Common Name

Triadenum virginicum Trichophorum alpinum

Marsh St. John’s-wort Alpine bulrush

Trichophorum ceaspitosum

Tufted bulrush

Tsuga canadensis Typha angustifolia Typha latifolia Typha X glauca

Eastern hemlock Narrow-leaved cat-tail Broad-leaved cat-tail Hybrid cat-tail

Ulmus americana Utricularia gibba

American elm Humped bladderwort

Utricularia intermedia

Northern bladderwort

Utricularia macrorhiza

Great bladderwort

Utricularia purpurea

Purple bladderwort

Utricularia radiata

Small floating bladderwort

Utricularia subulata

Subulate bladderwort

Vaccinium corymbosum Vaccinium fuscatum

Highbush blueberry Black highbush blueberry

Vaccinium macrocarpon

Large cranberry

Veratrum viride Verbena urticifolia

False hellebore White vervain

Veronica scutellata Viburnum dentatum Viburnum lentago

Marsh speedwell Arrow-wood Nannyberry

Viburnum nudum var. cassinoides

Wild raisin

Viola cucullata Viola lanceolata

Blue marsh violet Lance-leaf violet

Viola macloskeyi spp. pallens Viola x primulifolia Vitis riparia

Northern white violet Primrose-leaf violet River-bank grape

Habitat Comments A variety of pool habitats Northern pools with peat/muck substrates1 Northern pools with peat/muck substrates1 A variety of pool habitats Inland saline pools5 A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 A variety of pool habitats Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 Aquatic macrophytes and semi aquatic pool species6 A variety of pool habitats Oligotrophic (nutrient poor) pools3 Oligotrophic (nutrient poor) pools3 A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 A variety of pool habitats A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3 Oligotrophic (nutrient poor) pools3 A variety of pool habitats Oligotrophic (nutrient poor) pools3 A variety of pool habitats A variety of pool habitats Mesotrophic to eutrophic (nutrient rich) pools3

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APPENDIX 5.1 (CONTINUED) Plant Species Associated with Vernal Pools in Northeastern North America Scientific Name

Common Name

Wolffia spp.

Wolffia

Woodwardia areolata Woodwardia virginica

Netted chain-fern Virginia chain-fern

Xyris difformis

Yellow-eyed grass

Xyris smalliana Zanthoxylum americanum

Small’s yellow-eyed grass Northern prickly ash

1

Habitat Comments Aquatic macrophytes and semi aquatic pool species6 Atlantic coastal plain pools4 Oligotrophic (nutrient poor) pools3 Oligotrophic (nutrient poor) pools3 Atlantic coastal plain pools4 Mesotrophic to eutrophic (nutrient rich) pools3

In northern climates, postglacial paludification (the process of basin filling with peat or muck) creates numerous vernal pools in peatland settings. In warmer climates some of these species occur as peripheral or disjunct outliers in bogs and bog-like environments. 2 Vernal pools support a large suite of annuals throughout the Northeast. Because annuals compete poorly with established perennials, they generally occur on recently exposed substrates. Some of these species are also characteristic of coastal plain wetlands and other wetlands farther south. 3 The nutrient regime of vernal pools varies widely across the region, ranging from oligotrophic to eutrophic. Plant species generally indicative of the more oligotrophic pools are often more common in northern parts of our region. 4 The Atlantic coastal plain is a well defined, wetland-rich physiographic region. Some of the plants associated with Atlantic Coastal plains occur farther inland, especially south of our region. 5 Inland saline wetlands are very uncommon in the region and some function as vernal pools. Occurrences in New York, Michigan, and elsewhere are characterized by these species. 6 The occurrence of aquatic macrophytes and semiaquatic species in a vernal pool usually indicates that at least a portion of the pool experiences prolonged periods of inundation, extending well into the growing season. Such a hydrologic regime has been described as semipermanently flooded.

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Diversity and Ecology of Vernal Pool Invertebrates Elizabeth A. Colburn, Stephen C. Weeks, and Sadie K. Reed

CONTENTS Invertebrate Distributions, Life Histories, and Dispersal .....................................107 Factors Influencing Invertebrate Distributions and Life Cycles...............107 Life History Strategies of Vernal Pool Invertebrates ................................108 Dispersal ....................................................................................................109 Basics of Invertebrate Community Ecology .........................................................110 Common Invertebrates of Vernal Pools ................................................................112 Large Crustaceans......................................................................................112 Fairy Shrimp (Order: Anostraca).....................................................112 Clam Shrimp (Orders: Laevicaudata, Brevicaudata, and Spinicaudata) ....................................................................................112 Tadpole Shrimp (Order: Notostraca) ...............................................114 Small Crustaceans......................................................................................114 Ostracodes (Order: Podocopida)......................................................114 Copepods (Class: Copepoda)...........................................................114 Water Fleas (Order: Anomola) ........................................................114 Worms ........................................................................................................115 Free-Living Flatworms (Class: Turbellaria) ....................................115 Oligochaetes (Class: Oligochaeta)...................................................115 Molluscs.....................................................................................................115 Snails (Class: Gastropoda, Order: Basommatophora).....................116 Fingernail Clams (Class: Bivalvia)..................................................116 Aquatic Insects ..........................................................................................117 Caddisflies (Order: Trichoptera) ......................................................117 Aquatic Beetles (Order: Coleoptera) ...............................................117 True Bugs (Order: Hemiptera).........................................................118 Damselflies and Dragonflies (Order: Odonata) ...............................118 True Flies, Exclusive of Mosquitoes (Order: Diptera).................... 118 Mosquitoes (Order: Diptera)............................................................119 105

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Water Mites................................................................................................120 Conservation Recommendations ...........................................................................121 Pool Protection Efforts ..............................................................................121 Habitat Enhancement and Aesthetics ........................................................121 Mosquito Control.......................................................................................122 Pesticides and Other Chemicals ................................................................123 Public Education........................................................................................123 Summary ................................................................................................................123 Acknowledgments..................................................................................................124 References..............................................................................................................124

Hundreds of invertebrate species can be found in vernal pools across northeastern North America — a dramatic contrast to the more than dozen or so amphibians, handful of reptiles, and few opportunistic bird and mammal species that breed, feed, or water in pools. Many invertebrates are temporary water specialists that occur in no other habitats and thus represent important components of local and regional biodiversity. Some are rare or endangered. Ecologically, invertebrates are key to energy and nutrient cycling in vernal pools and play important roles throughout the food web, both as prey and as predators. Additionally, invertebrates provide innumerable examples of adaptation and beauty. Changes in hydrology, water quality, vegetation, and light, as well as the introduction of new species, all can profoundly alter invertebrate communities in vernal pools. The best known pool invertebrates are large crustaceans — fairy, clam, and tadpole shrimp — and aquatic insects, especially larval caddisflies, damsel and dragonfly nymphs, and mosquitoes (Eriksen and Belk 1999). These represent only a fraction of the fauna. Less well-recognized, but equally important ecologically, are rotifers, gastrotrichs, worms (flatworms, roundworms, horsehair worms, aquatic earthworms, and leeches), small crustaceans (water fleas, copepods, and ostracodes), molluscs (snails and fingernail clams), arachnids (water mites and spiders), and a wide variety of aquatic insects (including water beetles and bugs, and many kinds of two-winged flies) (Williams 2006) (Color Plate 16*). We generally lack adequate information on distribution and trends in abundance for even the best known of the invertebrates found in vernal pools, such as fairy shrimp (Belk et al. 1998; Jass and Klausmeier 2000). Vernal pools with different hydroperiods and patterns of flooding typically contain different, though often closely related, species of invertebrates (Wiggins et al. 1980; Williams 1997; Colburn 2004). Thus, a landscape containing a cluster of pools with different hydrogeological characteristics (Chapter 2, Rheinhardt and Hollands; and Chapter 3, Leibowitz and Brooks) is likely to support a greater overall richness of invertebrates and to contribute more to regional biodiversity than a single pool or series of similar pools. Unfortunately, many studies of animal life in vernal pools identify invertebrates only to the level of genus and often only to family or order, so that the true diversity represented by vernal pool invertebrates goes unrecognized (Figure 6.1). * See color insert following page 132.

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Number of Taxa Recorded

Level of Identification Affects Recorded Biodiversity 80

Order

70

Family

60

Genus

50 40 30 20 10 0 Pool 1

Pool 2

FIGURE 6.1 Comparative data from two New England vernal pools sampled in 1997, illustrating how the taxonomic level to which animals are identified influences the measured biodiversity (richness). (From E.A. Colburn, unpublished data.)

In this chapter, we look at general patterns and trends in the distributions and ecology of invertebrates in vernal pools. First, we review invertebrate life-history strategies and community ecology in the context of pool habitat characteristics, especially hydrology. In many cases ecological patterns are suggested by studies carried out elsewhere; there is a need for fundamental ecological work on vernal pool invertebrates in the glaciated Northeast. Next, we briefly introduce some of the most characteristic groups and species, especially those that are restricted to vernal pools and have particularly interesting adaptations and life histories. Finally, we discuss conservation issues and make recommendations based on what is known about the ecology of vernal pool invertebrates. For more in-depth taxonomic and life history details, readers are referred to the cited literature and Colburn (2004).

INVERTEBRATE DISTRIBUTIONS, LIFE HISTORIES, AND DISPERSAL FACTORS INFLUENCING INVERTEBRATE DISTRIBUTIONS

AND

LIFE CYCLES

A commonly cited benefit of life in vernal pools is the release from predation (and competition) from fish and invertebrates that cannot withstand drying (Williams 1997). This relative freedom from predators allows pool inhabitants unprecedented access to the abundant detrital and algal food (Bärlocher et al. 1987). Vernal pools are not predator-free, however, and some pool invertebrates’ life histories and behavior may be tailored to avoid predation (Soderstrom and Nilsson 1987; Schneider and Frost 1996; Brendonck et al. 2002). For example, fairy shrimp (Eubranchipus spp.) mature, drop their eggs on the pool bottom, and die by late spring before the water warms, oxygen levels decline, and predaceous salamander and beetle larvae become abundant. The eggs dry over winter and hatch the following spring. Young Stagnicola

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elodes (snails) adapt to pool drying by climbing shrubs and trees to aestivate; they return to the pools in fall. This behavior may help the snails avoid parasitism by sciomyzid fly larvae (Jokinen 1978). Similarly, predator life cycles may track prey populations. The complexity of such interactions highlights how pool alterations can have unexpected ecological effects (see below). The distributions and trophic relationships of aquatic invertebrates vary with physical substrate, vegetation, and food; changes in any of these may alter the community (e.g., Merritt and Cummins 1996). For example, herbivores are more likely to occur in vernal pools with open canopies, abundant vegetation, and algal growth than in small, closed-canopy pools where the main food source is detritus from annual leaf fall. Habitat variables are strong drivers of invertebrate life histories in vernal pools and may be especially important for rare species. Every species must deal with pool drying and the between-year variability in timing of pool filling and total pool duration. Some species, especially molluscs, are sensitive to calcium and pH and do not occur in pools where these are low. Many pools freeze solid in winter, excluding those species lacking freeze-tolerant life stages. Summer produces high daily and seasonal temperature variations. Turbidity and seasonally high solute concentrations, low dissolved oxygen, and variable pH can pose problems for some aquatic species (Williams 1987).

LIFE HISTORY STRATEGIES

OF

VERNAL POOL INVERTEBRATES

Understanding the wide range of ways that animals deal with complex environmental conditions will contribute to an appreciation of year-to-year variations in community composition in vernal pools. The variety of strategies also illustrates how changes in habitat associated with development or other human activities can have a range of effects, depending on the species involved and the habitat characteristics that are altered. Because hydrology is ephemeral, or at least highly variable (Chapter 3, Leibowitz and Brooks), vernal pool invertebrates need to start their lives quickly and complete the aquatic portions of their life cycles rapidly (Williams 1987). Such conditions select for two general life history strategies: (1) “early colonization,” so that animals can move into new sites wherever conditions are favorable, and (2) “drying response,” i.e., an ability to avoid, resist, or tolerate pool drying (Wiggins et al. 1980; Williams 1996, 1997). Many animals are permanent residents that remain in the pool sediments and become active as soon as water appears and when other conditions (e.g., temperature) are suitable. Some, including molluscs such as the fingernail clam, Sphaerium occidentale, burrow into the mud and become dormant as juveniles or adults. Others hatch from desiccation-resistant eggs that can lie in the sediment for months and, in some cases, up to decades, serving as what is known as an “egg bank” (e.g., many crustaceans, including the common fairy shrimps, Eubranchipus neglectus, in the Midwest, E. vernalis in the East, and E. bundyi in the North). Dormancy that begins only when pools start to dry allows some permanent residents, such as the water flea, Daphnia pulex, or the pond snail, Fossaria

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modicella, to grow and reproduce as long as water is present. Other species have an obligatory dormant period. Rapid growth and early transformation to adults is seen in many pool inhabitants. The lives of some pool insects include a mixture of short aquatic phases, drought-resistant terrestrial adults, and eggs that resist drying for a few months (e.g., the mosquito Ochlerotatus [formerly Aedes] excrucians and the “log-cabin caddisfly,” Limnephilus indivisus) (see Chapters 6 through 9 in Colburn 2004). Like amphibians, many mobile aquatic insects are migrants that use vernal pools only seasonally. Mosquitoes in the genus Culex overwinter as terrestrial adults and migrate to flooded pools in spring to lay their eggs. Water boatmen, backswimmers, and some predaceous diving beetles migrate between permanent waters where they overwinter and vernal pools where they feed and, in many cases, breed. The larvae of some water mites are parasitic on some of these migrants; they avoid seasonal drying and are dispersed to new pools as their hosts fly first to permanent waters and then to vernal pools in spring and summer. Life history strategies of animals in vernal pools respond to local habitat variability. For instance, some fairy shrimps’ eggs are deposited at a depth level that maximizes the chance that when the eggs are flooded, enough water will be present to let the life cycle be completed before the pool dries. Eggs of many species hatch only when certain cues are present (e.g., average temperature, daylight, osmotic shock, and fill level) (Brendonck 1996; Dodson and Frey 2001). Because such cues are sometimes unreliable, most species with egg banks have a “bet-hedging” strategy: only some eggs hatch at any filling in case the pool dries before the life cycle can be completed (Fryer 1996; Simovich and Hathaway 1997; Ripley et al. 2004). As with the long lives and multiple breeding opportunities of amphibians, these strategies let invertebrates adapt to a range of conditions and contribute to the unique and variable communities in vernal pools.

DISPERSAL Vernal pools are isolated from permanent water bodies, yet, once flooded, they are rapidly populated by a variety of aquatic invertebrates. How do these animals colonize the pools? In existing pools, we have seen that many species survive drawdown via eggs or drought-resistant larvae and hatch or become active upon flooding. In contrast, species without stages that can withstand drying or freezing in the sediment colonize vernal pools each year. In new vernal pools, the sediment lacks an egg bank and other dormant stages. Readily dispersed migratory species, such as flying insects, are the earliest colonizers, finding newly formed and freshly flooded pools in as little as 24 h (Grensted 1939; Williams 1987). Most of the species that, once established, can persist by remaining dormant in the sediment during drawdown tend to be less mobile and are dispersed by wind or water, or carried by larger animals (e.g., fingernail clams and crustacean eggs carried by birds, fairy-shrimp eggs transported by crayfish, and leeches dispersed by turtles) (Chapter 9, Mitchell et al.; and Chapter 6 in Colburn 2004). They arrive more slowly, the rate depending primarily on the distance to the nearest source pool (Maguire 1963). Constructed vernal pools, detention basins, and

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other impoundments are often colonized in this way. These dispersal mechanisms also regulate recolonization of pools after local populations have been eliminated due to unfavorable hydrology, predation, or other causes (Chapter 3, Leibowitz and Brooks). For these reasons and more, it is important to maintain a mosaic of pools well distributed in the landscape.

BASICS OF INVERTEBRATE COMMUNITY ECOLOGY Invertebrates represent most of the animal species, numbers, and biomass in land, sea, and freshwater ecosystems, including vernal pools, and their ecological importance is proportional to their numbers (Strayer 2006). They play three major roles in vernal pools: (1) helping to cycle algae and dead plant material into animal life; (2) controlling the populations of other animals by competition and predation; and (3) serving as prey for other animals (Figure 6.2). The aquatic communities of vernal pools can be relatively complex, with many kinds of animals that exhibit a broad range of ecological interactions and collectively occupy a range of trophic levels within pool food webs (Williams 1987, 1997) (Figure 6.2). Some species eat plants and algae. Most taxa — worms, ostracodes, caddisflies, midges, and molluscs on the pool bottom, and filter-feeding crustaceans and insects in the water — feed on detritus, making large amounts of nourishing food available to the rest of the community (detritus, mainly in the form of leaves from the surrounding forest, constitutes more than 50% of the energy input into vernal pools) (Barlöcher et al. 1978). Others are predators and parasites (see Chapter 13 in Colburn 2004). Competition and predation strongly structure pool communities. Competition can occur between dramatically divergent taxa. Snails compete with American toad (Bufo americanus) tadpoles for algae in streamside pools in Kentucky (Holomuzki and Hemphill 1996). In Europe, co-occurring mosquito larvae and toad tadpoles negatively affect one another (Blaustein and Margalit 1994). Unquestionably, hundreds of interactions occur among members of the aquatic communities in northeastern vernal pools. Equally important are the effects of intraspecific competition on invertebrate growth, reproduction and survival. For example, high intraspecific densities reduce growth in parasitic water mite larvae and clam shrimp and decrease survival in temporary-pool mosquitoes (Lanciani 1976; Gleiser et al. 2000; Weeks and Bernhardt 2004). Predators such as dragonfly nymphs, diving-beetle larvae, flatworms, and salamander larvae can dramatically affect invertebrate species’ abundances and the composition of the entire community (Blaustein et al. 1996; Brendonck et al. 2002; Eitam et al. 2002). Interactions between amphibians and invertebrates, with invertebrates serving as prey in some cases, and as predators in others, are a common and necessary component of normal functioning in vernal pool ecosystems. For instance, egg predation by leeches (Cory and Manion 1953) and giant-tube, casemaking caddisfly larvae (Ptilostomis and Banksiola spp.) can influence the hatching success of wood frogs (Rana sylvatica) and spotted salamanders (Ambystoma maculatum); predation by dragonfly nymphs affects the survival of toads, chorus frogs (Pseudacris spp.), and salamanders, whereas amphibian larvae consume a wide array

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FIGURE 6.2 A generalized vernal-pool food web. Herbivorous grazer/scrapers and filterfeeders feed on algae and living plants; microbes decompose and detritivores consume dead plant and animal materials; and predators and parasites feed on the living animals that are sustained by the rich plant-derived diet of the pool bottom and water column. (Colburn, E.A. 2004. With permission.)

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of invertebrate prey (Brockelman 1969; Smith 1983; Stout and Stout 1992; Rowe et al. 1994). In other parts of the world, introduced fish or dragonfly nymphs have disrupted food webs and threatened native species by altering predator–prey relationships in pools (Courtenay and Meffe 1989).

COMMON INVERTEBRATES OF VERNAL POOLS LARGE CRUSTACEANS Six major groups of large crustaceans occupy vernal pools in the northeastern United States and Canada. Typical — and indicative — of temporary waters are fairy shrimp, clam shrimp, and tadpole shrimp (Table 6.1). All are found in temporary waters worldwide, all have similar life-history strategies that include production of resting eggs that lie in the egg bank and hatch upon flooding at a later time, and all “hedge their bets” through staggered hatching (see above). Isopods, amphipods (Color Plate 16), and crayfish occur in a variety of aquatic habitats and are not discussed here. Fairy Shrimp (Order: Anostraca) Among the general public interested in natural history, fairy shrimp are probably the best known of the invertebrates unique to vernal pools. In our region, the common species are in the genus Eubranchipus. The eggs typically require cold-conditioning and drying before they will hatch. Once flooded, eggs typically hatch in 1–14 d, depending on temperature. Animals are sexually mature in as few as 2–4 weeks, although maturation can be delayed by colder water temperatures. Fairy shrimp can be recognized by their large size — up to 2 cm (0.8 in.) — and orientation during swimming: they swim “upside down,” with their numerous, feathery, plate-like appendages aimed upwards (Color Plate 16). Males are recognized by the enlarged second antennae (“claspers”) that are used to grasp females during mating. Females have a clear “brood pouch” in which eggs are held for fertilization and often a bright blue patch near this pouch. Both sexes are typically clear or white but can take on various colors, including blue, red, and orange. These interesting crustaceans are primarily filter feeders that consume algae, zooplankton, and even bacteria (Dodson and Frey 2001). They tend to swim up in the water column but will hide in the leaf litter when disturbed. Males actively search for mates and thus are often more conspicuous than females. Because of their inability to avoid fish predators, fairy shrimp are found exclusively in fishless ponds. Also, because eggs require a period of drying, fairy shrimp are not common in semipermanent pools with little fluctuation in water depths. Several species are rare or endangered in our region. Clam Shrimp (Orders: Laevicaudata, Brevicaudata, and Spinicaudata) In vernal pools, different species of clam shrimp can be found primarily from early May to mid-September. Many species have restricted distributions and are considered rare. The bivalved carapace of clam shrimp is either spherical or oval

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TABLE 6.1 Large Branchiopod Species of Vernal Pools, Including Seasonal Information and Geographic Location (by U.S. State/Canadian Province within the Glaciated Northeast) Genus

Species

Locationa

Season

A. Fairy shrimp Branchinecta Eubranchipus

paludosa bundyi

Su W, Sp

Streptocephalus

intricatus ornatus holmanii neglectus vernalis serratus sealii

W, W, W, W, W, W, W,

brachyurus mexicanus gynecia lenticularis diversa1 agassizii2

Sp, Su Su Su Su Su Su

MA, IL, IN, MI, NH, OH, RI, AB, ON IL, OH, AB MA, OH, PA MA IL, IN, MI, OH CT, MA

cousii

W, Sp

MN

Sp Sp Sp Sp Sp Sp Sp, Su

AB, LB, NS, QB IL, IN, MA, MI, MN, NH, NY, OH, VT, WI, AB, ON, QB MA, ME, AB MN, WI, AB CT, IL, MN, NJ, NY, OH IL, IN, MI, OH, ON CT, MA, ME, NJ, NY, PA, RI IL, IN, OH, WI IL, MN, NJ, NY, AB

B. Clam shrimp Lynceus Cyzicus Caenestheriella Limnadia Eulimnadia

C. Tadpole shrimp Lepidurus

Note: W= winter form; Sp = spring form; Su = summer form) a

Location codes for (1) U.S. states: CT = Connecticut, IL = Illinois, IN = Indiana, MA = Massachusetts, MI = Michigan, MN = Minnesota, NH = New Hampshire, NJ = New Jersey, NY = New York, OH = Ohio, PA = Pennsylvania, RI = Rhode Island, VT = Vermont, WI = Wisconsin; (2) Canadian provinces: AB = Alberta, LB = Labrador, NS = Nova Scotia, ON = Ontario, QB = Quebec. 1Includes E. thomsoni and E. inflecta. 2Includes E. stoningtonensis.

and can be clear to dark brown. Because they look much like small clams (4–20 mm) (0.15–0.78 in), they are often misidentified as freshwater bivalves. Some species are easy to overlook, as they tend to be on pool bottoms, where they scavenge among the leaf litter, or are actually slightly buried in the sediment. Lynceus brachyurus, a broadly distributed species in vernal pools with an adult diameter of 5 mm (0.19 in), is a filter feeder that swims in the water column. Clam shrimp usually develop faster and have shorter lives than fairy shrimp. Populations either comprise males and females, all females, or males and hermaphrodites (Sassaman 1995).

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Tadpole Shrimp (Order: Notostraca) In our study area, tadpole shrimp have been described only from Minnesota, where Lepidurus cousii can be found rooting around pool bottoms (Rogers 2001, D. Batzer, personal communication). They are omnivorous scavengers and opportunistic or facultative predators (Weeks 1990). Superficially resembling amphibian tadpoles or miniature horseshoe crabs, these “living fossils” are generally the largest branchiopods in vernal pools where they occur, reaching lengths of 4 cm (1.57 in).

SMALL CRUSTACEANS Some of the most diverse vernal pool inhabitants are small crustaceans in the classes Ostracoda (seed shrimp) and Copepoda (copepods), and the Order Anomola (cladocerans, or water fleas) (for details and species lists, see Colburn 2004) (Color Plate 16). All three groups are found worldwide. Most are filter feeders and detritivores, but they include a broad diversity of ecological types. All are important prey for other animals in vernal pools, and all contribute desiccation-resistant eggs to the egg bank. Many species are undescribed (King et al. 1996). Ostracodes (Order: Podocopida) Ostracodes are small, bivalved, benthic crustaceans with a spherical, ovoid, or elongate-cylindrical shape. They look much like white, brown, green, or purple sesame seeds, reaching ~2 mm (0.07 in) in length in our region. Ostracodes are the oldest microcrustaceans known (Delorme 2001) with at least 29 species associated with vernal pools, where they are scavengers, herbivores, and detritivores in the sediment. Copepods (Class: Copepoda) Copepods constitute the most diverse group of the microcrustaceans, with over 10,000 described species (Williamson and Reid 2001). At least 16 species are found in vernal pools. Copepods are cylindrical to tear-drop-shaped, with a long, bifurcated tail with several setae, and with two antennae used in some species for rapid swimming (Color Plate 16). They can be planktonic or benthic and include filter feeders, omnivores, and carnivores. Some diaptomid copepods reach several millimeters in length, are bright blue, and are readily visible as they swim upside-down in the water column in early spring. Water Fleas (Order: Anomola) Water fleas, or cladocerans, are small (generally <5 mm [0.19 in]), planktonic or benthic microcrustaceans (Color Plate 16). At least 17 species have been reported from vernal pools. Most are filter feeders, using their plate-like appendages to create currents within their bivalved carapaces from which they filter out small food particles. Ironically, when food becomes superabundant, water fleas can starve because the energy required to clean their filtration apparatus is greater than their

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food intake (Dodson and Frey 2001). Cladocerans are clear to a yellowish color and swim in jerky, small jumps. They either brood live young under their carapace or produce desiccation-resistant eggs (ephippia) that will lie dormant in the egg bank until conditions are favorable for hatching. Many of these crustaceans reproduce via “cyclic parthenogenesis,” wherein all-female populations reproduce asexually for most of their lives, and then produce males and reproduce sexually (producing the ephippia) as the pond is finally drying up. Daphnia pulex, commonly studied in biology courses, is widely distributed and abundant in vernal pools.

WORMS Vernal pools support a wide variety of worms from several phyla, including Platyhelminthes (flatworms), Annelida (leeches and earthworm-like segmented worms), Nematoda (roundworms), and Nematomorpha (horsehair worms). Worms play key roles in vernal pools as predators, scavengers, and detritovores (for more information on worms in vernal pools, see Colburn 2004). Free-Living Flatworms (Class: Turbellaria) Related to the Planaria that most people see in biology classes, but usually without the distinctive triangular head, the dozen or so species of vernal-pool flatworms are small (mostly <5 mm [0.19 in] long and 1–2 mm [<0.07 in] wide), flattened, drably colored (coming in grays, light browns, pale pinks and, in one species, bright lime green), and slow-moving; they tend to remain hidden under leaves on the pool bottom (Color Plate 16). They are permanent residents that survive pool drying by fragmenting into a series of small pieces that become hardened and resist drying until the pool refloods and water temperatures are low. Flatworms are cold-water specialists. Best observed in vernal pools in winter or early spring, they are important predators and scavengers (Kenk 1949; Wiggins et al. 1980; Ball et al. 1981). Oligochaetes (Class: Oligochaeta) Oligochaetes in vernal pools look like small, freshwater earthworms. As on land, they are key to energy cycling: they ingest sediment, absorb nutrients, and produce castings that are then colonized by microbial decomposers and grazed by other animals, including amphibian tadpoles. They are found in the decomposing leaves on the pool bottom, and in late summer or fall they are among the most abundant animals living in the wet pool substrate. To survive pool drying, these worms fragment into cysts, encase themselves in a coat of protective mucus, or deposit eggs in desiccation-resistant cocoons (Kenk 1949; Wiggins et al. 1980).

MOLLUSCS Air-breathing snails and fingernail clams (also known as pill clams) are common in many vernal pools. Their shells on a dry pool bottom indicate the seasonal presence of water there.

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Snails (Class: Gastropoda, Order: Basommatophora) Gilled snails with opercula that close off the shell do not occur in vernal pools; all of the snails in pools are pulmonates, or air-breathers. Most of the 19 species reported from vernal pools occur widely in floodplains and other kinds of wetlands, but the common stagnicola (Stagnicola elodes), the polished tadpole snail (Aplexa elongata), and the toothed planorbid (Planorbula armigera) are especially characteristic of vernal pools (see Chapter 7 in Colburn 2004). Snails often hang upside-down from the water’s surface, taking air into the mantle cavity, from which they absorb oxygen into their blood. Most are grazers, feeding on algae, aquatic plants, dead plant and animal matter, and small organic particles on the water’s surface and pool bottom. However, the common stagnicola is a predator, feeding on mosquito larvae and other prey. Snails are preyed upon by a variety of invertebrates and vertebrates and are hosts for parasitic flukes — including species that parasitize amphibians — and sciomyzid fly larvae. When vernal pools dry, most snails aestivate by burrowing into the sediment, where relative humidity remains high, and secreting a mucus membrane across their shell opening. Some species only resist drying as juveniles, whereas others can do so as adults. Most snails can grow for as long as water is available. High reproductive output and continuous growth help compensate for naturally high juvenile mortality in these seasonally drying habitats. When pools flood, animals emerge from the mud, feed, grow, mature, mate (they are hermaphroditic and can mate with any other individual), and lay eggs. They may produce several broods during a single season. Young snails hatch directly and start at once to feed and grow. The cycle continues until pool drying. Fingernail Clams (Class: Bivalvia) Fingernail clams are so-called because their adult size is about that of a human fingernail. They are highly efficient filter-feeders (McMahon and Bogan 2001) and, unlike freshwater mussels which have a mobile aquatic larva, they bear live young that are released as miniature replicas of their parents. Four of the five common species occur in a wide range of habitats, but Herrington’s fingernail clam (Sphaerium occidentale) is a vernal-pool specialist. Like snails, fingernail clams survive pool drying by remaining dormant in the pool sediment. Broadly distributed species of Musculium and Sphaerium can resist drying only as newly hatched juveniles. They emerge in spring-filling pools as waters start to warm, feeding and growing until ready to reproduce, and releasing young that immediately enter summer diapause. Mature individuals continue to feed and produce young until pool drying, when they die. In fall-filling pools, young may emerge from diapause and grow until temperatures become cold, resuming growth in spring. In contrast, the vernal pool-specialist Herrington’s fingernail clam tolerates drying in all life stages and thus can feed and grow continuously from hatching until pool drying. It produces more young than other fingernail clams found in vernal pools and lives for three years, as opposed to a one-year lifespan for most other species, and thus can compensate for high juvenile mortality and a short growing

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season in short-hydroperiod pools (Heard 1977; Mackie 1979; McKee and Mackie 1980, 1981).

AQUATIC INSECTS Hundreds of species of aquatic insects occur in vernal pools, including members of the orders Trichoptera (caddisflies), Coleoptera (water beetles), Odonata (dragonflies and damselflies), Hemiptera (water bugs), and Diptera (true flies, including midges, crane flies, and horseflies). Each common order contains multiple genera and species. Some may be widely distributed in vernal pools, whereas others are quite localized. Ephemeroptera (mayflies) (Color Plate 16), Plecoptera (stoneflies), and Megaloptera (alderflies) are relatively uncommon in vernal pools and will not be addressed here. Of all the insects found in vernal pools, mosquitoes (Order Diptera, Family Culicidae) have the greatest potential influence on the conservation of vernal pools due to their links to public health and strong public and governmental sentiment in favor of destroying breeding habitats. Caddisflies (Order: Trichoptera) Caddisflies are aquatic as larvae and pupae. Many are easily recognized by the cases or retreats they construct with silk and either pebbles, sticks, or leaves. The cases (Color Plate 16) represent an important adaptation for life in nonflowing waters such as ponds and wetlands, allowing the larvae to create water currents that increase oxygen flow (Wiggins 1996). The larvae have three pairs of legs; elongate, cylindrical bodies; soft, thin-skinned abdomens; a thickened head; and a hardened plate on the first thoracic segment. A pair of prolegs, each with a claw-like hook, is found at the end of the abdomen. Like moths and butterflies, adults hold their wings together above the body when at rest. Caddisfly larvae are highly diverse in their feeding strategies and include shredder-detritivores, shredder-herbivores, collector-gatherers, collector-filterers, scrapers, and engulfer-predators. The most common caddisflies in vernal pools have adults that diapause during hot, dry periods, later emerging to produce eggs that resist drying on the pool bottom until flooded. Larvae are found in vernal pools around 1–3 d after flooding, and adults emerge in late spring/early summer, depending on the species (Wiggins 1973). The empty cases on the dry bottom provide evidence during drawdown of a pool’s existence. Aquatic Beetles (Order: Coleoptera) The water beetles are in the largest order of insects and can be found in just about any vernal pool sampled. They include species of whirligig beetles that swim on the surface, predaceous diving beetles (some with fierce larvae known as “water tigers”), water scavenger beetles, crawling water beetles, minute moss beetles, snout beetles, and others. They comprise shredder-herbivores, collector-gatherers, collector-filterers, scrapers, and engulfer-predators. Water beetles are aquatic as larvae and adults but pupate on land. The larvae have three pairs of legs; thick, hardened skin on their head; and, often, large pincer-like mandibles. In adults, the front wings are modified into hard plates or “elytra” that cover the hind wings and abdomen.

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Some adults diapause in the substrate when pools dry. Others are migrants and arrive in vernal pools anywhere from just a few days after pond filling to several weeks later, and they may remain present until drawdown (Williams 1987). A few water beetles have diapausing eggs, but most species’ larvae appear after eggs are laid in the water by resident adults or by adults dispersing into the vernal pool to breed (Wiggins et al. 1980). Beetles show some of the greatest overall biodiversity in vernal pools, and their distributions may vary with forest composition and other local factors. Some species are restricted to vernal pool habitats, and some may be rare. True Bugs (Order: Hemiptera) True bugs include backswimmers, water boatmen, giant water bugs, creeping water bugs, water striders, water scorpions, and marsh treaders. Nymphs and adults occur in the same habitat. Nymphs look like adults with undeveloped wings. The mouthparts are modified into a cone or beak, and each leg has two claws. All are piercerpredators (except for the water boatmen, most of which are collector-gatherers) that feed on other invertebrates and on larval amphibians. Hemipterans do not undergo egg diapause; most are migratory. Eggs are laid when adults arrive at the pools and hatch within 1–2 weeks; nymphs grow rapidly in order to be ready to fly from the pool before it dries (Voshell 2002). Damselflies and Dragonflies (Order: Odonata) Damselflies and dragonflies are aquatic only as nymphs. They are recognized by the long lower lip (labium) that folds back against the head and is used as a powerful pincer to capture prey. Nymphs have wing pads and two claws on the end of the legs. Damselfly nymphs have three plate-like gills extending from the end of the abdomen. The colorful adults have very long abdomens and large heads and eyes. Dragonflies hold their wings out to the sides of their body when at rest and damselflies hold them together, or nearly so (i.e., Lestes spp.), above the body. All odonates are engulfer-predators. Adults of some species, such as the common green darner (Anax junius), migrate from the south to breed in vernal pools. In others, the females lay diapausing eggs in aquatic plants or on the pool bottom, and the eggs remain dormant until the next pond filling (Wiggins et al. 1980; Voshell 2002). Closely related species may occur in adjacent pools with different hydrologic regimes. True Flies, Exclusive of Mosquitoes (Order: Diptera) The true or two-winged flies include the mosquitoes (see below), midges, phantom midges (see Color Plate 16), craneflies, horseflies, marsh flies, and common flies. In water-dependent groups, larvae and pupae are aquatic, and adults are terrestrial. Unlike other insects found in vernal pools, the larvae of true flies lack segmented legs. The thorax and abdomen are soft and thin-skinned, and the head is either continuous with the thorax or thick skinned and separated from the thorax. The diversity of this group also equates to diverse distributions and ecology. Most dipterans are collector-gatherers, but some are scrapers, shredder-detritivores, and

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engulfer-predators. They can undergo long egg diapause during the dry period, and eggs hatch just a few days after the vernal pool is hydrated (Voshell 2002). Mosquitoes (Order: Diptera) The best known (and least loved) dipterans are the mosquitoes (family Culicidae). About 30 species have been identified from vernal pools (see Colburn 2004). The eggs of many species overwinter in the sediment and hatch when flooded, but Culex females overwinter as adults and lay their eggs in spring on the water’s surface. In early spring, mosquito larvae are present in the thousands in some vernal pools. They eat decaying material, microorganisms, pollen, and small particles on the surface or in the water. They are fed upon by snails, bugs, copepods, beetle larvae, caddisflies, phantom midges, odonate nymphs, newts, and salamander larvae; fewer than one percent of larvae survive to adulthood (Collins and Washino 1985). Like all dipterans, the aquatic larvae are legless. They have a round head, a swollen thorax, bristly hairs all over their bodies, and typically a tubular siphon at the end of the abdomen through which they obtain air at the water’s surface, where the larvae tend to congregate. When disturbed, larvae (“wrigglers”) thrash about. After going through several molts, larvae transform into pupae (“tumblers”), which are somewhat comma shaped, with a large swollen upper end containing the head, upper body, a pair of horn-like breathing tubes, legs, and developing wings; the narrow abdomen extends below. Once the body has been reorganized, the pupal skin splits and the adult emerges. Only females bite: the blood meal provides protein that is used to produce eggs. Depending on the species, females lay their eggs on the water’s surface or on the damp substrate of a drawn-down pool. In our geographic region, mosquitoes are largely nuisances that annoy humans with their buzzing and cause discomfort but no lasting harm with their bites. However, two mosquito-borne diseases, West Nile virus (WNV) and eastern equine encephalitis (EEE), are of public health concern and have important implications for vernal pools. These are primarily viral diseases of birds, but they can be transmitted to horses, humans, and other mammals by mosquitoes that have bitten an infected bird. From both EEE and WNV, birds suffer the most illness and mortality. Because EEE and WNV are transmitted by mosquitoes, there is a major focus on controlling mosquito populations, and because mosquitoes are a substantial part of the fauna of vernal pools, these habitats are vulnerable to mosquito control activities. However, both EEE and WNV are transmitted to humans only if a mosquito first bites an infected bird. Most mosquito species found in vernal pools do not feed on birds (and most do not feed on humans, either, although some important pest species do breed in vernal pools). The most common mosquito transmitting EEE is Culiseta melanura, which breeds preferentially in hardwood swamps and is not commonly found in vernal pools. The most common vectors of WNV are Culex spp., which similarly are not common in vernal pools. However, more than 60 species of mosquito are known to carry WNV, and some of the common species from vernal pools have tested positive for WNV (Centers for Disease Control and Prevention 2006a, 2006b). Note that mosquito-control activities usually involve altering hydrology, introducing predators, and applying pesticides to breeding areas. Therefore,

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FIGURE 6.3 Generalized life history of water mites in vernal pools. (Smith 1997. With permission.)

diverse food webs, sensitive faunas, and long-term community viability (including the viability of natural mosquito predators) are at risk if mosquito-control efforts focus on vernal pools.

WATER MITES Around 50 species of water mites (Acari) are known from vernal pools, and there are probably more. These are tiny (usually <5 mm [0.19 in]), round, seemingly headless, 8-legged animals; they come in reds, yellows, greens, blues, and browns, and can be observed crawling on the substrate and swimming in the water. As larvae, they parasitize adult aquatic insects (Figure 6.3). Some are attached to their hosts as the latter fly around the pools seeking food or mates. These parasites can be so dense that they affect the hosts’ ability to fly and reproduce. Once fed, the larvae drop off of the hosts and back into the pool, where they transform into nymphs that prey on the eggs of crustaceans or insects, or on insect larvae (especially midges and mosquitoes). The nymphs transform into predatory adults. Unless they migrate as parasitic larvae attached to hosts, water mites withstand pool drying as dormant adults or nymphs. We refer interested readers to additional information in Smith et al. (2001).

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CONSERVATION RECOMMENDATIONS Because invertebrate distributions and life cycles are closely tied to habitat variables (such as hydrology, water quality, and both in-pool and surrounding vegetation), activities that alter any of these variables have the potential to alter invertebrate communities. Inadequate knowledge of the species in vernal pools and of their interrelationships means that there is a risk of losing rare species and altering community dynamics as pools and their watersheds are altered by human activities. Natural year-to-year variability in weather and pool characteristics, and the high plasticity of invertebrate life cycles, make it difficult to evaluate the effects of human alterations, especially subtle changes over time. Various factors threaten invertebrates in vernal pools. Direct threats include: ditching and pesticide use for mosquito control; filling; excavation for detention basins, fish ponds, mosquito control, and wildlife habitat enhancement; sedimentation; and chemical contamination from runoff. Less direct but potentially serious threats include altered hydrology, water quality, and food associated with changes in watershed land use or cover, atmospheric deposition, and climate change. Many of these, such as pool destruction and watershed activities that alter hydrology or water quality, affect both vertebrates and invertebrates. Alterations of forest composition, whether through forestry, clearing for development, or natural succession can change inputs of light and leaf litter, affecting the base energy sources for pools and the invertebrate communities therein. Below, we comment briefly on several threats that we believe specifically affect invertebrates in vernal pools. Additionally, best management practices for forestry (Chapter 13, deMaynadier and Houlahan) and development (Chapter 12, Windmiller and Calhoun), to the extent they maintain water quality, hydrology, and natural vegetation adjacent to pools, will also benefit invertebrate conservation.

POOL PROTECTION EFFORTS A wide range of hydroperiods in temporary waters contributes to aquatic biodiversity. In particular, although small, short-duration pools tend to support fewer species, they also tend to support taxa that do not occur or reproduce successfully in longerhydroperiod pools. Conservation efforts often explicitly exclude small, short-duration pools because relatively fewer amphibian species breed in such pools compared to longer-hydroperiod, annual and semipermanent pools, and because there has been speculation (with little empirical evidence) that short-hydroperiod pools are sinks in which amphibian breeding effort is wasted. This is problematic from the perspective of invertebrate biodiversity. We suggest that the full range of pool sizes and hydroperiods needs to be protected to ensure the maintenance of regional biodiversity and the persistence of invertebrate metapopulations.

HABITAT ENHANCEMENT

AND

AESTHETICS

Some efforts to enhance the value of vernal pools for amphibian populations, especially mole salamanders (Ambystoma spp.), have involved dredging annual pools to increase their hydroperiods, even to the extent of changing them to permanent or

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semipermanent pools (Colburn, personal observation). Additionally, many vernal pools are excavated by individual property owners to create “water features” in gardens, to eliminate the unsightly appearance that many pools take on in the summer, and/or to allow the stocking of ornamental fishes such as koi (Cyprinus carpio) or of frogs such as bullfrogs (Rana catesbiana), which are readily available from some garden centers. Such activities are of concern from several perspectives. First, excavation of the substrate removes the egg bank to which many generations of permanent-resident crustaceans and other invertebrates have contributed. It also removes insect eggs, dormant cysts of flatworms and oligochaetes, aestivating molluscs, and a host of other species. Even if some individuals should persist, the process would likely significantly reduce the genetic diversity of local populations, very possibly dooming many of them to local extirpation. Some of the lost taxa may be important food sources for the very amphibians that are the target of conservation. Second, by increasing the hydroperiod, and especially by eliminating regular drying, the pool is made potentially hospitable to long-lived, drought-intolerant predators commonly excluded from seasonally drying pools, including several species of dragonfly nymphs, backswimmers, giant water bugs, and predaceous diving beetles. These predators are more widely distributed than many of the taxa typical of short-duration pools and are less likely to be restricted to vernal-pool habitats. They may exclude invertebrate taxa that originally inhabited the pool, and they may prey on larvae of vernal pool amphibians, potentially contributing to decreased reproductive success over time — an effect opposite to that intended. Third, stocking of koi, bullfrogs, and other predators can devastate the native invertebrate community. Before more pools are dredged, we believe there is a need for: (1) long-term studies to determine the overall reproductive success of important amphibian populations in pools of different hydroperiods; factoring in the normal variability in flooding durations and the large natural variation in numbers of transforming juveniles across years; (2) comparative long-term studies of invertebrate populations (especially predators) and amphibian reproductive success in pools in which hydroperiods have been altered vs. those that are allowed to dry naturally; and (3) a reassessment of management aims for wildlife reserves to determine whether alteration of pool hydroperiods makes good conservation sense from the perspective of both amphibian and invertebrate biodiversity.

MOSQUITO CONTROL Ditching, draining, filling, excavation, and the application of pesticides all dramatically alter vernal pool habitats and can adversely affect the entire pool community. Individuals interested in and concerned about vernal pools and their wildlife need to (1) educate their neighbors and public health officials about the larger ecosystem values of vernal pools, (2) engage in public discussions of the relative risks of infection from serious diseases, and of the nuisance aspects of mosquitoes vs. risks to wildlife of mosquito control at individual pools, (3) help to minimize breeding habitats (such as tires, gutters, and open containers) in which Culex spp. breed preferentially, and (4) encourage people to use insect repellents, wear long sleeves and pants, and avoid areas where mosquitoes congregate at dawn and dusk.

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If mosquito control is absolutely critical for a specific vernal pool, the use of the microbial larvicide Baccillus thuringiensis var. israeliensis (Bti), which kills mosquito larvae and related flies such as midge larvae, is preferable to ditching, excavation, introduction of fish, or the use of broader spectrum pesticides. However, all of the affected insects are important components of the food web, and removing them can have potentially wide-ranging, unintended ecosystem effects.

PESTICIDES

AND

OTHER CHEMICALS

Invertebrates are often highly sensitive to water chemistry and are good water quality indicators (Rosenberg and Resh 1993). Very little is known about how pollutants affect invertebrates in vernal pools (Chapter 11, Boone and Pauli). For instance, of the hundreds of vernal pool invertebrates, only Daphnia pulex is routinely used in bioassays of pesticide effects on “non-target” species. Thus, we cannot predict the overall impacts of common pesticide formulations on pool fauna. Similarly, effects of contaminants in runoff and precipitation are generally unknown.

PUBLIC EDUCATION Aquatic invertebrates are fascinating, beautiful, and critically important components of vernal-pool ecosystems. Their diminishment decreases overall biodiversity and weakens the web of life connecting forests, waters, and humans. The loss of upland woods, associated vernal pools, and aquatic biodiversity, is ongoing. To counter it, public awareness and appreciation of vernal pools and their biota must be greatly enhanced, and substantial areas of intact landscape must be acquired and conserved.

SUMMARY Aquatic macroinvertebrates make up most of the animal species and biomass in vernal pools. Because the species that occur in short-duration pools are different from those in pools with longer hydroperiods, and because vernal pool species differ from those in permanent waters, pool invertebrates contribute significantly to local and regional biodiversity. They play key roles in the transfer of energy from leaves and other detritus into animal biomass, serve as food for vertebrate predators (including turtles and salamander larvae), and structure the populations of other species (including amphibians) by predation and competition. Their life cycles are complex and closely related to hydroperiod and other habitat variables. Some species can grow and develop whenever conditions are favorable. For others, highly specific cues of temperature, water level, and chemistry stimulate hatching, growth, and maturation. The wide variety of strategies for dealing with seasonal pool drying ranges from egg banks, in which dormant cysts remain viable for decades, to facultative dispersal from permanent waters into flooded pools for feeding and breeding. The protection and maintenance of a diverse habitat mosaic of vernal pools with a range of hydroperiods and other physical conditions is key to the long-term conservation of vernal pool invertebrate communities.

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ACKNOWLEDGMENTS We thank M. Simovich, D. Batzer, A. Calhoun, B. Swartz, P. deMaynadier, and an anonymous reviewer for helpful feedback on earlier drafts of this chapter, and I. M. Smith, J. Semroc, and J. McDonald for permission to use illustrations, and J. Cossey for assistance in production of Color Plate 16.

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Rowe, C.L., Sadinski, W.J., and Dunson, W.A. (1994). Predation on larval and embryonic amphibians by acid-tolerant caddisfly larvae (Ptilostomis postica). Journal of Herpetology 28: 357–364. Sassaman, C. (1995). Sex determination and evolution of unisexuality in the Conchostraca. Hydrobiologia 298: 45–65. Schneider, D.W. and Frost, T.M. 1996. Habitat duration and community structure in temporary ponds. Journal of the North American Benthological Society 15(1): 64–86. Simovich, M.A. and Hathaway, S.A. (1997). Diversified bet-hedging as a reproductive strategy of some ephemeral pool anostracans (Branchiopoda). Journal of Crustacean Biology 17: 38–44. Smith, D.C. (1983). Factors controlling tadpole populations of the chorus frog (Pseudacris triseriata) in Isle Royale, Michigan. Ecology 64: 501–510. Smith, I.M. (Ed.) (1997). Assessment of Species Diversity in the Mixed Wood Plains Ecozone. Ecological Monitoring Coordinating Office, Environment Canada, Burlington, ON. Smith, I.M., Cook, D.R., and Smith, B.P. (2001). Water mites (Hydrachnida) and other arachnids. In Thorp, J.H. and Covich, A.P. (Eds.). Ecology and Classification of North American Freshwater Invertebrates, 2nd ed. Academic Press, San Diego, CA, pp. 551–659. Soderstrom, O. and Nilsson, A.N. (1987). Do nymphs of Parameletus chelifer and P. minor (Ephemeroptera) reduce mortality from predation by occupying temporary habitats? Oecologia 74: 39–46. Stout, B.M., III, and Stout, K.K. (1992). Predation by the caddisfly Banksiola dossuaria on egg masses of the spotted salamander Ambystoma maculatum. American Midland Naturalist 127: 368–372. Strayer, D.L. (2006). Challenges for freshwater invertebrate conservation. Journal of the North American Benthological Society 25: 271–287. Voshell, J.R. (2002). A Guide to Common Freshwater Invertebrates of North America. The McDonald and Woodward Publishing Company, Blacksburg, VA. Weeks, S.C. (1990). Life-history variation under varying degrees of intraspecific competition in the tadpole shrimp Triops longicaudatus (Leconte). Journal of Crustacean Biology 10: 498–503. Weeks, S.C. and Bernhardt, R.L. (2004). Maintenance of androdioecy in the freshwater shrimp, Eulimnadia texana: field estimates of inbreeding depression and relative male survival. Evolutionary Ecology Research 6: 227–242. Wiggins, G.B. (1973). A contribution to the biology of caddisflies (Trichoptera) in temporary pools. Royal Ontario Museum, Toronto, ON, Canada. Life Sciences Contribution No. 88. Wiggins, G.B. (1996). Larvae of the North American Caddisfly Genera (Trichoptera), 2nd ed. University of Toronto Press, Toronto, ON, Canada. Wiggins, G.B., Mackay, R.J., and Smith, I.M. (1980). Evolutionary and ecological strategies of animals in annual temporary pools. Archiv für Hydrobiologie (Suppl.) 38: 97–206. Williams, D.D. (1987). The Ecology of Temporary Waters. Timber Press, Portland, OR. Williams, D.D. (1996). Environmental constraints in temporary waters and their consequences for the insect fauna. Journal of the North American Benthological Society 15: 634–650. Williams, D.D. (1997). Temporary ponds and their invertebrate communities. Aquatic Conservation-Marine and Freshwater Ecosystems 7: 105–117. Williams, D.D. (2006). The Biology of Temporary Waters. Oxford University Press, Oxford. Williamson, C.E. and Reid, J.W. (2001). Copepoda. In Thorp, J.H. and Covich, A.P. (Eds.). Ecology and Classification of North American Freshwater Invertebrates. Academic Press, San Diego, CA, pp. 915–954.

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Ecology and Conservation of PoolBreeding Amphibians Raymond D. Semlitsch and David K. Skelly

CONTENTS Amphibian Complex Life Cycle ...........................................................................128 Amphibian Distributional Patterns ........................................................................131 Vernal Pool Amphibians............................................................................131 Hydroperiod ...............................................................................................132 Canopy .......................................................................................................132 Population Dynamics.............................................................................................134 Community Dynamics ...........................................................................................136 Spatial Ecology......................................................................................................137 Conservation Implications .....................................................................................139 Summary ................................................................................................................141 Acknowledgments..................................................................................................142 References..............................................................................................................142

Our concern over the decline of amphibian populations and species extinctions has raised many questions about the causes and potential solutions (e.g., Blaustein et al. 1994; Houlahan et al. 2000; Semlitsch 2003). Recently, it was determined that amphibians are more threatened than either birds or mammals (Stuart et al. 2004). Although no single cause for all declines has surfaced, six common threats are known: disease, introduction of exotic species, chemical contamination, commercial exploitation, global climate change, and habitat loss and alteration (Semlitsch 2003). Among these, most biologists agree that habitat loss and alteration is the number one factor contributing to global declines. This is especially true in North America, where aquatic breeding habitats such as vernal pools receive little, if any, protection and are disappearing at an alarming rate (Comer et al. 2005; but see state exceptions Burne and Griffin 2005). To combat the loss of these small wetlands, it is important to understand what role they play in the larger forested ecosystem where they are found and discuss how their loss might affect other components of forest biodiversity and function (e.g., importance of amphibians in local food chains; Paton 2005). We

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can advance this understanding by focusing on the ecology of amphibians, and their dependence on both vernal pools and the surrounding forested habitat for completion of their life cycle and for long-term persistence. The majority of amphibian species worldwide have a complex life cycle (Semlitsch 2003). Within northeastern North America, roughly 48 species of amphibians occur (Conant and Collins 1998; Petranka 1998) and fully 27 of 48 species regularly use either vernal or other seasonal pools (Colburn 2004; Table 7.1). All of the 27 species using seasonal pools have a complex life cycle and may play important ecosystem roles such as the following: Larval anurans (frogs and toads) are consumers of primary production in the form of periphyton and phytoplankton (e.g., Seale 1980). All larval caudates (salamanders) and some anurans are consumers of secondary production in the form of zooplankton, aquatic insects (including mosquitoes), and larval anurans. On land, all amphibians consume small invertebrates often not available to other vertebrate groups. Amphibians comprise a large amount of protein biomass that is readily available in the forest food chain (e.g., to fish, snakes, birds, mammals; reviewed by Davic and Welsh 2004). They serve as nutrient vectors connecting aquatic and terrestrial ecosystems through seasonal emigration and immigration processes that disperse protein and nutrients between habitats (e.g., Regester et al. 2006). Our objectives in this chapter are to provide: (1) an overview of the ecology of pool-breeding amphibians drawing on studies from across North America, (2) a framework for understanding amphibian dependence on vernal pools as well as surrounding terrestrial ecosystems in the northeastern region, and (3) the essential features that are necessary for conservation of pool-breeding amphibians.

AMPHIBIAN COMPLEX LIFE CYCLE All pool-breeding amphibians in northeastern North America possess a complex life cycle that has an aquatic larval stage and a terrestrial juvenile/adult stage. Aquatic larvae feed, grow, and develop in pools until metamorphosis is complete. After metamorphosis, they emigrate as juveniles to forested terrestrial habitats where they remain until they reach reproductive maturity and, eventually, most migrate back to aquatic breeding sites (Wilbur 1980). Thus, the pool and the surrounding terrestrial habitat are essential to completion of the species’ life cycles. Metamorphosis is the developmental mechanism that allows individuals to make the transition between the two environments and produces a radical change in morphology, physiology, ecology, and behavior. In contrast, some amphibians in the Northeast have simple life cycles; the redback salamander, (Plethodon cinereus) has direct development, having lost the aquatic larval stage, and is completely terrestrial, whereas the mudpuppy (Necturus maculosus) does not metamorphose and is completely aquatic. It is thought that the amphibian complex life cycle is maintained evolutionarily by natural selection to exploit the benefits of both the aquatic and terrestrial

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TABLE 7.1 Amphibian Species in Northeastern North America That Regularly or Occasionally Breed in Vernal Pools

Scientific Name

Vernal Pools Are Primary Breeding Habitat

SALAMANDERS Jefferson salamander Blue-spotted salamander Spotted salamander Marbled salamander Small-mouthed salamander Eastern tiger salamander Silvery salamander (JJL) Tremblay’s salamander (JLL) Four-toed salamander Eastern red-spotted newt

CAUDATA Ambystoma jeffersonianum A. laterale A. maculatum A. opacum A. texanum A. tigrinum Formerly A. platineum Formerly A. tremblayi Hemidactylium scutatum Notophthalmus viridescens

Yes Yes Yes Yes Yes Yes, in parts of range Yes Yes Yes No, but commonly used

FROGS AND TOADS Eastern spadefoot American toad Fowlers toad Blanchard’s cricket frog Northern cricket frog Spring peeper Upland chorus frog Mountain chorus frog Western chorus frog Cope’s treefrog Gray treefrog American bullfrog Green frog Pickerel frog Northern leopard frog Southern leopard frog Wood frog

ANURA Scaphiopus holbrookii Bufo americanus B. fowleri Acris blanchardi A. crepitans Pseudacris crucifer P. feriarum P. brachyphona P. triseriata Hyla chrysoscelis H. versicolor R. catesbeiana R. clamitans R. palustris R. pipiens R. utricularia R. sylvatica

Yes No No No No No, but commonly used No No Yes, in parts of range No No, but commonly used No No No No No Yes

Common Name

Source: Conant and Collins (1998).

environments (Wassersug 1975). The length of time larvae remain in pools is quite variable and is generally thought to be an adaptation to exploit resource-rich but ephemeral aquatic habitats. Generally, larvae that remain in the aquatic environment longer reach a larger size at metamorphosis and achieve a greater portion of their final adult size (Wilbur and Collins 1973; Werner 1986). Larger size at metamorphosis is associated with increased fitness (and hence ability to survive to reproduce) of adults in both frogs and salamanders (e.g., Smith 1987; Semlitsch et al. 1988; Berven 1990). Ephemeral aquatic habitats also generally contain fewer anuran

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predators than permanent water bodies, as many predatory species cannot survive and complete their life cycles when pools dry. Because pools are temporary habitats and are only seasonally available, metamorphosis is maintained to escape into more “permanent” terrestrial habitats that do not carry the risks associated with drying pools. Thus, natural selection also maintains variability in the timing of metamorphosis to escape the dangers of desiccation in ephemeral pools and to track spatial and temporal variability in drying rates of pools. Although little is known about the terrestrial stage of many amphibians, most species spend the majority of their life on land, where they grow and reach reproductive maturity after two to three years and can often live for five to 15 or more years. Dispersal to new pools over land also occurs only in the terrestrial stage. One of the most important aspects of amphibian life histories is how closely many aspects of their life cycle are associated with the filling and drying of vernal pools. The timing of their life cycle varies geographically with climatic conditions. For example, the breeding migration of spotted salamanders (Ambystoma maculatum) in the Northeast occurs in very early spring when pools are full and timed to coincide with melting of ice and snow, making open water (at least along the edge) available for mating and egg deposition (e.g., Shoop 1965; Whitford and Vinegar 1966). Males often arrive earlier than females to maximize the number of mating opportunities, whereas females often arrive later to maximize mate choice. Females may also arrive later to ensure eggs are deposited after the potential for pond freezing is past (Harris 1980), when the water levels in pools are at their maximum depths, and when food resources for larvae such as zooplankton are readily available. Autumn breeding in species like the marbled salamander (Ambystoma opacum) is thought to represent an extreme adaptation to allow larvae the maximum potential to hatch and develop early in seasonal pools. Adults often arrive from August to September in the Northeast when pools are completely dry, mate on land, and deposit and guard eggs under debris or grass clumps along the margin of the dry pool bed. Eggs begin development but do not hatch until flooded by water when low oxygen triggers hatching (Petranka et al. 1982). Larvae then overwinter in the pool and attain relatively large body sizes before other spring-breeding species arrive. They are often predators on the larvae of spring-breeding anuran and caudate species due to their large relative size. Timing of metamorphosis also closely coincides with the drying of pools during the summer months, allowing larval growth to be maximized, while minimizing the risk of larval desiccation. Some species of anuran tadpoles such as the American toad (Bufo americanus) can speed up development in rapidly drying pools in response to reliable environmental cues (e.g., water level, higher temperature, crowding). In this way, they metamorphose before they become trapped and die. Species such as the red-spotted newt (Notophthalmus viridescens), under certain environmental conditions, can adjust to periods of long inundation by delaying metamorphosis for extended periods and can even reproduce in the larval stage (i.e., paedomorphosis or neoteny; Healy 1973). Thus, northeastern amphibians with complex life cycles have numerous features of their biology that make them well adapted to exploit vernal pools.

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AMPHIBIAN DISTRIBUTIONAL PATTERNS Glaciation defines the geographic scope of this book, as well as the amphibian membership of vernal pools within northeastern North America (Chapter 2, Rheinhardt and Hollands). Virtually every pool in the region is home to species that arrived from somewhere not covered by Pleistocene ice. This fact is of enormous importance to understanding the distribution of northeastern vernal pool amphibians. Amphibians have moved hundreds of kilometers to reach their present day distributional limits. In general, fewer species are found farther from areas of glacial refugia — that is, farther north. But the south–north axis also defines a gradient of climate that appears strongly limiting to amphibians (Duellman and Sweet 1999). Most species tend to have ranges centered in the southern portion of the region. Amphibians in boreal and sub-boreal environments must contend with extremely short growing seasons and winter cold (Duellman and Sweet 1999). Many species appear unable to cope with these extremes. The southernmost part of the focal region (Illinois) is home to 41 amphibian species, whereas just a single species, the wood frog (Rana sylvatica), is found in northern Labrador. Although northward attrition implies strong variation in species composition across the Northeast, this impression is, in part, misleading. Across much of the region, roughly 20 species of amphibians are found and turnover in species composition (gamma diversity) is extremely low. Amphibian biologists from Maine airdropped into Wisconsin would be able to identify 14 of the 18 species found 1,200 km (746 mi) away from their home state. Constancy in species composition likely reflects the common geographic origins of colonists as well as the recent upheaval that created and then exposed one of the densest concentrations of vernal pools on earth.

VERNAL POOL AMPHIBIANS What is a vernal pool amphibian? Any answer to this nontrivial question must be provided with the caveat that there are numerous definitions and policies offered by many different institutions and agencies that use vernal pool associations of amphibians as a criterion for defining and protecting wetlands (Calhoun and deMaynadier 2004; Calhoun et al. 2005). From a purely biological perspective, it is easy to make the case that vernal pools are important for most amphibians. Even when they are not used by a species for breeding, smaller pools tend to be the most numerous wetlands (Semlitsch and Bodie 1998; Gibbs 2000) and provide hospitable habitat for amphibians moving through the terrestrial environment (Table 7.1). Even if we restrict our definition to just those species breeding in vernal pools, the picture is not simplified. If vernal pools are monitored long enough, most species present within a region can be discovered breeding there, if only sporadically or in some part of the region (Skelly et al. 1999; Halverson et al. 2003; Skelly et al. 2003; Whiting 2004). One reason is the tremendous climate-driven temporal variation in vernal pool inundation periods. During a run of wet years, a vernal pool that dries during a season of average rainfall can remain filled for a year or more (e.g., Semlitsch et al. 1996; Chapter 3, Leibowitz and Brooks). This will allow species like green frogs (Rana clamitans), most often described as permanent pond

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inhabitants, time to arrive and breed (Skelly et al. 2005). In the same pool during an extreme drought, successful breeding can be restricted to one or two species that breed in early spring and have extremely rapid larval development (e.g., wood frogs, eastern spadefoot toads [Scaphiopus holbrookii]). These patterns have sometimes been portrayed as aberrant phenomena. Such a characterization misses the important point that vernal pools are highly dynamic environments: they vary among pools and across years to an extreme degree. It can be misleading to characterize vernal pools according to an average condition or by their typical inhabitants. Nevertheless, we can restrict our definition further to include only those species that breed primarily or solely within vernal pools. This is the perspective familiar to regulators and other environmental professionals. For example the U.S. Environmental Protection Agency and various state governments define species such as wood frogs, spotted salamanders, eastern spadefoot toads, and others that are broadly distributed across the Northeast as “vernal pond indicators.” In some cases, presence of breeding individuals of such species is used to define a wetland as a vernal pool (e.g., Calhoun et al. 2003; Chapter 10, Mahaney and Klemens). Because of their interest from both regulatory and scientific perspectives, these amphibians have been subject to close ecological study, yielding an extensive catalog of the factors that can affect distribution (reviewed by Skelly 2001). Here, we focus on two abiotic factors, hydroperiod and canopy, that are particularly important for understanding vernal pool species distributions.

HYDROPERIOD Vernal pools are defined by periodic drying. The likelihood and timing of drying within a pool have enormous effects on which amphibian species will breed (Semlitsch et al. 1996; Skelly et al. 1999; Snodgrass et al. 2000; Babbitt et al. 2003; Gamble et al. 2006) and how they fare (Skelly 1996). In general, species with longer larval periods tend to restrict their breeding to pools of longer duration (Skelly 1996; Skelly et al. 1999). Egg mass densities also tend to be higher in longer duration vernal pools (Egan and Paton 2004; Baldwin et al. 2006a). In a year of near-average rainfall, entire cohorts of larval wood frogs failed due to drying in 35% of their breeding pools at the Yale Myers Forest, Connecticut (E. Lee, personal communication). These and comparable findings (Semlitsch et al. 1996; Skelly 1996) imply that annual drying serves as an active distributional constraint on vernal pool amphibians.

CANOPY A second factor affecting many vernal pools is the presence of forest canopy. Most of the focal region is coincident with the forested realm of North America. Because pools drying seasonally also tend to be small in surface area, vernal pools are susceptible to overtopping by terrestrial woody vegetation. As this vegetation grows and matures, it can deeply shade a vernal pool (Skelly et al. 2002; Halverson et al. 2003; Skelly et al. 2005). Light levels in closed canopy pools can be indistinguishable from those measured above the floor of a mature forest (Halverson et al. 2003).

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Shading has important consequences for vernal pool amphibians, as it does for terrestrial organisms. Foremost among these is alteration of temperature. Average water temperature can differ by as much as 2–3°C and peak daytime temperatures can be more than 10˚C higher in an open wetland (e.g., Skelly et al. 2002). For ectothermic (“cold-blooded”) animals such as amphibians, rates of both development and growth are functions of temperature. The consequences of shading are magnified by the time boundary imposed by hydroperiod. Although it might seem that shaded pools should survive longer due to lower rates of evaporation from the pool surface, the opposite is generally true. Forest growth moves water demand up to the canopy where rates of evapotranspiration more than compensate for any decreased evaporation from the pool surface (Brooks 2004). Long-term observations suggest that hydroperiod of wetlands beneath accreting forests can decline as much as one week (Skelly et al. 1999). Canopy has a separate set of effects mediated through changes in the rate and constitution of primary production. Both decreases in standing crop and alterations in composition of attached algae and other food sources (Skelly et al. 2002) are characteristic of closed canopy pools, which in turn are associated with decreased digestive efficiency of vernal pool tadpoles (Skelly and Golon 2003) and lower rates of growth and development (Skelly et al. 2002). Field experiments showing that food addition has greater positive effects on growth and development in shaded vs. open pools underscore the importance of food mediated effects of canopy development (Skelly et al. 2002). Whatever their origin, canopy has strong effects on the amphibian composition within vernal pools (Figure 7.1). Many species are sensitive to canopy closure and are found infrequently in shaded pools (Skelly et al. 1999; Skelly et al. 2005). Furthermore, field transplant experiments confirm that open canopy specialists perform relatively poorly when placed in closed canopy environments (Werner and Glennemeier 1999; Skelly et al. 2002; Skelly et al. 2005), highlighting the challenging nature of closed canopy vernal pools for some species. Exceptions, such as marbled salamanders, spotted salamanders and wood frogs that perform well under shaded conditions, are the very species that we identify most closely with forested vernal pools in the Region (Table 7.1). When considering the role of canopy cover, however, we need to include the effects on the terrestrial as well as the aquatic environment. Although open canopy over pools increases productivity, many vernal pool species are heavily dependent on forested terrestrial habitat, either avoiding open areas or suffering negative effects from factors such as dehydration (Rothermel and Semlitsch 2002). Because of this, pool-breeding specialists such as the wood frog, spotted salamander, and marbled salamander are unlikely to be found breeding in pools surrounded by large areas of open habitat. Because shade is more likely to be reduced, rather than increased, by anthropogenic habitat change, populations of these species are also more likely to be at risk than are species such as green frogs or spring peepers (Pseudacris crucifer) that frequent open areas. A further consideration when evaluating the consequences of shade over vernal pools comes from recent studies of amphibian population biology (summarized in the following section). These studies suggest that changes in aquatic life-history stages, such as increased production of larvae, are unlikely to

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Mean Light Level [GSF]

1.0 0.8 0.6 0.4 0.2 0.0 0.0

0.2

0.4

0.6

0.8

1.0

% of Pools Present

FIGURE 7.1 The data points represent the proportion of pools where each species was found breeding, plotted against average light level (measured as global site factor [GSF] during the leaf-on period). Data are derived from the distribution of eight amphibian species across 17 vernal pools at the Yale Myers Forest, Connecticut. The eight species are Bufo americanus, Pseudacris crucifer, Hyla versicolor, Rana clamitans, R. sylvatica, Ambystoma maculatum, A. opacum, and Notophthalmus viridescens. With the exception of A. opacum, which was present exclusively in heavily shaded ponds, species found in fewer locations tend to be found in more open pools. Species found in most or all of the pools (A. maculatum, R. sylvatica) bred in ponds that ranged from extremely low light (GSF = 0.08) to extremely sunny (GSF = 0.96) but were on average shaded (GSF = 0.31). (Data from Skelly et al. 2005. With permission.)

be driving population trends alone, and that terrestrial habitat conditions and adult survival should be of primary conservation concern. Thus removing forest around a breeding pool may increase larval productivity, but, for obligate vernal pool species, any beneficial population effects may be outweighed by potential reductions in adult survival and breeding in subsequent years.

POPULATION DYNAMICS The historic view of population dynamics in pool-breeding amphibians is that regulation occurs primarily in the larval aquatic stage, although theoretically, it could also occur in the terrestrial stage or both stages (Wilbur 1980). This historic view follows from the high larval densities observed in natural populations (e.g., up to 4,000 per m2 for anurans; Woodward 1982; Petranka 1989) and high species diversity in many aquatic habitats (e.g., <14 species in northeastern pools but >20 in the southern U.S.; Dodd 1992; Semlitsch et al. 1996). It was long thought that densitydependent and species interactions are likely important for regulating natural larval populations (Wilbur 1980; Pechmann 1994). Field studies have demonstrated a strong negative effect of density on growth and survival of larvae (Smith 1983; Petranka 1989; Van Buskirk and Smith 1991; Scott 1994). These studies show that as larval density increases, larvae grow and develop more slowly, larval period

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increases, size at metamorphosis is reduced, and fewer individuals reach metamorphosis (<5% of larvae normally metamorphose; Herreid and Kinney 1966; Licht 1974; Semlitsch 1987). Small size at metamorphosis can result in poor physiological and locomotor performance in the terrestrial environment (Goater et al. 1993), lower juvenile survival, later first reproduction, and smaller size at first breeding (Smith 1987; Semlitsch et al. 1988; Berven 1990). As larval density decreases, the same larval traits are positively affected and populations experience higher metamorphic success. But in most species, successful larval development to metamorphosis in natural aquatic habitats is affected by the interaction of multiple factors, typically related to the drying rate of pools, interspecific competition for food, and the presence and abundance of predators (Semlitsch et al. 1996). All of these factors are consistent with density-dependent regulation in the larval stage. Several recent findings, however, suggest that regulation of amphibian populations can also occur in the terrestrial stage and likely interacts with density-dependence in the aquatic stage. First, a field experiment that manipulated the density of metamorphs in terrestrial pens indicated that survival was higher at lower densities, and survival was enhanced even more when metamorphs originated from low-density aquatic habitats and were reared in low-density terrestrial habitats (Pechmann 1994). Second, the use of ecological sensitivity models and demographic population models indicate that postmetamorphic vital rates and adult habitat size strongly influence population dynamics of amphibians (Biek et al. 2002; Halpern et al. 2005). The most interesting implication stemming from this new paradigm — that of terrestrial regulation of amphibian populations — is that loss of terrestrial habitat surrounding vernal pools could be just as detrimental to population persistence as loss of the wetland. Thus, populations are likely regulated in both the aquatic and terrestrial stage such that they persist over time by a combination of the number and quality of metamorphosing larvae leaving a pool and the number of terrestrial juveniles that survive to be recruited into the adult breeding population. A set of species persists in a given area because each species episodically and under the right environmental conditions produces large numbers of metamorphosing juveniles (e.g., Gill 1978; Semlitsch 1983; Berven 1990; Pechmann et al. 1989; Semlitsch et al. 1996). Reproductive failures are common among amphibians, at least in regions where wetlands are subjected to rapid drying or other catastrophic events (e.g., in South Carolina depressional wetlands reproductive failure rates were 42–56% for 13 species over 16 years; Semlitsch et al. 1996). Yet, adults reproduce over multiple years and many species (especially Ambystoma salamanders) have a life expectancy great enough (five to 15 yrs) to experience a few “booms” in metamorph recruitment that compensates for adult attrition. Short-lived (<2 years) species like spring peepers or chorus frogs (Pseudacris triseriata) are vulnerable to local extinction after just a couple years with negligible metamorph recruitment. Modeling of amphibian populations indicates that long-lived species can “store” recruits in terrestrial habitats during these infrequent reproductive booms, whereas short-lived species cannot and depend more directly on larval success in aquatic habitats (Halpern et al. 2005). This pattern of “boom or bust” population dynamics contrasts greatly with the constant low-level, annual reproductive success exhibited by most mammals and

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birds. This characteristic of amphibian populations means that multiple years of reproductive failure due to unfavorable pool conditions, such as rapid drying during drought years or from anthropogenic factors like building ditches or introducing fish, can result in decline and eventual extinction of species at the pool level (e.g., Semlitsch et al. 1996; Chapter 8, Gibbs and Reed), and local landscape level. Because adult amphibians have a strong preference to return to ponds where they first breed (e.g., Oldham 1966; Breden 1987; Berven and Grudzien 1990), metamorphosing juveniles are likely the primary dispersal stage (sensu Gill 1978). A high rate of successful metamorphosis is critical to maintain local adult populations and, through dispersal, to reestablish extirpated populations or found new populations. So, although vernal pools are especially critical for reproduction in short-lived species, terrestrial habitats are especially critical for adult populations in long-lived species, and the connections among pool populations are essential for higher-level regional persistence.

COMMUNITY DYNAMICS Vernal pool amphibian species typically are found in multispecies assemblages that include other amphibian taxa and a wide variety of invertebrates. During recent decades there have been many experiments that have found strong effects of competition and predation on focal amphibian species (reviewed by Wilbur 1997; Skelly and Kiesecker 2001). These findings have been widely interpreted to mean that vernal pool amphibian distributions in nature are likely to be functions of both predator and interspecific competitor distributions (Alford 1999). Specifically, because pools with longer hydroperiods tend to have more diverse and voracious predators (Wellborn et al. 1996), it has been hypothesized that predation would reduce density to a greater degree in longer duration pools. Conversely, in the most ephemeral pools, the effects of interspecific competition are assumed to be strongest where low levels of predation would allow for high densities of larval amphibians (Morin 1983). Collectively, this synergism among hydroperiod, predation, and interspecific competition has been predicted to lead to segregated distributions among larval amphibians. Stronger competitors should have more rapid development, be more susceptible to predators, and therefore concentrate in ephemeral ponds lacking fish and other predators. Slow-developing species should be less susceptible to predators and should be present in ponds of longer duration. In a general sense, natural history patterns are consistent with these predictions; a number of studies have shown that related species fall out on the hydroperiod gradient as expected (Werner and McPeek 1994; Skelly 1995a, 1995b, 1996). It is clear that biotic interactions are critically important for the distributions of vernal pool amphibians. Some of the strongest biotic effects on amphibians are widely agreed to come from fish predators (e.g., Maret et al. 2006). Field observations and whole pond manipulations show that fish presence is a critical determinant of amphibian oviposition patterns. Some species such as wood frogs breed rarely, if at all, in the presence of fish (Hopey and Petranka 1994) and are known to move into wetlands following local extinction of fish due to winterkill or drought-related

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drying (Werner et al., in review). Experiments and anecdotal reports show that many important predatory fish species can have devastating effects on amphibian species commonly associated with vernal pools (Smith et al. 1999). Because fish are only associated with northeastern vernal pools under unusual conditions (e.g., floodplain pools, abandoned beaver flowages), fish predation may be most helpful in understanding why many species are restricted to vernal pools (Skelly et al. 1999).

SPATIAL ECOLOGY Understanding vernal pool amphibian population dynamics requires an understanding of spatial context due to their use of multiple habitats and the patchy distribution of breeding pools (Chapter 3, Leibowitz and Brooks; Chapter 14, Baldwin et al.). In this section, rather than considering the ways in which pools can differ from each other, we consider the ways in which terrestrial context can influence amphibians breeding in vernal pools. Specifically, we review evidence suggesting that isolation among pools and the state of the uplands surrounding pools affect amphibian populations. The metapopulation concept (a cluster of populations) has long been used as a framework for thinking about the spatial ecology of amphibians (Gill 1978; Chapter 8, Gibbs and Reed). Whereas vernal pool amphibians spend much of their lives in the terrestrial environment, most adults migrate no more than tens to hundreds of meters from breeding pools (Color Plate 17; Regosin et al. 2003; Semlitsch and Bodie 2003). This generalization has two critical implications. First, it means that landscape changes within the core terrestrial habitat surrounding a vernal pool can have direct impacts on a large fraction of the terrestrial members of its breeding population (Semlitsch and Bodie 2003; Trenham and Shaffer 2005). Second, the incremental destruction of breeding pools and other small wetlands increases pond isolation, potentially severely impairing connectivity among populations (Gibbs 2000; Semlitsch and Bodie 1998; Chapter 16, Windmiller and Calhoun). Loss of connectivity can be important for vernal pool amphibian populations that depend on dispersal among ponds. Can a species be absent from a vernal pool because of isolation from other pools? The answer appears to be yes, even within the northeastern region where interpool distances can be relatively modest (Skelly et al. 1999). Sparsely available long-term data show that species are less likely to be present, and are less likely to persist, when the nearest sources of colonists are farther away (Skelly et al. 1999). These are important results implying that longterm persistence of a species within a pool may depend on successful dispersal of individuals from other pools (the “rescue effect”). There is even stronger evidence that terrestrial landscape composition surrounding vernal pools is critical for amphibian populations. Although results vary among species, a number of recent studies show quite clearly that vernal pool species are more likely to be present in landscape contexts dominated by forest cover and that increasing landscape conversion and fragmentation by agriculture, roads, and suburban or urban land uses is associated with species absences (Gibbs 1998; Homan et al. 2004; Porej et al. 2004; Price et al. 2004). Some studies have gone beyond simple positive and negative associations to reveal strong scale dependence in

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100 c) 300 m 80 60 40 20

Forest (%)

m

b

r2

0–30 30–100

2.97 0.55

–33.41 30.86

0.96 0.47

0– 1 10 0 –2 20 0 –3 30 0 –4 40 0 –5 50 0 –6 60 0 –7 70 0 –8 80 0 – 90 90 –1 00

0

Upland forest (%)

FIGURE 7.2 Percent occurrence of spotted salamanders (Ambystoma maculatum), as a function of land cover (percentage of upland forest within a 300 m (984 ft) radius) measured from the edge of suitable breeding pools. Two regression lines are joined at the point of a critical threshold in the relationship between forest cover and salamander presence. (Homan et al. 2004. With permission.)

patterns between land cover types and species presence-absence (Price et al. 2004). As one example, Homan et al. (2004) estimated thresholds describing changes in the relationship between forest cover and vernal pool species presence. For spotted salamanders, there was a strong overall relationship between percentage of forest cover and the likelihood of species presence regardless of scale of estimation, which ranged from 100 m (328 ft) to 1,000 m (3,281 ft) radius (Figure 7.2). Finer scales of estimation focusing on the uplands immediately surrounding pools, however, revealed an additional threshold requirement for forest cover of 30%. Below this value, spotted salamanders were unlikely to be present. In addition to providing nonbreeding habitat, the structure of uplands may influence amphibian distributions by affecting dispersal. A number of studies show that vernal pool amphibians have strong preferences for different land cover types (Gibbs 1998; deMaynadier and Hunter 1999; Montieth and Paton 2006; Patrick et al. 2006), with most species in the focal region selecting partially to mostly closed canopy forest settings. Further evidence for preference for closed canopy forest is provided by studies showing that amphibians placed in open, unforested areas do not move as far and survive poorly compared with amphibians moving within forested habitat (Rothermel and Semlitsch 2002; Mazerolle and Desrochers 2005), perhaps because amphibians desiccate more rapidly when moving in the open. Open environments may also affect the ability of amphibians to navigate (Rothermel 2004; Mazerolle and Desrochers 2005). Either because of habitat changes or because of loss of connectivity, landscapes altered by humans typically have lower species abundance even when vernal pools remain (Gibbs 1998; Skelly et al. 2006). In a study of forested, suburban, and urban

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landscapes in Connecticut, Skelly et al. (2006) found a reduction in amphibian species richness of more than two thirds (from >3 species per pool to <1 species) with increasing urbanization. Vernal pool indicator species such as wood frogs are particularly hard hit by landscape conversion, disappearing in degraded landscapes even where vernal pools are still present (Gibbs 1998; Skelly et al. 2006).

CONSERVATION IMPLICATIONS There are three essential components that need to be addressed in conservation plans for amphibians using vernal pools: (1) the area containing the local population that includes the breeding pool, the surrounding terrestrial nonbreeding habitats, and the juxtaposition of the two (= complementation sensu Dunning et al. 1992), (2) the metapopulation, including the terrestrial matrix between populations, and (3) natural disturbance processes that create new pools or reset succession of pools or terrestrial habitat (Semlitsch 2000; Semlitsch and Rothermel 2003). The number and quality of metamorphosing larvae leaving a pool, and the number of juveniles surviving to maturity and recruited into the terrestrial adult population determine success at the local population level. Juvenile survival and time to maturity depend on the size and quality of core terrestrial habitat (carrying capacity) adjacent to pools (Semlitsch and Bodie 2003). The radius of habitat required by most adult amphibians ranges from 142–289 m (462–939 feet) from the wetland edge (mean minimum estimates for 32 species from Semlitsch and Bodie 2003). Frogs, in general, require significantly more habitat than salamanders (Rittenhouse and Semlitsch, unpublished data), and females have been shown to travel and overwinter farther from pools than males (Regosin et al. 2005). Estimates compiled for 12 species common to the northeast region indicate an average distance of 123 m (404 ft) and a maximum of 278 m (913 ft) from pools is needed to encompass local populations around vernal pools (Table 7.2). Land use activities that degrade or truncate the terrestrial core habitat will limit the carrying capacity of populations and potentially their long-term viability (Halpern et al. 2005). Because edge effects from surrounding land use can also impact amphibians, an additional 25–50 m (81–163 ft) buffer is required to protect the terrestrial core habitat (Murcia 1995; deMaynadier and Hunter 1998). Metamorphs are also critical to maintain other local populations through dispersal (i.e., in source-sink dynamics; Pulliam 1988). We know that local species populations are subjected to extinction periodically, even under natural conditions, primarily due to stochastic events like drought (Semlitsch et al. 1996), and through anthropogenic factors like draining, ditching, filling, pollution, and fish introduction. Dispersal occurs mostly by juveniles (e.g., Breden 1987; Berven and Grudzien 1990) and connectivity among pools is critical to maintaining amphibian metapopulations. Alteration and loss of pools reduces the total number or density of pools where amphibians can reproduce and provide dispersers. Reduced pool density increases the distance between neighboring pools, thereby affecting critical recolonization processes (e.g., Semlitsch and Bodie 1998). This adverse effect is critical because most individual amphibians cannot migrate long distances due to physiological limitations of water loss (Spotila 1972). An estimate of genetic dispersal distance

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TABLE 7.2 Summary of Terrestrial Migration Distances (in Meters) for Adult Salamanders and Frogs Surrounding Vernal Pools and Other Aquatic Breeding Sites State Caudata Ambystoma jeffersonianum

Ambystoma laterale Ambystoma maculatum

Ambystoma opacum Ambystoma texanum Ambystoma tigrinum Anura Acris crepitans Bufo americanus Hyla versicolor Pseudacris triseriata Rana clamitans Rana sylvatica

Mean/Range/Maximum (Sample Size)

Reference

Indiana Kentucky Michigan Michigan Vermont Massachusetts

Mean = 252, range: 20–625 (86) Mean = 250 (10) Mean = 39, range: 8–129 (8) Mean = 92, range: 15–231 (45) Mean = 93, range: 30–205 (6) Maximum > 300 (7)

Indiana Kentucky Michigan Michigan Michigan New York Vermont Indiana Kentucky Massachusetts Indiana

Mean = 64, range: 0–125 (7) Mean = 150, range: 6–220 (8) Mean = 67, range: 26–108 (2) Mean = 103, range: 15–200 (14) Mean = 192, range: 157–249 (6) Mean = 118, range: 15–210 (8) Mean = 137, range: 52–219 (5) Mean = 194, range: 0–450 (12) Mean = 30 (6) Range: 114–381 (20) Mean = 52, range: 0–125 (10)

Williams 1973 Douglas and Monroe 1981 Wacasey 1961a Wacasey 1961b Faccio 2003 Regosin, Homan, and Windmiller, unpublished data Williams 1973 Douglas and Monroe 1981 Wacasey 1961a Wacasey 1961b Kleeberger and Werner 1983 Madison 1997 Faccio 2003 Williams 1973 Douglas and Monroe 1981 Gamble, unpublished data c Williams 1973

New York

Mean = 60, range: 0–286 (27)

Madison and Farrand 1998

Illinois Ontario Missouri Indiana

Range: 8–22 (189) Range: 23–480 (176) Mean = 172, maximum = 271 (20) Mean = 75, maximum = 213 (9)

O’Neil 2001a Oldham 1966a Johnson et al. 2006 Kramer 1973

New York Ontario Maine Massachusetts

Mean = 121, maximum = 360 Mean = 137, maximum = 457 Mean = 192.5, range: 102–340 (8) Maximum = 472

Lamoureux and Madison 1999 Oldham 1967a Baldwin et al. 2006b Windmiller 1996

a

Hand collecting marked individuals. Hand collecting unmarked individuals. c Incidental recaptures of individuals traversing drift fences at fixed distances from known breeding ponds. b

Source: References are taken from Appendix 1 in Semlitsch and Bodie 2003 or provided in the References section.

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for wood frog populations averages only 1,126 m (3,694 ft), suggesting that migration and gene flow are near zero beyond these distances (Berven and Grudzien 1990; Chapter 8, Gibbs and Reed). Semlitsch and Bodie (1998) demonstrated in South Carolina that the loss of all natural wetlands <4.0 ha (9.9 ac) in size would increase the nearest-wetland distance from 471 m (1,545 ft) to 1,633 m (5,358 ft). This distance is likely greater than can be traversed by most species. In addition, land use that alters the matrix between populations can render it unusable or less permeable to migrating amphibians (e.g., peat mining, Mazerolle 2001; pastureland, Rittenhouse and Semlitsch 2006; roads, deMaynadier and Hunter 2000) thereby reducing or disrupting recolonization (Joly et al. 2001). Thus, the loss or alteration of wetlands as well as the terrestrial matrix could severely impede rescue and recolonization processes, and place populations of amphibians in remaining wetlands at increased risk of extinction (Laan and Verboom 1990; Joly et al. 2001; Marsh and Trenham 2001). Natural disturbance processes responsible for resetting succession or in some cases even creating new wetlands must not be ignored or suppressed by management (Semlitsch and Rothermel 2003). Although glacial processes originally created most vernal pools in the northeastern region (e.g., kettle holes, Colburn 2004; Chapter 2, Rheinhardt and Hollands), some were created by the scouring process of flooding in river floodplains, landslides, and windfalls (e.g., tip-ups in shallow forested wetlands). Maintaining these disturbance processes is important to balance the loss of seasonal pools in certain areas due to the deterministic process of succession. Reversing succession by fire is also potentially important where wildfires were historically common, such as in dry, sandy coastal regions (e.g., pine barrens of New Jersey and Long Island). In more inland regions, beaver were likely important to reverse succession by flooding forests and killing trees to create open canopy ponds (sensu Gill 1978). Without these disturbance processes present on the landscape, amphibian species favoring early successional breeding habitats (e.g., chorus frogs, toads, tiger salamanders [Ambystoma tigrinum]) will decline or disappear from local populations, thereby favoring species associated only with later successional stages (Skelly et al. 1999, Table 7.1). Every effort should be made to preserve the structure, function, and diversity of vernal pools, their spatial arrangement and connectivity, and the surrounding terrestrial habitat for pool-breeding amphibians so that costly and problematic species recovery and habitat restoration or mitigation procedures are not necessary.

SUMMARY We have emphasized important features of the ecology of amphibians in the northeastern region that use vernal pools. These amphibians share a common historical and biogeographic context that may account for broad similarity in species complements inhabiting vernal pools over a relatively large area. Yet, species composition within individual pools is highly variable among pools and even between years. Forest canopy conditions over vernal pools can have strong effects on amphibian species composition. Many species are sensitive to canopy closure and are found infrequently in cool, shaded pools. There are also a number of specialized amphibian

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breeders, including ambystomatid salamanders and wood frogs, that are often associated with shaded pool conditions. Although amphibians are well adapted to natural variability in pool flooding and drying, anthropogenic influences can significantly increase or decrease the length of time pools are inundated with negative impacts to some species. Regulation of population size is determined by metamorph recruitment from aquatic habitats, and (especially for long lived species) the carrying capacity of terrestrial habitats. Composition of the terrestrial habitat surrounding pools is important to amphibians because it contains the adult breeding populations; removal of surrounding forests would be detrimental to many species. Further, if terrestrial habitats are altered by incompatible land use, they can offer resistance to dispersal among pools, thereby affecting rescue and recolonization processes important to the persistence of species at a regional level.

ACKNOWLEDGMENTS We thank Aram Calhoun, Phillip deMaynadier, Dana Drake, Kealoha Freidenburg, Elizabeth Harper, Dan Hocking, Tracy Langkilde, Eric Lee, Peter Paton, David Patrick, Mark Urban, and Bryan Windmiller for reviewing the manuscript. R. Semlitsch was supported by NSF Collaborative Grant DEB 0239943 and D. Skelly was supported by a grant from the Department of Defense Multidisciplinary University Research Initiative.

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Population and Genetic Linkages of Vernal PoolAssociated Amphibians James P. Gibbs and J. Michael Reed

CONTENTS The Physical Setting for Demographic and Genetic Processes: How Populations are Organized on the Landscape ..............................................150 Drift and Inbreeding ..............................................................................................156 Extinction–Recolonization Dynamics and Local Adaptation ...............................158 Conservation Implications .....................................................................................161 Acknowledgments..................................................................................................163 References..............................................................................................................163

Population persistence requires a favorable balance between recruitment and loss of individuals over time. Persistence is driven by population size, local population dynamics, metapopulation dynamics (i.e., local extinctions, colonization, and dispersal), and stochastic events (Vandermeer and Goldberg 2003). These processes also shape the distribution of genetic diversity of individuals in a population (Harrison and Hastings 1996). Genetic variation is associated with short-term population persistence in species that typically outbreed (Frankham et al. 2002) and ultimately determines a population’s capacity to adapt to a changing environment, particularly to rapid changes wrought by human activities (Stockwell et al. 2003). Consequently, understanding population genetic linkages is an important focus for conservation biologists and land managers concerned with the fate of any organism. Understanding population and genetic linkages of vernal-pool-dependent amphibians is challenging because of several complicating aspects of the biology of these organisms. One is that the vernal pools that underpin the organization of breeding populations are geographically scattered (Burne and Griffin 2005). However, it is not necessarily the case that a patchy distribution of breeding sites results in isolated breeding populations (Smith and Green 2005). For example, following breeding many species redistribute themselves across uplands surrounding pools. Such is the case with many Ambystoma salamanders that may move up to hundreds of meters to terrestrial foraging and overwintering sites on the forest floor (e.g., root

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channels, small mammal burrows, woody debris) (Madison 1997; Madison and Farrand 1998; Regosin et al. 2005). As a consequence, many organisms that depend on vernal pools for breeding undergo pronounced annual redistributions from being highly clustered at breeding pools during one season to highly dispersed in terrestrial habitats at others. This frequent and dramatic population redistribution might suggest that amphibian populations are linked broadly across the landscape. However, a high degree of tenacity by adults to particular breeding sites occurs in many species (Semlitsch 2000). Under conditions of site tenacity, vernal pool amphibians may be confined to relatively isolated breeding populations that overlap with individuals from other such populations on the uplands surrounding breeding pools but only infrequently exchange breeders with them. Adding to the complexity of population dispersion and connectivity, vernal pools can produce massive numbers of metamorphs that can move 10 km or more in “one-way” dispersive movement (Smith and Green 2005). Such movements mix gene pools of adjacent breeding populations. Exactly how restricted adult migration interacts with potentially extensive juvenile dispersal to structure breeding populations across the landscape is a central question, but one that remains poorly resolved. It generally requires intensive species- and site-specific research to determine if individuals distributed across a network of vernal pools represent a single population integrated through regular exchange of dispersers, a set of subpopulations only periodically connected by dispersal (that is, a metapopulation), or a suite of completely isolated and demographically independent units (Gill 1978; Smith and Green 2005). Migration, and particularly dispersal, are the key drivers of population genetic structure but are notoriously difficult aspects of any organisms’ demography to track. Yet recent improvements in methods for tracking amphibian movements using indirect methods (Spear et al. 2005) and direct monitoring of radio-, radar-, or radioactively tagged individuals (e.g., Kleeberger and Werner 1983; Madison 1997; Leskovar and Sinsch 2005) combined with simple dedication to carrying out exhaustive, large-scale field studies (e.g., Regosin et al. 2003) are resulting in a rapidly accumulating body of knowledge about the specific nature of population genetic structure in vernal pool breeding amphibians. We review this literature here.

THE PHYSICAL SETTING FOR DEMOGRAPHIC AND GENETIC PROCESSES: HOW POPULATIONS ARE ORGANIZED ON THE LANDSCAPE The physical layout of the landscape defines the demographic arena by determining where breeding populations can assemble. Essential parameters are the number of vernal pools, their sizes, the amount of associated nonbreeding habitat required by the species (e.g., terrestrial forest), and their degree of demographic isolation from one another. As an example, consider data from the recent statewide survey of vernal pools performed by the Massachusetts Natural Heritage Program (Burne 2001; Chapter 4, Burne and Lathrop). Vernal pools were identified from high resolution, leaf-off aerial photography. These surveys suggest a typical density of about 1–2

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Distance between vernal pools (m)

2500

2000

1500

1500

500

0 0

1

2

3

Vernal pool density

4

5

6

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(number/km2)

FIGURE 8.1 The geographic footprint of vernal pools that underpins population-genetic processes in vernal pool associated wildlife, including amphibians. Patterns are drawn from Burne’s (2001) surveys of ca. 30,000 vernal pools in central Massachusetts. Data points represent values from 500 randomly selected, 1-km-radius, circular, nonoverlapping areas sampled from across a broad segment of mid-Massachusetts. These geographic parameters — pool density and interpool distance — represent the physical arena within which demographic and genetic processes in vernal pool breeding organisms unfold.

pools/km2 (2.6–5.2/mi2) (Figure 8.1). Vernal pools were generally separated by 500–1,000 m (1,640–3,281 ft), with matrix landscapes including urban-to-rural and other ecological gradients (e.g., elevation, distance from large rivers, etc.), although there is high variance in average density (see also, Grant 2005). In more heavily urbanized New Jersey, average vernal pool density is about 0.6 pools/km2 (1.6/mi2) (Lathrop et al. 2005), and dewpond density in Sussex, England, has been estimated at about 0.2/km2 (0.5/mi2) (Beebee 1997). By their very nature, the density of vernal pools on a landscape can differ by year, with lower densities in dry years (e.g., Bauder 2005). How might average density and interpool distance translate into functional demographic units for the amphibians dependent on them? The key consideration for estimating the effective number of breeding sites that might comprise a population is the scale of dispersal, which is the successful movement of current and future breeding individuals between populations. Because the term “migration” has different definitions in ecological literature, we use the following definitions in this paper. Dispersal is sometimes referred to in the amphibian literature as migration. Here

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we define dispersal as being the permanent, one-way movement of an individual from a breeding or natal site to another site. Migration is typically regarded as the outbound movement of an individual from a breeding or natal site and subsequent inbound travel back to that same site. Consequently, to avoid confusion, we refer to an individual that permanently leaves a population to be a disperser rather than as an emigrant. Because dispersing individuals inherit genes in one population and integrate them through breeding into another, they effect “flow” of genes from one local population to another (Wright 1943; Slatkin 1994). In contrast, migrating individuals leave and return to the same site, so migration (by our definition) does not cause gene flow in pool-breeding amphibians. As a result, dispersal increases genetic diversity within populations, owing to importation of new genetic material, while simultaneously reducing genetic differences among populations, thereby diluting local genetic distinctions. Surprisingly low levels of gene flow can preclude differentiation (differences in alleles and allele frequencies among sites increasing over time) under the assumptions of identical selective pressures and lack of genetic drift (e.g., Slatkin 1994, terminology in bold is defined in Table 8.1). Based on population genetics theory, Mills and Allendorf (1996) proposed that just 1–10 effective dispersers (i.e., disperse and enter the breeding population) per year are required to prevent genetic differentiation assuming the sites are under similar selective pressures. These predictions are generally borne out in the field, as in the case of California tiger salamanders (Ambystoma californiense), in which interpond movements generate a constant, if low, supply of immigrants to most ponds thereby precluding genetic divergence among local populations over large areas (Trenham et al. 2001). Similar genetic cohesion despite a fragmented distribution has been observed in Moroccan water frogs (Rana saharica, Buckley et al. 1996). Studies of dispersal by amphibians suggest that adults display relatively low rates of movement between populations (Gill 1978; Breden 1987; Berven and Grudzien 1990; Sinsch and Seidel 1995, but for exceptions see Peter 2001 and Trenham et al. 2001). Owing to their permeable skin and sensitivity to desiccation, coupled with small body size, most amphibians do not move long distances. Because adults of vernal pool breeding amphibians are generally faithful to breeding sites, juveniles tend to be the primary dispersal stage (e.g., Gill 1978; Breden 1987; Berven and Grudzien 1990; Funk et al. 2005a), and a great deal of movement can occur during the fall and winter (Regosin et al. 2005). What is the typical scale of dispersal distances for amphibians? Dispersal distances can be estimated directly via tracking marked individuals (e.g., Breden 1987), by estimating the rate of range expansion in invading amphibians (such as the cane toad Bufo marinus in Australia, e.g., Phillips et al. 2006), or by looking at genetic similarity among populations (Jehle et al. 2005). Each approach, however, has its limitations. Individually marked animals are increasingly difficult to track as dispersal distances increase (Koenig 1999), and it can be difficult to determine if individuals breed once they disperse. Making estimates based on range expansion probably underestimates dispersal ability because multiple dispersal events might be required to successfully expand a species’ range. Direct genetic measures, in contrast, reflect resulting patterns of dispersal with subsequent breeding, but might

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TABLE 8.1 Some Terms (Bold-Faced in Text) Relevant to Population Genetics Census population size

Dispersal Effective population size Fitness Genetic drift Gene flow

Genetic neighborhood Homozygosity Deleterious allele Inbreeding Microsatellite marker Migration

Neutral genetic marker

Outbreeding depression

Population bottleneck

All individuals in a population, including those breeding plus those that are not (e.g., those too old or too young to breed) (see also effective population size) The permanent, one-way movement of an individual from a breeding or natal site to another site (see also migration) An estimate of the number of individuals effectively contributing to a breeding population (see also census population size) The relative contribution of an individual’s genotype to the gene pool of the next generation The random loss of alleles over generations due to what is in effect sampling errors due to small population size The result of dispersing individuals that inherit genes in one population and integrate them through breeding into another, thereby effecting the transfer of genes from one local population to another The collection of individuals scattered across the landscape that are linked through potential gene flow The probability of possessing two identical forms of a particular gene, i.e., being genetically invariant A form of a gene that has a deleterious effect on an individual and thereby reduces its fitness Mating with relatives Regions within DNA sequences where short sequences of DNA are repeated in distinctive tandem arrays (see also neutral genetic marker) The outbound movement of an individual from a breeding or natal site and subsequent inbound travel back to that same site (see also dispersal) Genetic variants with no known association to the fitness of individuals that are useful for tracking the patterns of movements of individuals among populations (see also microsatellite marker) Fitness reduction caused by mating between distantly related individuals that can undermine local adaptation or disrupt combinations of genes favored by natural selection A severe reduction in population size; results in genetic drift

express historic rather than current patterns of connectivity. Another source of information on the rates that individuals move among populations comes from the recolonization of local populations after extirpation. For example, in 3 species of amphibians, isolations of >1 km (0.6 mi) produced “empty ponds” (Laan and Verboom 1990). Distances at which potentially suitable ponds remain uncolonized can reliably reflect the spatial dimensions of demographic processes (Sjögren 1991). Based on a comprehensive review of the published literature, Smith and Green (2005) suggested that amphibian populations are not as isolated as is commonly thought and suggest a distance threshold for demographic and genetic isolation of 11–13 km (6.8–8.1 mi) in frogs and toads and 8–9 km (4.9–5.6 mi) in salamanders. Thus,

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interpond distances <10 km (6.2 mi) might be sufficient to avoid genetic differentiation (although major barriers to movement could cause differentiation over shorter distances, e.g., Figure 8.2). It is important to note that dispersal by vernal pool breeding amphibians does not typically occur in the manner of the random diffusion process often used to conceptualize it. In fact, various landscape features strongly influence movements. Potential barriers to movement include roadways (Vos and Chardon 1998; Lehtinen et al. 1999), habitats lacking forest cover (Dodd and Cade 1998; deMaynadier and Hunter 1999; Vasconcelos and Calhoun 2004), as well as natural topography (e.g., dry, steep slopes, Gill 1978), whereas streambeds are potential conduits to movement (Beshkov and Angelova 1981; Beshkov et al. 1986; Gibbs 1998). Consequently, the effective distance (rather than linear distance) is affected by landscape structure interacting with the behavioral responses of the amphibian. Knowing typical amphibian dispersal distances to an order of magnitude, however, might be of little practical value to resource managers or land-use planners at a particular site. Species-specific (and sometimes site-specific) data are required for this purpose. For example, for wood frogs, an estimate of effective dispersal distance based on genetic data (genetic neighborhood size) was just 1,126 m (3,694 ft) (Berven and Grudzien 1990), implying that beyond this distance dispersal, and thus gene flow, is near zero. This distance is greater than movements recorded from direct observations of this species (Regosin et al. 2003; Baldwin et al. 2006). Assuming Berven and Grudzien’s (1990) estimate of genetic neighborhood size for wood frogs is representative of actual populations, we can make a rough estimate of the number of breeding sites potentially interacting to form a population. A radius of about 1 km for a genetic neighborhood size coupled with a density of 1.5 pools/ km2 (3.9/mi2) (Figure 8.1) translates to ~5 ponds occurring within a genetic neighborhood of wood frogs in this region. Given the range of vernal pool densities across the landscape in our example (Figure 8.1), effective numbers of breeding populations for wood frogs would vary from a low of 1 vernal pool to a high of 10. If the distribution of vernal pools depicted in Figure 8.1 is representative of the northeastern U.S., and Berven and Grudzien’s (1990) estimate (which was done in the southeastern U.S.) is valid for this region as well, it suggests that spatial organization of wood frog breeding populations in the northeastern U.S. can vary dramatically with substantially different consequences for population genetic processes. At one extreme, wood frogs might occur in demes of a single, or few, isolated populations in which genetic interaction with other populations is minimal. In such situations, populations would be relatively prone to loss of genetic variation, as a function of 1/effective population size, which itself is usually only a fraction (10%) of the actual population size (Crow and Kimura 1970). At the other extreme, wood frogs could occur in large aggregates of local populations, resulting in frequent genetic interaction and relatively little loss of genetic variability or local divergence, even over extended periods of time. Making inferences about population structure based solely on average dispersal distances of individuals, however, is problematic. The conundrum is that although average dispersal distances might be comparatively small, given high local abundances of many amphibians and characteristically high rates of reproduction,

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FIGURE 8.2 Schematic illustrating key concepts of population genetic linkages in vernal pool breeding amphibians. Pool-based breeding populations are indicated with filled dots A–H with population size proportional to size of dot. Genetic neighborhoods: Individuals in A–G potentially comprise a single genetic neighborhood because they all fall within 10 km (6.2 mi) of one another, that is, within the dispersal range of many amphibians. Conduits to gene flow: Despite the proximity of B to C individuals in C may be more closely related to those in A because C and A are connected by a streambed — a conduit to dispersing animals. Anthropogenic barriers to dispersal: Despite the proximity of pool D to breeding pools at location E, individuals in D may be more closely related to those in A, B, and C because of a long-standing anthropogenic barrier to dispersal — a raised, xeric railroad bed — between D and E. Natural barriers to dispersal: Despite the proximity of E and F the occurrence of an intervening salt marsh likely limits movement by amphibians between them. Local adaptation: Despite the proximity of F and G, individuals in these pools may exhibit strong local divergence for important fitness-related traits because breeding occurs in open canopy pools in F and closed canopy pools in G, very different environments and selection regimes for pool-breeding amphibians. Genetic isolation: Individuals in H likely are isolated genetically from all other individuals due to anthropogenic and natural barriers and simple geographic distance. Genetic drift and inbreeding: Population B is small and may frequently undergo random changes in allele frequency caused by genetic drift thereby leading to local genetic divergence, but its proximity to A and C suggests that any divergence is quickly mitigated by gene flow from A or C. Moreover, despite its isolation from other populations, D likely is not susceptible to drift or inbreeding because of its persistently large size. In contrast, H is small and isolated, and if it does not succumb to local extinction it likely will exhibit local divergence caused by genetic drift and lack of gene flow from other populations. Temporal change in population genetic structure: The assemblage of individuals across the entire landscape may consist of highly persistent components of population genetic structure — the large populations A, D, and G in more stable habitats, e.g., deeper, larger pools — as well as more ephemeral components: all other populations in smaller, shallower pools, which may exhibit local extinctions in drought years and recolonization by dispersal from A, D, and G.

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enormous numbers of juveniles may in fact disperse across the landscape (e.g., wood frogs, Berven 1990). Long distance dispersal is also very difficult to study and likely underestimated (Marsh and Trenham 2001). Because few migrants are needed to homogenize local populations genetically (Mills and Allendorf 1996), cumulative gene flow across generations may be sufficiently high to prevent local differentiation. This is further complicated because some landscape features inhibit dispersal (discussed above), functionally increasing the distances among vernal pools (Figure 8.2). Combining vernal pool densities within genetic neighborhoods with estimates of the number of individuals breeding in each pool can help refine estimates of the aggregate operational population sizes. Without knowing the numbers of individuals occurring within genetic neighborhoods, how these numbers change across years, and the rates of local extinction and recolonization, however, we lack a sense of the degree to which stochastic genetic processes owing to small population size might further affect population and genetic linkages of vernal-pool associated amphibians.

DRIFT AND INBREEDING Mating with relatives is consanguineous mating, also called inbreeding. Inbreeding is unavoidable in populations of small sizes but also occurs in larger populations when there is preferential mating of relatives. A related concept is genetic drift, the random loss of alleles over generations due to what is in effect sampling errors; i.e., through chance, some alleles unique to individuals are not passed on to their offspring. Drift and inbreeding erode genetic diversity and largely are functions of population size and to some extent mate selection behavior (e.g., avoiding mating with relatives obviously reduces inbreeding). Because loss of genetic variability is a function of effective population size (Crow and Kimura 1970), drift is particularly significant in small populations. The effective size of a population can be thought of as the number of individuals actively participating in breeding within the population. The total number of individuals counted in a population is the census size and includes all breeding individuals as well as many that are not (e.g., those too old or too young to breed). Thus, the effective size is usually much smaller than the census size (Frankham et al. 2002). Both drift and inbreeding are concerns for organisms such as vernal pool breeding amphibians because mating among relatives is difficult to avoid in small, randomly mating populations. The ultimate consequence of both drift and inbreeding is loss of genetic diversity; with increasing homozygosity comes greater expression of deleterious alleles. This fitness depression occurs in many natural populations, particularly in species that typically outbreed (that is, naturally avoid mating with relatives; see Crnokrak and Roff 1999; Frankham et al. 2002). Fitness problems associated with inbreeding have been observed in some amphibian species (e.g., Andersen et al. 2004, Rowe and Beebee 2005). A less common problem in wild populations of vertebrates is outbreeding depression, which results from dismantling of associations among genes that underpin local adaptive complexes by interbreeding between populations that are differentiated genetically. This has been reported for the common frog (Rana temporaria) (Sagvik et al. 2005), but probably is not normally a problem in natural populations unless dispersal is facilitated by

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human actions, such as translocation between distant or environmentally different sites. How large are amphibian breeding populations? As an example, Egan and Paton (2004) reported that in a survey of 124 ponds in western Rhode Island most ponds had 50 egg masses or fewer, ranging from 1–1,033. Given that female wood frogs typically lay a single egg mass per year (Berven 1990), egg mass counts can provide a rough index of the number of adult females in a given breeding population and hence an index of its census size. These data suggest that wood frogs occur primarily in localized groups of relatively small numbers (≤100) of individuals potentially linked genetically to three to five other such groups within a small area (3 km2 or 1.2 m2) via dispersal. How might these census sizes relate to effective population sizes in amphibians? In a review of effective population sizes in pool-breeding amphibians, Rowe and Beebee (2004) reported that effective sizes relative to census population sizes are generally <0.20. In other words, the number of individuals counted may be 2 to 5 times the number effectively breeding. This suggests that wood frogs might be organized among three to five local, interacting sites in effective breeding units of 10 to 20 individuals. This estimate is close to that of another estimate of effective population size of wood frogs (38–78; Berven and Grudzien 1990) and consistent with other pool- and pond-breeding amphibians (Table 8.1). Population fluctuations over time also affect the rate of loss of genetic variability, and the average rate of loss is not simply a matter of averaging effective population sizes over time (Crow and Kimura 1970). Effective population sizes are averaged across years or generations as a harmonic mean because years with small population sizes (population bottlenecks) contribute disproportionately to the average effective population size. This is because as a population’s size gets smaller, genetic variability is lost at a proportionately faster rate. Repeated population bottlenecks, in particular, promote genetic drift (Frankham et al. 2002). Notably, amphibians undergo much higher annual variation in population size than do most other terrestrial vertebrates (Gibbs et al. 1998; Green 2003). By virtue of the dynamic nature of their breeding habitats, some pool-breeding amphibians frequently undergo extreme bottlenecks owing to annual differences in breeding site quality, and extinction and recolonization of local populations. Reproductive failure is frequent, even at highquality breeding areas, especially owing to variation in precipitation, which is the source of much of the water that sustains aquatic breeding areas (Brooks 2004). For example, estimated annual reproductive failure rates were 42–56% for 13 species over 16 years in South Carolina (Semlitsch et al. 1996). We conclude that local population sizes and temporal fluctuations in vernal pool breeding amphibian populations are well within the realm where significant drift and inbreeding can occur, yet their effects may be mitigated by dispersal among breeding populations — less so in areas where pool densities are very low. In addition, anthropogenic changes that reduce population size (via road mortality or habitat degradation) and increase population isolation (loss of neighboring breeding pools or increased landscape barriers) accelerate the rates of drift and inbreeding. Consequently, the potential importance of loss of genetic variability to the persistence of local populations should be evaluated on a landscape-by-landscape basis (Figure 8.2).

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EXTINCTION–RECOLONIZATION DYNAMICS AND LOCAL ADAPTATION Having patchily distributed populations can add another layer of complexity to population dynamics and genetic linkages across a landscape. If populations are situated in different environments, then divergent selection pressures in these distinct environments may result in significant adaptive changes over time (Stockwell et al. 2003). Such adaptive changes would show a distinct spatial pattern of genetic differentiation across a landscape (Figure 8.2). Such patterns caused by adaptation, however, can be masked or overwhelmed by genetic drift or dispersal. Specifically, dispersers from nearby populations that are under different selective pressure could prevent differentiation despite local environmental selective pressures. In addition, in very small populations, or in those that go through a severe bottleneck, selection for local adaptation can be overcome by random loss of alleles. This would affect the type, rather than amount, of differentiation. The potential for local adaptation is an important issue for conservationists and resource managers who frequently are interested in management actions such as translocations of individuals that can disrupt patterns of local adaptation (Dodd and Siegel 1991). Extinction–recolonization dynamics are particularly relevant to consider in this context because they heavily influence the opportunity for local adaptation to occur. Frequent dispersal that permits recolonization of locally extinct populations can sustain populations over large areas (cf. Hanski 1999), and likely affect many vernal pool dependent species (Marsh and Trenham 2001). Recolonization following local extinctions results in homogenizing genetic variability across a landscape. Local conditions can, however, strongly dictate how extinction–recolonization dynamics play out in a particular population. Wood frogs are an example — they apparently occur in regions with very different population structures. That is, there are some regions where opportunity for drift and inbreeding is pronounced, gene flow is limited, and local differentiation is possible, whereas in other regions large effective numbers in a high density of breeding populations with extensive gene flow likely preclude significant local differentiation. Moreover, in any given landscape wood frogs may breed in small, shallow pools subject to annual variation in water availability and hence frequent reproductive failure as well as the fringes of more permanent wetlands such as ponds, lakes, and beaver meadows where reproduction likely occurs on a more predictable basis (Skelly 2004; Petranka et al. 2004). Thus wood frogs may have highly persistent components of population genetic structure that might permit local adaptation to occur as well as highly ephemeral ones that would preclude it, all within the same landscape. Surprisingly little work has been conducted on the capacity for local adaptation in vernal pool dependent organisms. One exception has been adaptations of developmental physiology to locally variable thermal environments in wood frogs (Freidenburg and Skelly 2004; Skelly 2004). Specifically, wood frogs occur in an area of northeastern Connecticut in both forested wetlands with closed canopies and relatively cooler water temperatures and wetlands with a forest canopy cleared by reinvading beaver (Castor canadensis) and subsequently higher water temperatures. These contrasting thermal environments are often as little as 10 to 100 m (32.8 to

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328.1 ft) apart, well within the dispersal range of wood frogs. Notably, embryos taken from egg masses at the sunnier beaver-created wetlands hatched at lower rates when raised under shaded conditions. Moreover, larvae from beaver-created wetlands were more tolerant of higher temperatures than were those from forested wetlands. Similar evolutionary responses over similar spatial scales have been observed for antipredator responses in wood frogs (Relyea 2002). These studies imply that populations of wood frogs can diverge from one another over short distances, suggesting a capacity for rapid evolutionary response to environmental changes if selection pressures are intense enough to overcome the diluting effects of gene flow. Local adaptation may not be unusual in vernal pool breeding amphibians. For example, morphology and physiology are related to pool drying in the common frog Rana temporaria (Laurila et al. 2002; Johansson et al. 2005b). Similarly, there is evidence of a genetic basis for local adaptation to acid tolerance in brown frogs Rana arvalis (Merila et al. 2004). Italian agile frog (Rana latastei) populations occurring less than 50–60 km (31.1–37.3 mi) apart also have significant differences in possibly adaptive traits (Ficetola and De Bernardi 2005). If selection pressures are not strong, however, gene flow may remain a significant constraint to local adaptation. For example, despite strong selection for avoidance behavior toward predatory fishes in the streamside salamander Ambystoma barbouri, Storfer and Sih (1998) found that modest levels of gene flow limit the capacity for local adaptation in predator-avoidance behavior. We conclude that local adaptation may be a germane issue for conserving vernal pool breeding amphibians, particularly in the cases of stable and isolated populations or those occupying very different ecological situations. Specifically, it might be inadvisable to translocate individuals among sites where local selective pressures are likely to be different and natural dispersal is unlikely to occur. Interestingly, habitat fragmentation that reduces gene flow could accelerate local adaptation and divergence through drift if demographic conditions remain suitable for local populations to persist. As evident from the review above, contemporary population genetic structure reflects the history of dispersal, local colonization and extinction, past fluctuations in population sizes, the distribution and connectivity of populations across the landscape, local selective pressures, and possibly nonequilibrium conditions in a population. This array of interacting factors largely precludes making simple predictions of how any given vernal-pool-dependent amphibian population will be structured genetically. Even application of sophisticated molecular methods may reveal clear patterns of population structure but not their causes. For example, two extant populations may exhibit close genetic affinity because a population now extinct (and unrecognized) once occurred and served as a “stepping stone” between them for dispersers. Such historical legacies in population genetic structure are a concern in the context of landscapes fragmented by human activities where population locations and movement patterns may have been radically altered over a short period of time, yet allele frequencies have not yet reached an equilibrium that reflects contemporary patterns of dispersal. Last, most genetic markers surveyed are selectively neutral and the significance of any patterns observed to fitness-related traits remains elusive. This said, matrix congruence methods that link population genetic

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survey data with the composition of the landscape in which the population being surveyed is embedded offer much promise. These approaches allow researchers to test what specific landscape elements facilitate or hinder movement in the landscape. Although available for decades (e.g., Douglas and Endler 1982), such methods are being repackaged as the field of “landscape genetics” (e.g., Spear et al. 2005) and offer much promise for explaining the evolutionary forces generating the patterns observed in spatial distributions of neutral genetic markers among populations. Are populations of vernal pool dependent amphibians highly structured at the local level and, if so, why? Based on Berven and Grudzien’s (1990) report that dispersal rates in wood frogs were too low to manifest gene flow beyond a distance of about 1 km (0.6 mi), Squire and Newman (2002) predicted rapid increases in genetic differentiation among populations separated by more than a few kilometers. Most local populations had similar allele frequencies (based on microsatellite markers), even at distances greater than several kilometers, although those separated by a distance of over 200 km (124.3 mi) had distinctly different frequencies of neutral alleles. Squire and Newman (2002) concluded that genetic differentiation in this species may not arise until much greater distances than indicated by Berven and Grudzien (1990). This could be due to large sizes of local populations that buffer against genetic drift, or to greater dispersal than expected due to the flat, forested uplands surrounding their study populations facilitating sustained dispersal. Results from Squire and Newman’s (2002) study differ somewhat from those of other studies on frogs and salamanders (Table 8.2). Lack of comparability among studies due to uses of different molecular markers and the small number of studies conducted to date make drawing conclusions about the general spatial scale at which amphibian populations are genetically differentiated problematic, but it appears that salamanders have more restricted gene flow than do frogs (Table 8.3) (see also Smith and Green 2005). As a reminder, however, observing fine-scale genetic differentiation of amphibian populations across a landscape does not mean that the population fragments are differentiated in a biologically meaningful way. The majority of approaches currently in use for quantifying population genetic structure focus on selectively neutral alleles. Consequently, although these analyses provide insight regarding population connectivity across a landscape, it is not clear whether the genetic differentiation observed

TABLE 8.2 Effective Population Size Estimates for Amphibians Species Red-spotted newts (Notophthalmus viridescens) Long-toed salamander (Ambystoma macrodactylum) Common frog (Rana temporaria) Wood frog (Rana sylvatica) Common toad (Bufo bufo)

Estimate 25–185 23-207 32 38–78 21–46

Source Gill 1978 Funk et al. 1999 Seppa and Laurila 1999 Berven and Grudzien 1990 Scribner et al. 2001

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TABLE 8.3 Estimates of Geographical Distances at Which Significant Genetic Structuring Occurs in Amphibian Populations Distance <2 km (<1.2 mi) <2.3 km (<1.4 mi) 0.5 to 9.0 km (0.3 to 5.6 mi) 0.26 to 11.8 km (0.2 to 7.3 mi) <15 km (<9.3 mi) 1 km (0.6 mi) 5 km (3.1 mi) ~5 km (~3.1 mi)

Species

Source

Common toad (Bufo bufo)

Scribner et al. 2001

Common frog (Rana temporaria) Natterjack toad (Bufo calamita)

Reh and Seitz 1990, Hitchings and Beebee 1997 Rowe et al. 2000

Tungara frog (Physalaemus pustulosus)

Lampert et al. 2003

Columbia spotted frog (Rana luteiventris)

Funk et al. 2005b

Blotched tiger salamander (Ambystoma tigrinum melanostictum) Streamside salamander (Ambystoma barbouri)

Spear et al. 2005

Long-toed salamander (Ambystoma macrodactylum)

Storfer 1999 Tallmon et al. 2000

is biologically important. Resource managers, therefore, can use genetic differentiation of neutral alleles to understand demographic connectivity across a landscape, but they should be cautious about making inferences from surveys of neutral markers about the efficacy of translocation for site recolonization or population rescue. The key issue is whether local adaptation occurs and could be disrupted.

CONSERVATION IMPLICATIONS Simple directives for conserving vernal-pool associated amphibians are difficult to come by. Even widespread species of Rana and Ambystoma frequently targeted for management efforts have been the focus of surprisingly few studies of their population structure. This said, our review points to some considerations that land managers should make in devising effective conservation plans. Perhaps the most salient is the spatial scale at which planning should occur. Our review of the population genetics literature on pool-breeding amphibians, as well as another review of primarily demographic studies by Smith and Green (2005), suggests that biologically significant population genetic linkages typically occur in neighborhoods of pool-based populations located within 10 km (6.2 mi) of one another. Similarly, recent studies of long-term population dynamics in pond breeding frogs and salamanders by Petranka et al. (2004) and Gibbs et al. (2005), as well as spatial scale of strongest population-habitat correlations by Houlahan and Findlay (2003), also suggest that population dynamics likely operate at the spatial scale of 10 km (or more) radius “neighborhoods.” This spatial scale is considerably larger than the “pool-as-population” perspective that pervades most thinking on how best to conserve vernal pool organisms (Jehle et al. 2005). Thus, vernal pool managers concerned with maintaining functional demographic and evolutionary

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units of these organisms should expand their perspectives and geographic scope of planning to a sufficient spatial scale needed to encompass interacting sets of poolbased populations. Maintaining dispersal connections among pools is clearly vital because dispersal is ultimately what sustains genetic neighborhoods and persistent populations of poolbreeding amphibians. Maintaining dispersal connections involves maintaining specific dispersal routes between pools, as well as associated upland habitat surrounding vernal pools for adults. The 30 m (~100 ft) buffers often espoused for vernal pool protection (e.g., Semlitsch 1998) are not sufficient to protect populations of many pool-breeding amphibians. In terms of dispersal routes, many studies have shown pronounced effects of natural and anthropogenic barriers on gene flow (e.g., Vos et al. 2001; Hitchings and Beebee 1997; Johansson et al. 2005a). We now have the analytical tools to understand how and where populations are connected and can generate reliable information for intelligent planning. The work of Spear et al. (2005) exemplifies the emerging field of landscape genetics and is a model for understanding how landscape configuration determines population connectivity. Similar studies should be conducted on many other pool-breeding amphibians, especially incorporating anthropogenic aspects of landscape structures that can be controlled to some extent by land managers at the site level and through legal regulation at the landscape level. Managers should recognize that extinction and recolonization in amphibian populations tends to be more closely associated with changes in pond quality rather than chance population extinctions, as is often assumed (Marsh and Trenham 2001). Therefore, deterministic extinction of a breeding population occupying an individual pool after several decades may be a normal event due to ecological succession, but long-term amphibian persistence requires a reasonable likelihood of a similar breeding area arising nearby or the existing site being restored and recolonized. The key issue is that natural processes of pond succession and pond formation should be kept in balance. Such is not the case in many areas where rates of pond loss greatly exceed rates of pond creation (e.g, Beebee 1997). Moreover, degradation and loss of vernal pools and associated nonbreeding habitat (e.g., Homan et al. 2004; Herrmann et al. 2005) reduces the effective density of ponds, which in turn increases the distance between neighboring ponds and reduces gene flow and the probability of recolonization (Gibbs 1993). There is a real need to maintain and perhaps restore pools in areas where they have been depleted in order to reestablish pool neighborhoods and the dispersal linkages within them. Finally, observations of strong genetic divergence via local adaptation among nearby populations for several species of pool-breeding amphibians (e.g., Freidenburg and Skelly 2004; Skelly 2004; Relyea 2002; Johansson et al. 2005a; Laurila et al. 2002; Merila et al. 2004; Ficetola and De Bernardi 2005) suggests caution be exercised when securing individuals to supplement or recolonize restored or created sites. Translocation or supplementation activities that transport individuals among populations could disrupt local adaptation, reduce evolutionary potential, and possibly cause outbreeding depression (see Sagvick et al. 2005), thereby undermining the positive intent of such actions (Ficetola and De Bernardi 2005). Because the correlation between neutral and adaptive variation can be low, relying only on neutral

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markers in population assays may not reveal patterns of evolutionarily significant, intraspecific diversity (Crandall et al. 2000). Whatever the case, our review suggests that stock used for such actions be derived from nearby populations, preferably within 10 km (6.2 mi) and from populations from similar ecological conditions to the reintroduction/supplementation site. In practice, local adaptation can be difficult to detect and represents a complex genetic response to multiple environmental gradients. Therefore, drawing stock from multiple, local sources under similar ecological conditions to the release site may be the best strategy for improving the likelihood of reestablishment if the selection gradients and patterns of local adaptation are not well known.

ACKNOWLEDGMENTS We are grateful to Aram Calhoun and Phillip deMaynadier for extending the invitation to contribute this chapter, their patience awaiting its completion, and their constructive comments for improving it. Two anonymous reviewers also made many useful suggestions.

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Mills, L.S. and Allendorf, F.W. (1996). The one-migrant-per-generation rule in conservation and management. Conservation Biology 10: 1509–1518. Peter, A.K.H. (2001). Dispersal rates and distances in adult water frogs, Rana lessonae, Rridibunda, and their hybridogenetic associate R-esculenta. Herpetologica 57: 449–460. Petranka, J.W., Smith, C.K., and Floyd, S.A. (2004). Identifying the minimal demographic unit for monitoring pond-breeding amphibians. Ecological Applications 14: 1065–1078. Phillips, B.L., Brown, G.P., Webb, J.K., and Shine, R. (2006). Invasion and the evolution of speed in toads. Nature 439: 803. Regosin, J.V., Windmiller, B.S., and Reed, J.M. (2003). Terrestrial habitat use and winter densities of the wood frog (Rana sylvatica). Journal of Herpetology 37: 390–394. Regosin, J.V., Windmiller, B.S., Homan, R.N., and Reed, J.M. (2005). Variation in terrestrial habitat use by four pool-breeding amphibian species. Journal of Wildlife Management 68: 1481–1493. Reh, W. and Seitz, A. (1990). The influence of land use on the genetic structure of populations of the common frog Rana temporaria. Biological Conservation 54: 239–249. Relyea, R.A. (2002). Local population differences in phenotypic plasticity: predator-induced changes in wood frog tadpoles. Ecological Monographs 72: 77–93. Rowe, G., Beebee, T.J.C., and Burke, T. (2000). A microsatellite analysis of natterjack toad, Bufo calamita, metapopulations. Oikos 88: 641–651. Rowe, G. and Beebee, T.J.C. (2004). Reconciling genetic and demographic estimators of effective population size in the anuran amphibian Bufo calamita. Conservation Genetics 5: 287–298. Rowe, G. and Beebee, T.J.C. (2005). Intraspecific competition disadvantages inbred natterjack toad (Bufo calamita) genotypes over outbred ones in a shared pond environment. Journal of Animal Ecology 74: 71–76. Sagvik, J., Uller, T., and Olsson, M. (2005). Outbreeding depression in the common frog, Rana temporaria. Conservation Genetics 6: 205–211. Scribner, K.T., Arntzen, J.W., Cruddace, N. et al. (2001). Environmental correlates of toad abundance and population genetic diversity. Biological Conservation 98: 201–210. Semlitsch, R.D. (1998. Biological delineation of terrestrial buffer zones for pond-breeding salamanders. Conservation Biology 12: 1113–1119. Semlitsch, R.D. (2000). Principles of management for aquatic breeding amphibians. Journal of Wildlife Management 64: 615–631. Semlitsch, R.D., Scott, D.E., Pechmann, J.H.K., and Gibbons, J.W. (1996). Structure and dynamics of an amphibian community: evidence from a 16-year study of a natural pond. In Cody, M.L. and Smallwood, J.A. (Eds.). Long-Term Studies of Vertebrate Communities, Academic Press, San Diego, CA, pp. 217–248. Seppa, P. and Laurila, A. (1999). Genetic structure of island populations of the anurans Rana temporaria and Bufo bufo. Heredity 82: 309–317. Sinsch, U. and Seidel, D. (1995). Dynamics of local and temporal breeding assemblages in a Bufo calamita metapopulation. Australian Journal of Ecology 20: 351 361. Sjogren, P. (1991). Extinction and isolation gradients in metapopulations: the case of the pool frog (Rana lessonae). Biological Journal of the Linnean Society 42: 135–147. Skelly, D.K. (2004). Microgeographic countergradient variation in the wood frog, Rana sylvatica. Evolution 58: 160–165. Slatkin, M. (1994). Gene flow and population structure. In Real, L.A. (Ed.). Ecological Genetics, Princeton University Press, Princeton, NJ, pp. 3–17.

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Smith, M.A. and Green, D.M. (2005). Dispersal and the metapopulation paradigm in amphibian ecology and conservation: are all amphibian populations metapopulations? Ecography 28: 110–128. Spear, S.F., Peterson, C.R., Matocq, M.D., and Storfer, A. (2005). Landscape genetics of the blotched tiger salamander (Ambystoma tigrinum melanostictum). Molecular Ecology 14: 2553–2564. Squire, T. and Newman, R.A. (2002). Fine-scale population structure in the wood frog (Rana sylvatica) in a northern woodland. Herpetologica 58: 119–130. Stockwell, C.A., Hendry, A.P., and Kinnison, M.T. (2003). Contemporary evolution meets conservation biology. Trends in Ecology and Evolution. 18: 94–101. Storfer, A. (1999). Gene flow and population subdivision in the streamside salamander, Ambystoma barbouri. Copeia 1999: 174–181. Storfer, A. and Sih, A. (1998). Gene flow and ineffective antipredator behavior in a streambreeding salamander. Evolution 52: 558–565. Tallmon, D.A., Funk, W.C., Allendorf, F.W., and Dunlap, W.W. (2000). Genetic differentiation among long-toed salamander (Ambystoma macrodactylum) populations. Copeia 2000: 27–35. Trenham, P.C., Koenig, W.D., and Shaffer, H.B. (2001). Spatially autocorrelated demography and interpond dispersal in the salamander Ambystoma californiense. Ecology 82: 3519–3530. Vandermeer, J.H. and Goldberg, D.E. (2003). Population Ecology: First Principles. Princeton University Press, Princeton, NJ. Vasconcelos, D. and Calhoun, A.J.K. (2004). Movement patterns of adult and juvenile Rana sylvatica (LeConte) and Ambystoma maculatum (Shaw) in three restored seasonal pools in Maine. Journal of Herpetology 38: 551–561. Vos, C.C. and Chardon, J.P. (1998). Effects of habitat fragmentation and road density on the distribution pattern of the moor frog, Rana arvalis. Journal of Applied Ecology 35: 44–56. Vos, C.C., Antonisse-De Jong, A.G., Goedhart, P.W., and Smulders, M.J.M. (2001). Genetic similarity as a measure for connectivity between fragmented populations of the moor frog (Rana arvalis). Heredity 86: 598–608. Wright, S. (1943). Isolation by distance. Genetics 28: 114–138.

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9

The Importance of Vernal Pools to Reptiles, Birds, and Mammals Joseph C. Mitchell, Peter W.C. Paton, and Christopher J. Raithel

CONTENTS Reptiles ..................................................................................................................170 Turtles ........................................................................................................170 Vernal Pool Specialists.....................................................................171 Vernal Pool Generalists....................................................................173 Lizards and Snakes ....................................................................................174 Birds.......................................................................................................................176 Mammals................................................................................................................177 Conservation Implications .....................................................................................181 Summary ................................................................................................................182 Acknowledgments..................................................................................................184 References..............................................................................................................184

Many species of amphibians breed in vernal pools, and of the vertebrates linked to these pools in glaciated northeastern North America, frogs and salamanders are the most commonly studied and best understood (see Colburn 2004; Chapter 7, Semlitsch and Skelly). Although reptiles, birds, and mammals in the region do not regularly breed in pools, these wetlands may be directly used for foraging or resting areas or may indirectly support these vertebrates through production and export of food in the form of invertebrates and amphibians (DeGraaf and Yamasaki 2001). Some species may be dependent on vernal pools for long-term population stability and growth (Joyal et al. 2001; Grgurovic and Sievert 2005). Unfortunately, little attention had been paid to the functions provided to vertebrates by the vernal pools of our region, with the exception of amphibians and some species of turtles. Indeed,

169

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few publications have focused on interactions of reptiles, birds, and mammals with vernal pool environments and their animal communities (Paton 2005). Across North America, considerable research has been conducted on vertebrates associated with vernal pools in California (Silveira 1998; Zedler 2003), the Prairie Pothole Region (Austin 2002), the playas of the southern Great Plains (Davis and Smith 1998; Haukos and Smith 2003), and the Carolina bays of the southeastern U.S. (Pechmann et al. 1989; Burke and Gibbons 1995; Sharitz 2003). Our review of the services provided to these vertebrates by vernal pools in northeastern North America is limited by a dearth of published or documented observations. In her book on the natural history and conservation of vernal pools in our region, Colburn (2004) listed five species of turtles, three snakes, eight birds, and 12 mammals (including nine bats) that gain resources from this habitat type. Her compilation was based on 36 published papers and several personal observations on the ecology and life history of these animals. Habitat associations of turtles that use vernal pools in the region have been examined by several researchers (Graham 1995; Joyal et al. 2001; Milam and Melvin 2001; Compton et al. 2002), but the ecology of turtles in these systems is not as well understood. Even less is known about resources derived from vernal pools by lizards, snakes (Roe et al. 2003), birds (Hanowski et al. 2006), or mammals (Brooks and Doyle 2001), although many species are known to occur in these wetlands (see review by DeGraaf and Yamasaki 2001). In this chapter, we review the available literature and anecdotal observations provided by colleagues on the services to vertebrates provided by vernal pools. Furthermore, our request to researchers throughout northeastern North America resulted in a number of unpublished observations, and literature or reports we bring to light here. Scientific and common names follow Crother et al. (2000), American Ornithologists Union (1998), and Whitaker and Hamilton (1998). Our review highlights that many species of vertebrates use vernal pools to meet their habitat requirements for foraging, aestivation, drinking, resting, and as cover. However, compared to amphibians, our understanding of the ecological role that vernal pools provide to reptiles, birds, and mammals is in its infancy.

REPTILES Carolus Linnaeus, the “father of taxonomy,” said that reptiles, especially snakes, are loathsome and foul creatures; it is not surprising so little was known about them in the late 1700s. We now know that reptiles are critical linkages between aquatic and terrestrial habitats. They, like amphibians, may be considered elements of the hidden biodiversity in the landscape. We seldom see or encounter many of them at any one time and are often unaware of how many there may be. Discovering turtles, snakes, or lizards often requires specialized techniques and can be very rewarding.

TURTLES These extraordinary creatures, with shells modified from ribs and breast plate bones, face challenges from habitat fragmentation and urbanization for which they are not

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TABLE 9.1 The Number (%) of Reptile, Bird, and Mammal Species in Northeastern North America That Are Common, Uncommon, Rare, or Absent from Vernal Pools Order Snakes Turtles Waterfowl Shorebirds Songbirds Other waterbirdsb Other landbirdsc Bats Small: Insectivores Meso: rodents, rabbits, mustelids Large: carnivores, deer, moose

Common

Uncommon

1 2 4 0 7 17 15 0 12 4 2

6 6 9 9 30 2 7 0 17 25 4

(3) (9) (12) (5) (64) (30) (40) (11) (40)

(14) (27) (27) (20) (23) (7) (14) (58) (69) (60)

Rare 15 6 16 21 81 3 11 15 0 0 0

(35) (27) (48) (46) (62) (10) (22) (100)

Absent

Na

21 8 4 15 12 5 17 0 1 7 0

43 22 33 45 130 27 50 15 30 36 6

(49) (36) (12) (34) (9) (19) (34) (3) (19)

a

Total number of species known from the region. Waterbirds include: Gaviiformes, Podicipediformes, Pelicaniformes, Ciconiformes, and Gruiformes c Landbirds include: Falconiformes, Columbiformes, Cucliformes, Strigiformes, Caprimulgiformes, Coraciiformes, Apodiformes, and Piciformes. b

Source: Information in this table is based on published natural history information, from textbooks cited and our knowledge of habitat selection of various taxa. We determined how many species occurred within the study area boundaries, and we assessed which species may use vernal pools. From these data, we were able to quantify percent occurrence in vernal pools. Again, we state that these estimates only describe potential use.

prepared (Chapter 12, Windmiller and Calhoun). Vernal pools help to support many turtle species in the face of wetland habitat degradation. Turtles acquire nutrients from vernal pools and transfer them to terrestrial habitats in the form of eggs which they deposit in the ground. Their movements across landscapes are accomplished by learning and complex navigational abilities. Twenty-two species are known to occur in northeastern North America (Ernst et al. 1994; Ernst and Ernst 2003), of which 14 (64%) derive food, shelter, and other benefits from vernal pools (Table 9.1; Appendix 9.1). Freshwater turtles in this region provide aquatic and terrestrial linkages in three ways: foraging in vernal pools, use of vernal pools for resting, aestivating, and overwintering, and linking aquatic and terrestrial habitats by moving among vernal pools and other wetlands on the landscape. Vernal Pool Specialists Three species in northeastern North America typically spend varying amounts of time in vernal pools as part of their annual movements within their home ranges: spotted turtle (Clemmys guttata), Blanding’s turtle (Emydoidea blandingii), and

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wood turtle (Glyptemys insculpta), with the first two species occurring in vernal pools more than other reptiles in the region (Joyal et al. 2001; Compton et al. 2002; E.A. Johnson, American Museum of Natural History, personal communication). Wood turtles are well known in this region for occupying streams during winter and adjacent uplands during spring and summer, and occasionally occurring in vernal pools, especially near streams or rivers (Ernst et al. 1994). In some landscapes, Blanding’s turtles occupy multiple, isolated vernal pools as temporary shelters during female movements to nesting sites, and at other times during their extensive seasonal terrestrial movements among freshwater marshes and other wetlands (Breckenridge 1944; Joyal et al. 2000; Kiviat et al. 2004; Beaudry et al. 2005). Distances traveled by individual turtles during single activity seasons from marsh wetlands to vernal pools and nesting sites in Maine ranged up to 6.8 km (4.2 mi) (Joyal 1996) and up to 2.9 km (1.8 mi) in Minnesota (Piepgras and Lang 2000). Home range sizes of Blanding’s turtles exhibit a positive relationship with distances among wetlands (Piepgras and Lang 2000). Turtles in Maine occupied small wetlands that were ≥50 cm (19.7 in) in depth and ≤0.5 km (0.3 mi) from occupied wetlands that received over 3 hours of sun per day and had hydroperiods that extended until August (Joyal 1996). Landscapes that did not meet these criteria, however, lacked Blanding’s turtles. Blanding’s turtles in suburban eastern Massachusetts moved from hibernacula to ephemeral pools between mid-April and the end of May, had home ranges that averaged 22 ha (54 ac), and home range lengths that averaged over 850 m (2,789 ft) (Grgurovic and Sievert 2005). Blanding’s turtles traveling long distances between wetlands, vernal pools, and nesting sites in their home ranges risk harmful interactions with humans, road mortality, and barriers in the landscape. As suggested earlier, habitat preferences of turtles are dependent on landscape context. In landscapes where vernal pools are prevalent and few other wetland types exist, some species may show preferences for vernal pools. However, the same species may not choose to enter these pools in landscapes where large wetland complexes are dominant, such as swamps or river flood plains. As an example, of 51 radio-tagged Blanding’s turtles studied by Grgurovic and Sievert (2005) over 2 years, 86% used vernal pools by traveling distances of >500 m (1,640 ft). Two female Blanding’s turtles in Maine moved at least 620 m (2,034 ft) between the same small vernal pool and a scrub-shrub wetland in their extensive nesting excursions (Joyal et al. 2000). However, B. Windmiller (Hyla Ecological Services, personal communication) and colleagues studied 20 radio-tagged Blanding’s turtles in a landscape that contained a large artificial wetland complex and rarely detected individuals venturing into vernal pools. Spotted turtles (Figure 9.1) are also closely associated with vernal pools in some landscapes, although Milam and Melvin (2001) found that this species used uplands and vernal pools in proportion to their availability. In Maine, spotted turtles foraged and basked in vernal pools and some individuals even were detected in these pools year-round (Joyal 1996; Joyal et al. 2001). Nearly all of the unoccupied pools studied by Joyal were ≤0.14 ha (0.35 ac) in size, received <6 hours of sunlight per day, and were <0.25 km (<0.16 mi) from hibernation wetlands. These omnivorous turtles move among small, shallow wetlands to forage, bask, and mate. Spotted turtles in Massachusetts emerge in late March or early April from overwintering sites in

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FIGURE 9.1 Spotted turtles (Clemmys guttata) find mates, prey, and refuge in vernal pools of all types in the Northeast. Photo by Mike Jones.

permanent wetlands and move up to 1 km (0.6 mi) overland to upland vernal pools, where they stay 20–150 days until nesting or when the pools dry out (Milam and Melvin 2001). Some turtles overwinter in ponds, and are occasionally seen swimming under the ice. Milam and Melvin (2001) also recorded spotted turtles consuming wood frog (Rana sylvatica) egg masses and amphibian larvae. Spotted turtles, like Blanding’s, require a mosaic of wetland and terrestrial habitat types to obtain the resources they need for survival. Vernal Pool Generalists Other species in the region occur in vernal pools opportunistically in which they forage for food, find shelter, and occasionally overwinter. Two habitat and foraging generalists, the snapping turtle (Chelydra serpentina), a large omnivore that seldom basks, and the painted turtle (Chrysemys picta), an omnivore that basks frequently, forage occasionally in vernal pools (DeGraaf and Rudis 1983; Kenney and Burne 2000; Brown and Jung 2005). Painted turtles and snapping turtles have been documented overwintering in a vernal pool embedded in a shrub wetland in Vermont (Faccio 2001). Wood turtles forage on amphibian eggs and larvae in vernal pools (Kenney and Burne 2000). The Eastern box turtle (Terrapene carolina) is typically considered a terrestrial species, but may spend over 20 days annually in vernal pools during hot summers, presumably to keep from overheating and possibly to forage

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for animal prey in very shallow water (Ernst et al. 1994; Kenney and Burne 2000; Donaldson and Echternacht 2005; E.A. Johnson, personal communication). Highly aquatic turtles may occasionally occur in vernal pools if they have at least a temporary, nearby connection to permanent water. For example, a stinkpot (Sternotherus odoratus) was documented in a vernal pool adjacent and sometimes connected to a slow-moving stream in New Jersey (E.A. Johnson, personal communication). The occurrence of freshwater turtles in vernal pools is thus contextdriven. Utilization of landscape features, such as vernal pools, will vary geographically and as a function of habitat availability. Thus, extrapolation of one’s understanding of turtle foraging behavior in vernal pools in one area to another may not be realistic. Densities of freshwater wetlands, including vernal pools, in the landscape appear to directly influence the presence and population viability of Blanding’s turtles and spotted turtles, and may be important to some other species depending on availability of other wetlands on the landscape. Elements of human construction, such as roads and urbanized zones, within the range of these species will only serve to hinder or prevent interwetland movements (Rubin et al. 2001; Chapter 12, Calhoun and Windmiller). Understanding regional densities of vernal pools, distances among them, and turtle use of the landscape (home ranges) is thus an important requirement for managers seeking to maintain populations of these increasingly rare turtles. Extensive movements among habitat types, including vernal pools, by many turtles requires conservation strategies that operate at landscape scales. Seven species of turtles are classified as species of concern, threatened, or endangered by provincial, state, or federal regulatory agencies in the Northeast (Table 9.2). Species that are listed in over five states or provinces in the region include spotted turtle, wood turtle, and Blanding’s turtle. Only the bog turtle (Glyptemys muhlenbergii) is federally listed in the U.S. as threatened, although this species occurs primarily in wetlands other than vernal pools. Information on how vernal pools fit in the life histories and ecologies of these rare species in various parts of their ranges would lead to more effective protection and management.

LIZARDS

AND

SNAKES

Lizards and snakes are classified together because of their ancestral relationships. Several lizards have no legs, whereas all snakes lack them. Only eight species of lizards occur in the glaciated northeast of North America (Conant and Collins 1998; Appendix 9.1). We found no literature and received no observations on occurrence in vernal pools by these sun-loving, terrestrial reptiles. All of them are invertebrate predators and are not known to eat amphibians in any of their life history stages. They choose to enter water only as a means of escape from potential predators. Lizards are generally only detected near vernal pools if basking logs and snags connect to the shoreline. Forty-three species of snakes occur in glaciated northeastern North America, of which 22 (51%) regularly feed or bask in vernal pools (Conant and Collins 1998; Ernst and Ernst 2003; Table 9.1, Appendix 9.1). The copper-bellied watersnake (Nerodia erythrogaster), a semiaquatic species that occurs in parts of Indiana,

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FIGURE 9.2 Eastern ribbonsnakes (Thamnophis sauritus sauritus) frequent vernal pools in the glaciated Northeast where they specialize on amphibian prey, especially frogs, toads, and tadpoles. Photo by Joseph C. Mitchell.

Kentucky, Michigan, and Ohio (Roe et al. 2003), forages in vernal pools extensively for amphibian adults and their larvae during their primary activity period in the spring and summer (Minton 2001; Roe et al. 2003). Hibernacula are underground in areas at or above maximum groundwater levels along the edges of vernal pools (Kingsbury and Coppola 2000). The eastern ribbonsnake (Thamnophis s. sauritus) (Figure 9.2) is a slender snake that preys on small frogs and often occurs in grassy habitats along marsh and stream edges in our region (Ernst and Ernst 2003). They forage extensively in vernal pools, sometimes appearing when frog metamorphs emerge from the water (Klemens 1993; Kenney and Burne 2000; P. deMaynadier, personal communication). At least one snake specializes in amphibians that breed in vernal pools. Eastern hog-nosed snakes (Heterodon platirhinos), a species of sandy soils, primarily eat toads (Bufo spp.). Hog-nosed snakes will appear at vernal pools when toads are breeding and when juveniles emerge following metamorphosis. Other snakes occasionally forage in these pools when amphibian prey are abundant and readily available, but are more likely to be found in semi-permanently or permanently-flooded marshes, ponds or lakes. Northern watersnakes (Nerodia sipedon) occur in many aquatic habitats and occasionally forage on emerging amphibians in vernal pools (Ernst and Barbour 1989; Ernst and Ernst 2003; JCM, personal observation). Plains gartersnakes (Thamnophis radix), a widespread grassland species, have been found

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preying on wood frogs and tiger salamanders (Ambystoma tigrinum) in Minnesota by Breckenridge (1944). Common gartersnakes (Thamnophis sirtalis), another widely distributed semiaquatic generalist, and northern watersnakes have been reported as predators in vernal pool habitats in Maine, Massachusetts, and Minnesota (Breckenridge 1944; Ernst and Barbour 1989). Baldwin et al. (2006) found several radio-tagged wood frogs consumed by adult common gartersnakes, and McDonough-Haughey (2005) documented these snakes in Connecticut preying on 12 radiotagged adult spotted salamanders (Ambystoma maculatum). These snakes seem to know when amphibians are available, particularly during migration events and emergence of metamorphs. Snakes do not have to visit pools to benefit from their potential prey that arrive at or depart from these sites on regular schedules annually. Frogs and salamanders disperse into the forest often over great distances (Pauley et al. 2000; Chapter 7, Semlitsch and Skelly). Snakes forage for these vernal pool animals in terrestrial habitats by scent-trailing or by finding them opportunistically (Ford and Burghardt 1993). The impact of snake predators on vernal pool amphibian populations that have already dispersed has never been studied. Several species of snakes in northeastern North America are protected by federal, state, and province laws and regulations. The Midwestern copper-bellied watersnake (Nerodia erythrogaster) is a threatened species under the U.S. Endangered Species Act (Table 9.2). The eastern ribbon snake is another semiaquatic predator that is listed in five states and two provinces (Table 9.2). The behavior of snakes in vernal pool systems is a potentially fascinating subject to explore. How do snakes know when to be at vernal pools to intercept prey? How do they learn about these migratory events in the first place? Are vernal pools included within their normal home ranges? Do they sense a chemical odor emitted by ponds or amphibians over long distances? As with turtles, management of semiaquatic snakes in one’s region requires protection and maintenance of habitat mosaics that include landscapes with vernal pools.

BIRDS Unlike most reptiles, birds are highly visible vertebrates in the landscape. As a group, more people watch these vertebrates than any other. Yet, surprisingly very few scientists have investigated avian species composition patterns near vernal pools (but see Hanowski et al. 2006; Scheffers et al. 2006), and we know of no studies of avian foraging or nesting behavior near vernal pools. Of the approximately 285 species of birds that breed or migrate through the region (DeGraaf and Yamasaki 2001, Ehrlich et al. 1988), some 232 (81%) may be observed at vernal pools during portions of their annual activity cycle (Table 9.1, Appendix 9.1). To our knowledge, only one study has investigated forest passerine bird ecology in and near vernal pools in the glaciated Northeast. Hanowski et al. (2006) found no significant differences in community composition among forest birds near vernal pools in Minnesota compared to adjacent mature forest habitats. Mature forestassociated birds decreased in number and species richness following clearcutting around seasonal ponds, although early successional species increased (Hanowski et

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al. 2006). Thus, management of forests around vernal pools may affect the composition of the bird community. In contrast in Tennessee, Scheffers et al. (2006) found significantly greater avian abundance, species richness, and diversity near vernal pools compared to adjacent upland sites, which they attributed to the greater abundance of aerial invertebrates at the pools. Thus, as with other vertebrates, avian density near vernal pools appears to vary as a function of landscape composition, but clearly warrants more study. Most birds that occur near vernal pools forage in vegetation above and around the pool, although many species prey on aerial invertebrates. R.T. Brooks (U.S. Forest Service, personal communication), for example, has often encountered blackand-white warblers (Mniotilta varia) near vernal pools during the breeding season, especially those pools with abundant shrubs. Many species of birds nest in or near vernal pools or use them for foraging and shelter, including wood duck (Aix sponsa) and American black duck (Anas rubripes), although both species primarily nest near other types of wetlands (DeGraaf and Yamasaki 2001; S. Faccio, personal communication). Barred owls (Strix varia) have been observed foraging at vernal pools in New Jersey and Vermont during wood frog breeding periods (S. Faccio, Vermont Institute of Natural Science, personal communication; J.H. Heilferty, N.J. Department of Environmental Protection, personal communication). Belted kingfishers (Ceryle alcyon) and hawks (Buteo spp.) killed wood frogs in Pennsylvania (Seale 1982). Unknown species of raptors preyed on wood frogs during their postbreeding migration in Maine (Baldwin et al. 2006). Large mixed species flocks of blackbirds (mostly grackles [Quiscalus sp.]) were observed preying on emerging wood frog metamorphs in Pennsylvania (R.T. Brooks, personal communication). Wading birds, such as great blue herons (Ardea herodias) and green herons (Butorides virescens), have been seen feeding on wood frog tadpoles at vernal pools in Rhode Island (P. Paton, personal observation). As with snakes, predatory birds seem to know when to arrive to forage on amphibians as they appear in large numbers. Birds may very well play an underappreciated role in the population ecology of amphibians in vernal pools, but conversely, the population ecology, reproductive success, and survival of avian species may to some extent depend on vernal pool productivity. The relationships of birds to vernal pool biota need elucidation to provide biologists with the tools they need to effectively manage and protect these vertebrates. Sixty-five species of birds that are listed by various states or provinces as species of concern, threatened or endangered are associated with vernal ponds in some way in the Northeast (Table 9.2). Thus, birds should be considered when developing conservation plans for vernal pools.

MAMMALS People are drawn to mammals at least as much as birds, if not more. The body size, diet, habitat requirements, and ecological diversity of this vertebrate group ensure that some of them interact with other animals at vernal pools. Of the 86 species of mammals that occur in glaciated northeastern North America (Whitaker and

American bittern Great blue heron Black-crowned night heron Glossy ibis Green-winged teal Hooded merganser Red-shouldered hawk Broad-winged hawk

Spotted turtle Wood turtle Blanding’s turtle Eastern mud turtle Illinois mud turtle Eastern box turtle Lake Erie watersnake Broad-banded watersnake Copper-bellied watersnake Eastern ribbonsnake Western ribbonsnake

SE

PA

SC

SC

SE

SE SC SC SC SC SC

SC

SC

SC

SP

SC

SC

SC SP

RI

SC

CT

SC SC ST

NY

SE

SC

SC SC ST

MA

ST

SC

SE

ST SC SE

ME

NH

Birds

SC SC

SE

SE

SC

FT

ST

SE

FT

SC FT

SC

ST

Reptiles SE SE SE SE

OH

IN

VT

ST

FT

ST

MI

SE

SE

ST

SE

SE

ST

SE

IL

ST

SE SE

SE ST ST

WI

MB

SC

SC

PE

PE SC PT

ON

PE SC PT

QE

NL

CANADA

SC

NB

PT

SC PE

NS

178

Species

U.S.

TABLE 9.2 Northeastern Listed Species That Are Common or Uncommon at Vernal Pools

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ST

PA

SC

NY

CT

SC

SC

SC

SC SC SC

RI

SC

MA

SE SC

SC

ME

VT

Mammals

NH

U.S.

SE

SC

SE

IN

SE

SC

ST

SC SC

OH

MI

IL

WI

MB

SC SC

ON

QE

NL

CANADA NB

NS

Sources: Pennsylvania (www.pgc.state.pa.us/pgc/cwp); New York (www.dec.state.ny.us/website/dfwmr/wildlife/endspec); Connecticut (dep.state.ct.us/cgnhs/nddb); Rhode Island (www.dem.ri.gov/programs/bpoladm/plandev/heritage/pdf/animals.pdf); Massachusetts (www.mass.gov/dfwele/dfw/nhesp/nhrare.htm); Maine (www.state.me.us/ifw/wildlife/etweb/state_federal_list.htm); New Hampshire (www.wildlife.state.nh.us/wildife/nongame/endangered_list.htm); Vermont (www.vtfishandwildlife.com/); Indiana (www.in.gov/dnr/fishwild/endangered); Ohio (www.ohiobiologicalsurvey.org); Illinois (dnr.state.il.us/espb/datelist.htm); Wisconsin (www.dnr.state.wi.us/org/er/working_list/taxalists); Canada: (www.cosewic.gc.ca/eng/sct1/index_e.cfm)

Note: Pennsylvania (PA), New York (NY), Connecticut (CT), Rhode Island (RI), Massachusetts (MA), Maine (ME), New Hampshire (NH), Vermont (VT), Ohio (OH), Michigan (MI), Illinois (IL), Wisconsin (WI), Minnesota (MN), Manitoba (MB), Ontario (ON), Quebec (QE), Nova Scotia (NS), Newfoundland (NF); FE = federal endangered, FT = federal threatened, SE = state endangered, ST = state threatened, SC = species of concern, PT = province threatened, PE = province endangered.

Water shrew Star-nosed mole New England cottontail Southern flying squirrel Woodland vole Southern red-backed vole Fisher River otter Moose

Virginia rail Sora White-throated sparrow Dark-eyed junco

Species

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Hamilton 1998), 78 (91%) may obtain resources from and interact with other species in vernal pools (Table 9.1, Appendix 9.1). Bats often feed on aerial invertebrates over open water (Vaughn et al. 1997) and along vegetation edges (Grindal and Brigham 1999) including habitats associated with larger vernal pools. In northern Wisconsin and upper Michigan, Francl (2005) documented little brown bats (Myotis lucifugus), northern myotis (M. septentrionalis), and big brown bats (Eptesicus fuscus) foraging at woodland vernal pools, with this activity decreasing as pools dried up. Echolocation calls of Myotis species were more frequently recorded over vernal pools than over larger, open-canopy wetlands (Brooks and Ford 2005). No northeastern North American bat is known to prey on frogs (Whitaker and Hamilton 1998), but an unidentified species was recovered from an amphibian pitfall trap in Maine (P. deMaynadier, personal communication). At least two species of terrestrial small mammals actively forage in vernal pools. Water shrews (Sorex palustris) inhabit riparian zones near streams, sphagnum swamps, emergent marshes, and vernal pools where they forage on aquatic and nonaquatic insects (Whitaker and Hamilton 1998). Star-nosed moles (Condylura cristata) are also wetland specialists, where they use their 22 supersensitive appendages on the tip of their nose to search for earthworms and other invertebrate prey items. One of these moles was captured in a pond with a minnow trap placed 45 cm (18 in) underwater (Eadie and Hamilton 1956). Other small mammals occasionally appear in and around vernal pools. Brooks and Doyle (2001) captured three species of shrews (masked shrew [S. cinereus, 13.7% of 2,124 captures], smoky shrew [S. fumeus, 0.4%], and short-tailed shrew [Blarina brevicauda, 2.0%]) at vernal pools in central Massachusetts. By using drift fences set adjacent to vernal pools in Vermont, Faccio (2001) captured large numbers of masked shrews and smoky shrews, and fewer numbers of meadow voles (Microtus pennsylvanicus), white-footed mice (Peromyscus leucopus), woodland jumping mice (Napaeozapus insignis), star-nosed moles, and hairy-tailed moles (Parascalops breweri). During the same study, S. Faccio (personal communication) observed an eastern chipmunk (Tamias striatus) eating the snout of a gravid wood frog at a small vernal pool in early May. He also observed three other wood frogs and a Jefferson salamander (Ambystoma jeffersonianum) with similar bite marks. Carnivores tend to have large home ranges and are habitat generalists. Thus, although several large carnivores may occasionally find drinking water at vernal pools, there are few indications that vernal pools provide essential foraging habitat for any of these species in our region (DeGraaf and Yamasaki 2001; Whitaker and Hamilton 1998). Still, pools can provide important additional foraging opportunities, particularly during amphibian spring migrations. For example, Vogt (1981) observed a mink (Mustela vison) preying on wood frogs at a breeding pond in Wisconsin. Seale (1982) suspected predation on wood frogs by raccoons (Procyon lotor) in Pennsylvania. Raccoons are persistent and common predators in Maine vernal pools and quickly learn to forage and kill animals in pitfall arrays around wetlands (P. deMaynadier, personal communication). Red foxes (Vulpes vulpes), gray foxes (Urocyon cinereoargenteus), striped skunks (Mephitis mephitis), Virginia opossums (Didelphis virginiana), and black bears (Ursus americanus) undoubtedly obtain water from vernal pools and in some cases forage on animals trapped in drying pools

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(Brown and Jung 2005). Of the large mammals that use vernal pools for drinking and foraging on aquatic vegetation, white-tailed deer (Odocoileus virginianus) and moose (Alces alces) appear to be the most common (Brown and Jung 2005). R.T. Brooks (personal communication) has often encountered moose at vernal pools and moose tracks in drying pools, and in the summer of 2005 startled a moose that had been lying down in a pool to cool off. Some mammals, like birds and reptiles, appear to opportunistically prey on amphibians at vernal pools when they are seasonally abundant. Highly energetic, insectivorous shrews are likely opportunistic predators of amphibians and other small vertebrates when they are encountered. Mid-sized mammals, such as raccoons, may obtain a considerable amount of energy from adult and metamorphic amphibians. The impact of these mammals on amphibian populations has not been evaluated. Thus, some mammals, like other vertebrates, provide critical links in energy flow dynamics between vernal pools and terrestrial ecosystems. Seven species of bats that may forage in or around vernal pools are protected in northeastern North America (Table 9.2), including the federally listed Indiana myotis (Myotis sodalis), which ranges into Connecticut, Massachusetts, Vermont, Virginia, and New Hampshire. Water shrews are listed in three states (Table 9.2). Vernal pool ecology and management should be included in any conservation plan developed for these species.

CONSERVATION IMPLICATIONS Vernal pools must be considered important components of the landscape and integral parts of functional ecosystems. Because many reptiles, birds, and mammals may regularly use vernal pools for food and water, protection of these wetlands from loss and alteration would enhance conservation of many vertebrate populations, not just amphibians. Unlike the exceptional value of vernal pools for amphibian (Semlitsch and Bodie 2003; Chapter 7, Semlitsch and Skelly) and some invertebrate populations (Chapter 6, Colburn et al.), their value for reptiles, birds, and mammals remains largely undocumented. Loss of vernal pools would decrease sources of food and water and likely compromise the long-term viability of some local populations (Gibbons et al. 2000). Loss of small wetlands such as vernal pools has a much greater effect on the dynamics of wetland animals than would be predicted by their size alone (Gibbs 1993). Even the smallest vernal pool should not be discounted as an important resource to vertebrate populations. Of all the reptiles that use vernal pools in northeastern North America, Blanding’s turtles and spotted turtles appear to be the most directly dependent on this type of wetland for foraging, mating, aestivating, and overwintering in some landscapes. The federally threatened copper-bellied watersnake depends on vernal pools and their associated topography for hibernation and summer foraging areas. The increasingly rare eastern ribbonsnake frequently forages in vernal pools on amphibians, particularly emerging metamorphs. Other snakes appear seasonally at these pools when they forage for amphibians. Wood ducks and American black ducks nest near vernal pools and use them for foraging and shelter. Other birds, such as herons and

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some owls prey on amphibians and other animals in these habitats. Bats, shrews, star-nosed moles, and raccoons are regular visitors to vernal pools where they prey on invertebrates and vertebrates. Many of these vertebrates may be important regulators of amphibian and invertebrate populations through predator–prey interactions. The large energetic yield of metamorphic amphibians probably fuels a considerable portion of the higher trophic levels. The productivity of vernal pools in terms of number of metamorphs and biomass is often very high (Pechmann et al. 1989). Vernal pools, therefore, are critical components of local and regional ecosystems and their inhabitants. Managers of vernal pools and their vertebrate populations should always be cognizant of all the users of vernal pools, as well as the myriad of interactions that occur among them. Conservation and protection of vernal pools would be enhanced if management efforts focused on maintaining multitaxa community interactions. Such interactions cannot be maintained unless both the vernal pool habitat and surrounding forests are managed with all vertebrate populations in mind. The spatial configuration of these seasonal, ephemeral wetlands on the landscape may play a critical role in the dynamics of these vertebrate populations and in the dynamics of the entire ecosystem. Many vertebrates move between and among vernal pools during their daily, seasonal, annual, and lifetime activities to obtain resources at different stages of their life cycles. Shifts in habitat use from one life history stage to another as they age and develop are commonplace in some of these vertebrates. Most vertebrates are dependent on several to many pools and an ability to move among them. Some species need to use them as temporary stepping stones to move between more permanent wetlands. Others capitalize on the rich energy sources of animals, such as amphibians, that use vernal pools for breeding sites. A variety of natural and unnatural processes affect the ability of these vertebrates to accomplish their needs. Ecological succession and disturbances in the forests of northeastern North America can affect the quality of vernal pools through timing of canopy closure, gap formation, and transpiration effects on local hydrologies (see Shugart 2004 for a readable review of forest dynamics). When seeking to manage or protect these keystone wetlands or rare species, biologists should not ignore the spatial arrangement of vernal pool density on the landscape, the needs of their vertebrate occupants, and local ecosystem dynamics. Human interference through urbanization, road construction, and other forms of land alteration curtail these natural processes and will result in the decline and even extirpation of some vertebrate populations in northeastern North America. Natural habitat mosaics are required by most, if not all, species. Thus, a primary goal managers should seek to achieve is to maintain natural processes in these environments. Management that results in habitat homogenization should be avoided (Law and Dickman 1998).

SUMMARY Reptiles, birds, and mammals provide important linkages between aquatic and terrestrial ecosystems, and among aquatic sites. They are understudied players in the population dynamics of amphibians and invertebrates that breed in vernal pools. Although no reptile, bird, or mammal is a vernal pool obligate, these vertebrates

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often acquire water, shelter, refuge from heat, food, and overwintering sites on a regular basis from these pools. Many local populations may need vernal pools for important sources of drinking water, particularly in landscapes with low densities of other wetland types. Many of these vertebrates likely play significant roles as predators of larval and adult amphibians and wetland invertebrates. As such, they may directly affect survival, reproductive success, and recruitment of pool-breeding amphibians and invertebrates. They are also important in the transfer of energy from vernal pools to upland habitats by eating individuals at the pool and moving the undigested energy to other sites. Thus, the value and roles of reptiles, birds, and mammals in vernal pools and the ecosystems in which they occur cannot be discounted. We determined that 64% of the freshwater turtles in the region may occur in vernal pools, of which 11 are protected in the U.S. and Canada (Table 9.2). No species of lizard is known to depend on vernal pools for survival, although their predation on emerging aquatic invertebrates may provide an energetic link. Twentytwo species (51%) of snakes forage, drink, or bask at vernal pools and prey on amphibians produced seasonally. Of the approximately 285 species of birds that breed or migrate through northeastern North America, 81% may forage, or nest over and around vernal pools. Many of the 86 species of mammals that occur in the glaciated Northeast may use vernal pools, at least seasonally for foraging or drinking. Bats are well known for drinking from such small bodies of water. Mid-sized mammalian predators such as raccoons, gray and red foxes, Virginia opossums, and striped skunks may be regular visitors to vernal pools and important sources of mortality for pool-breeding amphibians. Small and mid-sized mammals frequently kill and eat the abundant prey produced by vernal pools. Large mammals are often seen in these wetlands while drinking. All these species contribute in varying ways to the energetic link between aquatic and terrestrial ecosystems. Wood frogs are a common prey source for numerous vertebrate predators at vernal pools in glaciated northeastern North America. What roles do these species play in the population dynamics of wood frogs? Wood frogs are the target of many terrestrial vertebrates as adults (this review), as well as other amphibians, and are also eaten by invertebrates while they are tadpoles (Kenney and Burne 2000). Metamorphs of other amphibians are also important prey for vertebrate predators. No studies have been published on the effects of vertebrate predation on frog and salamander populations; however, losses by seasonal predation (particularly at breeding pools) can be very high (Vasconcelos and Calhoun, 2006). There is so little published information on vertebrate use of vernal pools, other than on amphibians, that only broad inferences can be made about the importance of vernal pools to reptile, bird, and mammal populations in northeastern North America. Our review highlights the need for research on services provided to these vertebrates by vernal pools in this region and probably elsewhere. Such work would greatly enhance our knowledge of the value of vernal pools to the entire vertebrate community and the ecosystems in which they are embedded. This information will also allow us to more effectively manage these habitats and their rare species.

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ACKNOWLEDGMENTS Anecdotal observations were kindly provided by Robert T. Brooks, Steve Faccio, John Heilferty, Elizabeth Johnson, and Joan Erenfeld. Phillip deMaynadier and Stan Moore provided pertinent literature. Betty Tobias, interlibrary loan sleuth of the University of Richmond, was instrumental in finding obscure papers. The editors of this book, R.T. Brooks, and the other reviewers helped to improve the manuscript.

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DeGraaf, R.M. and Yamasaki, M. (2001). New England Wildlife: Habitat, Natural History, and Distribution. University Press of New England, Hanover, NH. Donaldson, B.M. and Echternacht, A.C. (2005). Aquatic habitat use relative to home range and seasonal movement of eastern box turtles (Terrapene carolina carolina: Emydidae) in eastern Tennessee. Journal of Herpetology 39: 278–284. Eadie, W.R. and Hamilton, W.J., Jr. (1956). Notes on reproduction in the star-nosed mole. Journal of Mammalogy 37: 223–231. Ehrlich, P., Dobkin, D.S., and Wheye, D. (1988). The Birders Handbook: A Field Guide to the Natural History of North American Birds. Simon and Schuster, New York. Ernst, C.H. and Barbour, R.W. (1989). Snakes of Eastern North America. George Mason University Press, Fairfax, VA. Ernst, C.H. and Ernst, E.M. (2003). Snakes of the United States and Canada. Smithsonian Institute Press, Washington, D.C. Ernst, C.H., Lovich, J.E., and Barbour, R.W. (1994). Turtles of the United States and Canada. Smithsonian Institution Press, Washington, D.C. Faccio, S.D. (2001). Biological Inventory of Amphibians and Reptiles at the Marsh-BillingsRockefeller National Historical Park and Adjacent Lands. Final Report, National Park Service, Woodstock, VT. Ford, N.B. and Burghardt, G.M. (1993). Perceptual mechanisms and the behavioral ecology of snakes. In Seigel, R.A. and Collins, J.T. (Eds.). Snakes, Ecology and Behavior. McGraw-Hill, New York, pp. 117–164. Francl, K.D. (2005). Bat Activity in Woodland Vernal Pools. Final Report. USDA Forest Service, Ottawa National Forest and University of Notre Dame, Department of Biological Sciences, Notre Dame, IN. Gibbs, J.P. (1993). Importance of small wetlands for the persistence of local populations of wetland-associated animals. Wetlands 13: 25–31. Gibbons, J.W., Scott, D.E., Ryan, T.J., Buhlmann, K.A., Tuberville, T.D., Metts, B.S., Greene, J.L., Mills, T., Leiden, Y., Poppy, S., and Winne, C.T. (2000). The global decline of reptiles, déjà vu amphibians. BioScience 50: 653–666. Graham, T.E. (1995). Habitat use and population parameters of the spotted turtle, Clemmys guttata, a species of special concern in Massachusetts. Chelonian Conservation Biology 1: 207–214. Grindal, S.D. and Brigham, M.R. (1999). Impacts of forest harvesting on habitat use by foraging insectivorous bats at different spatial scales. Ecoscience 6: 25–34. Grgurovic, M. and Sievert, P.R. (2005). Movement patterns of Blanding’s turtles (Emydoidea blandingii) in the suburban landscape of eastern Massachusetts. Urban Ecosystems 8: 203–213. Hanowski, J., Danz, N., and Lind, J. (2006). Response of breeding bird communities to forest harvest around seasonal ponds in northern forests, USA. Forest Ecology and Management 229: 63–72. Haukos, D.A. and Smith, L.M. (2003). Past and future impacts of wetland regulations on playa ecology in the southern Great Plains. Wetlands 23: 577–589. Joyal, L.A. (1996). Ecology of Blanding’s (Emydoidea blandingii) and spotted (Clemmys guttata) turtles in southern Maine: population structure, habitat use, movement, and reproductive biology. M.S. thesis, University of Maine, Orono, ME. Joyal, L.A., McCollough, M., and Hunter, M.L., Jr. (2000). Population structure and reproductive ecology of Blanding’s turtles (Emydoidea blandingii) in Maine, near the northeastern edge of its range. Chelonian Conservation and Biology 3: 580–588.

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Joyal, L.A., McCollough, M., and Hunter, M.L., Jr. (2001). Landscape ecology approaches to wetland species conservation: a case study of two turtle species in Maine. Conservation Biology 15: 1755–1762. Kenney, L.P. and Burne, M.R. (2000). A Field Guide to the Animals of Vernal Pools. Massachusetts Division of Fisheries and Wildlife, Natural Heritage and Endangered Species Program, and Vernal Pool Association, Westborough, MA. Kingsbury, B.A. and Coppola, C.J. (2000). Hibernacula of the copperbelly water snake (Nerodia erythrogaster neglecta) in southern Indiana and Kentucky. Journal of Herpetology 34: 294–298. Kiviat, E., Stevens, G., Munger, K.L., Heady, L.T., Hoeger, S., Petokas, P.J., and Brauman, R. (2004). Blanding’s turtle response to wetland and upland habitat construction. In Swarth, C.W., Rosenburg, W.M., and Kiviat, E. (Eds.). Conservation and Ecology of Turtles of the Mid-Atlantic Region, A Symposium. Bibliomania! Salt Lake City, UT, pp. 93–99. Klemens, M.W. (1993). Amphibians and Reptiles of Connecticut and Adjacent Regions. Bulletin Number 112. State Geology and Natural History Survey Connecticut, New Haven, CT. Law, B.S. and Dickman, C.R. (1998). The use of habitat mosaics by terrestrial vertebrate fauna: implications for conservation and management. Biodiversity and Conservation 7: 323–333. McDonough-Haughey, C. (2005). Dispersal ecology of pond-breeding amphibians. M.S. thesis, University of Rhode Island, Kingston, RI. Milam, J.C. and Melvin, S.M. (2001). Density, habitat use, movements, and conservation of spotted turtles (Clemmys guttata) in Massachusetts. Journal of Herpetology 35: 418–427. Minton, S.A. (2001). Amphibians and Reptiles of Indiana. Indiana Academy of Science, Indianapolis, IN. Paton, P.W.C. (2005). A review of vertebrate community composition in seasonal forest pools on the northeastern United States. Wetlands Ecology and Management 13: 235–246. Pauley, T.K., Mitchell, J.C., Buech, R.R., and Moriarty, J.J. (2000). Ecology and management of riparian habitats for amphibians and reptiles. In Verry, E.S., Hornbeck, J.W., and Dolloff, C.A. (Eds.). Riparian Management in Forests of the Continental Eastern United States. Lewis Publishers, Boca Raton, FL, pp. 169–192. Pechmann, J.H.K., Scott, D.E., Gibbons, J.W., and Semlitsch, R.D. (1989). Influence of wetland hydroperiod on diversity and abundance of metamorphosing juvenile salamanders. Wetlands Ecology and Management 1: 3–11. Piepgras, S.A. and Lang, J.W., (2000). Spatial ecology of Blanding’s turtle in central Minnesota. Chelonian Conservation and Biology 3: 589–601. Roe, J.H, Kingsbury, B.A., and Herbert, N.R. (2003). Wetland and upland use patterns in semi-aquatic snakes: implications for wetland conservation. Wetlands 23: 1003–1014. Rubin, C.S., Warner, R.E., Bouzat, J.L., and Paige, K.N. (2001). Population genetic structure of Blanding’s turtles (Emydoidea blandingii) in an urban landscape. Biological Conservation 99: 323–330. Scheffers, B.R., Harris, J.B.C., and Haskell, D.G. (2006). Avifauna associated with ephemeral ponds on the Cumberland Plateau, Tennessee. Journal of Field Ornithology 77: 178–183. Seale, D.B. (1982). Physical factors influencing oviposition by the wood frog, Rana sylvatica, in Pennsylvania. Copeia 1982: 627–635.

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Semlitsch, R.D. and Bodie, J.R. (2003). Biological criteria for buffer zones around wetlands and riparian habitats for amphibians and reptiles. Conservation Biology 17: 1219–1228. Sharitz, R.R. (2003). Carolina bay wetlands: Unique habitats of the southeastern United States. Wetlands 23: 550–562. Shugart, H.H. (2004). How the Earthquake Bird Got Its Name and Other Tales of an Unbalanced Nature. Yale University Press, New Haven, CT. Silveira, J.C. (1998). Avian uses of seasonal forest pools and implications for conservation practice. In Witham, C.W., Bauder, E.T., Belk, D., Ferren, W.R., Jr., and Ornduff, R. (Eds.), Ecology, Conservation, and Management of Vernal Pool Ecosystems — Proceedings from a 1996 Conference. California Native Plant Society, Sacramento, CA, pp. 92–106. Vasconcelos, D. and Calhoun, A.J.K. (2006). Monitoring created seasonal forest pools for functional success: a 6 year case study, Sears Island, Maine. Wetlands 26: 992–1003. Vaughn, N., Jones, G., and Harris, S. (1997). Habitat use by bats (Chiroptera) assessed by means of a broad-band acoustic method. Journal of Applied Ecology 34: 716–730. Vogt, R.C. (1981). Natural History of Amphibians and Reptiles in Wisconsin. Milwaukee Public Museum, Milwaukee, WI. Whitaker, J.O. and Hamilton, W.J., Jr. (1998). Mammals of the Eastern United States. Cornell University Press, Ithaca, New York. Zedler, P.H. (2003). Seasonal forest pools and the concept of “isolated wetlands.” Wetlands 23: 597–607.

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APPENDIX 9.1 Status of reptiles, mammals, and birds associated with vernal pools in glaciated northeastern North America. We classified species as either common (high probability of being detected at a vernal pool) or uncommon (moderate probability). Behaviors exhibited at pools include foraging (F), thermoregulation (T), mating (M), aestivation (A), or nesting (N). For reptiles only, we listed distinct subspecies because subspecies are often listed by regulatory agencies. Birds rarely found in vernal pools are not included. Common Name

Species

Status

Use

Snapping turtle Western painted turtle Midland painted turtle Eastern painted turtle Spotted turtle Wood turtle Blanding’s turtle Illinois mud turtle Mississippi mud turtle Eastern mud turtle Eastern box turtle

Turtles Chelydra serpentina Chrysemys picta bellii Chrysemys picta marginata Chrysemys picta picta Clemmys guttata Clemmys insculpta Emydoidea blandingii Kinosternon flavescens spooneri Kinosternon subrubrum hippocrepis Kinosternon subrubrum subrubrum Terrapene carolina carolina

uncommon uncommon uncommon uncommon common uncommon common uncommon uncommon uncommon uncommon

F,T F,T F,T F,T F,T,M,A F, T F,T,M,A F,T F,T F,T F,T,A

Western mudsnake Yellow-bellied watersnake Copper-bellied watersnake Broad-banded watersnake Diamond-backed watersnake Northern watersnake Northern watersnake Red-bellied snake Eastern ribbonsnake Northern ribbonsnake Common gartersnake

Snakes Farancia abacura reinwardtii Nerodia erythrogaster flavigaster Nerodia erythrogaster neglecta Nerodia fasciata confluens Nerodia rhombifer rhombifer Nerodia sipedon sipedon Nerodia sipedon pleuralis Storeria occiptomaculata Thamnophis sauritus sauritus Thamnophis sauritus septentrionalis Thamnophis sirtalis sirtalis

uncommon common common uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon

F F F F F F F F F,T F,T F,T

Virginia opossum Arctic shrew Masked shrew Water shrew Northern short-tailed shrew Star-nosed mole Eastern cottontail Eastern chipmunk Gray squirrel Southern flying squirrel Northern flying squirrel

Mammals Didelphis virginiana Sorex arcticus Sorex cinereus Sorex palustris Blarina brevicauda Condylura cristata Sylvilagus floridanus Tamias striatus Sciurus carolinensis Glaucomys volans Glaucomys sabrinus

uncommon uncommon common uncommon common uncommon uncommon uncommon uncommon uncommon uncommon

F F F F F F F F F F F

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APPENDIX 9.1 (CONTINUED) Common Name

Species

Status

Use

Beaver Deer mouse White-footed mouse Southern red-backed vole Meadow vole Woodland vole Muskrat Nutria Coyote Red fox Gray fox Raccoon Fisher Long-tailed weasel Mink Striped skunk River otter White-tailed deer Moose

Castor canadensis Peromyscus maniculatus Peromyscus leucopus Clethrionomys gapperi Microtus pennsylvanicus Microtus pinetorum Ondatra zibethicus Myocaster coypus Canis latrans Vulpes vulpes Urocyon cinereoargenteus Procyon lotor Martes pennanti Mustela frenata Mustela vison Mephitis mephitis Lontra canadensis Odocoileus virginianus Alces alces

uncommon uncommon common common common uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon common common

F F F F F F F F F F F F F F F F F F F

American bittern Great blue heron Green heron Black-crowned night-heron Glossy ibis Canada goose Wood duck American black duck Mallard Green-winged teal Ring-necked duck Hooded merganser Red-shouldered hawk Broad-winged hawk Wild turkey Virginia rail Sora Least sandpiper Wilson’s snipe American woodcock Mourning dove Downy woodpecker Northern flicker Olive-sided flycatcher Eastern wood-pewee

Birds Botaurus lentiginosus Ardea herodias Butorides virescens Nycticorax nycticorax Plegadis falcinellus Branta canadensis Aix sponsa Anas rubripes Anas platyrhynchos Anas crecca Aythya collaris Lophydytes cucullatus Buteo lineatus Buteo platypterus Meleagris gallopavo Rallus limicola Porzana carolina Calidris minutilla Gallinago delicata Scolopax minor Zenaida macroura Picoides pubescens Colaptes auratus Contopus cooperi Contopus virens

uncommon uncommon uncommon uncommon uncommon uncommon common uncommon common uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon

F F F,N F F F F,N F,N F,N F F,N F,N F F F F F F F F F F F F F

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APPENDIX 9.1 (CONTINUED) Common Name Eastern phoebe Great crested flycatcher Eastern kingbird Red-eyed vireo Blue jay Tree swallow Black-capped chickadee Tufted titmouse White-breasted nuthatch House wren Blue-gray gnatcatcher Veery Wood thrush American robin Gray catbird Cedar waxwing Yellow warbler Black-and-white warbler American redstart Northern waterthrush Ovenbird Common yellowthroat Scarlet tanager Eastern towhee Chipping sparrow Song sparrow Swamp sparrow White-throated sparrow Dark-eyed junco Northern cardinal Red-winged blackbird Common grackle Brown-headed cowbird Baltimore oriole

Species Sayornis phoebe Myiarchus crinitus Tyrannus tyrannus Vireo olivaceus Cyanocitta cristata Tachycineta bicolor Poecila atricapillus Baeolophus bicolor Sitta carolinensis Troglodytes aedon Polioptila caerulea Catharus fuscescens Hylocichla mustelina Turdus migratorius Dumetella carolinensis Bombycilla cedrorum Dendroica petechia Mniotilta varia Setophaga ruticilla Seiurus noveboracensis Seiurus aurocapillus Geothlypis trichas Piranga olivacea Pipilo erythrophthalmus Spizella passerina Melospiza melodia Melospiza georgiana Zonotrichia albicollis Junco hyemalis Cardinalis cardinalis Agelaius phoeniceus Quiscalus quiscula Molothrus ater Icterus galbula

Status common uncommon uncommon common uncommon uncommon common common uncommon uncommon uncommon uncommon uncommon common uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon uncommon common common uncommon

Use F F F F F F F F F F F F F F F F F,N F F F F F,N F F F F,N F F F F F,N F F,N F

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Section III Conserving Vernal Pools in Human-Modified Landscapes

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10

Vernal Pool Conservation Policy: The Federal, State, and Local Context Wende S. Mahaney and Michael W. Klemens

CONTENTS The Vernal Pool Regulatory Framework...............................................................195 Canada — Federal and Provincial Wetland Policies and Regulations.....195 U.S. — Wetland Regulations ....................................................................197 Federal Level....................................................................................197 SWANCC and Its Implications for Vernal Pool Conservation ........199 State Level........................................................................................201 Vernal Pool Regulation and Protection at the Local Level ......................203 Regulatory Challenges and Solutions..............................................204 Planning Challenges and Solutions .................................................207 Conservation Recommendations ...........................................................................209 Summary ................................................................................................................210 Acknowledgments..................................................................................................210 References..............................................................................................................210

Governments at all levels in North America recognize the many public values that wetlands provide, including flood control, water quality maintenance, wildlife habitat, and outdoor recreation (Mitsch and Gosselink 2000). As such, a variety of wetland regulatory programs have been established to help protect these values and to stem the loss of wetland resources. Within the conterminous U.S., more than half of the 89.5 million hectares (221 million acres) of wetlands existing at the time of European settlement have been lost, leaving 43.6 million hectares (107.7 million acres) (Dahl 1990, 2006). Canada has 127 million hectares (314 million acres) of wetland remaining, a loss of 20 million hectares (49 million acres) of wetlands having occurred since the 1800s. Historically, conversion for agriculture has resulted in the majority of wetland losses in both countries (Dahl 1990, Government of Canada 1991). Recent wetland losses are largely attributable to urban and rural 193

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FIGURE 10.1 Development of adjacent terrestrial habitat around vernal pools is one of the greatest threats to pool-breeding amphibians. (Photo by R. F. Baldwin.)

development (Dahl 2006), being perhaps the greatest threat to vernal pools and other small wetlands that can fall under regulatory thresholds (Figure 10.1). The steady decline in wetland loss in the late 20th century can be attributed to government regulatory programs, public education, elimination of incentives to drain wetlands, and voluntary programs to restore and conserve wetlands on private lands. The most recent assessment in the U.S. (1998 to 2004) shows a net gain in wetland acreage of 77,630 ha (191,750 acres). This gain, however, is mostly due to the artificial creation of almost 281,500 ha (700,000 acres) of permanent freshwater ponds (Dahl 2006) — wetland gains that do not necessarily benefit vernal pool species. Quantifying the historic loss of vernal pools in glaciated northeastern North America is difficult but probably mirrors or exceeds trends cited above given their small size and difficulty of recognition. Undoubtedly, large numbers of vernal pools have been lost since European settlement began, and many of those remaining have been altered by human activity including agriculture, ditching, plowing, dredging, and forest clearing (Chapter 12, Windmiller and Calhoun; Colburn 2004). Recent increases in public awareness of and interest in vernal pools and their specialized fauna has heightened discussions of vernal pool protection through regulation and an assortment of other conservation measures (see Chapter 12, Chapter 13, and Chapter 16 regarding voluntary conservation of vernal pools; Colburn 2004). This chapter provides an overview of existing wetland regulatory programs in northeastern North America at the federal, state, provincial, and local government

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levels and highlights their relevance to vernal pool conservation. A discussion of the recent noteworthy U.S. Supreme Court case, Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers (SWANCC) is provided because of its important implications for vernal pool protection. The issues grappled with in this case are relevant to seasonal and geographically isolated wetland conservation in general and transcend political boundaries.

THE VERNAL POOL REGULATORY FRAMEWORK CANADA — FEDERAL REGULATIONS

AND

PROVINCIAL WETLAND POLICIES

AND

Wetland protection in Canada emphasizes a public policy and education-based approach, rather than one based on regulatory control of wetlands. Even so, Canada recognizes the role that regulation can play in an overall strategy for wetland conservation. There are a variety of environmental laws at the federal, provincial, and territorial levels that factor into protecting the public interest in wetlands, although many of these statutes are not specifically focused on wetland conservation or vernal pools (Lynch-Stewart et al. 1999). The Canadian Wetland Inventory, launched in 2002, is Canada’s first nationwide wetland mapping and monitoring project, and results of this will help to guide future governing of wetland resources. Wetlands in Canada are generally under the authority of the provincial governments, except those on federal lands, such as national parks, and those in the two northern territories where most wetlands remain under federal management (LynchStewart et al. 1999). This provincial authority stems from their ownership of natural resources within their boundaries and their jurisdiction over civil rights. In Canada, 89% of all land is either federal crown land (41%) or provincial crown land (48%), leaving only a small portion of land in private ownership (http://www.thecanadianencyclopedia.com). Crown lands, however, are mostly located in the relatively unpopulated, northern reaches of Canada. The Federal Policy on Wetland Conservation (Government of Canada 1991) provides a framework for wetland conservation in Canada. It applies to all government departments and establishes a goal of “no net loss of wetland functions” on all federal lands. The policy incorporates wetland conservation into the daily business of the federal government and applies to all federal lands, programs, funding, and decisions. The policy applies to all wetlands, regardless of size, and focuses on the conservation of wetland function, not just acreage. This policy provides an important opportunity to protect vernal pools because it allows for consideration of impacts to the critical terrestrial habitat that is so crucial for sustaining pool-breeding amphibian populations (A. Hanson, Canadian Wildlife Service, personal communication). There is no single piece of legislation that implements this policy (Austen 2005). Instead, it works through a variety of existing programs and regulations including the Migratory Birds Convention Act, Canada Wildlife Act, National Parks Act, Canada Ocean Act, Fisheries Act, Canadian Environmental Assessment Act, Income Tax Credit Act of Canada, and the Species at Risk Act.

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Programs like the National Parks Act and Canada Wildlife Act focus on designating and managing important wetlands as protected areas, either on federal or private land. Other programs have broader application (e.g., the Fisheries Act). The Canadian Environmental Assessment Act is an important tool to ensure that the objectives of the Federal Policy on Wetland Conservation are adhered to by federal projects and that the public can participate in decisions about federal projects that could harm wetlands (Austen 2005). The ability of the federal government to regulate activities that would affect wetlands is limited to areas of federal responsibility. Canada’s provinces and territories have enacted a variety of statutes pertaining to wetlands and other waterbodies such as land-use planning, protected areas (e.g., provincial parks), and wildlife management, all of which play some role in wetland conservation. Northeastern provinces take a variety of approaches to wetland conservation (see Austen [2005] for an overview of wetland policy in Atlantic Canada) that can be enhanced or modified to improve protection of vernal pool resources. New Brunswick implemented its major wetlands management tool, the New Brunswick Wetlands Conservation Policy, which includes a goal of “no net loss of wetland functions” (http://www.gnb.ca/0078/reports/wetlands/wetlands.pdf) in 2002. New Brunswick regulates activities in wetlands and other watercourses through the Watercourse and Wetland Alteration Regulation permit program under their Clean Water Act. This permit program regulates a variety of activities including depositing or removing soil, building structures, pumping water, or removing vegetation. Only projects impacting more than 1 ha (2.47 acres) of wetland require a permit, leaving a major loop-hole for destroying or degrading most vernal pools. In 2003, Prince Edward Island adopted a Wetland Conservation Policy for Prince Edward Island that applies to all wetlands and has a goal of ensuring “no net loss” of wetlands and wetland functions. The policy directs the Department of Fisheries, Aquaculture, and Environment to use a strict sequencing approach of avoidance, minimization, and finally compensation when regulating wetlands under the Province’s Environmental Protection Act (EPA). This policy applies to all wetlands regardless of ownership and is enabled by the EPA, which requires a permit for wetland alterations. The EPA regulates a broad array of activities that impact wetlands including dredging, filling, draining, and excavating. Increasing public awareness and agency enforcement is resulting in more wetland regulation through the EPA in recent years (Lynch-Stewart et al. 1999). Newfoundland and Labrador, which have extensive peatlands, regulate activities impacting wetlands under the Water Resources Act, which has a focus on protecting the hydrological functions of wetlands (http://www.env.gov.nl.ca/env/env/waterres/policies/PDWR97-2.asp). Adequate protection of vernal pools may be difficult to achieve, as developments are largely judged on their potential to impact water quality and quantity, flooding, and other hydrologic functions. Newfoundland and Labrador also have a Policy Directive for Development in Wetlands, but notably the policy focuses on allowing certain activities in wetlands rather than on protection and does not set a goal of “no net loss” (Austen 2005). Wetlands in Nova Scotia are managed under the 2006 Wetland Designation Policy. This policy directs that activities impacting a wetland require a Wetland Alteration Approval from Nova Scotia’s Department of Environment and Labour

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under the Environment Act (http://www.gov.ns.ca/snsmr/paal/el/paal586.asp). Approval is required regardless of the size of alteration or the size of the wetland, which should facilitate protection of vernal pools. Nova Scotia has not yet committed to “no net loss” of wetlands. Lynch-Stewart et al. (1999) point out that most assessments of Canadian wetland protection efforts find that more regulations are unnecessary. Rather, existing tools need to be better utilized. Many federal and provincial laws are believed to have unfulfilled potential to aid in wetland conservation and could be used to assist in vernal pool conservation efforts.

U.S. — WETLAND REGULATIONS Federal Level The Federal Water Pollution Control Act Amendments, now known as the Clean Water Act (CWA), were enacted by the U.S. Congress in 1972 and substantially amended again in 1977 and 1987. The intent of the CWA is to “restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.” The CWA is the primary federal law protecting water quality and it prohibits the discharge of pollutants into waters without a permit. Wetland regulation is primarily accomplished through Section 404 of the CWA. The jurisdictional scope of the CWA is “navigable waters,” which are defined as “waters of the U.S., including the territorial seas.” The scope of jurisdiction under the CWA has been discussed variously over the years in agency regulations, legislation, and judicial decisions (FR 68, 1991, Jan. 15, 2003) and most recently with respect to isolated wetlands (including vernal pools). The U.S. Army Corps of Engineers (the Corps) determines jurisdiction over waters and wetlands by either (1) documenting their connections to any downstream navigable waters or to interstate commerce or (2) by determining that wetlands are adjacent (i.e., bordering, contiguous, or neighboring) to other “waters of the U.S.” The Corps’ New England District offers guidance on determining adjacency that includes ecological considerations, including the migration distances of vernal pool breeding amphibians (see Color Plate 17) (http://www.nae.usace.army.mil/reg/AdjacencyGuidance.pdf). Some northeastern vernal pools do not fall under Corps’ jurisdiction, for example, when a pool is geographically isolated within an upland landscape. Section 404 of the CWA generally prohibits the discharge of dredged or fill material into waters of the U.S. without a permit, but Section 404(f) exempts normal farming, silvicultural, and ranching activities and the construction of farm and forest roads that may affect vernal pools. Section 404 also does not regulate all activities that could impact pools, including certain excavation or drainage activities and some types of vegetation removal. Furthermore, Section 404 does not directly regulate activities that occur in terrestrial areas that affect pool functions and amphibian nonbreeding habitat. When a project triggers jurisdiction over wetlands, however, impacts to uplands that affect wildlife can be considered. These limitations of the Section 404 program present notable hurdles for adequately protecting vernal pools and their wildlife habitat functions.

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Decisions regarding application of the Section 404 program are reached through input from a number of federal agencies. The Environmental Protection Agency (EPA) has the primary responsibility for carrying out all aspects of the CWA. EPA developed the substantive environmental standards that must be adhered to in order to obtain a Section 404 permit,* whereas the Corps administers the day-to-day permitting responsibilities through its 38 district offices. Before issuing a permit, the Corps must ensure that a project proposal is the “least environmentally damaging practicable alternative,” and that the project proponent has sequentially avoided, minimized, and compensated for impacts to wetlands. The Corps cannot issue a permit if a project is determined to be in contrast to the public interest, which requires a balanced consideration of a broad array of factors including economics, aesthetics, land-use, floodplain values, safety, fish and wildlife values, and water quality. The Corps uses two categories of permits — individual (or “standard”) and general permits. General permits apply to activities that the Corps determines are substantially similar in nature and result in minimal environmental impacts. Several states in the northeastern U.S. have programmatic general permits that are premised on an existing state wetland regulation program and designed to avoid duplication of effort. The Corps uses a programmatic general permit to authorize a variety of activities in five New England states (see permits at http://www.nae.usace.army.mil/reg/index. htm), Pennsylvania, Minnesota, and Wisconsin. The New England general permits contain special restrictions to protect vernal pools. For example, projects that would impact a vernal pool are usually not allowed to proceed under the permit’s nonreporting category. Instead, such projects are reviewed by the Corps and the federal resource agencies to assure that impacts to pools are adequately assessed, including consideration of impacts to adjacent upland forest. A variety of other federal and state agencies play an important role in the Section 404 permit process, including the U.S. Fish and Wildlife Service, the National Marine Fisheries Service, and state natural resource agencies. These agencies review permit applications and provide recommendations to the Corps on how projects can be modified to avoid, minimize, and compensate for impacts to wetlands resources. Although the CWA is the primary federal regulatory avenue for protecting wetlands, we note that the CWA was not specifically designed as a wetlands protection program, but rather as a water quality statute. This is perhaps most evident when considering wetland wildlife habitat functions. For vernal pool breeding amphibians that rely heavily on nearby forested habitats for survival, the CWA only provides limited opportunity to consider upland needs. Although the Corps’ permits often protect vernal pools themselves, they usually do not adequately protect the surrounding terrestrial habitat, dooming pool-breeding amphibian populations to decline and possible local extirpation. It becomes even more difficult to adequately protect vernal pools when several distinct wetland fill projects impact a related complex of pools spread over a large forested landscape. The CWA does allow for consideration of cumulative impacts but, in practice such assessments are often absent and usually far from adequate, with the review process largely focused on the individual project * The Guidelines for the Specification of Disposal Sites for Dredged or Fill Material (40 CFR Part 230), commonly referred to as the § 404(b)(1) Guidelines, are found at 45 FR 249, Dec. 24, 1980, 85336-85357.

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at hand. In short, it is difficult to hold one project accountable for habitat impacts related to other nearby projects. SWANCC and Its Implications for Vernal Pool Conservation On January 9, 2001, the U.S. Supreme Court issued a decision in SWANCC that limits the jurisdictional scope of the Section 404 permitting programs as it applies to isolated waters of the U.S. (Kusler 2004). Even though SWANCC is a U.S. court decision, it provides a valuable lesson for all of North America regarding the need for local, state, and provincial governments to be cognizant of their essential role in wetland protection in balance with actions at the federal level. In writing for the majority (a 5-4 decision), Chief Justice Rehnquist held that the Corps’ denial of a Section 404 permit for the Solid Waste Agency of Northern Cook County (Illinois) to fill several permanent and seasonal ponds for the development of a landfill was invalid because the Corps lacked jurisdiction over these ponds under the CWA. The Corps had asserted jurisdiction because the ponds provided habitat for many species of migratory birds, including serving as a great blue heron (Ardea herodias) rookery. The Court found that the Corps had exceeded their regulatory authority and held that the CWA is not intended to protect isolated, intrastate, nonnavigable waters (including isolated wetlands) based solely on their use by migratory birds. Prior to SWANCC, the Corps used the “migratory bird rule” to exert jurisdiction over a broad range of waterbodies and wetlands that could be used as habitat by birds protected by migratory bird treaties or by other migratory birds which cross state lines.* In regulatory preambles (e.g., 51 FR 41206, Nov. 13, 1986), both the Corps and EPA provide examples of the types of links to interstate commerce that could serve as the basis for jurisdiction over isolated waters, including use of waters as habitat by birds protected by migratory bird treaties. Although these examples were neither a rule nor entirely about birds, they became commonly known as the “migratory bird rule.” Although SWANCC held that the migratory bird rule was invalid for exerting jurisdiction over isolated waters that are intrastate and nonnavigable, it failed to clarify exactly which waters and wetlands are still regulated under Section 404 (see Downing et al. 2003 for further discussion of SWANCC). The court did indicate that isolated waters might be jurisdictional if they had a “significant nexus” to navigable waters, although it did not speak to how such a nexus could be demonstrated. In 2003, the Corps and EPA considered regulatory changes in response to SWANCC, but ultimately decided not to issue a new rule on wetland jurisdiction and to instead “preserve the federal government’s authority to protect our wetlands.” Isolated wetlands occur throughout northeastern North America, with their extent depending on a variety of factors including topography, climate, and hydrologic forces (Chapter 2, Rheinhardt and Hollands). Examples include vernal pools, kettlehole bogs, natural or artificial ponds, and prairie potholes, all of which Tiner (2003a) * Downing et al. (2003) provide a comprehensive discussion of the history of CWA jurisdiction, with an emphasis on isolated waters and wetlands.

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describes as “geographically isolated” wetlands because they are surrouuinded by uplands. Since SWANCC, several efforts have been made to estimate the extent of isolated wetlands in a variety of geographic areas across the U.S. (Tiner 2003b; Kusler 2004). Extending such analyses to implications for CWA jurisdiction, however, is difficult without clear guidance from the Corps and EPA on the jurisdiction of isolated wetlands. Analyses done since SWANCC find that the Corps is often not asserting jurisdiction over isolated waters using its remaining regulatory authority (GAO 2005; Schaeffer and Himmelsbach 2005). Although the impact of SWANCC on the federal regulation of wetlands, including vernal pools, may never be fully understood (Tiner 2003b; Zedler 2003), it is important to note that several states still have regulations that embrace isolated wetlands, regardless of the status of federal jurisdiction. At least some vernal pools in our region are no longer considered jurisdictional under the CWA (see Text Box A). This is most likely for vernal pools geographically isolated within an upland landscape, particularly when distant from other jurisdictional wetlands or waters. Vernal pools that abut or occur within a larger wetland complex are more likely to be jurisdictional, for example, where a forested wetland system is considered adjacent to another body of water in the U.S. Small vernal pools surrounded by uplands have always been particularly vulnerable to destruction, even when considered jurisdictional, because of their size, ephemeral nature, and a lack of understanding of their importance as wildlife habitat. The loss of federal protection due to SWANCC, even if only applicable to some vernal pools, will exacerbate the historical threats to these wetlands and the wildlife communities that depend on them.

TEXT BOX A. The Effect of SWANCC on Vernal Pool Jurisdiction Under the Clean Water Act. The New England District of the Corps in Concord, Massachusetts, has made jurisdictional determinations on a number of vernal pools since SWANCC (http://www.nae.usace.army. mil/reg/Jurisdiction2.asp). In Swampscott, Massachusetts, the Town asked for a jurisdictional determination for wetlands on a property proposed for a new school. A vernal pool used for breeding by wood frogs (Rana sylvatica) was determined to be isolated and therefore not a water of the U.S. This determination was made because of the lack of either a hydrological or ecological connection to a nearby jurisdictional wetland and the fact that the pool was more than 152 m (500 ft) from the nearest jurisdictional wetland (i.e., not adjacent). The New England District uses a 152 m “rule of thumb” for determining whether a wetland meets the concept of “neighboring” under the criteria for an “adjacent wetland.” In another case in Templeton, Massachusetts, the Corps determined that within a 21.5 ha (53 acres) parcel containing over 6.1 ha (15 acres) of jurisdictional forested wetlands, two wetlands were isolated with no nexus to interstate commerce. One of these wetlands is a vernal pool that supports breeding wood frogs but is located over 305 m (1,000 ft) from the nearest waterway. Both of these isolated wetlands were documented to be used by migratory birds. Despite these two cases, the New England District reports that some vernal pools are still considered jurisdictional (R. Ladd, U.S. Army Corps of Engineers, personal communication).

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*Just prior to publication of this book, the U.S. Supreme Court ruled in another case having implications for vernal pool conservation: On June 19, 2006 in the Rapanos v. U.S. decision, the U.S. Supreme Court vacated and remanded for further proceedings two Sixth Circuit opinions holding that the ACOE had jurisdiction over wetlands adjacent to a tributary of navigable waters (i.e., waters of the United States). There was no majority on the Court. Klein et al. (2006) discussed this decision in terms of the biological nexus that occurs between “waters of the U.S.” and adjacent or isolated wetlands, having direct relevance upon vernal pool regulation by the ACOE. The Rapanos decision was disappointing to all parties as it left a broad area of interpretation as to ACOE jurisdiction (i.e., the “nexus test”). Rapanos failed to bring the long-awaited legal and administrative clarity to ACOE jurisdiction vis a vis vernal pools.

State Level States use a number of approaches to protect wetland resources (ELI 2005). Currently, 15 states have their own comprehensive wetland regulatory programs. The majority of these states occur in the Northeast, providing another valuable avenue for the protection of vernal pools. New Jersey and Michigan have assumed the CWA Section 404 permitting program, although the Corps still maintains permitting authority in certain waters, including those subject to the ebb and flow of the tide and traditionally navigable waters. States without their own regulatory programs can still play an important role in federal wetland regulation through the CWA Section 401 water quality certification program. States can develop “water quality standards,” either specific to wetlands or more generic to all waters of the state, which are then used to assess the impact of proposed projects on wetlands. States can deny water quality certification or impose modifications or conditions on Section 404 permits being considered by the Corps. By developing water quality standards for wetlands that include consideration of vernal pool ecology, states may have an important opportunity to further protect these wetlands. Within the Northeast, Connecticut, Maine, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont have their own wetland regulatory programs. Most of these programs define wetlands and determine their boundaries in the same manner as the Corps. Most states regulate wetlands regardless of size, except for New York (most wetlands less than 5 hectares [12.4 acres] are not regulated) and Michigan (some wetlands less than 0.4 hectares [5 acres] are not regulated), which face a major hurdle in protecting vernal pools because of their minimum size thresholds for regulatory consideration. Since SWANCC, Wisconsin, Indiana, and Ohio have taken action to improve protection of isolated wetlands that are no longer regulated by the Corps. These states now require a state water quality certification or other permit for projects that would place fill material in isolated waters that no longer need a Section 404 permit. Wisconsin was the first to address the regulatory gap left by SWANCC, signing Act 6 into law on May 7, 2001, to allow state regulation of nonfederal isolated wetlands through their existing water quality certification program. These state measures should help protect those vernal pools left vulnerable by the SWANCC ruling.

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Among states with their own wetland regulatory programs, Maine, Massachusetts, Connecticut, and New Jersey are notable for having special provisions related to vernal pools. For example, Connecticut regulates wetlands through the Inland Wetlands and Watercourses Act of 1972, which largely passes regulatory authority down to the municipal level through a local Inland Wetlands and Watercourses Commission (Pressier et al. 2000). Most municipalities have developed their own wetland regulations, under guidance from the state, with some towns specifically including vernal pool protections. In 1987, Massachusetts became the first state to adopt specific regulatory protections for vernal pools. Massachusetts protects certain vernal pools under several laws, including the Wetlands Protection Act (Massachusetts General Laws Chapter 131 Section 40), which is administered through local conservation commissions. Under the Wetlands Protection Act, up to 100 feet beyond the boundary of a pool may also be protected, but only if this area is a regulated wetland. To receive protection under most of these laws, a vernal pool must be officially certified through a field documentation process overseen by the Massachusetts Natural Heritage Program (http://www.mass.gov/dfwele/dfw/nhesp/nhvernalcert.htm). The certification of a vernal pool, however, does not usually translate into adequate protection, as the surrounding critical terrestrial habitat required by pool-breeding amphibians is still largely vulnerable to development. Maine has designated high value vernal pools as “significant wildlife habitat” (see Text Box B) under their Natural Resources Protection Act (NRPA), which provides for the regulation of wetlands and other important natural resources (38 M.R.S.A. §§ 480-A to 480-Z). In April 2006, Maine adopted a definition for identifying significant vernal pools (Significant Wildlife Habitat Rules, Chapter 335, Section 9 under NRPA) based on the abundance or presence of certain vernal pool indicator species (fairy shrimp, wood frogs, and blue-spotted and spotted salamanders) or use by state-listed threatened or endangered species. A significant vernal pool includes the “critical terrestrial habitat” within a 76-m (250-ft) radius around the pool from the high water mark. While still short of the 226-m (750-ft) conservation zone identified by Calhoun and Klemens (2002) as essential for the longterm survival of vernal pool breeding amphibian populations, Maine is now a leader in northeastern North America for the extent of upland life zone habitat that is regulated around high-value vernal pools. The impact of this “significant wildlife habitat” designation for the conservation of vernal pools in Maine is still to unfold. As with most jurisdictions, Maine is still challenged to adequately protect the terrestrial habitat that is critical for vernal pool breeding amphibians.

TEXT BOX B. The Long Road to Vernal Pool Protection in Maine Although designated as “significant wildlife habitat” in 1995 by the State of Maine, the requirement that significant vernal pools be defined and mapped by the Maine Department of Inland Fisheries and Wildlife was never acted on due to lack of agency resources, the difficulty of mapping small wetlands with aerial photography, and an agency position that vernal pool protection might better be accomplished through nonregulatory efforts,

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such as the use of voluntary best management practices (e.g., Calhoun and Klemens 2002, Calhoun and deMaynadier 2004). Ten years later in September 2005, the Maine legislature amended the Natural Resources Protection Act (NRPA) to remove the statutory requirement to premap significant vernal pools. In the meantime, a work group of state and federal agencies, environmental consultants, and private conservation organizations worked for several years to develop a definition of a vernal pool and the criteria for designating a subset of high value “significant vernal pools.” These definitions were finally accepted by the State of Maine in April 2006, with the new regulatory protections becoming effective on September 1, 2007. Twelve years later, these often over-looked wetlands are on a path to wider recognition and better protection. Definition of a vernal pool and significant vernal pool in Significant Wildlife Habitat Rules, Chapter 335, Section 9 of NRPA: A vernal pool, also referred to as a seasonal forest pool, is a natural, temporary to semi-permanent body of water occurring in a shallow depression that typically fills during the spring or fall and may dry during the summer. Vernal pools have no permanent inlet and no viable populations of predatory fish. A vernal pool may provide the primary breeding habitat for wood frogs (Rana sylvatica), spotted salamanders (Ambystoma maculatum), blue spotted salamanders (Ambystoma laterale), and fairy shrimp (Eubranchipus spp.), as well as valuable habitat for other plants and wildlife, including several rare, threatened, and endangered species. A vernal pool intentionally created for the purposes of compensatory mitigation is included in this definition. Whether a vernal pool is a significant vernal pool is determined by the number and type of poolbreeding amphibian egg masses in a pool, or the presence of fairy shrimp, or use by threatened or endangered species as specified in Section 9(B). Significant vernal pool habitat consists of a vernal pool depression and a portion of the critical terrestrial habitat within a 250-foot radius of the spring or fall high-water mark of the depression.

Blue spotted salamander Spotted salamander Wood frog

VERNAL POOL REGULATION

presence of 10 or more egg masses presence of 20 or more egg masses presence of 40 or more egg masses

AND

PROTECTION

AT THE

LOCAL LEVEL

Protecting vernal pools requires engagement and cooperation of all levels of government, as well as the active support of local citizens. Although this is complicated and at times daunting, vernal pool protection is an attainable goal. We can point to numerous examples of sound conservation decision making that have linked regulatory programs at various levels with local communities to protect vernal pools. As discussed previously, most wetland regulatory programs do not encompass sufficient areas of adjacent terrestrial habitat to effectively conserve the biological functions of vernal pools. This presents a significant challenge, especially in an era where there is considerable emphasis on the perception of over-regulation. It is challenging to argue that despite myriad and often complex natural resource regulations, ecologically significant features like vernal pools are still highly vulnerable. The public often fails to recognize that individual wetlands have vastly different functions and values. Therefore, while it is generally accepted that loss of wetlands should be avoided, there is little understanding that the concept of “no net loss” of

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wetland acreage is quite different from “no net loss” of wetland function, complexity, and diversity. For example, land use planners and the public often see no ecological distinction between a manicured, grass-edged pond vs. a structurally complex, forested or shrub swamp system. In fact, many see the conversion of vegetated wetlands to ponds as a win-win situation that maintains a wetland while achieving a humanbased aesthetic goal. It is against this backdrop that new strategies for achieving meaningful vernal pool conservation should be developed. Because most land-use authority is divested by federal and state governments to the local level, conservationists are increasingly turning to the local decision-making process as the best opportunity for conserving vernal pools (Chapter 16, Calhoun and Reilly). In Canada, a region dominated by provincial and private land where federal powers are limited by the constitution, effective wetland conservation requires policy and action at the provincial and local levels (A. Hanson, personal communication). To achieve effective vernal pool conservation, local efforts must overcome both regulatory and planning challenges (Daly and Klemens 2005; Klemens and Johnson 2005). Creative ways to overcome these challenges can result in local jurisdictions being far more proactive and effective in vernal pool conservation than either federal or state/provincial regulatory authorities. Educating the public on the ecological values of pools and proactively working with developers to design environmentally sensitive projects is a strong start toward effective local conservation. The growth of regional and local land trusts in both the U.S. and Canada in the last 15 years is an indication of the growing focus on private land stewardship and local action, with less reliance on government action (http://www.lta.org/aboutlt/census.html, Campbell and Rubec 2006). Since 1995 in Canada, for example, over 40,000 hectares (99,000 acres) have been protected by private landowners in coordination with over 160 local land trusts through the Ecological Gifts Program. More than 40% of these property donations include wetlands. New England and other states in our region have been at the forefront of the land trust movement (Massachusetts is the birthplace of land trusts), leading the U.S. in both the number of land trusts and the amount of land protected as of 2003. For example, Maine is second only to California with over 520,000 hectares (1.3 million acres) protected, including important wetlands and vernal pools (http://www.lta.org/aboutlt/census.html). Regulatory Challenges and Solutions Focus on Threatened and Endangered Species The presence of federal and state/provincial protected species is often the sole wildlife focus of local land-use reviews. As most northeastern vernal pool-dependent species are not designated as endangered or threatened (but see Chapter 9, Mitchell et al. for listed species), their presence does not trigger intense scrutiny at the local level. Declining species that have not yet reached endangered or threatened status, however, provide an opportunity for cost-effective conservation. Thoughtful and informed land-use decisions made at the local level can help ensure that most of our region’s vernal pool species never attain the distinction of endangered or threatened status, in need of expensive emergency attention.

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Inadequate Standards for Biological Assessments While many local jurisdictions and other government agencies require that biological data are gathered as part of the land-use review process, there is little standardization of how those data are collected. A notable exception is the Federal Recovery Plan for the bog turtle (Clemmys muhlenbergii) (USFWS 2001), which standardizes the amount of search effort and the conditions under which searches should be conducted, as well as other field work parameters, to increase the likelihood of detection of this secretive species. The norm is for data to be collected in a manner that makes comparative reviews and decision-making difficult. Much public debate then focuses on the quality of the data, as opposed to the planning implications of a data set that is accepted by the project proponents, opponents, and decision-makers. Regulators and local communities can avoid this problem by clearly stating the types of data required for a comprehensive vernal pool survey. The goal is to avoid ambiguity and ensure that collected data will be helpful in assessing the potential impacts of a project. Over-Reliance on Regulations As discussed previously, there is a public perception that we are already “overregulated.” This perception in turn leads to the conclusion that by having so many regulations, everything must be sufficiently protected. In fact, existing regulations fall short of comprehensive vernal pool ecosystem protection. Vernal pools may best be protected at the local level by a townwide survey of vernal pools combined with an assessment of their integrity and productivity (Calhoun and Klemens 2002; Oscarson and Calhoun 2007) (Figure 10.2). The results of these surveys and assessments should be placed into a community’s master plan and include prescriptions for protecting those pools that have high conservation value. Compensation Instead of Avoidance Local decision makers must strike a balance between the interests of the community (i.e., “the commons” or a resource that is shared among a group of people, like drinking water) and the interests of the individual. Off-site compensation of impacts (e.g., creating a vernal pool elsewhere) can be appealing, as it creates a sense that the enviable win-win land-use decision is attainable. The concept that compensation is a tool of last resort, to follow avoidance and minimization, is sometimes forgotten. This works against vernal pool conservation, as vernal pool impacts are difficult to compensate given our current level of systems knowledge (Chapter 12, Windmiller and Calhoun). Citizens can argue effectively that avoidance should be the primary conservation strategy for important vernal pools, followed by minimization of impacts, with compensation generally a strategy of last resort. Fear of Takings Meaningful vernal pool conservation often requires a decrease in the impact size of a development project, either by reducing its overall scale or by increasing density into a smaller area. Proponents of development projects will often argue that such

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FIGURE 10.2 Local volunteers document vernal pool amphibian breeding activity to assess reproductive effort and to evaluate the importance of adjacent forest lands as amphibian nonbreeding habitat. (Photo by Aram J.K. Calhoun.)

modifications constitute a “taking” of land. In the U.S., the regulatory threshold of a de facto taking is very high; merely modifying a project through downsizing and clustering does not constitute a regulatory taking. Yet many local decision-makers are litigation-sensitive. The hint of a takings challenge is sufficient for them to permit development, even when feasible alternatives exist that would provide an economic return on the land while respecting public trust resources. Local decision-makers should understand that protection of the public trust in natural resources is a community value to which individual development projects must conform. These standards, however, must be applied even-handedly and transparently during all development reviews. Mandates at Cross-Purposes Protecting vernal pools can conflict with other legal mandates. Reductions in road widths, curbs, and cul-de-sacs, which protect critical terrestrial habitat areas and allow for movement of amphibians across the landscape, are often diametrically opposed to local and regional standards for road design and emergency vehicle access. In the U.S., CWA Phase II stormwater regulations, while promoting cleaner stormwater discharge, often impact wildlife populations by capturing and killing

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small amphibians and reptiles in networks of curbs, catch basins, and hydrodynamic stormwater cleaning chambers. Calhoun and Klemens (2002) provide a review of these issues. It is vital for local planners to address these issues and encourage appropriate modifications of development plans, often as part of the preapplication process. Although stormwater must be properly managed, techniques should be chosen in consideration of the vernal pool’s local watershed. Fortunately, there are a variety of low impact stormwater management techniques that can coexist with vernal pools, including mountable 4:1 road curbing, swales, and rain gardens. Planners and developers who engage in constructive dialog during project development have saved many vernal pools from the unintended impacts of misapplied stormwater management techniques, such as berming a vernal pool for stormwater retention. One of the major impediments for achieving land-use development patterns that conserve vernal pools is the current municipal zoning and regulatory frameworks. These rules and regulations often act as disincentives to create land-use patterns that encourage clustered housing, reduced road widths, and retention of natural vegetation. For example, Calhoun and Klemens (2002) discuss concentrating development in 25% of the critical upland habitat zone surrounding a vernal pool; yet, very few communities have the legal authority to create such intense land-use patterns in a suburban or rural setting. The town of Old Saybrook, Connecticut, passed a zoning amendment that allows intense clustering to achieve conservation goals (Section 56 of Town of Old Saybrook Zoning Regulations, “Open Space Subdivisions”). If conservation of natural systems is a community goal, then all codes, procedures, and regulations will need to be carefully examined and modified to encourage better stewardship. Planning Challenges and Solutions Make Vernal Pool Inventory and Assessment Data Accessible to All Stakeholders Information that can be used to inform land-use decisions is frequently in a format that is inaccessible to those who need it on a regular basis. The majority of individuals charged with making day-to-day decisions concerning development have neither the time nor the appropriate training to wade through scientific literature to extract relevant management implications and then correctly apply that knowledge to land-use issues. It is incumbent upon those who possess such knowledge to find mechanisms to deliver that information in a format that is accessible to local government, which is generally run by appointed or elected boards of citizens that lack specialized training in conservation and biodiversity. Few are fortunate enough to have a member trained in science or engineering. Publications such as Calhoun and Klemens (2002) attempt to fill this void by providing straightforward methods to assess vernal pools and prescriptions to conserve them in a development context. Researchers can help by giving municipalities access to pertinent data for use in their natural resources databases.

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Conserve Vernal Pools at the Regional Scale Planning should be conducted at regional scales, not at the scale of a single development. The ecosystem for a single vernal pool encompasses the adjacent terrestrial habitat (and commonly, other wetlands), which is often measured in tens of hectares. Many local development decisions are made on parcels that are a few hectares or less. Integrating an ecosystem-scale vision into a process that is usually focused on a much smaller scale is a significant challenge. This challenge can be addressed by creating large-scale, multijurisdictional conservation plans. Such plans can protect the terrestrial habitat required by vernal pool amphibians, as well as protecting vernal pool clusters. Protection of vernal pool clusters and the terrestrial habitat that occurs between these pools and other small wetlands will positively affect the survivorship of populations of species that use a variety of wetland habitats on an annual cycle, such as spotted turtles (Clemmys guttata) and Blanding’s turtle (Emydoidea blandingii) (Joyal et al. 2001), and also allow genetic exchange between populations of pool-breeding amphibians (Chapter 8, Gibbs and Reed). Such multijurisdictional biodiversity plans have been prepared for several sites in the tri-state New York Metropolitan Region by the Wildlife Conservation Society (Miller and Klemens 2002, 2004; Miller et al. 2005). Flexibility Is Key — Not All Pools Have Equal Conservation Value Biological systems are complex, and no two pools are ever identical. However, such variation complicates decision-making for those institutions and agencies seeking a standard response to land-use conservation questions. A “one size fits all” approach is particularly problematic, because vernal pools across a landscape may vary in productivity and ecological integrity. Therefore, it is critical to understand the quality of a pool and its ability to survive in the long-term, based on the amount and quality of terrestrial habitat that surrounds it, before making a land-use recommendation. For example, a pool that contains vernal pool-dependent amphibians, yet has lost the majority of its critical terrestrial habitat through prior development (see Figure 12.2), is not likely to provide long-term support for these amphibians. Therefore, it would be senseless to insist on a high level of landscape protection for that pool. Informed land-use decisions should be based on a critical evaluation of a pool’s conservation priority (Calhoun et al. 2005). Inventory and Assemble Data on Pool Resources to Facilitate Informed Development Most communities lack data on the natural resources within their jurisdiction. Fortunately more towns in our region are beginning to map natural resources, including vernal pools (see Case Study, Chapter 16, Calhoun and Reilly). The town of Washington, Connecticut, created a detailed natural resources inventory that was used to designate certain areas of the town as critical vernal pool habitat (Washington Conservation Committee 2000). Consequently, the town was able to direct developments away from their most important vernal pool ecosystems, while offering publicly available data that developers could use to better plan projects and avoid conflicts. The issue of transparency and prior identification of resources is critical to all involved. As promising as the efforts of some Connecticut towns are, they

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represent less than 5% of the 169 towns in Connecticut; most towns simply lack this vital information. Instead, they react to individual applications as they are received. The outcomes are often contentious and rarely result in comprehensive vernal pool protection. In Canada, the Ontario Vernal Pool Association is working to assist municipal planning authorities to fulfill their responsibilities under the Ontario Planning Act (OPA). Under the OPA, significant vernal pools designated as “natural heritage features” can be protected from “incompatible development.” The Association recognizes that municipalities often lack basic information about their vernal pools and knowledge of measures to protect these wetlands and works to assist local planning efforts. The Province of Ontario allows the municipal planning process to determine local natural heritage areas, which can include significant wildlife habitats like vernal pools (OMNR 2000). Ontario’s guide for identifying significant wildlife habitats provides a specific example of how a municipal planning authority can evaluate and protect their vernal pools (OMNR 2000).

CONSERVATION RECOMMENDATIONS In order to be effective in protecting the ecology of vernal pools, wetland regulations must recognize the critical importance of protecting the surrounding terrestrial habitat in addition to the pool itself. Additionally, regulations must acknowledge the importance of providing adequate connections between vernal pools and other wetlands, which may occur in clusters, to protect the genetic integrity of amphibian populations and to provide resting and foraging habitat for other wetland-dependent species. Because of the many challenges associated with affecting change in wetland regulations at the federal level to address only one particular type of wetland, the best strategy may be to work toward changes in either state or local regulations to accomplish better protection of vernal pools. Identification of high value vernal pools at the local level and active communication with state and federal regulators and developers should facilitate improved protection within existing regulatory frameworks. As already done in New England, the Corps should be encouraged to include specific protections for vernal pools in state general permits. Examples of such protections include (1) requiring review by the Corps and the resource agencies for any project impacting a vernal pool or its critical terrestrial habitat (regardless of the size of wetland fill) and (2) encouraging minimization of impacts to the surrounding forest habitat. In light of SWANCC, the scientific community recognized the need to promote additional research on how isolated waters and wetlands help to maintain the physical, chemical, and biological integrity of navigable waters and their tributaries (i.e., the Congressional intent of the CWA) (Leibowitz 2003). The ability to demonstrate a “significant nexus” between intrastate, nonnavigable, isolated waters and the remainder of the aquatic ecosystem (a notion introduced by the Supreme Court in SWANCC) could play an important role in determining the future extent of jurisdiction under the CWA (Downing et al. 2003). There is already a strong precedent for a close link between wetland science and development of wetland policy and regulation (Leibowitz and Nadeau 2003).

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For vernal pools, there needs to be better documentation of existing research and promotion of new research to demonstrate the ecological and hydrological connections between pools and navigable waters to assist the Corps in making a case for exerting jurisdiction over more vernal pools. Conservationists need to ensure that science underpins any policy or regulatory decisions made in light of SWANCC and to ensure that the goals of the CWA and Canada’s Federal Policy on Wetlands Conservation continue to be achieved.

SUMMARY There are many features of vernal pools that work against achieving adequate protection through wetland regulatory programs. Among these are their small size, their seasonality (both in hydrology and occupation by amphibians), the relatively inconspicuous nature of the fauna that use them, and their inextricable association with a large area of surrounding forest which is often upland. Often vernal pools are not identified until a development project is well into the planning or even permitting stage, making effective protection even more difficult. Nevertheless, given that many vernal pools occur on private property and that these pools provide public values that should not be entirely entrusted to private stewardship, wetland regulation coupled with landscape-scale planning needs to play a continuing role in a multifaceted vernal pool conservation strategy. Because of limitations to their authority, state, provincial, and federal governments are increasingly constrained in their efforts to protect small, isolated wetlands. Increased awareness and engagement of local jurisdictions and private landowners must be used in tandem with the protection afforded by federal, provinicial, and state regulation. Conservationists must also realize, however, that working with a diversity of local jurisdictions will present its own unique set of challenges and will require a great deal of sustained effort to gather locally specific biological data and formulate viable protection strategies. Meaningful vernal pool conservation will require the weaving together of strengths afforded by each level of government regulation combined with local participation.

ACKNOWLEDGMENTS This chapter benefited tremendously from the patience of and useful guidance from Aram J.K. Calhoun and the thoughtful comments of several reviewers.

REFERENCES Austen, E. (2005). A compensation process for wetland loss in Atlantic Canada. M.S. thesis, Dalhousie University, Halifax, Nova Scotia, CA. Calhoun, A.J.K. and Klemens, M.W. (2002). Best development practices: conserving poolbreeding amphibians in residential and commercial developments in the northeastern U.S. MCA Technical Paper No. 5, Metropolitan Conservation Alliance, Wildlife Conservation Society, Bronx, New York.

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Calhoun, A.J.K., Miller, N., and Klemens, M.W. (2005). Conservation strategies for poolbreeding amphibians in human-dominated landscapes. Wetlands Ecology and Management 13: 291–304. Calhoun, A.J.K. and deMaynadier, P. (2004). Forestry Habitat Management Guidelines for Vernal Pool Wildlife. MCA Technical Paper No.6, Metropolitan Conservation Alliance, Wildlife Conservation Society, Bronx, New York. Campbell, L. and Rubec, C.D.A. (2006). Land trusts in Canada building momentum for the future. Wildlife Habitat Canada, Ottawa, ON, CA. Colburn, E.A. (2004). Vernal Pools: Natural History and Conservation. McDonald and Woodward Publishing Company, Blacksburg, VA. Corps of Engineers and Environmental Protection Agency. (2003). Advance notice of proposed rulemaking on the clean water act regulatory definition of “waters of the U.S.” Federal Register 68(10): 1991–1998. Dahl, T.E. (1990). Wetland losses in the U.S. 1780s to 1980s. U.S. Department of the Interior, Fish and Wildlife Service, Washington, D.C. Dahl, T.E. (2006). Status and trends of wetlands in the conterminous U.S. 1998 to 2004. U.S. Department of the Interior, Fish and Wildlife Service, Washington, D.C. Daly, J. and Klemens, M.W. (2005). Integrating conservation of biodiversity into local planning. In Johnson, E.A. and Klemens, M.W. (Eds.). Nature in Fragments: The Legacy of Sprawl. Columbia University Press, New York, pp. 313–334. Downing, D.M., Winer, C., and Wood, L.D. (2003). Navigating through clean water act jurisdiction: a legal review. Wetlands 23: 475–493. ELI (Environmental Law Institute). (2005). State wetland program evaluation phase I. Environmental Law Institute, Washington, D.C. GAO (U.S. Government Accountability Office). (2005). Waters and wetlands. Corps of Engineers needs to better support its decisions for not asserting jurisdiction. Washington, D.C. GAO-05-870. Government of Canada. (1991). The federal policy on wetland conservation. Ottawa, ON CA 14 p. Joyal, L.A., McCollough, M.A., and Hunter, M.L., Jr. (2001). Landscape ecology approaches to wetland species conservation: a case study of two turtle species in southern Maine. Conservation Biology 15: 1755–1762. Klein, M.S., Klemens, M.W., and Merriam, D.H. (2006). Where’s Waldo? Finding federal wetlands after the Rapanos decision. Zoning and Planning Law Report 29(8): 1–14. Klemens, M.W. and Johnson, E.A. (2005). Creating a framework for change. In Johnson, E.A. and Klemens, M.W. (Eds.). Nature in Fragments: The Legacy of Sprawl. Columbia University Press, New York, pp. 349–362. Kusler, J. (2004). The SWANCC Decision: State regulations of wetlands to fill the gap. Association of State Wetland Managers, Inc. Retrieved October 3, 2005 from the World Wide Web: http://www.aswm.org/fwp/swancc/aswm-int.pdf. Leibowitz, S.G. (2003). Isolated wetlands and their function: an ecological perspective. Wetlands 23: 517–531. Leibowitz, S.G. and Nadeau, T. (2003). Isolated wetlands: state-of-the-science and future directions. Wetlands 23: 663–684. Lynch-Stewart, P., Kessel-Taylor, I., and Rubec, C. (1999). Wetlands and government — policy and legislation for wetland conservation in Canada. North American Wetlands Conservation Council (Canada). Ottawa, ON, CA. No. 1999-1. Miller, N.A. and Klemens, M.W. (2002). Eastern Westchester biotic corridor. MCA Technical Paper No. 4, Metropolitan Conservation Alliance, Wildlife Conservation Society, Bronx, New York.

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Miller, N.A. and Klemens, M.W. (2004). Croton-to-Highlands biodiversity plan: balancing development and the environment in the Hudson River Estuary Catchment. MCA Technical Paper No. 7, Metropolitan Conservation Alliance, Wildlife Conservation Society, Bronx, NY. Miller, N.A., Klemens, M.W., and Schmitz, J.E. (2005). Southern Wallkill biodiversity plan: balancing development and the environment in the Hudson River estuary watershed. MCA Technical Paper No. 8, Metropolitan Conservation Alliance, Wildlife Conservation Society, Bronx, New York. Mitsch, W.J. and Gosselink, J.G. (2000). Wetlands. 3rd ed. John Wiley and Sons, New York. Oscarson, D. and Calhoun, A.J.K. (2007). Developing vernal pool conservation plans at the local level using citizen scientists. Wetlands 27: 80–95. Ontario Ministry of Natural Resources (OMNR). (2000). Significant wildlife habitat technical guide. Queen’s Printer for Ontario, ON, CA. Pressier, E.L., Kefer, J.Y., Lawrence, J.D., Clark, T.W. (2000). Vernal pool conservation in Connecticut: an assessment and recommendations. Environmental Management. 26: 503–513. Schaeffer, E. and Himmelsbach, D. (2005). Drying out: wetlands opened for development by U.S. Supreme Court and U.S. Army Corps. Environmental Integrity Project, Washington, D.C. Tiner, R.W. (2003a). Geographically isolated wetlands of the U.S.. Wetlands 23: 494–516. Tiner, R.W. (2003b). Estimated extent of geographically isolated wetlands in selected areas of the U.S. Wetlands 23: 636–652. U.S. Fish and Wildlife Service (USFWS). (2001). Bog turtle (Clemmys muhlenbergii), northern population, recovery plan. Hadley, MA. Washington, Connecticut Ad Hoc Conservation Committee. (2000). Natural resource inventory report and recommendations. Washington, Connecticut: Ad Hoc Conservation Committee, Washington, CT. Zedler, P.H. (2003). Vernal pools and the concept of “isolated wetlands.” Wetlands 23: 597–607.

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Chemical Contamination of Vernal Pools Michelle D. Boone and Bruce D. Pauli

CONTENTS Contaminants and Effects on Vernal Pool Organisms ..........................................215 Sources of Contamination of Vernal Pools ...........................................................217 Forest Management Practices....................................................................217 Mosquito Control.......................................................................................220 Agricultural Practices ................................................................................221 Urban Development...................................................................................221 Complicating Factors.................................................................................222 Conservation Recommendations ...........................................................................223 Summary ................................................................................................................224 Acknowledgments..................................................................................................225 References..............................................................................................................225

Environmental pollution is a persistent and widespread problem that worsens as human population size increases; even remote habitats are not safe from exposure. Concern over environmental contamination began in earnest with the publication of the book Silent Spring (Carson 1962) and continues because tens of thousands of chemicals are registered for purposeful introduction into the environment, and many more are released as byproducts of industrial processes (Donaldson et al. 2002). At best, only basic toxicological effects are understood for most contaminants. Although large permanent wetlands are protected from direct contamination to some extent by federal regulations in both Canada and the U.S. (Chapter 10, Mahaney and Klemens), vernal pools are generally not protected from chemical pollution, including direct application of pesticides. Reasons for limited protection are practical; small, ephemeral ponds are difficult to map and, therefore, are not excluded from pesticide spray plans. However, vernal pools are of critical importance to taxonomic groups like amphibians and invertebrates (see Colburn 2004). Although habitat destruction and alteration are the primary threats to inhabitants of vernal pools

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(Chapter 13, deMaynadier and Houlahan; and Chapter 12, Windmiller and Calhoun), chemical contamination is a potentially detrimental form of habitat alteration. Sources of contamination may be from a point or a nonpoint source. Pointsource pollution includes any pollution emerging from a single identifiable and localized place, such as industrial sites and sewage treatment plants. Point-source pollution, in theory, should be easier to manage, monitor, and eliminate, because the source of contamination is known and the chemicals being released can be assessed directly. Nonpoint source pollution originates from numerous widespread, potentially global locations. These pollutants include fertilizers, herbicides, and insecticides from agricultural lands and residential areas, and oil, grease, and toxic chemicals from urban runoff. Nonpoint source pollution can also include compounds like heavy metals or brominated flame retardants (e.g., polybrominated diphenyl ethers), typically released from point sources such as landfills and sewage treatment plants, but which may also move through atmospheric transport and deposition. For instance, PCBs, which are released at a point source, can spread globally and accumulate in animals in remote areas at levels high enough to impair reproduction (discussed in Colborn et al. 1997). Both the origin of nonpoint source pollution and its effects may be difficult to pin-point, making critical cause-and-effect linkages challenging to determine. Testing for a range of potentially problematic environmental contaminants can be expensive, and there is a high likelihood of missing short-lived contaminants, although there are ways to test water source toxicity generally (see Bridges et al. 2004). However, examination of landscape-level patterns, weather patterns, and water sources (e.g., Davidson et al. 2001; Guerry and Hunter 2002) may indicate which contaminants are of most concern. Vernal pools may experience chemical contamination from both point and nonpoint sources, which increases the difficulty in determining the chemical or chemical mixtures of concern. However, pesticides (such as herbicides and insecticides) are identifiable sources of vernal pool contamination, and there is some information available on the ecotoxicology of pesticides in the aquatic environment, including effects on amphibians. Amphibians have received attention in ecotoxicological research recently because contamination has been listed as a potential cause of worldwide amphibian population declines (Corn 1994; Blaustein 1994; Stuart et al. 2004). Because amphibians can be top predators in ephemeral aquatic systems, and because amphibian responses to toxins are influenced by effects on the invertebrate and algal communities in vernal pools, amphibian communities may provide a model for understanding how vernal pool biota are affected by contamination. For this reason, we focus on this taxonomic group in our chapter (also see Chapter 7, Semlitsch and Skelly). In addition, amphibians are critical components of many ecosystems because they are abundant in number and total biomass (Burton and Likens 1975), they increase nutrient cycling where they are present (Beard et al. 2002), and they connect aquatic and terrestrial ecosystems through nutrient transfer (Wilbur 1980). Because amphibians need moisture for respiration, reproduction, and larval development (Duellman and Trueb 1994), they are dependent on local water resources and are susceptible to chemical contamination. Terrestrial contamination may also be important for adult life stages during hibernation (James et al. 2004 a, 2004b) or movement

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to wintering or breeding grounds. Because most North American amphibians have complex life histories with critical aquatic and terrestrial phases, it is important to understand environmental contamination in and around vernal pools. There have been numerous reviews (Cowman and Mazanti 2000; Linder and Grillitsch 2000; Sparling et al. 2000; Burkhart et al. 2003; Boone and Bridges 2003; Colburn 2004; Boone and James 2005) and books (Sparling et al. 2000; Linder et al. 2003) that have focused on the effects of contaminants on amphibians and their food webs. Our objectives here are to build on the previous work addressing the effects of contaminants on amphibians and to highlight the potential dangers for vernal pool species in northeastern North America. In this chapter, we discuss the sources of contamination for vernal pools, the consequences for the food webs that are exposed, and explore what can be done to reduce the problem of exposure.

CONTAMINANTS AND EFFECTS ON VERNAL POOL ORGANISMS Many contaminants have predictable effects on organisms based on their mode of action or based on how other structurally similar chemicals act. Thus, understanding the consequences of the direct effects of representative contaminants on individual physiology or behavior helps predict potential effects of a wider suite of contaminants. However, sensitivity of organisms to direct effects of individual contaminants may differ within (e.g., Bridges and Semlitsch 2000) and among (e.g., Mayer and Ellersieck 1986) species. Additionally, environmental factors can also influence toxicity. Northeastern North America has relatively cool summers and winters and is characterized by acidic soils (see Chapter 1, Colburn 2004). These characteristics can affect the toxicity and persistence of chemicals (Horne and Dunson 1995; Wojtaszek et al. 2004). Animals can also be affected through indirect effects when contaminants change the abundance of food resources or predators. For instance, Mills and Semlitsch (2004) showed that indirect contaminant effects altered the amphibian community through changes in plankton abundance. Arthropods may be more acutely sensitive to contaminants than are amphibians or fish (Mayer and Ellerseick 1986), so contaminant exposure that is sublethal to amphibians may eliminate or reduce organisms sharing their ecosystem. Therefore, with contaminant exposure, predators that play an important role in regulating amphibian communities may be eliminated while amphibians and fish persist (Boone and Semlitsch 2003; Relyea et al. 2005). In the end, the effect of contaminants in vernal pool ecosystems from both point and nonpoint sources will be a combination of both direct and indirect effects. Pesticides potentially contaminating vernal pools include insecticides in the organophosphate (e.g., malathion, trade name Cythion®) and carbamate (e.g., carbaryl, trade name Sevin®) families which are relatively short-lived chemicals that affect nervous system function. In terms of amphibians and their aquatic ecosystems, these chemicals are probably the best studied to date: they are known to alter predator-prey interactions (Bridges 1999; Boone and Semlitsch 2003), cause acetylcholinesterase inhibition (Johnson et al. 2005), alter larval development (Bridges

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2000; Boone and Semlitsch 2001, 2002), affect tadpole survival and survival to metamorphosis (Boone and James 2003; Mills and Semlitsch 2004; Relyea et al. 2005), and have been associated with amphibian population declines (Davidson 2004). Organochlorine insecticides have only limited use in North American agriculture because they are highly toxic (Kirk 1988), persistent, can bioaccumulate (Russell et al. 1995), and can disrupt endocrine function. However, some organochlorine insecticides (e.g., endosulfan, trade name Thiodan®) are still applied or are still present from past use, and can be acutely toxic to amphibians (Berrill et al. 1998). In fact, DDT residues may still be found in amphibians in our region (Russell et al. 1995). Although insecticides may be acutely toxic to invertebrates and amphibians and may pose the greatest direct threat to these species, herbicides disrupt photosynthetic processes and can affect algal food resources (Fairchild et al. 1994; Diana et al. 2000,) and the abundance or diversity of aquatic plants that provide environmental structure important for predator-prey interactions. Additionally, some herbicides appear to affect individuals negatively by disrupting endocrine function (Hayes et al. 2003; Howe et al. 2004), as well as by affecting survival and development (Boone and James 2003; Freeman and Rayburn 2005). Two of the most commonly used herbicides in North America, glyphosate (as incorporated in the common herbicide formulations Vision® and Roundup®) and atrazine (in Aatrex®), have been the focus of numerous studies with amphibians. Many studies suggest that these herbicides can have adverse impacts on amphibians in the wild through both direct and indirect pathways (e.g., Hayes et al. 2003; Wojtsazek et al. 2004; Relyea 2005a, 2005b; Rohr et al. 2006). Nonpesticide contaminants such as metals, PCBs, and fertilizers can also degrade vernal pools. Elevated levels of metals in nature can occur from mining, industrial, or other activities and can have diverse effects on amphibians including neurotoxicity, impaired larval development, and reduced survival to metamorphosis (Rowe et al. 2001; James and Little 2003; James et al. 2004a, 2004b; Unrine et al. 2004; James et al. 2005). Atmospheric deposition of mercury, which has negative effects on amphibian development and survival (Unrine et al. 2004) and may be associated with population declines (Bank et al. 2006), has also been of special concern in recent years and may be particularly problematic in northeastern North America (Bank et al. 2005). PCBs can also have negative effects on amphibian development and metamorphosis, can bioaccumulate in amphibian tissues, and can be transferred to amphibian predators (Gutleb et al. 2000; Woodlot Alternatives 2003). Fertilizer application is also a concern. Nitrogen deposition in the U.S. is highest in the Northeast and Midwest (Aber et al. 2001). Although ammonium nitrate fertilizer is often considered nontoxic to wildlife (Rand 1985), it can induce mortality and slow development (Baker and Waights 1994; Hecnar 1995; Rouse et al. 1999; Guillette and Edwards 2005) and can influence metamorphosis (de Wijer et al. 2003) in amphibians, and also increase algal abundance in wetlands (Boone et al. 2005). The carriers (e.g., surfactants) with which the active ingredients of pesticides are formulated can also have toxic effects on nontarget species, so knowing the active ingredient and its mode of action alone are not always sufficient to predict toxicity in the field. Surprisingly, commercial-grade pesticide formulations are not

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required to be tested under current regulations and obtaining a complete list of the ingredients in a pesticide formulation is often not possible because the carriers are often regarded as a trade secret, even when the commercial formulation is found to be toxic at environmental concentrations. For instance, formulations of glyphosate are highly toxic at low concentrations, whereas the active ingredient alone is not (Mann and Bidwell 2001; Howe et al. 2004; Relyea 2005ab). Further, mixtures of chemicals or combinations of stressors can have unexpected effects that may alter toxicity, although contaminant mixture studies are relatively rare (but see Britson and Threlkeld 1998, 2000; Rowe et al. 1998; Hopkins et al. 1999; Boone and James 2003; Boone et al. 2005).

SOURCES OF CONTAMINATION OF VERNAL POOLS Chemical contamination of vernal pools in northeastern North America can result from forest management, mosquito control, agriculture, industry, urban and other development, and atmospheric deposition–contamination sources that are similar throughout the world.

FOREST MANAGEMENT PRACTICES Although forests are not chemically treated to the degree that intensive agricultural areas are, chemical applications do occur in managed forests (Chapter 13, deMaynadier and Houlahan; Table 11.1). Herbicide applications typically occur once or twice during a 40–80 year silviculture-management cycle (Shepard et al. 2004; Michael 2004), whereas insecticide application may be repeated in the same region every year during a population outbreak of a defoliating insect pest like spruce budworm (Choristoneura fumiferana) or gypsy moth (Lymantria dispar). Many jurisdictions have established regulations for forestry management that have replaced the older organochlorine, organophosphorus, and carbamate insecticides to limit the applications only to biological and other lepidopteran-specific insecticides. Studies should be required, however, to determine if infrequent pesticide exposure will have lasting population-level consequences. Many populations of amphibians, for instance, have low to no juvenile recruitment in a given year and may rely on favorable environmental conditions to maintain populations through time (Semlitsch et al. 1996). An increased number of stochastic events such as periodic contamination of breeding sites may eliminate the recruitment that is necessary to maintain the population. Even one exposure to contaminants that reduce larval survival or compromise adult survival may be problematic at the population level, even if the occurrence is only periodic. Vernal pools may receive pesticides from accidental direct application or spray drift during forest insect control or vegetation management activities. For instance, in Canada, an estimated 18% of the forests are treated annually with herbicides, typically through aerially spraying (Thompson et al. 2004). Insecticides, especially the biological insecticide Bacillus thuringiensis var. kurstaki, are used in forest insect control programs in northeastern North America primarily against eastern spruce budworm, hemlock looper (Lamdina fiscellaria fiscellaria), and gypsy moth.

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TABLE 11.1 Potential Pesticide Contaminants for Vernal Pools Use Silvicultural insecticidesa

Jurisdiction Canadab

U.S.c

Silvicultural herbicides Canadab

U.S.d

Mosquito control chemicals

Canadae

U.S.f

Pesticide

Chemical Class

Bacillus thuringiensis var. kurstaki Biological Tebufenozide Insect growth regulator Trichlorfon Organophosphorus Bacillus thuringiensis var. kurstaki Biological Malathion Organophosphorus Esfenvalerate Synthetic pyrethroid Glyphosate Phosphonic acid 2,4-D Aryloxyalkanoic acid Simazine Triazine Triclopyr Pyridyloxyacetic acid Clopyralid Pyridinecarboxylic acid 2,4-D Aryloxyalkanoic acid Glyphosate Phosphonic acid Hexazinone Triazine-2,4-dione Imazapyr Imidazolinone Metsulfuron methyl Sulfonylurea Picloram Pyridinecarboxylic acid Sulfometuron methyl Sulfonylurea Triclopyr Pyridyloxyacetic acid Bacillus thuringiensis var. Biological/bacterial israelensis (larvicide) Bacillus sphaericus Biological/bacterial (larvicide) Methoprene Insect growth regulator (Larvicide) Chlorpyrifos Organophosphorus (Larvicide) Malathion Organophosphorus (Adulticide) Bacillus thuringiensis var. Biological/Bacterial israelensis (Larvicide) Bacillus sphaericus “ Temephos Organophosphorus (Larvicide) Methoprene Insect growth regulator (Larvicide) Larvicidal mineral oils N/A (Larvicide) Monomolecular surface films N/A (Larvicide) Malathion Organophosphorus (Adulticide)

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TABLE 11.1 (CONTINUED) Potential Pesticide Contaminants for Vernal Pools Use Mosquito control chemicals

Jurisdiction

Pesticide

U.S.f (continued)

Naled Permethrin Resmethrin Sumithrin

Chemical Class Organophosphorus (Adulticide) Synthetic pyrethroid (Adulticide) Synthetic pyrethroid (Adulticide) Synthetic pyrethroid (Adulticide)

a

Includes insecticides recently used for forestry in northeastern North America as opposed to all insecticides registered for this purpose. b From the Canadian Council of Forest Ministers, National Forestry Database System, http://nfdp.ccfm.org/compendium/index_e.php, accessed 12 December, 2005). c From U.S. Department of Agriculture Forest Service reports for the years 2000 to 2004, for applications to forest and rangeland area within National Forest Service lands in USDA Forest Service Region 9, reports available at: http://www.fs.fed.us/foresthealth/pesticide/reports.shtml, accessed 14 December, 2005. d The most common herbicides used as listed by Michael, J.L. (2004), Water, Air, and Soil Pollution Focus 4: 95–117, and Shepard, J.P., Creighton, J., and Duzan, H. (2004), Wildlife Society Bulletin 32: 1020–1027. e From Pest Management Regulatory Agency, Health Canada (http://www.pmra-arla.gc.ca/english/consum/mosquito-e.html#3, accessed 08 December, 2005). f From U.S. Environmental Protection Agency (http://www.epa.gov/pesticides/health/mosquitoes/mosquito.htm, accessed 08 December, 2000).

Herbicides are used in site preparation, weed control, and conifer release (i.e., thinning and removal of vegetation competing with commercially valuable trees; Chapter 13, deMaynadier and Houlahan; Colburn 2004; Shepard et al. 2004). Applications in the U.S. National Forestry system are also made for noxious weed control (Shepard et al. 2004). Generally, many of the herbicides used for forestry are also used on industrial sites, along rights-of-way, and on road and utility corridors. Some aquatic ecotoxicology information is available for forestry pesticides. Among the most well studied compounds, especially for amphibians (reviewed in Boone and Bridges 2003), is carbaryl, a short-lived insecticide used to control spruce budworm. Research with carbaryl indicates that direct effects under field conditions are less important than indirect food web effects (Mills and Semlitsch 2004); carbaryl can negatively impact salamanders by removing or reducing their food resource (zooplankton) but may also have some positive effects on anuran growth (at expected environmental concentrations) by increasing tadpole food resources (algae) through reducing zooplankton grazers. At the same time, effects of contaminants like carbaryl may be more serious in regions like northeastern North America, because the typically low pH can increase a contaminant’s environmental persistence (Gibbs et al. 1984).

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Tebufonozide, an insect growth regulator, is a targeted lepidopteran insecticide; it causes a premature fatal molt for some invertebrates. Tebufenozide, therefore, has restricted impacts on nontarget species including amphibians (Pauli et al. 1999), although potential effects on cladocerans in the treatment areas have been reported (Kreutzweiser et al. 1998). In comparison, the earlier broad-spectrum organophosphorus insecticide fenitrothion, which tebufenozide has replaced, could cause abnormal development, kill tadpoles at expected environmental concentrations (Berrill et al. 1994, 1995), and negatively affect zooplankton (Kreutzweiser and Faber 1999). The pyridine herbicide triclopyr (used to control woody plants and broadleaf weeds) and the herbicide glyphosate (a broad-spectrum herbicide) in some formulations can be toxic to amphibians at expected environmental concentrations from forestry application (Berrill et al. 1994; Chen et al. 2004; Howe et al. 2004; Thompson et al. 2004; Relyea 2005b). Although some suggest herbicides do not move much from the site of application (Michael 2004), Thompson et al. (2004) found glyphosate was measurable in wetlands adjacent to sprayed areas, and other studies suggest herbicides can readily move (e.g., Thurman and Cromwell 2000). Herbicides may alter the resource base of a community and thereby alter the entire food web (Boone and James 2003; Relyea et al. 2005). Forestry management, as well as agricultural practices, can alter nutrient and water cycling within aquatic systems — effects that may persist after harvesting and/or replanting. Harvesting can change the nutrient input to vernal pools in terms of leaf litter and soil erosion, and alter the nutrient content in water bodies (Chapter 13, deMaynadier and Houlahan; Colburn 2004). Further, fertilizers may be directly applied to these areas to promote forest growth. Nitrate fertilizers can positively influence algal populations by supplying limited nutrients, which can result in trophic cascades that increase the abundance of algae and zooplankton, thereby positively affecting salamander and anuran populations (Boone et al. 2005). However, nitrate addition can also result in eutrophication of wetlands, which can result in oxygen depletion and changes in water chemistry that can cause mortality across taxonomic groups. Because eutrophication has been associated with increased incidence of parasite infection and, hence, malformations in amphibians (Johnson and Chase 2004), increased nutrients in the environment could have important negative indirect effects on amphibians and the vernal pool community.

MOSQUITO CONTROL Application of pesticides for mosquito control may become more common as threats of mosquito-borne diseases become more prevalent. As a consequence, long-term viability of vernal pool communities may be threatened if ponds are frequently treated. Further, other attempts at biological control (for instance introducing fish such as mosquitofish, Gambusia spp., which may be viewed as a safer alternative to contaminants) could also negatively affect vernal pool breeders through predation (Wellborn et al. 1996). Vernal pools may be directly treated with larvicides for mosquito control, regardless of whether these pools harbor mosquitos of public health importance (see Chapter 6, Colburn et al. for a discussion of West Nile Virus). These larvicides can have negative effects on all species in vernal pools, especially

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invertebrates. Although a number of pesticides are registered for mosquito control in Canada and the U.S. (Table 11.1), the main compounds currently being used for larval mosquito control are the biological insecticides Bacillus thuringiensis var. israelensis (Bti, Vectobac®), B. sphaericus (Vectolex®), and the insect growth regulator methoprene (Altosid®). In one study, Hershey et al. (1998) treated ponds with methoprene and Bti, finding that exposure to both resulted in ponds with fewer insects, which may reduce predation but increase competition in amphibian communities. For amphibians, studies on the direct effects of Bti are rare, but Paulov (1985) suggested Bti endotoxins are not a direct toxic concern for amphibians. A similar conclusion was reported for B. sphaericus (Mathavan and Velpandi 1984). For control of adult mosquitoes, the organophosphorus insecticide malathion is often sprayed in urban or suburban areas. Malathion can cause acute toxicity to amphibian embryos and tadpoles (Hall and Kolbe 1980), have toxic developmental effects on amphibian larvae, and reduce disease resistance of amphibians (Taylor et al. 1999).

AGRICULTURAL PRACTICES Agricultural practices are negatively correlated with amphibian richness and diversity (Berger 1989, Bishop et al. 1999; Johansson et al. 2005), and agricultural pesticides are associated with increased amphibian deformities (Taylor et al. 2005), reduced hatching success (de Solla et al. 2002), and impaired immune response in metamorphs (Christin et al. 2003, 2004; Gilbertson et al. 2003). The effects of agricultural pesticides on amphibians have been reviewed elsewhere (for instance, Cowman and Mazanti 2000). However, because studies suggest that agricultural pesticides may undergo significant aerial movements (Davidson 2004; Johnson et al. 2005) and are ubiquitously distributed by groundwater, surface run-off, and surface water movement (White et al. 1981), the impacts of agricultural chemicals on vernal pool ecosystems deserves further study. Further, the potential for impacts on amphibians is high because these animals use both aquatic and terrestrial sites in these areas (Miaud and Sanuy 2005).

URBAN DEVELOPMENT The addition of roads to the landscape may increase the amount of wetland area available to amphibians and invertebrates through the creation of roadside ditches or even wheel ruts (Davis 1999; DiMauro and Hunter 2002), but these areas typically serve as habitat sinks because survival may be poor in these suboptimal habitats. Reasons for this are increased mortality from vehicles during migration (Gibbs 1998), inadequate hydrology, and contaminant exposure from highway runoff (including road salt, coal ash, petrochemicals, and polyaromatic hydrocarbons) that can affect amphibian growth as well as other components of the aquatic food web (Haskell 2000; Turtle 2000; Van Dolah et al. 2005). Vernal pools may also be contaminated by urban and golf course development (Colburn 2004) from which they may receive pesticides (including lawn care chemicals), household contaminants (e.g., paints), and sewage runoff. However, little information is available on concentrations or the effects of these contaminants. Riley

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et al. (2005) found that urbanization negatively affected amphibians in nearby communities; however, it was not clear what role chemical contamination played (Chapter 12, Windmiller and Calhoun).

COMPLICATING FACTORS The effects of contaminants in nature are rarely as easily seen as they may appear in laboratory experiments. Contaminant exposure may be persistent through time if land-use is consistent, or the exposure may occur sporadically or cyclically. Persistent exposure may be problematic for vernal pool communities and cause long-term changes in species composition. Further, species richness may be reduced as polluted communities are more likely to be a monoculture (Burnett 1997; Kupferberg 1997). Changes in the predator guild and amount of food resources available may abet species that are usually vulnerable to predators or are good or poor competitors for resources (Morin 1981), depending on whether contaminants reduce or increase resources and predators. Persistent exposure may also increase the likelihood of selection for tolerant genotypes. In the short-term this may allow populations to persist, but if selection results in reduced genetic diversity or if the resulting genotypes are poor competitors (e.g. Semlitsch et al. 2000), there may be long-term consequences if the environment changes or if a disease or pathogen is introduced. Additionally, chemicals may have no observable effects in the laboratory but may compromise immune function in the field. For instance, Linzey et al. (2003) found that the rate of trematode infection for marine toads (Bufo marinus) was correlated with organochlorine pollution and suggested that immunosuppression due to chemical exposure may increase parasite infection. The influence of contaminant exposure on the disease resistance of amphibians is a poorly studied area (but see Christin et al. 2003; Gendron et al. 2003; Gilbertson et al. 2003) even though amphibian diseases (e.g., chytrid fungus [Batrachochytrium dendrobatidis]) have been linked to amphibian population declines (Pounds et al. 2006). Environmental exposures often involve complex mixtures of contaminants. Effects of mixtures are complicated and poorly understood. Contaminants may have additive or synergistic effects directly on populations or may have indirect effects that can be compensated for with the addition of other contaminants; additionally, observed effects may be a combination of direct and indirect effects. The presence of multiple contaminants can also result in formerly sublethal concentrations of contaminants becoming toxic (e.g., Belden and Lydy 2000). Sometimes, however, if contaminant levels are sublethal, multiple environmental contaminants may alter an aquatic food web in such a way that it functions no differently than if it were not exposed to contaminants. For instance, in a study by Boone and James (2003), an herbicide and insecticide alone had negative and positive effects on anurans, respectively, through indirect effects on the food web; the combination of pesticides, however, had additive rather than synergistic effects, with the presence of one chemical balancing out the effect of the other. So, although multiple chemical factors may not be worse than the single chemical alterations through the food web, if chemicals interact synergistically, they may produce negative effects.

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At the same time, vernal pool communities will experience a number of natural as well as anthropogenic influences. The factors of competition, predation, and pond drying are the holy trinity of community regulation in amphibian populations (Semlitsch et al. 1996). These factors can influence the toxicity of contaminants and result in sublethal concentrations becoming lethal in the presence of another factor (e.g., predators, Relyea and Mills 2001; Relyea 2003, 2004). Further, the effect of contaminants in the presence of other factors can change competitive interactions and the tradeoff that amphibians make concerning the time to and size at metamorphosis (Boone and Semlitsch 2002; Boone et al. 2004). Animals in vernal pools have evolved in environments where they deal with multiple, natural stressors, therefore, to examine the effects of anthropogenic stressors, we must examine them in the presence of factors known to regulate communities.

CONSERVATION RECOMMENDATIONS Pollution of natural habitats is a consequence of human overpopulation and inadequate regulation and monitoring. Regulations have generally improved the environment by reducing emissions and controlling application rates and locations, and by lessening the amount of runoff and deposition. However, solving the problem of chemical contamination of vernal pools is not an easy task. There are a number of things that could be done to protect organisms that use vernal pools for part or all of their life cycle from unnecessary contamination. First, reducing the effects of some contaminants could be accomplished by regulations prohibiting their application, as in the case of some forest pesticides in Québec (Gagnon and Lambany 2000; Thompson and Pitt 2003) or restricting applications to narrow spectrum insecticides (as is occurring with forest insecticides). Other contaminants like PCBs are persistent, and we will continue to deal with their residues where they cannot be cleaned up or where there is no political will to do so. Second, in North America, federal toxicity testing regulations require aquatic toxicity data only for species most closely associated with permanent wetlands (e.g., fish) and disregard species adapted to temporary waters (e.g., many amphibians and specialized invertebrates). Federal regulatory processes should include tests aimed at protecting amphibians. Further, incorporating environmentally relevant testing, which would address critical habitat characteristics affecting toxicity (such as examining toxicity at a range of relevant temperatures and pHs under different light regimes), is important to consider. Standard toxicity tests do not account for cofactors or other indirect effects associated with habitat when compounds are tested or regulatory standards are established (but see Edginton et al. 2004; Wojtsazek et al. 2004). If the goal is to understand how populations and communities in nature (and in vernal pools) will be affected by expected environmental concentrations of contaminants, then incorporating important biological factors is essential. Additionally, requiring that contaminants also be tested in their commercial formulations is a necessary next step, because a number of the carriers have been found to be more toxic than the active ingredient in certain pesticide formulations. A broader effort is necessary if we are going to have stronger predictive power and a better ability to protect populations in nature.

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Third, vernal pools and other temporary wetlands will fail to be protected if surrounding terrestrial habitats are not protected. Terrestrial buffer zones and pesticide-free zones can be used to reduce the amount of contamination that reaches aquatic environments (deMaynadier and Hunter 1995; Jones et al. 1999; Houlahan and Findlay 2003), yet buffer zones are not required for most small ponds even though they are the most common wetland type (Smith et al. 2002; Ovaska et al. 2004). For this reason, creating terrestrial buffer zones around what is, in essence, critical terrestrial habitat, is also an important consideration for managers and regulators (Semlitsch and Bodie 2003). Fourth, examining the relationship between landscape-level processes such as forest management, agriculture, industry, and urban development and the “health” of wetlands (e.g., species richness, diversity, and presence of sensitive species) could help target research toward the greatest threats to vernal pool communities. There are many reasons why linking population declines or extinctions to contamination may be difficult, including the large number of environmental contaminants (Donaldson et al. 2002) and differences in sensitivity among species (Bridges and Semlitsch 2000, 2001), yet evidence suggests that contaminants are affecting species in nature (McAlpine et al. 1998; Davidson et al. 2001, 2002). Although these studies strongly suggest contaminants, particularly pesticides, may be involved in population declines, it is unknown whether this is through single contaminant effects or interactions with other environmental stressors. These studies do indicate that applications of wide-scale landscape approaches for studying the effects of contaminants on vernal pools would help focus research and recovery efforts. Finally, individual efforts may also be important in protecting vernal pool habitat and should not be overlooked. Maintaining pesticide-free yards, minimizing use of fertilizers, ensuring properly functioning septic systems, minimizing personal use of cosmetics, pharmaceuticals, and antibiotics, and reducing activities that result in increased burning of fossil fuels would likely help protect vernal pool species from pollution and its still poorly understood effects.

SUMMARY In conclusion, environmental contamination is a potential threat to all habitats, and particularly to areas like vernal pools where contamination is poorly regulated and may occur through direct application, pesticide spray drift, runoff, and atmospheric deposition. Chemical contamination threatens to compromise development of individuals, immune system function, population dynamics, community structure, and ecosystem function. In this chapter, we have outlined some of the contaminants of concern in the Northeast and the current understanding of how natural and anthropogenic factors may mediate their effects. However, the ecological effects of contaminants are poorly understood. At best, we know that contaminants can travel long distances through the atmosphere or through groundwater, that we have limited abilities to prevent this movement, and that mixtures of chemicals are environmentally ubiquitous yet the effects are poorly understood. Currently, vernal pools (as well as other aquatic habitats) and some of the species that inhabit them are not adequately protected or monitored by federal, provincial, or state regulations;

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therefore, species that utilize these habitats are at risk. For amphibians, this omission may be critical, given worldwide population declines of these species. We are only beginning to understand the effects that environmental contaminants have in real communities, yet new contaminants continue to be introduced in the environment every year. Many species in the Northeast rely on vernal pools and the surrounding landscape as critical habitat. The threat that chemical contamination, as another form of environmental degradation, poses to vernal pool communities requires urgent study.

ACKNOWLEDGMENTS This manuscript benefited from the comments of A. Calhoun, W. Hopkins, and one anonymous reviewer.

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Conserving Vernal Pool Wildlife in Urbanizing Landscapes Bryan Windmiller and Aram J.K. Calhoun

CONTENTS The Impacts of Urbanization on Vernal Pool Wildlife .........................................235 Direct Loss of Vernal Pools ......................................................................235 Loss of Neighboring Terrestrial and Wetland Habitat ..............................237 Increased Road Mortality ..........................................................................238 Barriers to Movement and Gene Flow......................................................239 Other Edge-Related Effects of Habitat Fragmentation.............................240 Persistence of Vernal Pool Ecosytems in Urbanized Landscapes and Conservation Opportunities ...................................................................................241 Conservation Recommendations ...........................................................................241 Inventory and Monitoring Opportunities in Urbanizing Landscapes .......242 Avoid and Minimize ..................................................................................242 Mitigate Unavoidable Impacts...................................................................243 Preservation, Restoration, and Enhancement ..................................244 Vernal Pool Creation........................................................................244 Mitigation Banking or In-Lieu Fee Programs.................................246 Use Published BMPs as Models, Not Gospel ..........................................246 Summary ................................................................................................................246 Acknowledgments..................................................................................................247 References..............................................................................................................247

The phrase “vernal pool” has been in the news frequently of late and is gradually creeping into the lexicon of nonecologists in many parts of North America. Popular discussion of vernal pools often centers on perceived conflicts between developers bent on building office parks and subdivisions and wader-clad conservationists speaking of disappearing frog and salamander populations. Historically, however, the public in North America has ignored these generally small and isolated wetlands. We had bigger swamps to drain, so to speak. When vernal pools were considered in popular circles it was most likely by mosquito

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control officers talking about the need to drain or poison these pestilential mosquito producers. Today, however, there are vernal pool conservation and education organizations in New England, Toronto, New York, and many other places in our subject region. Near some vernal pools, human spectators are almost as abundant as the migrating spotted salamanders (Ambystoma maculatum) and wood frogs (Rana sylvatica) they have come to watch. Frogs and salamanders, once shunned as vermin (see references to the Second Plague, Exodus 8:1–11), are now all the rage in cuddly toys and tee shirts. Perhaps many of us have developed a soft spot for vernal pools because they are so accessible to us. Throughout our region, an increasingly high percentage of people live only a short walk from a vernal pool, and this increase isn’t due to the frogs and turtles moving into our backyards; rather, we are moving into theirs. In recent decades, humans in the northeastern U.S. and eastern Canada have abandoned dense frogless inner city neighborhoods to flock to new homes in sprawling suburbs or to exurban developments (residential development beyond the suburbs) in areas formerly dominated by agriculture and forestry. At the turn of the millennium, 79% of people in both Canada and the U.S. lived in areas defined by their respective governments as “urban” (as opposed to “rural”; sources: www.canadainfolink.ca/ and U.S. Census Bureau). In the same period, exurban, suburban, and urban land uses collectively consumed nearly half (49%) of the U.S. Eastern Temperate Forest ecoregion, a fivefold increase from 1950 (Brown et al. 2005). As our human population sprawls across the landscape, the rate of increase in newly urbanized acreage far exceeds the rate of human population growth (Theobald 2005; Johnson and Klemens 2005). Even where human population growth is stable or low, the redistribution of human populations is profoundly changing the natural landscape. Migration of people from urban areas to low density, large-lot residential development is increasing. The relatively new development practice of first clearcutting and grading larger lots and then replacing native plant communities with manicured lawns and gardens transforms amphibian habitat from forest to “nonhabitat” and fragments potential forested corridors that help to link wetlands. Today, in much of our ecoregion, a turtle or salamander migrating to a vernal pool is far more likely to encounter lawns, roads, and buildings than cropland or clearcuts (Brown et al. 2005; Chapter 13, deMaynadier and Houlahan, for forestry impacts). Although agricultural impacts to vernal pools are not discussed in this volume, the effects of habitat loss on amphibian movement and summer and winter refugia are likely to be similar to effects from development. Urban landscape elements pose novel and severe dangers to vernal pool wildlife populations. Yet, until recently, relatively few researchers addressed the problems of vernal pool conservation in urbanized landscapes. In this chapter, we review the growing body of literature concerning the impacts of urbanization-related processes: forest loss and fragmentation, road kill and barriers to movement, and other edge effects, upon vernal pool wildlife, particularly amphibians and turtles. We also provide some general recommendations for vernal pool habitat conservation in urbanizing areas.

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THE IMPACTS OF URBANIZATION ON VERNAL POOL WILDLIFE Research in the past decade has provided much insight into the impacts of urbanization on vernal pool wildlife and has clearly demonstrated the need for landscape level conservation efforts that extend far beyond the border of a single vernal pool (Burke and Gibbons 1995; Windmiller 1996; Semlitsch 2002; Burne and Griffin 2005; Calhoun et al. 2005). The scope of this research is, however, uneven in its coverage. Although much has been learned about the relationship between wood frog (Rana sylvatica) and mole salamander (Ambystoma spp.) distribution and urban land cover, very little is known about the distribution of vernal pool invertebrates in human-dominated landscapes (Chapter 6, Colburn et al.). In eastern North America, most research on the effects of urbanization on vernal pool fauna has been conducted in the densely settled Boston–Washington corridor; fewer publications are available on urban impacts to vernal pools in eastern Canada, northern New England, and the Midwestern U.S. To date, correlational studies comparing vernal pool amphibian distribution to land cover are much more common than empirical studies examining the fate of particular amphibian populations following the construction of houses or other urban land cover within or near vernal pools. Finally, most research on vernal pools in urban environments has focused on documenting the impacts of urbanization on vernal pool wildlife; little is to be found in the literature on factors that favor the persistence of these same species in our increasingly urbanizing region. The sections that follow summarize these compelling, though incomplete, research findings on the various impacts of urbanization upon those vertebrate species most closely associated with vernal pools in our area: amphibians and turtles.

DIRECT LOSS

OF

VERNAL POOLS

Vernal pools have been lost to urbanization through complete or partial filling (Figure 12.1), draining, redirection of hydrological inputs, and the conversion of seasonally flooded pools into permanent ponds with fish (Colburn 2004). They have been destroyed for the purpose of converting land to human land-uses with higher economic value or in attempts to control mosquito populations (Chapter 6, Colburn et al.). Vernal pools are often small, seasonally flooded, and may be isolated from larger wetland systems (Chapter 2, Rheinhardt and Hollands). These characteristics make them particularly vulnerable to filling or direct alteration and also render vernal pools difficult to adequately protect through wetland regulations in the U.S. and Canada (Chapter 10, Mahaney and Klemens). In the Central Valley of California, King (1998) estimated that between 50 and 85% of presettlement vernal pool habitat had been destroyed, primarily through agricultural conversion. A recent study of historical wetland loss in the Nanticoke River watershed in Delaware and Maryland (Tiner 2005), found that the heaviest losses occurred among forested freshwater wetlands in either headwater or isolated landscape positions, precisely the type of wetland most likely to harbor vernal pool habitat in our region. Urbanization in the Northeast has resulted in the complete disappearance of vernal pools from many

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FIGURE 12.1 Direct vernal pool destruction still occurs, despite wetland regulations. Here, a vernal pool is being drained prior to filling during construction of a single-family house in Plainfield, CT. Photo courtesy of Vin Mullin.

core urban areas and in large net losses of vernal pools in suburban areas. In the vicinity of Boston, Massachusetts, seven of the most densely populated municipalities have no potential or known vernal pools within their limits (MASSGIS data; Burne 2001). Even in less densely populated suburbs, vernal pools are often absent from town centers and disproportionately clustered within larger tracts of protected open space (Figure 12.2; A. Calhoun, R. Baldwin, and D. Oscarson, unpublished data). Grant (2005) recently reported that the probability of potential vernal pool occurrence in central Massachusetts was inversely correlated with the presence of urban or commercial development and high-density residential land cover. Windmiller et al. (B. Windmiller, I. Ives, and D. Wells, unpublished data) found a highly significant inverse relationship between potential vernal pool density (MassGIS data) and human population density among Massachusetts towns with densities greater than 300 people km–2 (776 people mi–2), approximately the current median population density of Massachusetts. We have been unable to find any estimates of recent rates of vernal pool destruction in northeastern North America. In states that have had the most stringent wetland and vernal pool regulations, direct vernal pool filling or draining has been a relatively uncommon phenomenon in recent years (In Connecticut: M. Klemens, Wildlife Conservation Society, personal communication; in New Jersey, J. Heilferty, New Jersey Department of Environmental Protection, personal communication; and in Massachusetts, B. Windmiller, unpublished data).

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FIGURE 12.2 Cluster of vernal pools in high-quality forest surrounded by development in southern Maine (spring 2001, 1:12,000 CIR, Sewall Company, Inc.).

LOSS

OF

NEIGHBORING TERRESTRIAL

AND

WETLAND HABITAT

As large swaths of amphibian and reptile habitat in northeastern North America are converted from forest to urban land uses (Brown et al. 2005), vernal pools become increasingly embedded within a human-dominated matrix of roads and houses. Windmiller (1996) found that developed land (i.e., residential, commercial, roads) constituted 43% of the land cover within 300 m (985 ft) of vernal pools in a suburban Massachusetts town, and Egan and Paton (in review) found a mean value of 22% developed land (including roads) within 1,000 m (3,280 ft) of 40 vernal pools in western Rhode Island. In Westford, MA, until recently a rural town, 39% of sampled vernal pools lost 10% or more of total forest cover within 300 m of the pool edge just in the period 1985–1999 (B. Windmiller, I. Ives, and D. Wells, unpublished data). The consequences of preserving vernal pools but destroying adjacent terrestrial habitat are diverse and severe, including: 1. Reduction in the probability of amphibian population presence in otherwise suitable breeding sites (Windmiller 1996; Gibbs 1998; Homan et al. 2004; Rubbo and Kiesecker 2005; Clark et al., in review; Egan and Paton, in press). This trend shows a strong threshold effect, with the likelihood of presence decreasing sharply when forest cover declines below a certain level (threshold values of 44–51% forest cover within 1000 m reported for spotted salamanders and wood frogs by Homan et al. 2004, and Egan and Paton, in press.) 2. Reductions in the mean size of vernal pool-dependent amphibian populations and in the frequency of encountering relatively large populations (Windmiller 1996; Homan et al. 2004; Egan and Paton, in press). 3. Declines in wetland amphibian species richness with increasing urban land use (Lehtinen et al. 1999).

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There have been few case studies to date documenting the effects of such habitat conversion on vernal pool amphibian populations. Windmiller et al. (in press) reported the extirpation of a small population of wood frogs in Massachusetts following the conversion of 90% of adjacent upland forest into a cinema complex. The same authors also observed sustained declines of greater than 40% in wood frog and spotted salamander populations after the loss of 41% of adjacent upland forest to a residential subdivision. Similarly, there are few studies available on the effects of urbanization on the distribution of non-amphibian animal species associated with vernal pools. In densely human-populated urban environments in our region, aquatic and semiaquatic turtle species are uncommon and are likely to be confined to large (>1 ha; 2.47 ac) permanent wetland systems (B. Windmiller, personal observation). Although published research on the impact of urbanization on aquatic invertebrates of urban vernal pools is almost nonexistent (but see Brooks et al. 2002), studies of the invertebrate fauna of streams in highly urbanized contexts demonstrate lower levels of diversity compared to more rural landscapes (Moore and Palmer 2005). We likewise hypothesize that vernal pools in highly urbanized areas support fewer invertebrate species than pools in less developed landscapes.

INCREASED ROAD MORTALITY As all vernal pool-dwelling reptile and amphibian species commonly move between pools and the surrounding landscape, increasing urbanization around vernal pools, and the concomitant increase in road and traffic density, is likely to cause increased mortality for reptile and amphibian migrants. Given their slow speed and tendency to stop and withdraw into their shells when startled, there is little chance that individual turtles can survive repeated crossings across roads with moderate or high traffic rates (Gibbs and Shriver 2002). Furthermore, it is likely that populations of aquatic turtle species that use vernal pools and other seasonally flooded wetlands undertake more frequent overland movements in response to unstable hydrological conditions than do populations of the same, or other, species that remain in permanently flooded wetlands throughout the year. Turtle populations are particularly poorly equipped to absorb any incremental increase in adult mortality rates, given their generally long juvenile periods, relatively low reproductive rates, and low rates of survivorship among embryos and hatchlings (Congdon et al. 1993). Demographically, the impact of road mortality on turtle populations is exacerbated because gravid females often undertake long migrations to nesting sites (Joyal et al. 2001). Nesting females make up a disproportionately high share of the victims (Haxton 2000), and their loss is demographically costly to turtle populations. Recent research has confirmed that painted turtle (Chrysemys picta) and snapping turtle (Chelydra sepentina) populations in study areas in the northeastern U.S. have male-biased sex ratios and that the degree of male bias is positively correlated with road density in areas surrounding wetlands inhabited by the turtles (Marchand and Litvaitis 2004; Steen and Gibbs 2004). Studies of the long-term effects of roads on vernal-pool-associated turtle populations are lacking, but preliminary results from southern Maine are troubling (P. deMaynadier and

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J. Haskins, unpublished data). In an attempt to reconfirm the presence of two staterare vernal pool turtle species, spotted and Blanding’s turtles, at sites where they had been originally documented at least 10–30 years previously, the researchers visited 88 vernal pools and pocket swamps where turtles are relatively easy to count using repeated binocular surveys. They reported significantly fewer numbers of Blanding’s turtles from wetlands that were closer to major roads, concluding that the effects of road mortality and associated development may already be impacting local population distribution and trends (P. deMaynadier, personal communications). Likewise, vernal pool-dependent amphibians are highly vulnerable to road mortality as adults move to and from vernal pools during breeding migrations and as newly metamorphosed juveniles disperse into the surrounding landscape. Ashley and Robinson (1996) demonstrated the vulnerability of amphibians to road mortality in a 3-year study in Ontario; of 32,000 dead vertebrates counted, comprising 100 species, amphibians constituted 92% of all casualties. As with turtles, the lethality of roads to migrating amphibians may stem from the slowness with which amphibians cross roads, particularly in cool temperatures. Amphibian vulnerability to mortality on the road is increased by a behavioral tendency among many species to “freeze” upon the approach of cars (Mazerolle et al. 2005). As a result, a high proportion of frogs and salamanders attempting to cross roads are killed even at low traffic densities (e.g., less than three cars per minute; van Gelder 1973; Hels and Buchwald 2001). Several studies have demonstrated negative correlations between road density or traffic intensity and the abundance of some amphibian species. Fahrig et al. (1995) observed that the number of anuran choruses detected along road segments in Ontario declined with increasing traffic intensity. Vos and Chardon (1998), studying the temporary pool-breeding moor frog (Rana arvalis) in the Netherlands, calculated that the likelihood of finding moor frogs breeding in suitable habitat declined from 93% in pools with the lowest surrounding road density within the study area to 5% among pools with the maximum density of surrounding roads. Vos and Chardon (1998) calculated that the probability of moor frog occurrence was reduced by road proximity in 55% of a large study area in the Netherlands. Within our region, Egan and Paton (in press) found that road density in Rhode Island was negatively associated with spotted salamander and wood frog breeding population sizes in vernal pools at several spatial scales.

BARRIERS

TO

MOVEMENT

AND

GENE FLOW

Roads can also act as barriers to the movement of vernal pool wildlife if individual animals simply avoid crossing them; such barriers may result in fragmented populations that manifest greater levels of inbreeding (Vos et al. 2001), sharper variations in demographic factors such as sex ratios and age class distribution, and other factors that predispose small, isolated populations to extirpation (Hels and Nachman, 2002; Chapter 8, Gibbs and Reed). Amphibian avoidance of roads (even unpaved ones) was demonstrated by deMaynadier and Hunter (2000) for eastern newts (Notopthalmus viridescens) and the mole salamanders, A. maculatum and A. laterale. Fahrig

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et al. (1995) encountered fewer amphibians (living or dead) per unit effort along roads with the highest traffic densities in their study (6–9 vehicles/min) compared to roads with lower traffic densities. Besides roads, urban landscapes present other potential barriers to the movement of terrestrial animals between adjacent vernal pools and between vernal pools and other necessary habitats. Reh and Seitz (1990) observed that railroad tracks served to genetically isolate frog populations in the same manner as roadways. Likewise, large clearings, whether occupied by utility transmission corridors, golf course fairways, lawns, parking areas, or other anthropogenic land cover, may be avoided by some amphibian species, particularly salamanders (Windmiller 1996; deMaynadier and Hunter 1999; Rothermel and Semlitsch 2002; Mazerolle and Desrochers 2005; but see Montieth and Paton 2006). When amphibians do venture into fields and other areas cleared of forest cover, they may incur additional mortality and energetic costs as the result of a higher rate of water loss suffered while moving across open ground (Rothermel and Semlitsch 2002; Mazerolle and Desrochers 2005; Rothermel and Luhring 2005).

OTHER EDGE-RELATED EFFECTS

OF

HABITAT FRAGMENTATION

As natural habitats become increasingly fragmented in urbanized landscapes, an increasing proportion of vernal-pool-associated animals encounter human-created habitat edges surrounding lawns, roads, and athletic fields during their migrations. Thus, vernal pool wildlife face increasing exposure to potentially harmful processes associated with urban land use. Many chemicals associated with urban environments are known to be toxic to amphibian adults and larvae, including road salt (Turtle 2000), fertilizers (Hecnar 1995), and biocides (Relyea 2005; Chapter 11, Boone and Pauli). Proximity to houses and people can pose other hazards to vernal pool wildlife. Garber and Burger (1995) noted that a sharp decline in a wood turtle (Glyptemys insculpta) population in a Connecticut recreation area was associated with opening the land to human recreation and the likely removal of turtles as pets. Threatened and endangered turtle species, such as Blanding’s (Emydoidea blandingii) and spotted turtles (Clemmys guttata) in eastern North America, may also have a commercial value deriving from their rarity; poaching of adults and eggs may be a local and growing problem (B. Butler, Oxbow Associates, Inc., personal communication). Turtles and amphibians inhabiting areas near houses and other human-created habitat edges may also suffer from an increase in densities of edge-associated mammalian and avian predators, and domestic carnivores (i.e., cats and dogs). Raccoons (Procyon lotor), for example, which may exist in much higher densities in proximity to people than in forested rural areas (Gehrt 2004), kill and injure adult turtles and are effective egg predators (Congdon et al. 1987). Raccoons and skunks also kill and sometimes consume wood frogs and spotted salamanders migrating to and from vernal pools (Vasconcelos and Calhoun 2004; B. Windmiller, personal observation). Finally, the abundance of exotic plant species in wetland and upland habitats increases in urban areas (Hansen et al. 2005; Chapter 5, Cutko and Rawinski). Such exotic species may alter the chemical environment and invertebrate species

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composition of forest soils (Hansen et al. 2005) as well as vernal pools with unknown direct and indirect impacts upon vernal pool wildlife.

PERSISTENCE OF VERNAL POOL ECOSYTEMS IN URBANIZED LANDSCAPES AND CONSERVATION OPPORTUNITIES Fortunately, vernal pool wildlife species exhibit some degree of resistance and resilience to the impacts of urbanization. In some cases, relatively large populations of wood frogs, mole salamanders, spotted turtles, and other vernal pool wildlife can still be found in towns that are no longer rural. In suburban Massachusetts, Windmiller (personal observation) has observed a number of vernal pool amphibian populations, breeding close by the side of roadways, that have supported fairly high densities of car traffic for decades. Egan and Paton (in press) observed populations of wood frogs and spotted salamanders in landscapes with less than 15% forest cover in Rhode Island. Windmiller and colleagues have studied populations of wood turtles and spotted turtles, with well-represented juvenile age classes, inhabiting a drainage in densely settled Methuen, MA, sandwiched between an interstate highway and heavily trafficked state primary roadways (B. Windmiller and D. Wells, unpublished data). Clearly, we cannot be certain how long specific populations of vernal-poolassociated amphibians and reptiles will persist in suburban or exurban landscapes in the face of road mortality, genetic isolation and other attendant hazards of living amidst burgeoning human populations. Unfortunately, historical data on the distribution and abundance of vernal pool wildlife populations are few, and analyses of the proportion of these populations that have persisted over decades in urbanized areas are unavailable. To date, studies of vernal pool wildlife in urbanized areas have focused, appropriately enough, on firmly demonstrating the negative consequences of urbanization. Yet, exactly what percentage of the forest and other natural landscape features surrounding vernal pools needs to be preserved to yield a high probability of maintaining mole salamander or spotted turtle populations for decades to come? Furthermore, what habitat restoration or enhancement measures might be useful in mitigating damage to vernal pools and their adjacent terrestrial habitat matrix? To address these issues effectively, we will need future studies with a broadened focus. In addition to new research on the negative consequences of urbanization on vernal pool fauna, particularly invertebrates, we need an examination of the features of human-dominated landscapes most consistent with long-term persistence of vernal pool wildlife populations. What species can persist in human-dominated landscapes and how can we best design development practices to support them?

CONSERVATION RECOMMENDATIONS Positive steps for conserving pool-breeding amphibian habitat in urbanizing landscapes can be taken. Specific recommendations for vernal pool conservation,

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particularly at the local scale, can be found elsewhere in this volume (Chapter16, Calhoun and Reilly) and in existing Best Management Practices (BMP) (Calhoun and Klemens 2002; Calhoun and deMaynadier 2004; Ovaska et al. 2004). Here we provide some general guidelines for practitioners in the field.

INVENTORY AND MONITORING OPPORTUNITIES LANDSCAPES

IN

URBANIZING

Our overarching recommendation for vernal pool conservation is for communities and interested parties to recognize that the existing knowledge base and regulatory frameworks afforded by state, provincial, or federal agencies is inadequate. There is no substitute for detailed local knowledge about the location of vernal pools, their ecological health, and current and future threats based on local growth patterns (Chapter 14, Baldwin et al.). Detailed knowledge of this sort may be expensive to gather and constrained by access to private property. Therefore, in cases where vernal pools may be impacted by development projects, developers should be required to provide as much detailed information about pools within the project areas as befits the scale of their projects. Detailed accounts of the responses of target organisms and communities to habitat disturbances caused by construction projects are invaluable for assessing future project impacts. It is reasonable to require developers to bear the brunt of appropriate monitoring costs needed to assess the long-term impacts of their projects on vernal pools and other biological resources. Specific recommendations for monitoring are provided in Windmiller et al. (in press) and a good discussion of analytical methods to assess the degree to which ecosystem functions recover from a disturbance can be found in Parker and Wiens (2005).

AVOID

AND

MINIMIZE

The primary strategy for pool conservation should be to direct development away from vernal pools and the adjacent terrestrial habitat. Potential vernal pools, many of which can be mapped remotely (Burne 2001), should be safeguarded (unless project proponents demonstrate that the wetlands involved do not meet regulatory or BMP definitions of vernal pool habitat). As adequate terrestrial habitat cannot be maintained around all vernal pools, conservation efforts will require the use of some system of ranking the relative ecological value of vernal pool systems (Calhoun et al. 2005; and Chapter 16, Calhoun and Reilly). The most commonly adopted measures of the ecological importance of vernal pools are the presence of locally rare or threatened species, egg mass counts of target amphibian species, and species diversity measures. Because these measures vary locally and regionally, they must be adapted to local conditions and needs. Where development occurs within adjacent terrestrial habitats, impacts should be minimized by using management zone-based recommendations, as per Semlitsch and Bodie (2003) or Calhoun and Klemens (2002). BMPs for conserving vernal pool habitats generally use a concentric-circle model that represents a pool as a circle surrounded by radial management zones at distances established from data on pool-breeding amphibian movement patterns (see Figure 12.3). Current scientific

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Vernal pool depression: No disturbance Vernal pool envelope (100 feet from pool): No development and implementation of management recommendations Critical terrestrial habitat (100-750 feet from pool): <25% developed area and implementation of management recommendations Example of 25% development in critical terrestrial habitat

FIGURE 12.3 Suggested vernal pool management areas for pool-breeding amphibians. (From Calhoun, A.J.K. and Klemens, M.W. 2002. Best Development Practices: Conserving pool-breeding amphibians in residential and commercial developments in the northeastern U.S. MCA Technical Paper No. 5, Metropolitan Conservation Alliance, Wildlife Conservation Society, Bronx, New York. With permission.)

data suggest conserving terrestrial habitat in zones extending 150 to 300 m (500 to 1000 feet) from vernal pool boundaries (Semlitsch and Bodie 2003; Regosin et al. 2005). Above all, the purpose of BMPs and regulations is not to prevent development, but to redirect it (Preisser et al. 2000).

MITIGATE UNAVOIDABLE IMPACTS Direct loss of wetlands owing to filling or other alteration must be mitigated to ensure “no-net-loss” of wetland resources (Marsh et al. 1996; see Chapter 10, Mahaney and Klemens, for summary of wetland protections in Canada and U.S.). Compensatory tools include preservation of other wetlands, restoration or enhancement of wetlands, wetland creation, and in some cases, monetary compensation through mitigation banks or in-lieu fee programs (programs that require the developer to pay into an environmental fund administered by not-for-profits or government agencies; Gardner 2000). If loss is unavoidable, mitigation should focus on preservation of lands with existing natural vernal pool habitat (off-site or on-site), and restoration or enhancement of existing vernal pools and adjacent terrestrial habitat. The de novo creation of vernal pools in our region should be used as a last resort or should be coupled with one of the above strategies (see de Weese 1998). Created pools often fail to replicate vernal pool hydrology, and they may lure breeding amphibians away from more appropriate breeding areas (Vasconcelos and Calhoun 2004). Vernal pools support diverse plant and animal taxa and the efficacy of mitigation strategies may vary among these taxa. For example, created pools inoculated with rare plants may function as habitat for rare plants, but may fail to support the suite

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of amphibians and invertebrates associated with pools typical of the region. Invertebrate communities may change more dramatically than do amphibian communities in response to differences in hydroperiod (Colburn 2004), making replacement of natural invertebrate communities more difficult. We urge practitioners to clearly express their mitigation goals and to clearly articulate the methods that will be used to assess the success or redress the failure of the mitigation project. Preservation, Restoration, and Enhancement Given the complexity of vernal pool habitat (pool and adjacent terrestrial zones) and the spatial and temporal needs of pool-breeding amphibians (Chapter 7, Semlitsch and Skelly), conservation of intact habitat should be the primary goal of pool mitigation projects. However, preservation still results in a net-loss of wetlands and is often prohibitively expensive due to high land prices associated with rapidly urbanizing areas. The restoration and enhancement of degraded vernal pool habitat is another option. Agricultural fields, clearcuts, pasture, and other lands lacking impermeable surfaces, but that have historically supported pools, are good options for mitigation, assuming that there is suitable adjacent habitat. Additionally, there is much room for creative study and practice of restoration and enhancement techniques for adjacent terrestrial habitat around vernal pools (Windmiller 2006). Turtle nesting sites, for example, may be fairly easy to create and the availability of such nesting sites may be an important limiting factor for vernal pool-associated turtle species in some areas. Spotted salamanders are also known to distribute themselves nonrandomly in forested habitat surrounding breeding sites, and their density may be influenced by small mammal burrow density (Regosin et al. 2004) and possibly other types of natural crevices (Windmiller 2006). Once we know more about key habitat parameters for pool-breeding amphibians, forested habitat could be restored or enhanced. Vernal Pool Creation In our region where natural pools are still a common feature in less-developed landscapes, creation should be a last resort or should be coupled with preservation or restoration of vernal pool habitat. The National Research Council (2001) has identified vernal pools as the most difficult wetland to create. Lichko and Calhoun (2003) reviewed vernal pool creation projects in New England and found that most were unsuccessful in replacing vernal pool functions and lacked sufficient monitoring of those functions. It is particularly challenging to recreate the seasonal hydrology characteristic of vernal pools (Beaulieu 2006). There is a risk that inappropriately created vernal pool habitat will function as biological sinks or areas that attract breeding but do not support successful development of larvae to subadults. Additionally, newly created pools are often made at the margins of developed landscape where the wildlife species that use them are subject to potentially harmful edge effects as described above (e.g., pollution, high predation, and illegal collection). Given that vernal pool creation will be adopted, in some cases, as a mitigation measure, we offer some general guidance to ensure a higher rate of success if creation

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is among the strategies for compensation. Also note that the Native Plant Society of California (de Weese 1998) has published detailed policy guidelines for vernal pool mitigation. Refer to these guidelines for a more in-depth discussion of each tool. Although plant and invertebrate pool specialists are the conservation focus, their guidelines are generally suitable for pools in our region as well (see also de Weese 1998). •

•

•

•

• •

•

Collect baseline data on the pools being lost and on the wildlife populations that use them. Given the high natural variability in breeding population sizes and migratory patterns of many vernal pool amphibians and reptiles, multiyear baseline data is important to obtain, when possible (Windmiller et al., in press). When creating vernal pools, one should inventory natural pools and their associated wildlife populations in the project area. These may serve as paired controls in determining the effectiveness of the created vernal pools (Parker and Wiens 2005) and are also likely to serve as a source of colonizing animals. If creation is the only option, one should consider coupling creation with the preservation or restoration of existing vernal pools so that the mitigation ultimately makes a solid positive contribution to the resource (see California Native Plant Society mitigation guidelines, deWeese 1998); Postconstruction monitoring protocols should, if possible, exceed the 3–5 year period required by most regulatory agencies (deWeese 1996; Zedler 1996; Lichko and Calhoun 2003; Petranka et al. 2003a; Petranka et al. 2003b; Vasconcelos and Calhoun 2006; Windmiller et al., in press). Pools created for mitigation should be subject to following BMPs. Some artificial pools may be successful (e.g., former gravel pits, borrow pits, or pools created by road blockages). Many created pools have longer hydroperiods than natural pools and may be persistent during droughts. However, this longer hydroperiod will be suitable only for a subset of vernal pool flora and fauna. For this reason, creation may target a subset of pool-breeding fauna. Guidance for creating vernal pools has been published and should be consulted when mitigation includes creation of pools (Biebighauser 2003). However, the long-term success of created pools is still not well documented. We recommend that vernal pool creation projects take into account the caveats listed above and that results are studied at a sufficient scale in space and time to determine the effectiveness of the creation. Always consider the following: What vernal pool functions need to be replaced? Which species are targeted? Does the mitigation strategy result in net loss of wetland? How and when will the successful attainment of these goals be measured and judged? What specific strategies will be considered if the results fall short of expectations, and who will fund them?

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Mitigation Banking or In-Lieu Fee Programs Monetary compensation for wetland losses in the form of mitigation banks and inlieu fee programs is becoming increasingly popular in Canada and the U.S. Seen as an economically efficient way to offset ecological impacts to resources, banks and fee programs offer a creative alternative to on-site compensatory mitigation (Marsh et al. 1996; Gardner 2000; Stein et al. 2000). Criteria for debits/credits and compensation ratios should be tailored to the vernal pool resource, and this may best be done at local scales (Brown and Lant 1999).

USE PUBLISHED BMPS

AS

MODELS, NOT GOSPEL

Research on the ecology and conservation of vernal pool wildlife in urbanizing regions is still preliminary and very spotty in its coverage. Existing BMPs (e.g., Calhoun and Klemens 2002; Calhoun and deMaynadier 2004), were tailored to scientific data available when they were written, therefore they must be viewed as provisional best-attempts to provide useful recommendations. BMP models are generally designed to be used at the local scale and, as such, must be tailored to meet specific local conservation needs. For example, egg mass count thresholds for biological significance of pools will vary with region. Terrestrial habitat zones may not follow a concentric-circle pattern. In some cases it may be more economically feasible and ecologically effective to use directional management zones that target specific key nonbreeding habitat elements (e.g., forested swamps for wood frogs; Baldwin et al. 2006). Movement patterns of vernal pool wildlife are nonrandomly distributed in adjacent terrestrial habitat (Shoop 1965; Windmiller 1996; Vasconcelos and Calhoun 2004; Patrick et al. 2007). Rather than purchasing or protecting inappropriate habitat equally around the pool (per the concentric circle model), towns could save money and minimize conflicts by ensuring conservation of lands relevant to the terrestrial needs of the specific pool-breeding fauna locally present. In short, be flexible and creative in your application of BMPs to local landscapes.

SUMMARY The bad news for people interested in conserving vernal pool wildlife in urbanizing landscapes is manifest. Urbanization results in the loss of vernal pools and in the loss and fragmentation of terrestrial habitat integral to vernal pool communities. The consequences are severe: rapid extirpation of some populations and the endangerment of others through genetic isolation and increased mortality rates. Urbanization kills vernal pool amphibians and reptiles in ways as diverse as the urban landscape, ranging from direct habitat loss to a host of edge-related effects when vernal pool habitat is brought into proximity with houses, roads, and lawns. The good news is that vernal pools and most of the species that use them are still generally widespread in our region and show some degree of resilience in the face of urban sprawl. Moreover, recent BMP guidelines for vernal pool conservation offer guidance for redirecting development in ways that will, hopefully, minimize ensuing negative consequences to vernal pool wildlife.

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ACKNOWLEDGMENTS We would like to acknowledge the efforts of the Metropolitan Conservation Alliance and Maine Audubon Society for their on-going support and work to make vernal pools a part of developing landscapes. Thanks to three anonymous reviewers and Peter Paton for thoughtful input on our manuscript.

REFERENCES Ashley, P.E. and Robinson, J.T. (1996). Road mortality of amphibians, reptiles and other wildlife on the Long Point Causeway, Lake Erie, Ontario. Canadian Field Naturalist 110: 403–412. Baldwin, R.F., Calhoun, A.J.K., and deMaynadier, P.G. (2006). Conservation planning for amphibian species with complex habitat requirements: a case study using movements and habitat selection of the wood frog Rana sylvatica. Journal of Herpetology 40(4): 443–454. Beaulieu, P.G. (2006). Using groundwater monitoring wells for successful replications. Association of Massachusetts Wetland Scientists Newsletter, No. 56: 12–13. Biebighauser, T.R. (2003). A Guide to Creating Vernal Ponds. USDA Forest Service, 2375 KY Highway 801 South, Morehead, KY. Brooks, R.T., Miller, S.D., and Newsted, J. (2002). The impact of urbanization on water and sediment chemistry of ephemeral forest pool. Journal of Freshwater Ecology 17: 485–488. Brown, D.G., Johnson, K.M., Loveland, T.R., and Theobald, D.M. (2005). Rural land-use trends in the conterminous U.S., 1950–2000. Ecological Applications 15: 1851–1863. Brown, P.H. and Lant, C. (1999). The effect of wetland mitigation banking on the achievement of no-net-loss. Environmental Management 23: 333–345. Burke, V.J. and Gibbons, J.W. (1995). Terrestrial buffer zones and wetland conservation: a case study of freshwater turtles in a Carolina bay. Conservation Biology 9: 1365–1369. Burne, M.R. (2001). Massachusetts Aerial Photo Survey of Potential Vernal Pools. Massachusetts Division of Fisheries and Wildlife, Westborough, MA. Burne, M.R. and Griffin, C.R. (2005). Protecting vernal pools: a model from Massachusetts, USA. Wetlands Ecology and Management 13: 367–375. Calhoun, A.J.K. and deMaynadier, P. (2004). Forestry habitat management guidelines for vernal pool wildlife. MCA Technical Paper No. 6, Metropolitan Conservation Alliance, Wildlife Conservation Society, Bronx, New York. Calhoun, A.J.K. and Klemens, M.W. (2002). Best Development Practices: Conserving poolbreeding amphibians in residential and commercial developments in the northeastern U.S.. MCA Technical Paper No. 5, Metropolitan Conservation Alliance, Wildlife Conservation Society, Bronx, New York. Calhoun, A.J.K., Miller, N.A., and Klemens, M.W. (2005). Conserving pool-breeding amphibians in human-dominated landscapes through local implementation of Best Development Practices. Wetlands Ecology and Management 13: 291–304. Colburn, E.A. (2004). Vernal Pools: Natural History and Conservation. McDonald and Woodward Publishing, Blacksburg, VA. Congdon, J.D., Breitenbach, G.L., Van Loben Sels, R.C., and Tinkle, D.W. (1987). Reproduction and nesting ecology of snapping turtles (Chelydra serpentina) in southeastern Michigan. Herpetologica 43: 39–54.

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Joyal, L.A., McCollough, M., and Hunter, M.L., Jr. (2001). Landscape ecology approaches to wetland species conservation: a case study of two turtle species in southern Maine. Conservation Biology 15: 1755–1762. King, J.L. (1998). Loss of diversity as a consequence of habitat destruction in California vernal pools. In Witham, C.W., Bauder, E.T., Belk, D., Ferren, W.R., Jr., and Ornduff, R. (Eds.). Ecology, Conservation and Management of Vernal Pool Ecosystems — Proceedings from a 1996 Conference. California Native Plant Society, Sacramento, CA, pp.119–123. Lehtinen, R.M., Galatowitsch, S.M., and Tester, J.R., II. (1999). Consequences of habitat loss and fragmentation for wetland amphibian assemblages. Wetlands 19: 1–12. Lichko, L.E. and Calhoun, A.J.K. (2003). An assessment of vernal pool creation attempts in New England: a review of project documentation from 1991–2000. Environmental Management 32: 141–151. Marchand, M.N. and Litvaitis, J.A. (2004). Effects of habitat features and landscape composition on the population structure of a common aquatic turtle in a region undergoing rapid development. Conservation Biology 18: 758–767. Marsh, L.L., Porter, D.R., and Salvesen, D.A. (1996). Mitigation Banking: Theory and Practice. Island Press, Washington, D.C. Mazerolle, M.J. and Desrochers, A. (2005). Landscape resistance to frog movements. Canadian Journal of Zoology 83: 455–464. Mazerolle, M.J., Huot, M., and Gravel, M. (2005). Behavior of amphibians on the road in response to car traffic. Herpetologica 61: 380–388. Montieth, K.E. and Paton, P.W.C. (2006). Emigration behavior of spotted salamanders on golf courses in southern Rhode Island. Journal of Herpetology 40: 195–205. Moore, A.A. and Palmer, M.A. (2005). Invertebrate biodiversity in agricultural and urban headwater streams: implications for conservation and management. Ecological Applications 15: 1169–1177. National Research Council. (2001). Compensating for wetland losses under the Clean Water Act. National Academy Press, Washington, D.C. Ovaska, K., Sopuck, L., Englestoft, C., Matthias, L., Wind, E., and MacGarvie, J. (2004). Best management practices for amphibians and reptiles in urban and rural environments in British Columbia. BC Ministry of Water, Land, and Air Protection, Nainaimo, BC, Canada. Parker, K.R. and Wiens, J.A. (2005). Assessing recovery following environmental accidents: environmental variation, ecological assumptions, and strategies. Ecological Applications 15: 2037–2051. Patrick, D., Calhoun, A.J.K., and Hunter, M.L., Jr. (2007). The orientation of juvenile woodfrogs, Rana sylvatica, Journal of Herpetology 41: 158–163. Petranka, J.W., Kennedy, C.A., and Murray, S.S. (2003a). Response of amphibians to restoration of a southern Appalachian wetland: a long-term analysis of community dynamics. Wetlands 23: 1030–1042. Petranka, J.W., Murray, S.S., and Kennedy, C.A. (2003b). Responses of amphibians to restoration of a southern Appalachian wetland: perturbations confound post-restoration assessment. Wetlands 23: 278–290. Preisser, E.L., Kefer, J.Y., Lawrence, J.D., and Clark, T.W. (2000). Vernal pool conservation in Connecticut: Assessment and recommendations. Environmental Management 26: 503–513. Regosin, J.V., Windmiller, B.S., and Reed, J.M. (2004). Effects of conspecifics on the burrow occupancy behavior of spotted salamanders (Ambystoma maculatum). Copeia. 2004: 152–158.

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Regosin, J.V., Windmiller, B.S., Homan, R.N., and Reed, J.M. (2006). Variation in terrestrial habitat use by four pool-breeding amphibian species. Journal of Wildlife Management 69: 1481–1493. Reh, W. and Seitz, A. (1990). The influence of land use on the genetic structure of populations of the common frog Rana temporaria. Biological Conservation 54: 239–249. Relyea, R.A. (2005). The lethal impact of Roundup on aquatic and terrestrial amphibians. Ecological Applications 15: 1118–1124. Rothermel, B.B. and Semlitsch, R.D. (2002). An experimental investigation of landscape resistance of forest versus old-field habitats to emigrating juvenile amphibians. Conservation Biology 16: 1324–1332. Rothermel, B.B. and Luhring, T.M. (2005). Burrow availability and desiccation risk of mole salamander (Ambystoma talpoideum) in harvested versus unharvested forest stands. Journal of Herpetology 39: 619–626. Rubbo, M.J. and Kiesecker, J.M. (2005). Amphibian breeding distribution in an urbanized landscape. Conservation Biology 19: 504–511. Semlitsch, R.D. (2002). Critical elements for biologically-based recovery plans for aquaticbreeding amphibians. Conservation Biology 16: 619–629. Semlitsch, R.D. and Bodie, J.R. (2003). Biological criteria for buffer zones around wetlands and riparian habitats for amphibians and reptiles. Conservation Biology 17: 1219–1228. Shoop, C.R. 1965. Orientation of Ambystoma maculatum: movements to and from breeding ponds. Science 149: 558–559. Steen, D.A. and Gibbs, J.P. (2004). Effects of roads on the structure of freshwater turtle populations. Conservation Biology 18: 1143–1148. Stein, E.D., Tabatabai, F., and Ambrose, R.F. (2000). Wetland mitigation banking: a framework for crediting and debiting. Environmental Management 26: 233–250. Theobald, D. (2005). Landscape patterns of exurban growth in the USA from 1980 to 2020. Ecology and Society 10: 32. Tiner, R.W. (2005). Assessing cumulative loss of wetland functions in the Nanticoke River watershed using enhanced National Wetlands Inventory data. Wetlands 25: 405–419. Turtle, S.L. (2000). Embryonic survivorship of the spotted salamander (Ambystoma maculatum) in roadside and woodland vernal pools in southeastern New Hampshire. Journal of Herpetology 34: 60–67. van Gelder, J.J. (1973). A quantitative approach to the mortality resulting from traffic in a population of Bufo bufo L. Oecologia 13: 93–95. Vasconcelos, D. and Calhoun, A.J.K. (2004). Movement patterns of adult and juvenile wood frogs (Rana sylvatica) and spotted salamanders (Ambystoma maculatum) in three restored vernal pools. Journal of Herpetology 38: 551–561. Vasconcelos, D. and Calhoun, A.J.K. (2006). Monitoring created seasonal pools for functional success: a six-year case study of amphibian response, Sears Island, Maine. Wetlands 26: 992–1003. Vos, C.C. and Chardon, J.P. (1998). Effects of habitat fragmentation and road density on the distribution pattern of the moor frog Rana arvalis. Journal of Applied Ecology 35: 44–56. Vos, C.C., Antonisse-de Jong, A.G., Goedhart, P.W., and Smulders, M.J.M. (2001). Genetic similarity as a measure for connectivity between fragmented populations of the moor frog (Rana arvalis). Heredity 86: 598–608. Windmiller, B.S. (1996). The Pond, the forest and the city: spotted salamander ecology and conservation in a human-dominated landscape. Ph.D. thesis, Tufts University, Boston, MA.

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Windmiller, B.S. (2006). Population restoration and enhancement possibilities for amphibians and reptiles. Association of Massachusetts Wetland Scientists Newsletter 56: 9–10. Windmiller, B.S., Homan, R.N., Regosin, J.V., Willitts, L.A., Wells, D.L., and Reed, J.M. (In press). Two case studies of declines in vernal pool-breeding amphibian populations following loss of adjacent upland forest habitat. In Mitchell, J.C. and Jung, R.E. (Eds.). Urban Herpetology Herpetological Conservation No. 3, Society for the Study of Amphibians and Reptiles. Salt Lake City, UT. Zedler, J.B. (1996). Ecological issues in wetland mitigation: an introduction to the forum. Ecological Applications 6: 33–37.

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Conserving Vernal Pool Amphibians in Managed Forests Phillip G. deMaynadier and Jeffrey E. Houlahan

CONTENTS Introduction............................................................................................................254 Natural History ......................................................................................................255 A Complex Mosaic....................................................................................255 Philopatry and Movement Ecology...........................................................256 Vernal Pool–Forestry Relationships ......................................................................257 Vernal Pool Basin Relationships ...............................................................257 Physical Integrity .............................................................................257 Hydrology.........................................................................................258 Water Quality ...................................................................................259 Forest Canopy Relationships.....................................................................260 Clearcutting ......................................................................................260 Partial Harvesting and the Canopy Continuum...............................261 Forest Floor Relationships.........................................................................263 Forest Litter......................................................................................264 Coarse Woody Debris (CWD) .........................................................265 Conservation Recommendations ...........................................................................265 Habitat Management Guidelines for Preharvest Planning........................268 Habitat Management Guidelines for Harvest Operations.........................269 Vernal Pool Depression....................................................................269 Vernal Pool Protection Zone............................................................271 Vernal Pool Life Zone .....................................................................272 Summary ................................................................................................................273 Acknowledgments..................................................................................................274 References..............................................................................................................275

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INTRODUCTION Arguably the most conspicuous of natural elements in the Northeast are trees and for good reason, as the region ranks among the most forested in North America. All northeastern states and provinces are more than half forested, with forests in northern portions of the region dominating as much as 85% (New Brunswick) to 89% (Maine) of the landscape (Smith et al. 1994; Natural Resources Canada 2006). And yet it has not always been this way, with the region among the few in the world that is actually more forested today than it was 100 years ago (Foster 1995). Paradoxically, while northeastern landscapes today contain much of their natural forests they also host some of the densest, longest-settled human populations in North America. Starting in the early 1700s Europeans cleared much of the region’s forests for agriculture. However, beginning in the mid-1800s, farming declined across the Northeast with the result that abandoned pastures and fields were again reclaimed by forests whose legacy persists to this day (Irland 1982). The ebb, recovery, and present dominance of forestland profoundly influenced the historic distribution and status of the region’s wildlife (Litvaitis 1993; Wilcove 1999). Species requiring expanses of mature, mast-producing forest declined to a level of near-extinction (e.g., wild turkey, Meleagris gallopavo) or total extinction (e.g., passenger pigeon, Ectopistes migratorius). Other wide-ranging animals (e.g., timber wolf, Canis lupus, and woodland caribou, Rangifer tarandus caribou) were exposed to unsustainable levels of hunting and persecution, aggravated by the decline and fragmentation of previously remote forestlands. Fortunately, the region’s forest-dwelling frogs, toads, and salamanders neither required exceptionally large blocks of continuous forest nor attracted much hunting pressure or exploitation, with the result that our amphibian fauna remains mostly intact. More so perhaps than any other region in North America, the Northeast’s forests and the fate of the wildlife found here lie in private hands, by ownership or lease (i.e., Crown lands, Canada). As much as 90% of the commercial forest land in New England, for example, is privately owned (Irland 1982; Smith et al. 1994). Furthermore, most of the region’s private woodlands are subject to varying levels of forest management intensity, ranging from light firewood harvesting to large-scale commercial pulp and saw log production. Indeed, with private forestlands dominating the natural landscape, timber management is by definition the region’s most widespread land-use practice. Understanding forestry–wildlife relationships and, for our purposes, forestry–amphibian relationships, in particular, is thus critical if biologists, foresters, and landowners are to make informed decisions when affecting the quality and extent of managed forest habitat in the Northeast. Although still lagging behind that of other vertebrate groups, an impressive body of knowledge is accumulating on the effects of forest management practices on amphibians, mostly in North America (see reviews by deMaynadier and Hunter 1995 and Welsh and Droege 2001). Still, research on the specific effects of timber management on vernal pools and their fauna remains limited. This is of special concern in the Northeast where a high proportion (27 spp. or ~56%) of the salamander, frog, and toad fauna frequent vernal pool ecosystems for breeding, development, foraging, and hibernation (Chapter 7, Semlitsch and Skelly). Furthermore, vernal pools are

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nearly ubiquitous in northeastern forest landscapes where densities range as high as 13.5 pools/km2 (35 pools/mi2; Calhoun et al. 2003). As such, we suggest that it is nearly impossible to avoid at least incidental impacts, positive or negative, on habitat for vernal pool breeding wildlife during the course of most timber harvesting operations in northeastern forests. The purpose of this chapter is to introduce readers to specific aspects of the biology of pool-breeding amphibians relevant to forest management and to provide a review of the limited, but growing body of research concerning vernal pool amphibian responses to common forest harvesting practices. Additionally, we use the literature on forestry–vernal pool relationships to inform the development of specific Habitat Management Guidelines for conserving pool-breeding amphibians in managed landscapes. Our premise is that forest management, if practiced in an ecologically sensitive manner, is among the most compatible consumptive land uses for conserving important elements of vernal pool habitat.

NATURAL HISTORY Although amphibians are probably the most abundant vertebrate group in northeastern forests (Burton and Likens 1975; Hairston 1987), their small size, nocturnal activity, and often fossorial habits make them relatively inconspicuous and difficult to study. Consequently, most forest and wildlife managers are more familiar with the ecology of birds, mammals, and fish that has dominated investigations of forest wildlife relationships to date (Gibbons 1988). We provide a brief introduction to the ecology of vernal pool-breeding amphibians, focusing on aspects of their natural history relevant to forest ecosystems and their management.

A COMPLEX MOSAIC Most pool-breeding amphibians have complex life cycles (Wilbur 1980), beginning as aquatic eggs, hatching to gilled larvae, and metamorphosing into terrestrial, lunged adults within a few weeks (e.g., eastern spadefoot toad, Scaphiopus holbrookii) to a few months (e.g., mole salamanders, Ambystoma spp.) of hatching. The habitat mosaic required to host self-sustaining populations of pool-breeding amphibians is also complex and generally comprised of (1) temporary to semipermanent pools lacking fish (for adult breeding and larval development), (2) terrestrial foraging, resting, and overwintering sites, often spatially removed from breeding pools, and (3) a mostly forested matrix permeable to migrating adults and dispersing juveniles. The ecology of the aquatic phase of pool-breeding amphibians is relatively wellstudied (reviewed by Duellman and Trueb 1994, Alford 1999) with important effects on larval fitness and performance documented from both biotic (mainly competition and predation; Wilbur 1980; Hairston 1987), and abiotic factors (mainly temperature, water chemistry, and hydroperiod; Pechmann et al. 1989; Babbitt et al. 2003; Wellborn et al. 1996). Foresters and land managers have the potential to most directly affect the latter, through impacts and manipulations to physical basin integrity and marginal forest vegetation. Tree harvesting decreases pond shading and increases water temperature, often accelerating larval amphibian development, of potential

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benefit for some species (e.g., spring peepers, Pseudacris crucifer) and detriment for others (e.g., marbled salamanders, Ambystoma opacum) (Skelly et al. 2002, 2005). The effects of forestry activities on pond hydroperiod are potentially significant but also less predictable (see Vernal Pool Basin Relationships). Moving to a terrestrial environment places adult amphibians under a different set of constraints that are complicated by ectothermy, permeable skin, and small size. The moist, permeable skin of most adult, pool-breeding species serves as a partial respiratory organ (Stebbins and Cohen 1995), increasing their vulnerability to microhabitat drying. This skin also readily absorbs desiccants and toxins from the surrounding environment (Frisbie and Wyman 1991). Small size and linear proportions (in salamanders) contribute to a high surface area to volume ratio, further increasing the risk of adult, and especially juvenile, desiccation. In addition, amphibians are ectothermic in a region characterized by large intra-annual variation in temperature, including extended periods of subzero winter temperatures and hot, drying summer temperatures. Amphibians must thus respond to two pressing problems: how to prevent or cope with the potential freezing of internal body fluids, and how to forage, migrate, and otherwise stay active on the forest floor during periods of high temperatures and low relative humidity. As we will explore further, many pool-breeding amphibians avoid the problem of freezing and desiccation by selecting shaded, forested habitats that contain deep, moisture-trapping litter and woody cover, often with abundant small mammal burrows that provide access below the frostline (Faccio 2003; Regosin et al. 2003). The challenge to foresters is to conserve the integrity of these and other important elements of forest structure during the course of timber management.

PHILOPATRY

AND

MOVEMENT ECOLOGY

Investigations of amphibian breeding-site fidelity suggest that most pool-breeding amphibians are highly philopatric (Sinsch 1990; Smith and Green 2005). Berven and Grudzien (1990) found that all adult wood frogs were faithful to their first breeding pond and that 82% of juveniles were faithful to their natal pool. Vasconcelos and Calhoun (2004) documented similar breeding pool fidelity by adult wood frogs (88% female return rates; 98% male), and spotted salamanders (Ambystoma maculatum; 100% female and male). Additionally, nearly 100% breeding pond site fidelity has been documented for adult eastern newts (Notophthalmus viridescens) (Gill 1978). Site fidelity of this magnitude underscores the importance of avoiding seemingly small-scale disturbances to high value breeding pools that may have lasting impacts on localized amphibian populations. Successful upland migrations among breeding pools, summer foraging habitats, and overwintering locales are critical to meet the complex seasonal habitat requirements of adult pool-breeding amphibians. Both adult migration and juvenile dispersal through terrestrial ecosystems are complicated by desiccation risk for the reasons outlined above, and evidence is growing that several pool-breeding amphibians select for moist, shaded forest conditions during seasonal movements (deMaynadier and Hunter 1998, 1999; Rothermel and Semlitsch 2002; Patrick et al. 2006). To develop pool-specific habitat management guidelines we suggest that data

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on adult migration of pool-breeding amphibians is more informative than juvenile dispersal for two reasons. First, natal dispersal occurs over exceptional scales that often exceed forest management and ownership boundaries — e.g., over 1 km (0.6 mi) for Amystomatids (Funk and Dunlop 1999; Pechmann et al. 2001) and 2.5 km (1.6 mi) for wood frogs (Berven and Grudzien 1990) — complicating efforts to design management prescriptions around discrete elements (e.g., breeding pools). Secondly, relatively little is known about the habitat preferences of juvenile amphibians during their dispersal phase, and it is possible that an intensively managed forest matrix is more forgiving to short-term dispersal movements than to the more sedentary home-range and migration movements of adults of the same species (Gibbs 1998; deMaynadier and Hunter 2000; Marsh et al. 2004). Although more work is needed, knowledge of the habitat preferences and adult migration distances of poolbreeding amphibians in the Northeast is growing (Chapter 7, Semlitsch and Skelly; Color Plate 17) and serves as a foundation for our spatial recommendations for timber management planning around vernal pools.

VERNAL POOL–FORESTRY RELATIONSHIPS Given the complex life cycle of pool-breeding amphibians, it is important to consider potential effects that forest harvesting can have on the characteristics of both aquatic (breeding) and terrestrial (nonbreeding) habitat. To inform specific management recommendations for the conservation of both these habitats we organized our review around three elements that together define the local quality and extent of poolbreeding amphibian habitat in managed forest landscapes: the vernal pool basin and shoreline, overstory canopy cover in the surrounding forest, and the structure and condition of the forest floor.

VERNAL POOL BASIN RELATIONSHIPS Land use activities located directly within the vernal pool basin, and its associated riparian nursery habitat, can have important effects on the breeding success and long-term population viability of pool-breeding amphibians. Specifically, forestry practices can affect pool basin habitat characteristics through changes to the physical integrity of the depression, pool hydrology, water quality, and riparian tree canopy cover and composition. Physical Integrity It is well established that disturbance by heavy machinery can have lasting impacts on forest ecosystems (Martin 1988; Turcotte et al. 1991). Harvesting operations in the pool itself, even during winter, can remove basin or riparian vegetation that helps provide egg attachment sites, shade, and organic material to the vernal pool’s detrital foodchain. Furthermore, the basin of many pools is extremely heterogeneous, offering varied moisture and temperature conditions from the development of hummock topography, hardwood leaf litter wells, sphagnum moss, and accumulations of coarse woody debris. These moisture-trapping structures provide refuge to the eggs, larvae,

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metamorphs, and adults of various pool-breeding amphibians, reptiles and invertebrates at different times of the year and yet are readily compromised by heavy machinery operating in the pool basin. Hydrology Precautions should be taken to avoid harvest activities that alter pond hydroperiod — a key driver of amphibian and invertebrate community composition (reviewed by Wellborn et al. 1996 and Semlitsch 2003). Management activities that contribute to shortened hydroperiods can lead to pond-wide desiccation and mortality, or force amphibian larvae to develop more quickly — generally causing smaller body size at metamorphosis, decreased survival, lower female fecundity, and delays in first reproduction (Howard 1978; Semlitsch et al. 1988; Berven 1990). Alternatively, an artificially extended hydroperiod increases pond habitat suitability for predatory fish and invertebrates (e.g., odonata, coleoptera), and potentially competition and predation by other amphibians more closely associated with permanent waters (e.g., green frogs, Rana clamitans; bullfrogs, R. catesbiana). We briefly review three pool basin forestry activities with potential to affect hydroperiod, including soil disturbance (compaction and rutting), road construction, and local tree removal. Forest soils, particularly when wet, are vulnerable to rutting and compaction by heavy machinery used for harvesting and extraction (Nugent et al. 2003; Horn et al. 2004). Deep forest floor ruts that intersect pool basins can alter normal overland drainage patterns, artificially increasing or decreasing pool water-holding capacity depending on local topography (J. Houlahan, personal observation). Machinerycreated ruts in the surrounding forest floor proximate to breeding pools can affect the success of adult breeding migrations by potentially impeding or redirecting salamander movements (Means et al. 1996) or attracting frogs and salamanders to lay eggs in artificial rut pools that often dry prematurely and constitute ecological traps (DiMauro and Hunter 2002; P. deMaynadier, personal observation). Roads are often an unavoidable byproduct of timber harvesting and have important ecological impacts on streams, lakes, and smaller wetlands. In fact, it has been suggested that harvest roads have potentially larger impacts on hydrology than tree removal (Lockaby et al. 1997; Cornish 2001), with ditches, culverts, and road surfaces able to change the direction and speed of overland sheetflow. Recently, Gomi et al. (2006) reported that forest roads contribute significantly to detritus and sediment accumulation in streams. The effects of roads on vernal pool hydrology is not well-studied, but it seems reasonable to suggest that, given their generally small size and shallow depth, vernal pools may be especially sensitive to sheetflow alteration and sedimentation. Indeed, preliminary results suggest a negative correlation between forest road density and amphibian species richness in small New Brunswick ponds (Jacobs and Houlahan, in preparation). Finally, there is growing evidence that forest tree removal can influence the water table dynamics and hydroperiod of local wetlands. Generally, forest harvesting in forested bottomlands results in elevated water tables in the first few years after clearcutting due to decreased evapotranspiration (Sun et al. 2001; Pothier et al. 2003). More recently evidence suggests that although deforestation tends to increase water

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table elevation immediately after harvesting, the long-term effects are subtle and temporally variable, with higher water tables during the nongrowing season and lower water tables during the growing season (Bliss and Comerford 2002). Martin et al. (2000) also showed increases in water yield immediately after strip-cutting that lasted for three to six years, but these increases were followed by more than 20 years of below-average water yield due to the regeneration of rapid-growing pioneer species (e.g., Prunus spp., Populus spp.) with higher transpiration rates. Vernal pools are particularly vulnerable to changes in water table elevation since water loss (and presumably water gain) is a function of wetland perimeter to area ratio, a measure that is relatively high in small wetlands (Millar 1971). Water Quality One of the common effects of forest harvesting in or near the pool basin is diminished canopy cover over the breeding pool. Recent evidence suggests that amphibian species richness, growth, and development are lower in heavily shaded pools (Skelly et al. 2002, 2005), likely due to lower water temperatures and lower food quality (Halverson et al. 2003; Skelly et al. 2005). However, the conservation implications are complicated by the fact that several amphibian pool-breeding specialists (e.g., marbled salamanders; Chapter 7, Semlitsch and Skelly) and invertebrate specialists (e.g., fairy shrimp, Eubranchipus spp.; Ossman and Hanson 2002) thrive, or are found more often, in shaded pool locales. Perhaps less intuitive, but no less real, are the impacts to vernal pool water quality that result from watershed-scale forest management practices. Since the early experiments at Hubbard Brook (Bormann et al. 1968), it has become axiomatic that forest harvesting increases sedimentation and nutrient transport (Lamontagne et al. 2000) and lowers surface water quality in clear-cut watersheds (Martin et al. 2000). The evidence indicating that increased nutrient inputs are significant for lakes suggests that they are almost certainly significant for small, shallow vernal pools as well. Additionally, intensive forest management often includes conversion of mixed stands to predominately softwood plantations, and these changes in tree community composition can impact water quality. For example, Ito et al. (2005) found that watersheds dominated by coniferous trees exported more dissolved organic carbon (DOC) than those dominated by deciduous trees and that DOC levels were higher in lakes in conifer-dominated watersheds. Conversely, nitrate export to lakes is higher in deciduous forest-dominated watersheds (Ito et al. 2005). This suggests that intensive site conversion to softwood-dominated stands may result in higher DOC concentrations and lower nutrient levels in vernal pools. Interestingly, Waldick et al. (1999) found that amphibian species richness is lower and community composition different in ponds surrounded by conifer plantations than ponds surrounded by natural mixedwood forests. Chemicals are widely used in forestry in the Northeast including insecticides such as carbaryl, tebufenozide, and Bacillus thuringiensis, and herbicides like glyphosate and triclopyr (Chapter 11, Boone and Pauli). In most cases, these pesticides are applied aerially, making vernal ponds particularly vulnerable to contamination because of limited regulatory restrictions on aerial spraying around temporary

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water bodies and the difficulty of delineating buffer zones around small, widely distributed pools. Carbaryl is especially persistent under acidic conditions and has been demonstrated to have indirect effects on salamander populations. Tebufenozide, which has recently replaced fenitrothion as the insecticide of choice for controlling spruce budworm (Choristoneura fumiferana), has not been shown to have large effects on organisms in aquatic systems (Pauli et al. 1999) although there is evidence that it depresses cladoceran (often called daphnia) species richness (Kreutzweiser et al. 2004), a valuable prey source for pool-breeding fauna. Glyphosate is one of the most widely applied herbicides in forestry (Woodburn 2000), and it has, until recently, been considered relatively benign because it acts on a metabolic pathway that is only found in plants. However, commercial formulations include surfactants that prevent glyphosate from “beading up” and rolling off plant leaves, and these may be more toxic than glyphosate itself (Giesy et al. 2000). Generally, the use of surfactants should be avoided in proximity to high-value vernal pools as they facilitate absorption through the moist, permeable skin of amphibians and their ecological effects remain largely unknown.

FOREST CANOPY RELATIONSHIPS Clearcutting One of the most defining structural elements in any forest is its canopy, and the response of amphibian communities to canopy presence or absence has been relatively well-studied. Most North American studies examining the effects of clearcutting, for example, report significantly lower overall abundance (deMaynadier and Hunter 1995). More interestingly for our purposes, some amphibian groups are more sensitive to intensive canopy removal than others. A detailed review of only those studies including data for pool-breeding species native to the Northeast reveals a striking pattern (Figure 13.1). Specifically, the ratio of median abundance for each of four northeastern seasonal pool-breeding specialists was several times (3.7–5.5) greater in control stands than in clearcut stands, and exceeded the same ratio for North American amphibian taxa generally. Mole salamanders as a group (Ambystoma spp.), and spotted salamanders in particular, appear to be especially sensitive to large-scale canopy removal (Figure 13.1). The ratio for spotted salamanders is notable in that it exceeds that previously reviewed for Plethodontidae (5.0 times; deMaynadier and Hunter 1995), a family of terrestrial, lungless salamanders generally considered among the most sensitive of amphibian taxa to forest management and other practices that alter forest floor microclimate (Welsh and Droege 2001). An in-depth study of forest clearcutting and edge effects on a community of 14 species of amphibians in Maine yields further support for the premise that poolbreeding amphibians rank among the most sensitive of northeastern amphibian taxa to intensive harvest practices (deMaynadier and Hunter 1998). Specifically, in constructing a “management sensitivity index” composed of the ratio of abundance of relative forest interior to clearcut captures, three of the four species identified as most sensitive to the effects of complete canopy removal — redback salamanders (Plethodon cinereus), wood frogs, spotted salamanders, and blue-spotted salamanders (Ambystoma

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Median Abundance Ratio

6.00 5.00 4.00 3.00 2.00 1.00 0.00 S. holbrooki (n=3)

A. opacum (n=3)

R. sylvatica (n=5)

Ambystoma (n=7)

A. maculatum (n=5)

FIGURE 13.1 The median ratio of abundance from mature vs. clearcut forest for several poolbreeding amphibian taxa characteristic of the Northeast. The horizontal line indicates the same ratio for amphibian taxa generally across North America (n = 18 studies; from deMaynadier and Hunter 1995). Ratios were calculated from all datasets that permitted estimates of the relative magnitude difference in captures for mature (control) versus clearcut (treatment) stands. Independent estimates were calculated from mean captures, absolute totals, or frequency data, depending upon the reference consulted. (Contributing sources include: Bennett et al. 1980; deMaynadier and Hunter 1998; Enge et al. 1986; Grant et al. 1994; Mitchell et al. 1997; Patrick et al. 2006; Ross et al. 2000; Waldick et al. 1999. With permission.)

laterale) — were northeastern pool-breeding specialists. Furthermore, the effects of intensive canopy removal extended beyond the boundaries of harvested stands with edge effects reducing pool-breeding amphibian abundance levels at distances of 25–35 m (82–115 ft) into adjacent unmanaged forests. Partial Harvesting and the Canopy Continuum In contrast to clearcutting, the effects of partial harvesting and uneven-aged forestry practices are less understood, despite their greater frequency of use in most northeastern forests (Seymour 1995). Because the shade cast by standing trees in a partially harvested stand can have beneficial effects on forest floor microhabitats (e.g., shaded logs are significantly cooler and moister than unshaded logs; Heatwole 1962), it is likely that partial cutting practices have relatively less impact on sedentary species that spend most of their life on the forest floor. However, the question remains: how much canopy can be removed during partial harvesting before terrestrial pool-breeding populations respond with significant declines? Although there is a growing body of knowledge on the effects of partial canopy disturbance on amphibians generally (Pough et al. 1987; Mitchell et al. 1996; Messere and Ducey 1998; Sattler and Reichenbach 1998; Brooks 1999; Grialou et al. 2000; Moore et al. 2002; Knapp et al. 2003; Renken et al. 2004; Karraker and Welsh 2006), specific results for pool-breeding amphibians of the Northeast are limited (Ross et al. 2000; Patrick et al. 2006).

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In our view, the most illuminating investigation to date on the effects of partial harvesting on vernal pool amphibians comes from northern Pennsylvania (Ross et al. 2000) where 47 managed hardwood forest stands were selected to represent a continuum of canopy closure from a nearly intact overstory (unharvested for over 70 years), to a wide range of partially intact canopy stands (selection and diameterlimit harvests), to complete absence of any residual overstory (recent clearcuts). In this manner, the investigators were uniquely prepared to document potential thresholds in population responses to increasing levels of canopy removal associated with varying intensities of forest management. We reanalyzed the raw data from Ross et al. (2000) and found just such patterns (Figure 13.2A,B). When examining salamanders alone (12 spp. total), a clear trend emerges of increasing abundance with increasing basal area and canopy cover (Figure 13.2A), with a potential threshold of canopy cover at ~45–50%, beyond which salamander abundance levels increase dramatically. More interestingly for our purposes, a similar pattern and threshold (at ~50–55% canopy cover) persists when only a restricted sample of pool-breeding salamander specialists is examined (Ambystoma jeffersonianum, A. opacum, A. maculatum, Hemidactylium scutatum; Figure 13.2B). More fieldwork is needed to attempt replication of these results for other pool-breeding taxa and other forest types, but it appears that several highly characteristic pool-breeding amphibians of the Northeast are sensitive to harvesting practices that remove overstory canopy levels below a level of approximately 50%. Other studies examining the effects of partial harvesting have yielded results consistent with the patterns above, with few if any significant impacts documented in the abundance of resident salamander populations following light intensity canopy

Salamanders (no./stand)

600 500 400 300 200 100 0 0

20

40

60

80

100

% Overstory Cover FIGURE 13.2A Relationship between salamander abundance (12 spp) and overstory canopy closure for 47 forest stands in northeastern Pennsylvania (Pearson’s coefficient of correlation = 0.63; P<0.05). The arrow indicates a potential canopy threshold of ~45–50%, below which salamander abundance remains consistently low. (Data reanalyzed from Ross et al. 2000. With permission.)

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VP Salamanders (no./stand)

16 14 12 10 8 6 4 2 0 0

20

40

60

80

100

% Overstory Cover FIGURE 13.2B Relationship between vernal pool (VP) salamander abundance (4 spp; Ambystoma and Hemidactylium) and overstory canopy closure for 47 forest stands in northeastern Pennsylvania (Pearson’s coefficient of correlation = 0.34; P<0.05). The arrow indicates an approximate canopy threshold of ~50–55%, below which salamander abundance remains consistently low. (Data reanalyzed from Ross et al. 2000. With permission.)

disturbances, including selection harvests (Pough et al. 1987; Messere and Ducey 1998; Moore et al. 2002), thinnings (Brooks 1999; Grialou et al. 2000), and shelterwood harvests (Sattler and Reichenbach 1998; Mitchell et al. 1996; but see Knapp et al. 2003). The focus of most of these investigations has been plethodontid salamanders, a terrestrial-breeding family common to the Northeast but not characteristic of vernal pools. Nonetheless, to the extent that plethodontid salamanders are considered relatively sensitive to changes in microhabitat and microclimate associated with forest management (deMaynadier and Hunter 1995; Welsh and Droege 2001), we suggest that their apparent tolerance to less intensive silvicultural practices that maintain moderate levels of canopy cover may be indicative of a similar response by many of the region’s pool-breeding amphibian taxa (e.g., Ambystoma, Rana, Bufo, Hemidactylium).

FOREST FLOOR RELATIONSHIPS Investigations of impacts to pool-breeding amphibians following intensive canopy removal typically compare unmanaged or mature control stands with clearcut treatments (Figure 13.1). However, it is important to recognize that this does not necessarily suggest that forest age per se is critical for maintaining populations of sensitive species but, rather, emphasizes the importance of specific structural characteristics that are often well developed in late successional forests. More simply, forest age is likely an indirect measure of the actual microhabitat elements that are critical for determining habitat suitability for a particular suite of amphibian species (Welsh 1990; deMaynadier and Hunter 1995). This distinction is critical for managers of private forestlands that dominate northeastern landscapes because, while forest age is a relatively intractable variable that is slow to respond to management (or lack

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thereof), many of the specific forest structural elements of importance to poolbreeding amphibians (Table 13.1) can be conserved if ecologically sensitive harvest prescriptions are employed. Whether foraging within a moist litter layer beneath a decaying log or seeking refuge within a tree cavity or subterranean root channel, amphibians utilize a variety of microhabitat structures at the stand-level relevant to forest managers. We highlight the importance to pool-breeding species of two such elements of documented importance: forest litter and woody debris. Forest Litter The structure and composition of the forest floor’s organic layer is integral for organisms such as frogs or salamanders that spend most of their time there. Although invertebrate prey for amphibians is abundant on the forest floor (Gist and Crossley 1975), it is thought to be scarce or unavailable to some salamanders during dry periods that require retreating underground to avoid desiccation (Fraser 1976). In addition to providing habitat for a diverse community of prey, a thick and welldistributed litter base offers a protective foraging substrate by retaining moist conditions near the soil interface for a short period after rainfall events, thus prolonging the effective surface foraging time for salamanders (Heatwole 1962; Jaeger 1980). In northern hardwood and mixed wood forests of Vermont (Faccio 2003) and New Brunswick (Lavoie 2005), for example, the presence of Jefferson and spotted salamanders, respectively, was positively associated with the depth and extent of leaf litter (Table 13.1). Similarly, while sampling a larger community of 10 amphibian species (including wood frogs and other facultative pool-breeders) from stands dominated by northern hardwood and balsam fir (Abies balsamea) in the White Mountain National Forest, DeGraaf and Rudis (1990) reported that both diversity and evenness were correlated with litter depth (Table 13.1). The type and quantity of forest litter available to serve as refugia to vernal pool amphibians is indirectly affected by the history and intensity of forest management locally. After large-scale canopy removal, for example, reduced inputs combined with increased rates of decomposition lead to a decline in forest litter depth, with recovery to predisturbance levels requiring up to 50–80 years in northern hardwood forests (Likens et al. 1978; Hughes and Fahey 1994). Similarly, litter composition is a reflection of the local tree canopy and thus is also under the control of forest managers. Dramatic shifts in litter quality can be expected when converting natural hardwood or mixed wood stands to homogeneous conifer plantations with potentially negative effects for local vernal pool amphibians. Conifer litter is generally drier, warmer, and thinner than mixed or deciduous litter (DeGraaf and Rudis 1990; Waldick et al. 1999), and thus stands with uniform, planted conifer canopies may increase the risk of desiccation for amphibians and some forest floor invertebrates. In the black spruce (Picea mariana) plantations studied by Waldick et al. (1999) in New Brunswick, for example, summer forest floor temperatures exceeded the critical upper threshold (32º C) for spotted salamanders (Pough and Wilson 1977), a fact they suggest contributed to reduced abundance compared to neighboring, natural mixed species stands. Finally, needle-dominated litter is often more acidic than

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hardwood litter (Wyman and Jancola 1992) such that conifer-dominated plantations may develop soil conditions intolerable to some amphibians and their prey (Wyman and Hawksley-Lescault 1987; Waldick et al. 1999). This is of special concern in regions with soils of poor buffering capacity such as typifies much of the Northeast. Coarse Woody Debris (CWD) Although more patchy in distribution than leaf litter, the relatively consistent microclimate found within and beneath logs in close contact with the organic layer provides a valuable forest floor retreat for amphibians and their prey. Large logs of advanced decay class are particularly effective at buffering salamanders from warm temperatures and drying conditions on the forest floor (Mathis 1990; Fraver et al. 2002). The specific functional importance of CWD has been well-established for terrestrial salamanders (Plethodontidae) that depend on forest floor cover objects, both as breeding substrate and as moist refugia conducive to extended foraging when dry litter conditions otherwise preclude surface activity (Jaeger 1980). The upland, nonbreeding habitat preferences of pool-breeding amphibians are less understood, but significant selection for areas of the forest floor with an increased abundance of CWD has been reported in northeastern forests for spotted salamanders (Windmiller 1996; Waldick et al. 1999; Faccio 2003), Jefferson salamanders (Faccio 2003) and wood frogs (Ross et al. 2000; Baldwin et al. in preparation) (Table 13.1). Interestingly, while mole salamanders are frequently found beneath large logs or slabs of bark, especially during migration, one of the primary functions of CWD for Ambystoma may be indirect. As their name implies, mole salamanders spend a considerable amount of time underground, often occupying burrows created by small mammals and other animals (Semlitsch 1981; Madison 1997; Faccio 2003). Tracking individual spotted and blue-spotted salamanders using radio-telemetry, Windmiller (1996) found that most animals were encountered under or within 0.5 m (1.6 ft) of fallen tree trunks, tree stumps, and logs. Rather than selecting CWD per se as cover the animals were exploiting existing small mammal burrows (usually short-tailed shrews, Blarina brevicauda; personal communication) that were themselves associated with woody debris on the forest floor. A similarly close association between small mammal tunnels occupied by Jefferson and spotted salamanders and the proximity of CWD was recently documented in Vermont (Faccio 2003). The availability of small mammal burrows may in fact be a limiting factor for mole salamanders, affecting their distribution and abundance in terrestrial habitats by serving as refugia from desiccation, freezing, and predation (Regosin et al. 2003; Rothermel and Luhring 2005). As such, forest harvest practices that degrade forest floor habitat suitability for shrews and other burrowing small mammals (e.g., soil and litter compaction, reduced recruitment or removal of CWD) are likely to impact the quality and carrying capacity of nonbreeding habitat for pool-breeding salamanders as well.

CONSERVATION RECOMMENDATIONS We have reviewed several elements of breeding and nonbreeding habitat of importance to pool-breeding amphibians, all of which are subject to potential impact by

+5, c

+5, c

American toad (Bufo americanus)

+

+

Jefferson salamander (Ambystoma jeffersonianum) Wood frog (Rana sylvatica)

+4 (r2 = 0.59)

Litter Depth/Extent

+2,5

Woody Debris

Spotted salamander (Ambystoma maculatum)

Species Eastern newt (Notophthalmus viridescens)

Species/Communities

+2, 4, 5 (r2 = 0.65) 2

+3

+d,1,2 (r2 = 0.45) 1

+3, 6 (r2 = 0.51) 3

+2,4 (r2 = 0.43)2

Canopy Closure

+3 (r2 = 0.33)

+

+5

+1 (r2 = 0.62)

Understory Vegetationa

+1,4

+1,5

+3

Moistureb

Wyman 1988; 2deMaynadier and Hunter 1998; 3deMaynadier and Hunter 1999; 4Baldwin et al. 2006; 5Baldwin, et al., in preparation 1Pais et al. 1988; 2Ross et al. 2000; 3Rothermel and Semlitsch 2002

1

Pough et al. 1987; 2deMaynadier and Hunter 1998; 3Wyman 1988; 4Ross et al. 2000 1Wyman 1988; 2Windmiller 1996; 3deMaynadier and Hunter 1998; 4LaVoie 2005; 5Faccio 2003; 6Rothermel and Semlitsch 2002 Faccio 2003

1

Reference

266

TABLE 13.1 Significant Positive Associations of Northeastern Pool-Breeding Amphibians with Forest Microhabitats

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+g (r2 = 0.29)

Woody Debris

+ (r2 = 0.67)

Litter Depth/Extent

Understory Vegetationa

+h (r2 = 0.19)

Canopy Closure Moistureb

Ross et al. 2000

DeGraaf and Rudis 1990

Reference

h

g

f

e

d

c

b

a

Refers to percentage of cover of lower and midlevel woody shrub strata in all cases unless otherwise noted. For measurements taken at microsite (vs. stand) scale. Selection by adults and metamorphs in outdoor mesocosm experiment. Percent cover by ferns and (or) herbs. Rana sylvatica, Bufo americanus, and Plethodon cinereus comprised 90% of captures; dependent variable = H and J. Ambystoma maculatum, A. opacum, A. jeffersonianum, Rana sylvatica, R. palustris, R. clamitans, and R. catesbiana. Ranidae only (Rana sylvatica, R. catesbiana, R. clamitans, and R. palustris). Ambystomatidae (3 spp.) only; tree basal area vs. canopy closure.

Note: Results are from field studies of natural populations and represent significant associations at p <0.05. The coefficient of determination is provided as available.

Communities Ranidae, Bufonidae, and Plethodontidaee and otherse (10 spp.; New Hampshire) Ambystomatidae and Ranidaef (7 spp.; Pennsylvania)

Species/Communities

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intensive logging practices. Conversely, we also recognize that forest management, if practiced in an ecologically sensitive manner, can conserve, and even enhance, important elements of habitat structure and composition for pool-breeding fauna. To this end we offer a suite of Habitat Management Guidelines (HMGs; see also Calhoun and deMaynadier 2004) designed to protect high value vernal pools in working forest landscapes. Like the familiar Best Management Practices (BMPs) that foresters apply for the protection of water quality, soil integrity, and aesthetics, the HMGs for pool-breeding amphibians are designed to be voluntary, science-based, and readily transferable to managed landscapes. Notably, the recommendations outlined below are designed for use only in working forest landscapes where long-term timber management is the primary goal. For applications that involve development, roads, and other types of permanent habitat conversion and fragmentation readers should consult companion guidelines for developed landscapes (Chapter 12, Windmiller and Calhoun; Calhoun and Klemens 2002). Finally, we emphasize that the HMGs, although based upon best available science, are nonetheless presented as a working hypothesis of what is needed to conserve vernal pool habitat values in managed forests. We strongly encourage further applied research designed to test and refine these and other potential guidelines in the spirit of adaptive management (Walters 1986). This process of incorporating new knowledge should be informed by controlled and replicated experimental designs and, less formally, through case-study observations and documentation by the foresters, loggers, and land managers whose collective decisions shape the habitat potential of working forests for pool-breeding wildlife and other elements of biodiversity throughout the Northeast.

HABITAT MANAGEMENT GUIDELINES

FOR

PREHARVEST PLANNING

Some of the most important steps for conserving forest habitat for pool-breeding amphibians start in the office. Achieving specific forest harvest outcomes around vernal pools is easier if long-range planning has preidentified potential pools and their associated upland management zones. Consideration of the following planning steps prior to forest harvest activity will help avoid potential conflicts: •

•

•

Develop a strategy for documenting potential vernal pools using aerial photography (Chapter 4, Burne and Lathrop), National Wetland Inventory maps (e.g., PUB, PSS, and PFO classification codes; Cowardin et al. 1979), active ground reconnaissance, or incidental documentation during other management activities (e.g., timber cruising, harvest layout). Include vernal pools and surrounding upland management zones (detailed below) on all forest management maps and/or Geographic Information System layers used to track sensitive natural resources. Use these maps and associated databases to help design spring field surveys for confirming the presence of high value vernal pools hosting abundant indicator species. Consider treating pool clusters (three or more pools within a quarter mile of one another) as a single management unit, with a goal of maintaining

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•

•

•

269

contiguous forest between the pools. Extend the recommended upland management zones around the cluster, rather than around individual pools. Plan forest road and log landing construction to avoid vernal pools and nearby upland habitat. In addition to the permanent conversion of potential foraging and overwintering habitat, such areas contribute to polluted runoff and vehicular mortality. Plan clearcut harvests, plantations, and chemical applications (including pesticides, herbicides, and road dust treatments) to avoid vernal pools and their associated upland management zones. Some formulations used for these purposes can cause amphibian malformation or mortality, even at low concentrations (Chapter 11, Boone and Pauli). When possible, time harvest activities around vernal pools for winter, during frozen ground conditions. Adult and juvenile amphibians are often near the soil surface during other periods of the year, increasing their risk of mortality by heavy logging equipment.

HABITAT MANAGEMENT GUIDELINES

FOR

HARVEST OPERATIONS

The HMGs for harvest operations are designed to protect the vernal pool’s physical basin and water quality, and the integrity of surrounding forest habitat for critical components of pool-breeding amphibian life history including breeding, migration, dispersal, foraging, and hibernation. Although harvest strategies outlined in the HMGs generally lend themselves to uneven-aged management, it is not the intent of the guidelines to focus on specific silvicultural systems but rather to enumerate desired outcomes and structural habitat thresholds needed to conserve pool-breeding amphibians. The vernal pool HMGs for harvest operations are described for three management zones: the vernal pool depression, a vernal pool protection zone (31 m; 100 ft), and a vernal pool life zone (31–22 m; 100–400 ft). An abbreviated summary of the Management Zones and Guidelines for conserving pool-breeding amphibians during forest harvest operations is provided in Table 13.2. Vernal Pool Depression This zone includes the vernal pool depression at spring high water, which may not always be wet during the period when timber is being harvested. During the dry season, the high-water mark can often be determined by the presence of blackened, water- or silt-stained leaves, aquatic debris along the edges, or a clear change in topography from the pool depression to the adjacent upland. The primary management goal in this zone is to maintain the vernal pool’s water quality, physical basin topography, and associated vegetation in an undisturbed state. Management Rationale The pool basin is the primary breeding and nursery habitat for pool-dependent amphibians and invertebrates. Rutting or compaction in the pool can alter the pool’s water-holding capacity, disturb eggs or larvae buried in the organic layer, and alter the amphibian’s aquatic environment. Harvesting operations in the pool, even during

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TABLE 13.2 Summarized Habitat Management Guidelines for Conserving Pool-Breeding Amphibians during Forest Harvest Operations Management Zone (Radial Distance from Pool)

Managed Area a

Vernal Pool Depression 0.08 ha (0 m/ft) (0.2 acres)

Primary Habitat Value Breeding and Larval Habitat

Management Guidelines No Disturbance

• Water quality, hydrology, microrelief, egg attachment Vernal Pool Protection Zone (31 m/100 ft)

0.6 ha (1.4 acres)

Riparian Buffer and Staging Habitat Limited Harvest • Pool ecosystem: shade, organic inputs, riparian buffer • Juvenile nursery and staging habitat during natal dispersal • Adult concentration habitat during breeding migration

Vernal Pool Life Zone 5.3 ha Terrestrial Nonbreeding Habitat (31–122 m/100–400 ft) (13.0 acres) • Migration, dispersal, foraging, summer estivation, and hibernation • Primary adult nonbreeding habitat for 11+ months of the year

a

• >75% canopy cover • Frozen or dry soil operation • Avoid use of heavy machinery • No roads or landings • Avoid chemical application • Abundant CWD Partial Harvest • >50% canopy cover • Harvest openings <0.3 ha (3/4 acre) • Frozen or dry soil operation • Minimize roads and landings • Minimize chemical application • Abundant CWD

Acreage estimates based on a vernal pool with a 100 ft. diameter, or approximately 0.2 acres.

the winter, can disturb woody vegetation that may serve as egg attachment sites, organic inputs, and shade. Management Guidelines: 1. Mark the pool’s location. a. Identify the spring high water mark (during the wet season or using dry season indicators) and flag the pool’s perimeter during harvest layout and prior to cutting.

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2. Protect the pool basin and its natural vegetation. a. Leave the depression undisturbed. Avoid harvesting, heavy equipment operation, skidding activity, or landing construction in the vernal pool depression. b. Keep the pool free of sediment, slash, and tree-tops from forestry operations. Leave woody debris that accidentally falls into the pool during the breeding season (March to June) to avoid damaging egg masses. Trees and branches that fall naturally into pools provide valuable organic inputs and can serve as egg attachment sites. Vernal Pool Protection Zone (31 m [100 ft] around the Pool) This zone includes a 31 m (100 ft) radius around the pool measured from the spring high-water mark. The primary management goal for this zone is to protect the vernal pool and surrounding habitat by maintaining or encouraging a mostly closed canopy stand in a pole- or greater-size class that will provide shade, deep litter, and woody debris around the pool. Management Rationale The integrity of the forest immediately surrounding the pool depression is critical for maintaining water quality, providing shade and litter for the pool ecosystem, and providing moist, shaded, upland forest floor conditions. Aquatic systems generally derive most of their organic inputs from a distance of approximately one to two tree lengths (reviewed by Palik et al. 2000), underscoring the dual functions of the protection zone as both a riparian buffer with effects on the structure, temperature, chemistry, and food supply of the aquatic ecosystem, and as primary habitat for amphibians immigrating and emigrating from the pool. In the spring, high densities of adult amphibians occupy the habitat immediately surrounding the pool, followed in late summer by large numbers of recently metamorphosed salamanders and frogs. Juvenile mole salamanders are especially vulnerable to desiccation during the first months after metamorphosis (Semlitsch 1981; Rothermel and Semlitsch 2002) and dispersing wood frogs and spotted salamanders select for shaded, forested conditions immediately upon metamorphosis (deMaynadier and Hunter 1999; Vasconcelos and Calhoun 2004). Management Guidelines: 1. Mark the pool protection zone’s location. a. Based on the spring high water mark of the pool, flag the perimeter of the protection zone during harvest layout and prior to any cutting. 2. Maintain a mostly closed forest canopy. a. Maintain at least 75% canopy cover of trees at least 6.1–9.1 m (20–30 ft) tall, uniformly distributed throughout the zone. In understocked stands, delay harvest activity until overstory canopy cover has increased beyond 75%. 3. Protect the forest floor.

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a. Harvest only during completely frozen or completely dry soil conditions. Do not create ruts and minimize soil disturbance. b. Avoid the use of heavy machinery in this zone by employing techniques such as motor-manual crews, directional felling, and extended cable winching and/or booms. c. Avoid new road or landing construction. 4. Maintain coarse-woody debris. a. Leave a few larger or older legacy trees to serve as recruitment for coarse woody debris. b. Avoid disturbing fallen logs. Leave limbs and tops where felled, or return slash to the zone during whole-tree removal. 5. Avoid the use of pesticides, herbicides, and other chemicals. Vernal Pool Life Zone (31 to 122 m [100 to 400 ft] around the Pool) This zone includes a 31–122 m (100–400 ft) zone around the pool measured from the spring high-water mark. The primary management goal for this zone is to provide suitable upland habitat for local pool-breeding amphibian populations by maintaining or encouraging a partially closed-canopy stand that offers shade, deep litter, and woody debris well distributed around the pool. Management Rationale The vernal pool life zone is required to support the nonbreeding, upland life-history needs of pool-breeding amphibians. The zone’s radius is designed to address a portion of the habitat used by northeastern pool-breeding mole salamanders (Ambystoma spp) — an amphibian group that is among the most sensitive to upland forest habitat perturbations, and whose movement ecology is relatively well understood. The mean adult migration distance for five species of mole salamander (n = 17 studies) distributed throughout the glaciated Northeast is 118.3 m (388 ft) (Chapter 7, Semlitsch and Skelly; Color Plate 17), with many individuals migrating to even greater distances. Forest floor environments suitable for supporting amphibian populations are most likely to be maintained by light to moderate partial cuts within this management zone. Juvenile and adult wood frogs and spotted salamanders select mostly closedcanopy forests during emigration and dispersal in managed forest landscapes (deMaynadier and Hunter 1998, 1999; Vasconcelos and Calhoun 2004). Mole salamanders are often under or closely associated with woody debris on the forest floor (Faccio 2003). Dramatic shifts in forest cover type should be avoided, as amphibians are sensitive to the resulting changes in litter composition and chemistry (deMaynadier and Hunter 1995; Waldick et al. 1999). Rutting and scarification of the forest floor may impede salamanders from traveling to natural breeding pools by creating barriers along travel routes (Means et al. 1996) or shallow, anthropogenic “decoy pools” that may not hold water long enough to successfully produce juveniles (DiMauro and Hunter 2002).

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Management Guidelines: 1. Maintain a partially closed forest canopy. a. Maintain at least 50% canopy cover of trees at least 6.1–9.1 m (20–30 ft) tall, uniformly distributed throughout the zone. In understocked stands, delay harvest activity until overstory canopy cover has increased beyond 50%. b. Avoid canopy harvest openings greater than 0.3 ha (3/4 acre) in size. c. If even-aged management is practiced, extended shelterwood or similar systems with continuous partial overstory retention helps to maintain suitable forest floor conditions. 2. Maintain natural litter composition. a. Avoid significant shifts in forest cover type (e.g., hardwood or mixed wood to softwood) to minimize changes in natural litter composition. b. Avoid plantation silviculture in this zone. 3. Protect the forest floor. a. Harvest only during completely frozen or dry soil conditions. Do not create ruts. b. Minimize soil compaction and scarification from heavy machinery by using techniques such as: controlled yarding (i.e., preplanning location and spacing of trails and limiting the number of passes), minimizing sharp turns, and placement of slash to increase the bearing capacity of soils. c. Minimize the footprint of new roads or log landings by pre-planning their layout and construction either outside of the zone or at the outer portions of the zone. 4. Maintain coarse-woody debris. a. Leave a supply of larger or older trees, approximately 3–5/ha (1–2/acre), to serve as recruitment for larger diameter coarse-woody debris. b. Avoid disturbing fallen logs. Leave limbs and tops where felled, or return slash to the zone during whole-tree harvest treatments. 5. Minimize the use of pesticides, herbicides, and other chemicals. a. If chemicals must be sprayed in this zone, avoid use in the spring and late summer/fall when amphibian surface activity is greatest. 6. Extend the Vernal Pool Life Zone as far as practical. a. Where property boundaries and nonforest land-uses (e.g., residential areas, agricultural land) limit the extent of accessible forest in this zone to less than 122 m (400 ft), extend the life zone and associated HMGs as far as practical.

SUMMARY Northeastern North America is one of the few regions on earth with greater natural forest cover today than 150 years ago. With most of these forest lands in private

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ownership, as much as 90% in New England, timber management is by definition one of the region’s most widespread land practices affecting the quality and quantity of habitat for forest-dwelling wildlife. Furthermore, given the exceptionally high vernal pool densities found throughout much of the region, it is nearly impossible to avoid potential impacts, positive or negative, to pool-breeding amphibians during the course of most timber harvest operations. We review the ecology, movements and forestry-habitat relationships of several major pool-breeding amphibian taxa as a basis for informing a specific suite of Habitat Management Guidelines for conserving pool-breeding amphibians in managed forest landscapes. Designed to be voluntary, science-based, and realistic in application, the HMGs are recommended for landowners, loggers, and foresters who are striving to balance commercial timber interests with the protection of high-value breeding pools and critical elements of habitat structure in the surrounding upland forest. Specific guidelines are provided for both (1) preharvest planning and (2) active field harvest operations, where distinct management recommendations are offered for three zones: the vernal pool depression, a vernal pool protection zone (31 m [100 ft] around pool), and a vernal pool life zone (31–122 m [100–400 ft] around the pool) (Table 13.2). Although the breeding pool depression should be left completely undisturbed, we conclude that partial harvesting of the immediate upland forest surrounding vernal pools is compatible with the conservation of pool-breeding amphibian habitat if it is done in an ecologically sensitive manner that maintains a moderately shaded forest floor with deep, uncompacted litter and abundant coarse woody debris. We emphasize that the HMGs, although based upon best available science, are nonetheless a working hypothesis of what is needed to conserve vernal pool habitat values in managed forests, and therefore we encourage further research to help test, refine, and build upon their tenets. The challenge for those interested in amphibian-forestry relationships has evolved from simply documenting impacts, to identifying realistic harvest prescriptions that maintain critical components of the forest’s biological legacy capable of sustaining healthy amphibian populations.

ACKNOWLEDGMENTS Financial support for this research was provided by contributions to the Endangered and Nongame Wildlife Fund of the Maine Department of Inland Fisheries and Wildlife (Chickadee Checkoff and Conservation License Plate), Natural Sciences and Engineering Research Council, and The New Brunswick Wildlife Trust. The authors are grateful to Malcolm Hunter, Robert Bryan, and Suzanne Nash for valuable reviews of the manuscript and to Aram Calhoun for permitting inclusion of the Habitat Management Guidelines, which are closely modeled after those first presented in Calhoun and deMaynadier (2004). Finally, the first author wishes to thank his family whose support and encouragement made this project possible.

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Spatial Tools for Conserving PoolBreeding Amphibians: An Application of the Landscape Species Approach Robert F. Baldwin, Kathleen P. Bell, and Eric W. Sanderson

CONTENTS Landscape Species Conservation Approach..........................................................283 Application of the Landscape Species Approach in Maine .................................284 Amphibian Movements and Critical Habitats: The Biological Landscape (A) ..................................................................284 Exurban Growth: The Human Landscape in the Glaciated Northeast (B).............................................................................286 Identifying Target Landscapes (C) through Threat Analysis ...................287 Identifying Focal Landscapes: Applying Gap Analysis to Pool-Breeding Amphibians (D).................................................................289 Particular Relevance of the Landscape Species Concept for Conservation in our Region.......................................................................293 Conservation Recommendations ...........................................................................293 Summary ................................................................................................................294 References..............................................................................................................294

Most of us do not think we have much in common with salamanders, frogs, and toads, but the fact is, amphibians and people like to settle in some of the same places. Conservation planning for pool-breeding amphibians is challenging because of our shared fondness for forests and human’s relative disregard for wetlands. Spatial

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planning tools, like the landscape species approach (see Table 14.1 for an explanation of bolded terms), provide a means to anticipate and manage this conflict. Pool-breeding amphibians require breeding habitat (vernal pools), summer habitat (forests and forested wetlands), and suitable upland forest sites for hibernating. We use the term landscape in reference to the different kinds of ecosystems found in an area including pools, streams, upland forests, meadows, or other wetlands. The biological landscape for pool-breeding amphibians, or for any species, refers to the sum total of ecosystem types and the pattern they are found in that satisfy the requirements for any given population throughout the year. Human activities transform the landscape into human-modified landscapes or human landscapes by imposing different kinds of land uses (e.g., turning a wetland into a subdivision or a forest into a field) and activities (e.g., diversions of run-off, traffic patterns) in areas where pool-breeding amphibians live. There are many variations in humanmodified landscapes across the Northeast, from urban, to suburban, to rural and wild. The interface between human land use activity and the habitat needs of vernal pool wildlife is the focus of this chapter. Any human activity that negatively impacts pool-breeding amphibians is a potential threat that needs to be accounted for in conservation planning. Conservation planning requires identifying conflicts before

TABLE 14.1 Explanation of Terms (Bold-Faced in Text) Used to Describe Spatial Modeling Components Terms Ecosystem Landscape

Landscape species

Biological landscape Human landscape Target landscape

Focal landscape Exurban

Definition The dynamic and interrelating complex of plant and animal communities and their associated nonliving environment. A group of ecosystems within a conservation planning area. Landscapes can be described by composition (which ecosystems occur in the area) and pattern (the arrangement of those ecosystems). Species that require more than one ecosystem to survive. Landscape species have life history characteristics that make them particularly useful for identifying when and where human land uses may compromise ecological integrity of the overall landscape. Ecosystems used by a species within the conservation planning area. The spatial distribution of human activities within the conservation planning area. The intersection of the biological landscape and the human landscape. The overlay of the human landscape and the biological landscape helps identify threats to the landscape species and the landscape as a whole. Places within the conservation planning area where conservation action will be directed or focused. Developments (e.g., housing developments, golf courses, road networks) within formerly rural areas. Exurban development is intermediate between rural areas and suburban areas.

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they become problems, enabling resource managers or planners to make better choices. Improved planning can help satisfy the landscape needs of both amphibians and humans. In this chapter, we focus on a landscape planning technique called the landscape species approach, as it is particularly pertinent to pool-breeding amphibians because of their complex landscape requirements (i.e., disjunct breeding and nonbreeding habitats). We recognize that each pool-breeding amphibian species may have different landscape requirements. The landscape species approach accommodates the needs of multiple species through a map layering process (explained below). Other spatially explicit approaches to conservation planning, including gap (e.g., Jennings 2000) and threat analysis (e.g., Theobald 2003), may be easily incorporated into the landscape species approach, as we demonstrate here for pool-breeding amphibians. Together these techniques give local conservation planners a powerful set of methods to integrate information about the landscape requirements of focal wildlife species and humans, simultaneously. A review of all spatial techniques for conservation planning is outside the scope of this chapter, but additional information on gap and threat analyses can be found in: Bissonette and Storch (2003); Groves (2003); Falkner (1995); Lillesand and Kiefer (1994); Savitsky and Lacher (1998); and Scott et al. (2002).

LANDSCAPE SPECIES CONSERVATION APPROACH Landscape species are species whose habitat requirements make them useful for identifying when and where human land use may compromise natural habitat values of a region (Sanderson et al. 2002). Selection of landscape species must be context driven. For example, jaguar (Panthera onca) landscape requirements do not help conservation planning in Atlantic Canada. We suggest that pool-breeding amphibian species, because of their complex habitat requirements, are a landscape species whose habitat requirements provide a spatially explicit framework for wetland conservation planning in settled areas. In this manner, efforts to conserve pool-breeding amphibians can benefit the conservation of other taxa as well (Coppolillo et al. 2004). The landscape species approach was developed by the Wildlife Conservation Society’s Living Landscapes Program as part of a multiscale conservation planning process designed to protect species occupying human-dominated landscapes (WCS 2006). It is currently being tested in 12 different landscapes around the world, including African grasslands, South American mountains, Asian forests, and the Adirondack Mountains of New York. The strategy is to (1) prioritize action at the regional scale through spatial analyses incorporating habitat values (the biological landscape) and threats from human development (the human landscape), and (2) to identify critical elements of the landscape (the focal landscape) for conservation purposes. For pool-breeding amphibians these focal landscapes are often adjacent sets of breeding and nonbreeding habitats. For the purposes of conservation planning it is necessary to be clear about what landscape features (e.g., forested wetlands, pools, upland forest with well-drained soils) need to be conserved to maintain a viable focal landscape.

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For many species with complex habitat requirements, particularly pool-breeding amphibians, conservation planning is facilitated by using a focal landscape that maps out critical breeding and nonbreeding habitats in relatively close proximity so that amphibians can successfully migrate from one to the other. Requirements for each pool-breeding species are mapped and connected, and threats (e.g., potential road crossings) are evaluated in terms of their impact to the population.

APPLICATION OF THE LANDSCAPE SPECIES APPROACH IN MAINE Here we present an example of the landscape species approach for pool-breeding amphibian conservation based on wood frog (Rana sylvatica) radio-telemetry studies conducted in southern Maine. This region is typical of many less populated parts of the Northeast in that it has much remaining forest land and yet is undergoing rapid development. The study area includes four townships in southern Maine experiencing increasing rural–urban transition pressures similar to coastal and exurban (between suburban and rural) areas throughout the northeastern region of the U.S. and the Maritime Provinces of New Brunswick and Nova Scotia (Plantinga et al. 1999; Baldwin et al. 2007). Our approach to applying the landscape species concept to pool-breeding amphibians begins with an overview of the relevant biological and human landscapes. Although the terminology “biological” and “human” may seem odd to landscape ecologists who view all elements as biological, we suggest that this simple formulation assists with mapping natural and anthropogenic landscape features (Sanderson et al. 2002). In the following sections, we discuss each of the steps in applying the landscape species concept to pool-breeding amphibians (Figure 14.1, A–F as described below). Each step is illustrative of and modified from the general WCS landscape species model (Sanderson et al. 2002). In addition we integrated two spatial techniques — gap and threat analysis — into the WCS landscape species concept. Our discussion emphasizes how spatial data depicting amphibian habitat needs, human population growth, and existing conservation measures can be integrated using spatial modeling tools to support conservation planning for pool breeding amphibians. The data for these examples are drawn from a larger research project on land use and conservation of pool-breeding amphibian habitat (Baldwin 2005).

AMPHIBIAN MOVEMENTS LANDSCAPE (A)

AND

CRITICAL HABITATS: THE BIOLOGICAL

Understanding the movement patterns and nonbreeding habitat requirements of poolbreeding amphibians is of critical importance to spatial aspects of conservation planning. As described in other chapters (Chapter 7, Semlitsch and Skelly; Chapter 8, Gibbs and Reed), juvenile and adult life history needs define the biological landscape and frequently intersect with elements of the human landscape (e.g., roads), often with negative outcomes. We briefly review key life history components relevant for conservation planning.

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FIGURE 14.1 Flowchart summarizing the steps in implementing a landscape species approach for a single pool-breeding amphibian species. Based on elements of the biological landscape (A) as they intersect with the human landscape (B), target areas (C) are specified at the regional scale using a threat analysis. Within the target landscape, focal landscapes (D) are identified using gap analysis and expert opinion. Important biological elements (i.e., breeding sites, neighboring non-breeding habitat) are mapped (Figure 14.5). Simultaneously, local human features of the landscape, including roads and houses, are mapped. Human activities within the focal landscape that conflict with species requirements are the focus of conservation interventions (F). Monitoring enables adaptive management as new information becomes available. Steps A–F are discussed in the text.

As the seasons change in northeastern North America, surface waters wax and wane, ambient temperatures rise and fall, and, in response, pool-breeding amphibians expand and contract their activities. Movements have two primary purposes: dispersal and migration. Maintaining larger matrix habitat connectivity supports juvenile dispersal needed to maintain metapopulation processes (e.g., recolonizations following local extirpation) (Marsh and Trenham 2001). Pool-breeding amphibians generally require more space for dispersal functions than for migration (Semlitsch and Bodie 2003). For example, wood frog populations share genes with neighboring populations ranging from 1 to 5 km (0.62–3.1 mi) from breeding sites (Berven and Grudzien 1990; Squire and Newman 2002). The spatial arrangement of breeding pools, and habitat connectivity among them, are crucial for ensuring successful

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dispersal by pool-breeding amphibians and are addressed elsewhere in this volume (Chapter 3, Brooks and Leibowitz; Chapter 8, Gibbs and Reed). Pool-breeding amphibians migrate to breeding pools in the spring, neighboring wetlands and moist uplands for feeding during the summer (Heatwole 1961; Madison and Farrand 1998; Faccio 2003), and aquatic or terrestrial habitats for overwintering (Lamoureux and Madison 1999; Regosin et al. 2003). Because of their vulnerability to desiccation, amphibian migrations are often associated with rainfall events that help temporarily turn inhospitable uplands into moist habitats suitable for surface activity (Thorson 1955; Bellis 1962). Estimates for annual migrations for pool-breeding amphibians vary by species and study, but tend to be greater than 100 m (328 ft), and often several hundred meters away from breeding pools (Chapter 7, Semlitsch and Skelly; Color Plate 17). Migrations can have a high degree of spatial specificity, with amphibians often using the same directions and even specific routes year after year (reviewed by Stebbins and Cohen 1995; Vasconcelos and Calhoun 2004). Migrating pool-breeding amphibians often negotiate complex forest floor structures (deMaynadier and Hunter 1998; Faccio 2003), steep hills and forest openings (Baldwin et al. 2006b), streams (Faccio 2003), forest roads (Madison 1997; deMaynadier and Hunter 2000), and fields (Shoop 1965; Means et al. 1996; Gibbs 1998; Rothermel and Semlitsch 2002) to access breeding and nonbreeding habitats. Human landscape features located along these established routes, such as roads (Fahrig et al. 1995; Carr and Fahrig 2001), parking lots (Homan et al. 2003), and agricultural fields (Means et al. 1996; Kolozsvary and Swihart 1999), contribute to stress and annual mortality in many pool-breeding amphibian populations (Chapter 12, Windmiller and Calhoun). The seasonal regularity of these migratory routes indicates there may be limited flexibility in altering or destroying connections to breeding and nonbreeding habitat. Alternatively, this enduring migration route fidelity offers a clear prioritization of potential areas for conservation.

EXURBAN GROWTH: THE HUMAN LANDSCAPE NORTHEAST (B)

IN THE

GLACIATED

Residential and commercial developments, golf-courses, and road networks (among other features) fragment the biological landscape of pool-breeding amphibians (Chapter 12, Windmiller and Calhoun). This fragmentation can destroy habitat or threaten established migration routes and dispersal patterns, which may have negative consequences for metapopulation dynamics and long-term population viability. Residential development in exurban areas is considered the major threat to poolbreeding amphibians within our region (Homan et al. 2004; Rubbo and Kiesecker 2005). Development often coincides with conversion of lands from traditional rural uses such as agriculture and forestry to residential and commercial development (Irwin et al. 2003), resulting in permanent loss and degradation of amphibian habitat. In our southern Maine application, we use two spatial data layers to describe the impacts of a human landscape on pool-breeding amphibians (Box [B] in Figure 14.1). A development pressure layer was produced by multiplying U.S. Census blocklevel population density data for 2000 by growth rate data from 1990 to 2000 at the township scale, consistent with similar studies (Radeloff et al. 2000; Theobald 2003).

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Behavior of humans at the local level (i.e., whether to expand settlement or not) is influenced by conditions at the neighborhood scale (towns). For example, if a census block occurs in a rapidly growing area it is likely to expand in the future, whereas a census block in a slow-growing area, regardless of initial population density, is unlikely to grow as quickly (Baldwin 2005). However, growth has constraints imposed by land use and ownership. Protected lands cannot be developed, and zoning provides a further measure of restraint on growth. Because we are focused on habitat preservation, we used the current estimated protection level of lands as a constraint for our model. Therefore, the second spatial layer used to define the human landscape is a “protection level” data layer, derived from the gap analysis described below. Protection levels (PL) 1 through 3 were assigned to both state-regulated lands and conservation lands with varying levels of protection. State-regulated wetlands that receive a nominal amount of protection based on their size were assigned PL = 1, shoreland zones in which a certain amount of development and clearing is allowed, PL = 2, and state wildlife regulated habitats (i.e, endangered species habitats), PL = 3. Protection levels assigned to conservation lands were rated as: tree farms and other multiple use easements, PL = 1; publicly owned and managed forests, PL = 2; and reserves, PL = 3. Together, these two spatial data layers — development pressure and protection level — capture current, realistic information on the variation in residential growth pressures and existing land management regulations or protection.

IDENTIFYING TARGET LANDSCAPES (C)

THROUGH

THREAT ANALYSIS

Before making local conservation decisions, planners need to know where their effort will provide the greatest benefit. Threat and importance analyses (e.g., Noss et al. 2002; Theobald 2003) point to areas of the landscape with high biological values that are simultaneously facing the greatest relative degree of threat. Implementing threat analysis using spatial tools and time-series data allows conservation planners to make decisions incorporating an understanding of risk. Another important benefit is the efficient allocation of sparse conservation resources (Abbitt et al. 2000; Margules and Pressey 2000). We applied threat analyses to breeding and nonbreeding habitat of pool-breeding amphibians in rapidly developing portions of southern Maine as an example of how conservation planners can use spatial information on biological and human landscapes to identify target landscapes (Box [C] of Figure 14.1). From our southern Maine application, a cumulative “potential habitat value” index based on additive breeding pool and buffered core habitat values, was modified by a land use layer to produce an “actual habitat value” layer reflecting habitat quality. Essentially, the ideal landscape for pool breeding amphibians (i.e., with no human land use), was less ideal in places where human impacts were higher. To complete the threat analysis, we combined several spatial data layers. Development pressure and actual habitat value were multiplied, and then divided by the protection level value. This (and some rescaling) produced a threat index (0–4), with which the conservation opportunities in the landscape could be examined (for full methods description see Baldwin 2005).

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Town of Biddeford

Town of Kennebunkport

Highest threat, greatest value

Lowest threat, lowest value

FIGURE 14.2 Using threat analysis to identify priority conservation lands. Threat analysis that produced this map combined spatial data on wetland and neighboring amphibian habitat with projections of human development pressure (see text). High threat, high biological value landscapes are darker, while low threat and/or low biological value landscapes are lighter. Those agglomerations of grey-black cells (1 ha) are the targeted landscapes (priority conservation lands), within which local-scale conservation planning may occur.

Landscape cells (1 ha; 2.47 ac) with higher threat indices are considered higher conservation priority, i.e., target landscapes (Figure 14.2). The resulting town map (Figure 14.2) prioritizes areas that are threatened and have a high concentration of amphibian habitat values, bringing attention to significant unprotected habitat blocks (range 1–5 km2; 0.39–1.95 mi2; Baldwin 2005). Many such large forest blocks are typical of less developed portions of the Region, resulting from decades of farm abandonment and reforestation prior to urbanization (Foster 1992; Plantinga et al. 1999). Threat analyses produce important prioritization suggestions but, like all models, are subject to inherent assumptions. Conservation groups each have distinct objectives and resources and are therefore likely to conduct threat analyses differently. Urgency or threat as defined by this index may not be the sole criterion used to evaluate conservation priorities for pool breeding amphibians; cost efficiency or opportunity cost may also be considered. For example, in areas undergoing rapid residential growth, land values tend to be higher thereby raising the costs of conservation acquisitions. If budgets are limited, other biologically valuable lands, such as those with high actual habitat value, less development pressure, and low existing protection, may be more logical to target (e.g., Ando et al., 1998). Threat analyses are likely to be used increasingly in the future as an index for informing where

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conservation action should occur and which protection strategies should be employed (Chapter 10, Mahaney and Klemens; Chapter 16, Calhoun and Reilly).

IDENTIFYING FOCAL LANDSCAPES: APPLYING GAP ANALYSIS POOL-BREEDING AMPHIBIANS (D)

TO

When areas of conservation priority have been identified, focal landscape planning begins. First, specific focal landscapes (such as a vernal pool complex surrounded by residential development) must be identified. Expert opinion may be relied upon, but spatial, quantitative methods, including gap analysis, may be particularly useful. Gap analysis can help to identify where on the landscape particular biologically important areas already receive protection, and to what level. It is a process of layering mapped information on biodiversity values and protection level in order to identify “gaps” in biodiversity protection (Jennings 2000). The method was initially developed for vast landscapes (e.g., ecoregions). Thus, protection layers were typically federal and state lands with varying protection levels (e.g., national forest, national park, wilderness designation) (Scott et al. 1993), but we suggest that such analyses are also applicable at more local scales. Gap analysis identifies where focal landscapes may be in need of conservation attention. For example, in Kennebunkport in southern Maine (Figure 14.3), a significant cluster of pools and upland habitat falls immediately outside of conservation easement lands with little pool-breeding amphibian habitat protected inside the easement. Using such fine-scale mapping, we can also direct and focus conservation interventions (Box [F], Figure 14.1). These may include improved road crossings, reforestation, wetland restoration, landowner education (tax parcel maps may be used to access owners for direct outreach), or other localized conservation techniques (Chapter 16, Calhoun and Reilly; Chapter 15, Gruner and Haley). Gap analysis can offer information on the protection network of conservation lands, but also takes into account locally relevant development constraints such as wetland regulations. Using mapped regulatory protections and zoning ordinances, gap analysis has the potential to become a powerful tool for assessing gaps in protection network coverage for pool-breeding amphibian habitat (Baldwin 2005). In our southern Maine application, 49% of vernal pools mapped (through 1:12000 CIR aerial photography; Chapter 4, Burne and Lathrop) received no known protection (Figure 14.4). Of the protection afforded, 36% came from size-of-impact-based (>0.04 ha [one tenth of an acre] threshold) state-level regulation, excluding regulatory protection for the 76% of pools less than one tenth of an acre. Stronger regulation for small, isolated wetlands would help to protect a significant portion of the resource (Gibbs 2000). At the same time, the gap analysis reveals that conservation lands protect only 54% of pools, and 20% of neighboring nonbreeding habitat (Figure 14.4). Most of this protection is from small-scale (average 15 ha; 37 ac) lands in conservation easements held by private landowners. Finally, gap analysis also helps to identify where threats may lie (i.e., weak wetland regulations) and where unexpected assets exist (i.e., small easement holdings), allowing planners to generate a regionally specific conservation strategy.

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FIGURE 14.3 Close up of conservation gaps in amphibian non-breeding habitat in Kennebunkport, ME. Vernal pools (as delineated from 1:12000 CIR aerial photos), buffered with 250 m (820 ft) radii habitat areas, are shown in relation to existing conservation lands and shoreland zones. Such fine scale mapping can aid in identifying and selecting focal landscapes for conservation action.

Focal landscape planning identifies conflicts between human landscape features and amphibian habitat requirements in a spatially explicit format. By narrowing the areas of the landscape targeted for interventions, such planning avoids imposing unnecessary restrictions on human use of the landscape and supports flexible conservation approaches. When a site has been identified as having regional priority, it

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60 Conservation land Wetland regulation Shoreland zoning Wildlife habitat regulation

50

% Protected

40

30

20

10

0 Breeding Pools

250 m Life Zone

Habitat type

FIGURE 14.4 Results of regional (southern ME) gap analysis for breeding pools and nonbreeding habitat. The proportions of potential breeding pools (N = 542 in four towns) and surrounding critical habitat zones (250 m/820 ft pool radii referred to as “life zone” or terrestrial habitat) encompassed in protected lands are shown.

may be slated for conservation action and emerge as a focal landscape (Box [D] of Figure 14.1). Figure 14.5 presents a conceptual model of a focal landscape layer for a single pool-breeding amphibian species (the wood frog), based on a conservation planning approach described in Baldwin et al. (2006b). This landscape does not necessarily capture all of the habitat necessary to support other vernal pool fauna with differing movement and habitat requirements. Wood frogs and spotted salamanders (Ambystoma maculatum), for example, share vernal pools as breeding habitat but may have quite different nonbreeding habitat requirements (Faccio 2003; Baldwin et al. 2006). Focal landscape planning occurs locally (e.g., within towns) and therefore benefits from fine-scale spatial information on habitats and human landscape features. Where possible, field research should be considered as the preferred means for determining movement directions and corridors that can better inform focal landscape planning. Although field study requires time and money, it should become a required component of development permitting in our region. This finer level of information can help hone the focal landscape planning process toward a potentially smaller conservation area, better suited to meet the habitat needs of the target species.

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Breeding pool Adjacent non-breeding habitat (e.g., forested wetland for wood frogs) Functional migration habitat Wetland protection buffer

Upland overwintering habitat

b Circle is core terrestrial habitat zone (368 m radius) a Key habitat elements comprising the focal landscape for wood frogs

FIGURE 14.5 Schematic of a focal landscape layer for the wood frog. Additional species layers may be added to make a comprehensive, community level focal landscape. Landscape species layer (a) (e.g., wood frog) connects and protects neighboring habitat elements (e.g., vernal pools and nearby forested wetlands) within suggested maximum species-specific migration distances (e.g., 340 m [1,115 ft] for the wood frog; Baldwin et al. 2006). Additional wood frog habitat elements include wetland buffers to protect moisture and forest conditions within 30–50 m (98–164 ft) of the pool, and adjacent terrestrial over-wintering habitat within 50–100 m (164–328 ft) (Regosin et al. 2003). Human landscape elements that would be the focus of conservation intervention include the intersections of a road and lawn with the biological landscape. An alternative conservation strategy, the core terrestrial habitat zone of 368 m (1,207 ft) recommended for frogs (b) is shown for comparison (Semlitsch and Bodie 2003).

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PARTICULAR RELEVANCE OF THE LANDSCAPE SPECIES CONCEPT CONSERVATION IN OUR REGION

293 FOR

For vernal pools in glaciated northeastern North America, conservation actions frequently take the form of a habitat or development right purchase by a land trust, pool certification effort, or a regulatory approach imposed by the town, state, province, or federal government (Preisser et al. 2000; Colburn 2004; Calhoun et al. 2005). In each case, potential conflict can be avoided if a site plan incorporates the biological and human landscapes, targeting habitat elements essential for pool-breeding amphibians, and omitting nonessential areas. Compared to core-habitat approaches prescribing uniform-distance circular zones (reviewed in Semlitsch and Bodie 2003), focal landscapes require less land area, and can help capture critical habitats (e.g., forested wetlands) lying outside of the core terrestrial habitat zone (Baldwin et al., 2006; depicted in Figure 14.5). Site-based mapping, when applied to pool-breeding amphibian habitat, involves identifying critical neighboring habitats used by breeding populations, identifying migration patterns and corridors, and connecting critical habitats. Multiple focal species’ habitats may be mapped (i.e., wood frogs, spotted salamanders) so that the resulting overlay captures critical habitat elements for all known pool-breeding species at a particular site ([E] in Figure 14.1).

CONSERVATION RECOMMENDATIONS 1. Think of amphibian conservation in a spatially explicit manner. Poolbreeding amphibians require habitats that are often disjunct from one another, accessed by long distance migrations and juvenile dispersal. The landscape species approach should be considered by planners as a means of satisfying spatially complex amphibian habitat requirements, while providing planning flexibility. 2. Collaborate at all levels. Conservation planning in human-dominated landscapes requires close collaboration with and knowledge of local conservationists. They have local knowledge and can help to implement and monitor focal landscape plans (Chapter 16, Calhoun and Reilly). Importantly, these local sources (e.g., municipal governments) often provide access to fine-scale data (e.g., tax parcel maps). However, spatial planning may require computer resources that are not available to some conservation groups. Forming partnerships with academia can permit local planners and conservationists to harness the sophisticated analytical power needed to solve complex conservation planning issues (Theobald et al. 2000). 3. Use accurate spatial data. In order for spatial planning to work efficiently, accurate local-scale map data are needed. Use the most accurate remote detection methods available to determine locations of potential breeding sites (Chapter 4, Burne and Lathrop). 4. Before a focal landscape is accepted for conservation action, thorough field surveys should be conducted with two purposes: (1) to determine if

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the site, selected remotely, actually contains the biological values predicted — i.e., appropriate breeding levels and species composition, and (2) to determine movement patterns of resident amphibians. Ideally (though expensive), telemetry studies of resident amphibians should be conducted to determine locally specific movement corridors. We suggest that large development projects in sensitive areas provide the necessary funding for such field surveys. 5. Think in an interdisciplinary manner. Progress in pool-breeding amphibian conservation will follow not only from advancements in ecology but also from social science. As the landscape species concept illustrates, integration of the human and natural worlds requires integration of social and natural sciences. Research on land markets, land-use change, and land-owners (e.g., Bockstael 1996; Ando et al. 1998; Irwin et al. 2003; Polasky et al. 2005) has much to offer the conservation of vernal pool biota.

SUMMARY Rapid rates of development are altering landscapes throughout northeast North America, putting pressure on conservation planners to prioritize intervention efforts and to recognize the dynamic interactions between human land-use practices and amphibian habitat needs. We introduce a landscape species approach to help inform local conservation planning for pool-breeding amphibians. This powerful spatiallyexplicit approach incorporates human and biological elements of the landscape to: (1) establish conservation priorities at a regional scale (e.g., multiple townships), (2) identify focal landscapes at a local scale (e.g., single wetland complex), and (3) plan conservation interventions (e.g., improved road crossings, outreach, reforestation) at a site scale. Application of the landscape species concept to pool-breeding amphibian conservation may have the highest payoff in areas where escalating land values and rising conservation conflicts over private land development call for decision-making strategies to protect valued habitats while efficiently allocating conservation funds. Further refinement of this conceptual model for conservation planning rests on improved understanding and modeling of both the biological and human landscapes — an endeavor that stands to benefit from interdisciplinary collaboration among economists, landscape ecologists, conservation biologists, and locally-informed members of the public.

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Baldwin, R.F. (2005). Pool-breeding amphibian habitat use and conservation in southern Maine’s urbanizing landscape. Ph.D. dissertation. University of Maine, Orono, ME. Baldwin, R.F., Calhoun, A.J.K., and deMaynadier, P.G. (2006a). The significance of hydroperiod and stand maturity for pool-breeding amphibians in forested landscapes. Canadian Journal of Zoology. Baldwin, R.F., Calhoun, A.J.K., and deMaynadier, P.G. (2006b). Conservation planning for species with complex habitat requirements: a case study using movements and habitat selection by the wood frog (Rana sylvatica). Journal of Herpetology 40(4): 442–453. Baldwin, R.F., Trombulak, S.C., Anderson, M.G., and Woolmer, G. (2007). Projecting transition probabilities for roads at the ecoregion scale: a Northern Appalachian/Acadian case study. Landscape and Urban Planning 80(4): 404–411. Bellis, E.D. (1962). The influence of humidity on wood frog activity. American Midland Naturalist 68: 139–148. Berven, K.A. and Grudzien, T.A. (1990). Dispersal in the wood frog (Rana sylvatica): implications for genetic population structure. Evolution 44: 2047–2056. Bissonette, J.A. and Storch, I. (Eds.). (2003). Landscape Ecology and Resource Management: Linking Theory with Practice. Island Press, Washington, D.C. Bockstael, N.E. (1996). Modeling economics and ecology: the importance of a spatial perspective. American Journal of Agricultural Economics 785: 1168–1180. Calhoun, A.J.K., Miller, C.I., and Klemens, M.W. (2005). Conserving pool-breeding amphibians in human-dominated landscapes through local implementation of Best Development Practices. Wetlands Ecology and Management 13: 291–304. Carr, L.W. and Fahrig, L. (2001). Effect of road traffic on two amphibian species of differing vagility. Conservation Biology 15: 1071–1078. Colburn, E.A. (2004). Vernal Pools: Natural History and Conservation. Woodward Publishing Company, Blacksburg, VA. Coppolillo, P., Gomez, H., Maisels, F., and Wallace, R. (2004). Selection criteria for suites of landscape species as a basis for site-based conservation. Biological Conservation 115: 419–430. deMaynadier, P.G. and Hunter, M.L. (1998). Effects of silvicultural edges on the distribution and abundance of amphibians in Maine. Conservation Biology 12: 340–352. deMaynadier, P.G. and Hunter, M.L. (2000). Road effects on amphibian movements in a forested landscape. Natural Areas Journal 20: 56–65. Faccio, S.D. (2003). Postbreeding emigration and habitat use by Jefferson and spotted salamanders in Vermont. Journal of Herpetology 37: 479–489. Fahrig, L., Pedlar, J.H., Pope, S.E., Taylor, P.D., and Wegner, J.F. (1995). Effect of road traffic on amphibian density. Biological Conservation 73: 177–182. Falkner, E. (1995). Aerial Mapping: Methods and Applications. Lewis Publishers, Boca Raton, FL. Foster, D.R. (1992). Land use history (1730–1990) and vegetation dynamics in central New England, USA. Journal of Ecology 80: 753–772. Gibbs, J.P. (1998). Amphibian movements in response to forest edges, roads and streambeds in southern New England. Journal of Wildlife Management 62: 584–589. Gibbs, J.P. (2000). Wetland loss and biodiversity conservation. Conservation Biology 14: 314–317. Groves, C.R. (2003). Drafting a Conservation Blueprint: A Practioner’s Guide to Planning for Biodiversity. Island Press, Washington, D.C. Heatwole, H. (1961). Habitat selection and activity of the Wood Frog, Rana sylvatica Le Conte. American Midland Naturalist 66: 301–313.

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Homan, R.N., Regosin, J.V., Rodrigues, D.M., Reed, J.M., Windmiller, B.S., and Romero, L.M. (2003). Impacts of varying habitat quality on the physiological stress of spotted salamanders (Ambystoma maculatum). Animal Conservation 6: 11–18. Homan, R.N., Windmiller, B.S., and Reed, J.M. (2004). Critical thresholds associated with habitat loss for two vernal pool-breeding amphibians. Ecological Applications 14: 1547–1553. Irwin, E.G., Bell, K.P. and Geoghegan, J. (2003). Modeling and managing urban growth at the rural-urban fringe: evidence from a model of residential land use change. Agricultural and Resource Economics Review 32(1): 83–102. Jennings, M.D. (2000). Gap analysis: concepts, methods, and recent results. Landscape Ecology 15: 5–20. Kolozsvary, M.B. and Swihart, R.K. (1999). Habitat fragmentation and the distribution of amphibians: patch and landscape correlates of farmland. Canadian Journal of Zoology 77: 1288–1299. Lamoureux, V.S. and Madison, D.M. (1999). Overwintering habitats of radio-implanted green frogs, Rana clamitans. Journal of Herpetology 33: 430–435. Lillesand, T.M. and Kiefer, R.W. (1994). Remote Sensing and Image Interpretation. John Wiley and Sons, New York. Madison, D.M. (1997). The emigration of radio-implanted spotted salamanders, Ambystoma maculatum. Journal of Herpetology 31: 542–551. Madison, D.M. and Farrand, L. (1998). Habitat use during breeding and emigration in radioimplanted tiger salamanders, Ambystoma tigrinum. Copeia 1998: 402–410. Margules, C.R. and Pressey, R.L. (2000). Systematic conservation planning. Nature 405: 243–253. Marsh, D.M. and Trenham, P.C. (2001). Metapopulation dynamics and amphibian conservation. Conservation Biology 15: 40–49. Means, D.B., Palis, J.G., and Baggett, M. (1996). Effects of slash pine silviculture on a Florida population of flatwoods salamander. Conservation Biology 10: 426–437. Noss, R.F., Carroll, C., Vance-Borland, K., and Wuerthner, G. (2002). A multicriteria assessment of the irreplaceability and vulnerability of sites in the Greater Yellowstone Ecosystem. Conservation Biology 16: 895–908. Plantinga, A.J., Mauldin, T., and Alig, R.J. (1999). Land use in Maine: determinants of past trends and projections of future changes. United States Department of Agriculture, Forest Service, Pacific Northwest Research Station, Portland, OR. PNW-RP-511 Polasky, S., Nelson, E., Lonsdorf, E., Fackler, P., and Starfield, A. (2005). Conserving species in a working landscape: land use with biological and economic objectives. Ecological Applications, 15(4): 1387–1401. Preisser, E.L., Kefer, J.Y., Lawrence, J.D., and Clark, T.W. (2000). Vernal pool conservation in Connecticut: an assessment and recommendations. Environmental Management 26: 503–513. Radeloff, V.C., Hagen, A.E., Voss, P.R., Field, D.R., and Mladenoff, D.J. (2000). Exploring the spatial relationship between census and land-cover data. Society and Natural Resources 13: 599–609. Regosin, J.V., Windmiller, B.S., and Reed, J.M. (2003). Terrestrial habitat use and winter densities of the wood frog (Rana sylvatica). Journal of Herpetology 37: 390–394. Rothermel, B.B. and Semlitsch, R.D. (2002). An experimental investigation of landscape resistance of forest versus old-field habitats to emigrating juvenile amphibians. Conservation Biology 16: 1324–1332. Rubbo, M.J. and Kiesecker, J.M. (2005). Amphibian breeding distribution in an urbanized landscape. Conservation Biology 19: 504–511.

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Sanderson, E.W., Redford, K.H., Vedder, A., Coppolillo, P.B., and Ward, S.E. (2002). A conceptual model for conservation planning based on landscape species requirements. Landscape and Urban Planning 58: 41–56. Savitsky, B.G. and Lacher, T.E. (Eds.). (1998). GIS Methodologies for Developing Conservation Strategies: Tropical Forest Recovery and Wildlife Management in Costa Rica. Columbia University Press, New York. Scott, J.M., Davis, F., Csuti, F., Noss, R., Butterfield, B., Groves, C., Anderson, H., Caicco, S., D’Erchia, F., Edwards, T.C.J., Ulliman, J., and Wright, R.G. (1993). Gap analysis: a geographic approach to protection of biological diversity. Wildlife Monographs 57: 5–41. Scott, J.M., Heglund, P.J., Morrison, M.L., Haufler, J.B., Raphael, M.G., Wall, W.A., and Samson, F.B. (2002). Predicting Species Occurrences: Issues of Accuracy and Scale. Island Press, Wahsington, D.C. Semlitsch, R.D. and Bodie, J.R. (2003). Biological criteria for buffer zones around wetlands and riparian habitats for amphibians and reptiles. Conservation Biology 17: 1219–1228. Shoop, C.R. (1965). Orientation of Ambystoma maculatum: movements to and from breeding ponds. Science 149: 558–559. Squire, T. and Newman, R.A. (2002). Fine-scale population structure in the wood frog (Rana sylvatica) in a northern woodland. Herpetologica 58: 119–130. Stebbins, R.C. and Cohen, N.W. (1995). A Natural History of Amphibians. Princeton University Press, Princeton, NJ. Theobald, D.M. (2003). Targeting conservation action through assessment of protection and exurban threats. Conservation Biology 17: 1624–1637. Theobald, D.M., Hobbs, R.J., Bearly, T., Zack, J.A., Shenk, T., and Riebsame, W.E. (2000). Incorporating biological information in local land-use decision-making: designing a system for conservation planning. Landscape Ecology 15: 35–45. Thorson, T. (1955). The relationship of water economy to terrestrialism in amphibians. Ecology 36: 100–116. Vasconcelos, D. and Calhoun, A.J.K. (2004). Movement patterns of adult and juvenile Rana sylvatica (LeConte) and Ambystoma maculatum (Shaw) in three restored seasonal pools in Maine. Journal of Herpetology 38(4): 551–561. WCS [Wildlife Conservation Society] 2006. Living Landscapes: Conservation without borders. Internet website, http://www.wcslivinglandscapes.com/.

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15

Vernal Pools as Outdoor Laboratories for Educators and Students Hank J. Gruner and Richard D. Haley

CONTENTS Key Considerations for Field Study Programs .....................................................301 Vernal Pool Field Studies ..........................................................................302 Safety................................................................................................302 Ecological Impact Considerations ...................................................304 Handling and Keeping Live Animals ..............................................305 Legal Issues......................................................................................307 Partnership Roles among Educators, Students, Scientists, and Conservation Professionals....................................................................................307 How to Build Relationships among Educators, Scientists, and Conservation Professionals....................................................................................310 Steps Scientists and Conservation Professionals Can Take......................310 Steps Teachers Can Take ...........................................................................311 Steps Science Education Organizations Can Take....................................311 Selected Case Studies............................................................................................311 Summary ................................................................................................................314 Acknowledgments..................................................................................................315 References..............................................................................................................315

As anyone who has ever led a group to a vernal pool during the spring knows, few habitats offer as good an opportunity for connecting people with nature and for introducing them to community ecology. A visit to a vernal pool is a complete sensory experience, rapidly engaging all participants with the sound of calling frogs, the earthy forest aroma, and tactile sensations of searching under rotting logs or sorting through aquatic samples. Closer inspections yield new and unexpected discoveries, such as fairy shrimp, amphibian eggs, caddisfly cases, or even a salamander under a log (see Figure 15.1). 299

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FIGURE 15.1 Vernal pools provide a superb hands-on ecosystem that is inherently interesting to children. Students examining wood frog eggs in a Connecticut vernal pool. (Photo by Laurie Doss)

Of special significance to school teachers, vernal pools are frequently found on or near school grounds, with breeding activity taking place during the academic year. Vernal pools can be superb field study sites for students ranging from preschoolers to adults. Students can examine vernal pool life with no harm to the student or the organisms, and multiple life stages of several species can be observed directly. Vernal pools are also well suited for multidisciplinary activities. Educators have used field studies to involve students in learning about scientific content and methods with a wide variety of habitats, including rivers and streams (Holloway et al. 1998; Overholt and MacKenzie 2005), woodpecker habitat (Vierling et al. 2005), forests (Zucca et al. 1995; Markham 2000), amphibians and reptiles (Eareckson 2002; Tomasek et al. 2005), invasive worms (Gurwick and Krasny 2001), coastal systems (Childress and Hall 1998; Singletary 2000), ferns (Siry and Buchinski 2005), urban habitats (Fisman 2005), environmental health and humans (Rao et al. 2004; Sedlacek et al. 2005), and vernal pools (Potter 2001), connecting students to their community in a meaningful and engaging way. This approach to teaching has been termed “place-based education,” referring to studies that focus on the students’ local environment (Woodhouse and Knapp 2000). Woodhouse and Knapp (2000) describe five elements to place-based education: (1) the content is specific to the geography, ecology, sociology, politics, and other dynamics of a particular community; (2) it is inherently multidisciplinary; (3) it is inherently experiential; (4) it reflects an educational philosophy that is broader than “learn to earn”; and (5) it connects place

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with self and community. Vernal pool field studies fit this paradigm well and can evolve into community conservation projects (Lewicki 2000; Bartsch 2001; Fisman 2005). In this chapter we discuss key considerations for conducting field studies in general and in vernal pools specifically, partnership roles among educators, scientists and conservation professionals with the potential to advance vernal pool science and conservation, and recommendations for building such partnerships. We also provide selected case studies that illustrate the range of outcomes for school vernal pool studies, from conservation to research. Although the emphasis is on using vernal pools to teach science and engage students in conservation, some examples highlight other disciplines. Although the material is centered on vernal pool education for children, many of the resources and recommendations can be applied to education for adults. Therefore, our intended audience for this chapter includes grade K-12 teachers, educators associated with science or nature centers and nonprofit organizations, research scientists, and conservation professionals.

KEY CONSIDERATIONS FOR FIELD STUDY PROGRAMS Field study involves the processes of science to learn about local natural history. This can include learning about biology, ecology, geology, hydrology, weather and climate, and the interactions among them. Field study, by engaging students in the natural world, captures a student’s attention and fosters a strong interest in science. However, poorly designed studies can lead to confusion or disinterest on the part of students. Moss et al. (1998) found that studies that were not perceived as relevant by the students, or that did not involve students in all steps of the scientific method, were unlikely to keep students’ attention or improve their understanding of science. Key aspects of successful field studies include spending adequate time in the field, not only to follow protocols but to gain familiarity and understanding of the ecosystem being investigated; developing clear scientific questions — if possible, students should be involved in developing the questions; establishing relevance of the project (especially for older students) and not just engaging them in biological busy work; designing studies that are age-appropriate; making multidisciplinary connections e.g., incorporating art, technology, writing or other subjects that recognize diverse skills and talents while highlighting the need for holistic approaches to problem-solving; accommodating different learning styles, (e.g., visual, auditory, kinesthetic); and providing opportunities to analyze data — not simply gather it — with ample time for students to consider the results and ask further questions (Moss et al. 1998; authors’ experience). This last point is especially important, as recent research indicates that providing opportunities for students to analyze data, theirs or that of others, provides a significant boost to student learning in science (Penuel et al. 2003). Some basic steps need to be taken if teachers are to develop successful ecologically based field studies (Haley 2000; Brewer 2002, authors’ experience). Teachers need adequate opportunities to learn about the subject matter. Too often, teacher

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training is limited to short workshops that give teachers little time to develop a solid understanding of the subject content and study methods. For many teachers, training in how to conduct outdoor lessons and in linking field study curricula to education standards in science is needed (see section on How to Build Partnerships). Teachers need time to plan studies and to take students into the field. For this reason, projects should be implemented locally, preferably on school grounds or a short trip from the school. Involvement of more than one teacher at a school is necessary to make programs sustainable. Equipment and other resources must be provided or be available at low cost. Finally, projects should include follow-up interaction with scientists, conservation professionals, or other educators.

VERNAL POOL FIELD STUDIES Vernal pools are an excellent focus for place-based field studies. Place-based education continues to be popular with educators in an era of increased emphasis on curricula that teach to standardized tests. For example, field studies support learning outcomes identified in U.S. National Science Education Standards (AAAS 1993, NRC 1996), as well as in state and provincial standards. They call for direct experience with living things, life cycles, habitats for elementary students, and field study experience for middle and high school students. Vernal pool field activities are often relevant to those NRC standards dealing with the content and processes of science. For example, students in grades K-4 might explore life cycles of organisms (the content) by comparing larval and adult stages of a vernal pool breeding amphibian. This exploration might include developing a list of criteria for use in comparison, using a magnifying glass to examine the larvae, recording observations on a chart, and sketching the organisms making notations on the differences between the stages (the processes) (see Tables 15.1 and 15.2 for more examples). Several assessments indicate that inquiry based activities typical of such programs have a positive effect on student performance (Shymansky et al. 1983; Penuel et al. 2003; Ernst and Monroe 2004). There are many high quality vernal pool resources available to educators, including information on organisms and ecology (Kenney and Burne 2000; Colburn 2004; Brown and Jung 2005), educational resources that include multidisciplinary lesson plans (Childs and Colburn 1993; Kenney 2000; VINS 2002; Snow et al. 2005), and visual resources such as slide sets and posters (Kenney 2000; MDIFW 2005; EPA). For this reason, we are not providing specific vernal pool curricula, but rather are introducing some key considerations in setting up vernal pool field studies. Whether you are working with very young or older students, and regardless of your study objectives, there are several practical considerations for working with students in vernal pool settings. Safety The primary consideration is participant safety. Leaders should have current first aid certification and appropriate first aid equipment along on all field trips. Prior to a field program, the access route and study area should be checked for barbed wire

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TABLE 15.1 Vernal Pool Activities That Address the NRC Content Standards for Developing Scientific Inquiry Abilities National Research Council Standard (from NRC 1996)

Sample Educational Activities Involving Vernal Pools

K–4

Ask a question about objects, organisms, and events in the environment

K–4

Employ simple equipment and tools to gather data and extend the senses

K–4

Plan and conduct a simple investigation

K–4

Use data to construct a reasonable explanation

K–4

Communicate investigations and explanations Identify questions that can be answered through scientific investigation Design and conduct a scientific investigation

Open investigation of vernal pools, catching and examining organisms, making multiple visits to a vernal pool through the school year Use nets, strainers, magnifiers, rulers, measuring tapes, thermometers, and other tools to explore vernal pools Counting species present; sorting species by trophic level, classification, adaptations; compare multiple pools; compare with pond or stream Use species lists, temperatures, etc., to create graphs to describe pools, compare aquatic systems Create presentations, posters, PowerPoint slide shows, puppet shows, etc. about vernal pools Develop questions based on observations of vernal pools Conduct inventory, phenology, physical or other investigations on vernal pools, based on teacher assigned or student derived questions Use of nets, live traps, sampling, optical aids, measuring tapes, GPS, etc. in investigations Work out food chain and food web relationships in vernal pools; develop explanations for how species find vernal pools Compare species mix among wetland types and compare with predictions; test different sampling techniques and devices Compare and test hypothesis concerning: vernal pool species behavior or growth, vernal pool response to rain or snow events, species composition over time Create presentations, posters, PowerPoint slide shows, and educational materials Measure physical parameters, area, depth, changes in size, temperature, chemistry, count egg masses, estimate populations, track growth Read scientific literature on vernal pools, observe them, and develop questions Develop research questions on vernal pools through an inquiry process

Grades

5–8 5–8

5–8 5–8

5–8

5–8

5–8 5–8

9–12 9–12

Use appropriate tools and techniques to gather, analyze, and interpret data Develop descriptions, explanations, and models using evidence Think critically and logically to make the relationships between evidence and explanations Recognize and analyze alternative explanations and predictions

Communicate scientific procedures and explanations Use mathematics in all aspects of scientific inquiry Identify questions and concepts that guide scientific investigations Design and conduct scientific investigations

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TABLE 15.1 (CONTINUED) Vernal Pool Activities That Address the NRC Content Standards for Developing Scientific Inquiry Abilities Grades

National Research Council Standard (from NRC 1996)

9–12

Use technology and mathematics to improve investigations and communications

9–12

Formulate and revise scientific explanations and models using logic and evidence

9–12

Recognize and analyze alternative explanations and models

9–12

Communicate and defend a scientific argument

Sample Educational Activities Involving Vernal Pools Use sampling devices, data recorders, GPS units, digital cameras, chemical tests, measure pond size, depth, area, species mix, volume fluctuations, chemical change, population sizes Have multiple students investigate the same question regarding vernal pools, go through entire scientific method with vernal pool as subject Have students compare their results with those of published researchers, have student work reviewed by researchers Develop a one- or multiple-school vernal pool symposium to compare investigations; present survey results to town commissions

fences, slippery slopes, and other hazards. If the protocols include entering the pools, proper protective footwear should be worn. In cold or rainy weather, leaders should be alert for signs of hypothermia, especially with young children. For school programs, if the pool is distant from the school or away from school property, more than one adult should accompany the group. Vernal pool organisms pose negligible threats to people. Some Hemipteran insects, including backswimmers (Notonectidae), water scorpions (Nepidae), giant water bugs (Belostomatidae) and creeping water bugs (Naucoridae) can inflict painful bites if handled carelessly, but the effects are not dangerous and pass quickly. Care needs to be taken to recognize and avoid poison ivy (Rhus radicans) and poison sumac (Rhus vernix). Ecological Impact Considerations It is important to stress with all people involved in field studies that many vernal pool organisms can easily be disrupted or damaged by careless field techniques. Care should be taken not to trample plants and woody debris around the pool, as they often serve as shelter for amphibians and invertebrates (Snow et al. 2005). When amphibian egg masses are present, care should be taken not to disturb the masses or to dislodge them from branches or plants to which they are attached. Egg masses should be examined in situ whenever possible. If photography is necessary, a light-colored sheet of plastic held behind masses can facilitate photography without disturbing the subject. Sampling with nets should be done away from concentrations of egg masses, and stirring up of the leaf litter in the pool should be kept to a minimum in order to keep sediment from settling on egg masses (Snow et al. 2005).

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TABLE 15.2 Sample Vernal Pool Activities Relevant to United States National Science Education Content Standards

Grades

National Research Council Standard Area (from NRC 1996)

K–4

Characteristics of organisms

K–4

Life cycles of organisms

K–4

Organisms and their environments

K–4 5–8

Changes in environments Structure and function in living systems Populations and ecosystems

5–8 5–8 5–8 5–8 9–12 9–12 9–12 9–12 9–12

Diversity and adaptation of organisms Regulation and behavior Populations, resources, and environments Biological evolution Interdependence of organisms Matter, energy, and organization in living systems Behavior of organisms Environmental quality

Sample Educational Activities Involving Vernal Pools Sampling, observing, describing, and classifying organisms Multiple visits to pools to investigate amphibian and invertebrate life stages Investigating what group of species are dependent on vernal pools Observe changes in vernal pools over several months Investigate structural adaptations of vernal pool organisms Study of biotic and abiotic factors and trophic relationships in vernal pools Inventory of vernal pools organisms, investigation of structural and behavioral adaptations Learn about organisms abilities to survive changeable physical environment of vernal pools Investigate human-caused degradation of vernal pools Investigate related groups of organisms found in vernal pools Investigate food webs of vernal pools Trace the movement of matter and energy through vernal pools and surrounding forest Observational studies of vernal pool organisms Investigation impact on vernal pools of human activities, such as development, acid precipitation, other pollutants

Newly hatched amphibian larvae should not be netted, as they are very delicate. Never use a seine net to sample in pools, as such a large net could cause significant damage and disruption to pool animals and plant structure. Boots, nets, and other sampling equipment should be cleaned either with a weak bleach solution or with 70% ethanol, and thoroughly rinsed before sampling and between study sites (Brown and Jung 2005; USGS 2006) in order to prevent inadvertent transportation of pathogens and parasites among sites. Removable nets and washable clothing, including sneakers, should be machine-washed between site visits. Handling and Keeping Live Animals Interaction with vernal pool organisms is an important part of the learning process that can link field studies back to the classroom. Having students learn about the

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FIGURE 15.2 Students measure a spotted salamander using proper handling techniques during a field visit to a breeding pool in Connecticut. (Photo by Laurie Doss)

biology of particular organisms and prepare protocols for their care and handling provides an opportunity to promote research and problem-solving skills in a unique way. Care should be taken when handling amphibians. Handlers should not have insect repellent, sunscreen or other chemicals on their hands. Hands and the animals should both be kept moist. In the field, live amphibians at any life stage — egg, larvae, or adult — are best handled by placing them in small plastic aquaria that make passing them around and examining them easier for people and less potentially harmful to the organisms (see Figure 15.2). Invertebrates are also best handled in containers, with water for aquatic species, of course. Many educators find that using small plastic spoons facilitates the picking up and transfer of invertebrates from sampling nets to containers for closer examination. Live vernal pool animals, including amphibians and many invertebrates, make excellent subjects for classroom observation and care (Kenney 2000). However, educators should have a clear educational rationale for removing animals from the wild and be prepared for long-term care. Most wildlife officials now advise or require that live amphibians taken for educational use not be returned to the wild, but kept permanently in order to reduce the chance of introducing pathogens into wild populations. Adult amphibians should be kept in spacious terrariums with moist (but not soaked) substrate, which can be clean soil or one of the many commercial substrates now available. They should always have access to clean water and cover objects, and should be fed two to four times weekly with live invertebrates.

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Store-bought crickets are often used as food but should be enriched with either cricket food or cricket dusting compounds specifically made for amphibian nutrition. Earthworms also are a cost-effective food source. It is important to note that adult vernal pool amphibians are essentially terrestrial species and many, including ambystomatid salamanders, will die if kept permanently in water. Larval amphibians should be kept in aquaria with proper filtration. Avoid filtration systems that might pull larvae into the filter system with strong suction. Salamander larvae generally require live food and can be difficult to rear. Tadpoles are largely herbivorous and can be fed for extended periods on deep green lettuce that has been boiled briefly. Some people have also reported success raising larvae on small amounts of rabbit pellets. Many vernal pool invertebrates can be kept alive in aquaria easily if substrate from the pool is included in the tank (Kenney 2000). Note that certain invertebrates, such as predaceous diving beetles (Dytiscidae), either adults or larvae, will consume many other organisms in an aquarium, including amphibian larvae. Turtles should not be removed from vernal pools. Most of the turtles associated with these habitats are declining species, and many are protected by state, provincial or national laws. With the exception of snapping turtles (Chelydra serpentina), turtles can be handled, examined, and released without harm to the animals or people. Legal Issues Before visiting a vernal pool, be sure to determine the ownership of the land and secure any necessary permission. Pools located on public lands or owned by conservation groups may fall under special rules concerning collection or disturbance. For observational studies permits are generally not needed. However, if collection of live organisms for the classroom or as voucher specimens will be involved, it is important to secure necessary permits beforehand. Regulations on collecting amphibians (and in some cases, invertebrates) vary considerably among states and provinces. States and provinces list a few amphibian species as rare, threatened, or endangered. It is important to check with state or provincial wildlife officials regarding permits and regulations for individual species. Permits for educational use are usually not difficult to obtain, and the process itself can be an important lesson for students.

PARTNERSHIP ROLES AMONG EDUCATORS, STUDENTS, SCIENTISTS, AND CONSERVATION PROFESSIONALS Although there are many resources available for teachers to develop vernal pool lessons or projects on their own, field study programs can be significantly enriched by partnerships among educators, research scientists, and conservation professionals. Such partnerships can increase the relevance of the study for students, expand access to scientific resources, and strengthen the science content. Scientists and conservation professionals can provide professional development for teachers by increasing content knowledge and imparting new science skills. Educators and students, in turn,

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TABLE 15.3 Potential Benefits of Educator–Scientist Research Partnerships Benefits to Scientists

Benefits to Educators

Benefits to Students

Expanded opportunity for data collection from a broad geographic area or over a multiyear period

Increased content knowledge in biology, ecology, and the environmental or natural sciences

Increased level of engagement through involvement in real and relevant research

Infrastructure for simultaneous time-specific sampling

Increased skills in applying scientific methods

Better understanding of and stronger connection to natural resources within their community

Infrastructure for establishing long-term monitoring efforts

Opportunity to explore personal interests in natural history study

Exposure to scientists and potential career paths

Platform for testing new sampling or monitoring methods

Access to scientific equipment and other education resources

Opportunity to gain experience using scientific equipment

Potential new grant funding opportunities through education sources

Platform for integrating hands-on, inquiry-based learning within the curriculum

Increased critical thinking skills and understanding of the scientific method

Promotion of research, and of the researcher’s organization and its relevance to the community

Opportunity to highlight local relevance of science with students

Increased content knowledge in biology, ecology and the environmental sciences

Development of new communication skills

Opportunity to integrate multidisciplinary project with students (science, math, technology applications)

Increased understanding of the relationship between scientific disciplines including mathematics

Opportunity to share passion for science and the subject area

Public relations to strengthen support for science teaching in the community

Increased understanding of links between science, citizen action and environmental policy

Source: Modified from Berkowitz, A.R. 1997.

can contribute data toward research projects and even take an active role in vernal pool conservation. Linking educators and students with researchers conducting studies on vernal pools can yield benefits to all participants (see Table 15.3).

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Several factors must be considered when forging partnerships between educators and research scientists. Barstow (1997) identified three core “authentics” that we think are relevant to vernal pool studies and forging successful partnerships with scientists: (1) authentic science — the research must be real and central to the scientists work, and the students’ contribution must be meaningful; (2) authentic education — the student learning experience must be based on sound educational practice and involve the students in developing both content and skills and; (3) authentic partnership — scientists, students, and teachers must have a desire to participate and a respect for and willingness to learn more about each others’ domains. Participating scientists can strengthen the study, serve as role models and “windows” to career opportunities, and above all, share their passion and enthusiasm for science with students (see Calhoun et al. 2003). Vernal pool habitat studies can also easily lead to vernal pool conservation efforts. Working with conservation professionals (such as conservation commission members, foresters and wildlife managers, land use planners, and environmental policy makers) can provide mutual benefits. For students, it is a chance to see that a variety of stakeholders have roles in conservation, including scientists, government officials, advocacy groups, landowners, and citizens. For conservation professionals, the benefits can include student collection of data on vernal pools, and increased community awareness of the importance of vernal pools as a natural resource. Because of the potential ecological damage associated with development in and around vernal pools, opportunities for proactive involvement in vernal pool conservation are numerous (Chapter 16, Calhoun and Reilly). For example, students might become involved with municipal mapping projects to document the location of vernal pools, conduct ecological assessments to provide data for use in prioritizing pools for conservation, or become active in the management by monitoring and removing invasive plant species at degraded pools. Our case studies illustrate additional ways to use vernal pools to educate students and connect them to conservation. There are many publications available to guide educators and researchers in conservation work (see Diving into Wicked Big Puddles, Kenney 2000). For advanced students, more technical methods for inventory and monitoring of vernal pool organisms are available (Heyer et. al. 1994; Sutherland 1996; ASNH 1998; Mitchell 2000; Calhoun and Klemens 2002; see also Chapter 16, Calhoun and Reilly). Teachers must overcome key obstacles that might prevent scientists and conservation professionals from partnering with educators such as data quality and time constraints. Evaluations of data collected by schools participating in river and streammonitoring programs have yielded positive, but variable, results. For example, the accuracy of data generated by high school students monitoring Connecticut streams varied annually and ranged from 11–89% (depending on the variable) for nine chemical tests, temperature, and total dissolved solids during the period 1996–2005 (Sullivan and Gruner, Project SEARCH, unpublished data). Yet researchers working with students to census amphibian malformation rates in Michigan found that teachers and students can contribute to basic studies on the incidence, distribution, and abundance of malformation in a cost-effective manner (Chadde and Flaspohler 1999). Teachers can address these obstacles by developing data protocols (Chapter 16, Calhoun and Reilly), reviewing pertinent publications, and through

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early correspondence with researchers or knowledgeable staff at informal education organizations. Educational organizations (nature and science centers, museums, Audubon societies, land trusts, watershed associations and so on) can serve as a bridge connecting scientists, conservation professionals, and schools. They often employ educators with strong backgrounds in science and typically offer programs for audiences ranging from preschool through adult. Many have well-developed relationships with schools and can play an important role in fostering connections with scientists and conservation professionals and in linking students to local community conservation efforts. Such organizations can also help to address the issues of time constraints, meet teachers’ needs for establishing successful field study programs, help maintain data integrity, and serve as a catalyst for effective partnerships.

HOW TO BUILD RELATIONSHIPS AMONG EDUCATORS, SCIENTISTS, AND CONSERVATION PROFESSIONALS Any educator, researcher, agency professional or environmental educator can create and deliver good vernal pool education programs with the many resources available, but truly sustainable and effective programs are much more likely if all the professionals and organizations described in this chapter collaborate. We offer the following recommendations for fostering partnerships.

STEPS SCIENTISTS

AND

CONSERVATION PROFESSIONALS CAN TAKE

Partnerships among educators, students and scientists need not always be research based. This is especially true in the lower elementary grades where students do not yet have well-developed analytical skills (NSRC 1997). There are relatively simple ways for scientists to assist teachers and enhance science curriculum with little investment of time. Examples include loaning scientific equipment, visiting a classroom to introduce a topic or to provide a specific lesson on a survey technique or data analysis, training teachers in vernal pool ecology, or simply accompanying a class on a visit to a vernal pool to enrich the experience. To further the development of partnerships with schools we recommend that vernal pool researchers and conservation professionals consider the following: (1) invite science educators from schools and educational institutions to scientific conferences, workshops and meetings on vernal pools. Contact lists for schools can usually be obtained through state and provincial education agencies, and many states and provinces publish directories of nature centers; (2) contact faculty in university and college schools of education to learn about science education reform initiatives and to find educators or schools that may be interested in field study; (3) contact science education or environmental institutions to learn about their school and public education programs and how to become involved; (4) contact state or provincial education agencies to learn about science education reform initiatives and how to become involved; and (5) look for opportunities to apply for funding for collaborative projects that provide useful data to management organizations while involving volunteers in the collection of that

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data (the citizen-science approach). Research-based initiatives might include university scientists hiring high school students to assist in summer data collection for vernal pool studies, or conservation organizations (e.g., Audubon societies, The Nature Conservancy) employing summer interns to assist in vernal pool conservation or management projects. The North Carolina Museum of Life Science has prepared a guide for scientists who are considering working with schools (NCMLS 1996b).

STEPS TEACHERS CAN TAKE Teachers can take a number of proactive steps to forge connections with key partners: (1) Invite scientists and conservation professionals to local and statewide science education conferences. Contacts can be obtained from university, college, and state agency Web sites or by contacting nonprofit conservation and environmental education organizations; (2) Invite scientists to participate in local, regional, provincial, or statewide science reform initiatives; (3) Contact science educational or environmental institutions to learn about active research projects; (4) Contact nature centers, museums, or other nature education organizations and discuss forming a partnership to create vernal pool field study programs for your schools. The North Carolina Museum of Life Science has also prepared a guide for educators who are considering working with scientists (NCMLS 1996a).

STEPS SCIENCE EDUCATION ORGANIZATIONS CAN TAKE Science education organizations (e.g., nature centers, science museums) can play an important role in the partnerships. For example, they can facilitate connections among K–12 teachers and scientists, provide professional development workshops for K–12 teachers by recruiting scientists to co-present workshops with staff or by having researchers train staff in vernal pool biology, and seek funding for field-based education programs or conservation partnership initiatives. Science organizations have access to a variety of government education funds, foundations, and corporate support. Partnering with scientists and schools can attract funding to develop programs while helping support the organization’s operating budget, promote awareness of vernal pools and related science education for the general public, elected officials, and conservation commissions, and provide opportunities for staff to attend vernal pool conferences.

SELECTED CASE STUDIES The following cases are presented as examples of approaches for using vernal pools as an education resource, and to highlight programs that have successfully used investigations of vernal pools with K–12 students and teachers. In addition to integrating core science curriculum many of these programs have partnered educators with conservation professionals and engaged students in local conservation initiatives. The authors found that the majority of developed programs are in the northeastern U.S. Contacts in Canada and in the mid-Atlantic and Midwestern states indicated that vernal pool education programs are not as common in those areas,

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but that many conservation groups, educational organizations, government agencies and schools are now developing and beginning to implement vernal pool programs. Canada has become very active in promoting wetland conservation (e.g., see WILD Education, Canadian Wildlife Federation, http://www.wildeducation.org/connections/contewld.asp, and the Ontario Vernal Pool Association, http://www.ontariovernalpools.org).

Wicked Big Puddles and the Vernal Pool Association, Reading Memorial High School, Reading, MA (Kenney 2000; Vernal Pool Association, personal communication) The most ambitious and successful school-based education program based on vernal pools was created at the high school in Reading. In the 1990s, the State of Massachusetts Natural Heritage and Endangered Species Program developed a process for citizens to submit data to certify vernal pools. Using that as a starting point, teacher Leo Kenney built a curriculum entitled Diving Into Wicked Big Puddles to involve middle and high school teachers and students in the certification process. The curriculum incorporated such field skills as map reading, aerial photograph interpretation, mapping of vernal pools, plant identification, monitoring hydrology, recording pH and salinity measurements, field observation, and sketching. It also encouraged interdisciplinary approaches to learning including creation of printed materials and presentations, creating and selling t-shirts (Kenney 2000), presenting their findings to local government authorities, producing related posters and artwork in multiple media, and writing. This program was successful at Reading Memorial High School for over a decade, and it has also been successfully replicated at other schools, with students responsible for an estimated twothirds of the vernal pools certified in Massachusetts in the first three years of the program. The online resources provided by Reading Memorial High School’s Vernal Pool Association have been identified as a leading example of a quality Internet-based science project for education (Berg and Jefson 1998). A key feature of the Wicked Big Puddles program is its multidisciplinary approach. This is an example of how a motivated educator, using resources from conservation professionals and communicating with experts in government and informal education agencies, can develop a multidisciplinary education program that connects to real conservation work. Vernal Pool Billboard Project — Nessacus Middle School, Dalton, MA (T. Tyning, Berkshire Community College, personal communication) After completing a unit on endangered species, students at the Middle School held a contest to design a billboard concerning vernal pool protection. A billboard company donated a sign, and the winning entry was put up. This is an excellent example of students making the link between habitat protection and species protection as a result of contact with outreach educators who had developed expertise about vernal pools. Signs were also produced and erected at a vernal pool in Orono, ME, through collaboration between the middle school and the University of Maine (A. Calhoun, University of Maine, personal communication). Amphibian Migration Project — Doyon Elementary School, Ipswich, Massachusetts (L. Kenney, Vernal Pool Association, personal communication) A teacher working with a fifth-grade class used the “potential vernal pool locations” GIS map layer created by the Massachusetts Natural Heritage Program to locate research sites in town. The teacher and students then organized family evening programs to

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conduct field investigations at these sites during the spring breeding season to confirm the presence of vernal pools and identify locations where amphibian migratory routes crossed roads. Once the class had identified amphibian crossings, they worked with the Department of Public Works to design and install amphibian road crossing signs at these locations to promote public awareness, with the goal of reducing road mortality in these populations. Programs such as this involve students in the collection of data and the use of that data in conservation decisions. Amphibian Malformation Surveys Using Middle and High Schools in Michigan (J. Chadde, Michigan Technological University, personal communication) In a 1999 study assessing malformation incidence among frogs and toads in the western upper peninsula of Michigan, 10 schools (grades 5–12) sampled 19 wetlands, including vernal pools. The program was led by scientists from Michigan Technological University who provided training to participating teachers and was funded by the Michigan Department of Natural Resources Non-Game Wildlife Fund. This is an example of a partnership among educators, researchers and conservation professionals to gather data of interest to wildlife biologists and researchers (Chadde and Flaspohler 1999). Municipal Vernal Pool Assessment — Marvelwood School, Kent, CT (L. Doss, Marvelwood School, personal communication) As part of a field study course for her high school students, science teacher Laurie Doss has developed a partnership with the local Conservation Commission to map pools and to conduct biological and habitat assessments of vernal pools in the town. The town contracted with an environmental consulting firm to map the locations of potential pools. The students are following up on this information by collecting data at these locations using methods outlined in Calhoun and Klemens (2002). Data collected by the students are linked with maps using GIS, providing the town with baseline data for use in landuse planning and site design reviews. Students from the school have presented their studies at several environmental conferences in Connecticut. Partnerships with several local scientists were developed to provide students with training and ongoing technical support. Harvard Forest Schoolyard Freshwater Ecology: Vernal Pool Research Program, Petersham, MA (Snow et al. 2005; P. Snow, Harvard Forest, personal communication). This program was developed by researchers to involve schools in the full process of the scientific method. At Harvard University’s Research Forest, researchers train teachers in field ecology studies that can be conducted within walking distance of schools. While the program is intended for K–12 teachers, most teachers using the Vernal Pool Research section are elementary level. The program focuses on the hydrology of vernal pools, asking a short-term question (“How do water levels of our vernal pool change seasonally this year?”) and a long-term question (“How do water levels in vernal pools vary over time, and how do those water level variations affect animals that live in vernal pools?”) The protocols specify a minimum of annual visits. Students measure seasonal water level changes and share that information with Harvard Forest and with other schools through a Web site. Optional but popular activities include sampling and identifying organisms. Vermont Institute of Natural Science; Vernal Pools: Life in Temporary Ponds (VINS 2002; K. Jensen, Vermont Institute of Natural Science, personal communication). Part of the Vermont Institute’s (VINS) Environmental Citizenship program for middle schools, the Vernal Pool unit includes classroom activities to prepare students for field work with vernal pools, including raising vernal pool crustaceans in a classroom aquarium, a vernal pool species slide show, a food web mural activity, and training in the

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Vermont herpetological atlas and VINS vernal pool documentation projects. The field portion of the unit includes having students write observations, sample organisms, photograph animals, and record data on species present. Follow-up includes submission of records to the herpetological atlas and the vernal pool documentation project, and many optional activities. The activities are correlated to the Vermont Frameworks of Standards and Learning. From 1996 to 2002, the program served 82 teachers and reached an estimated 1,645 students across Vermont. This project is an example of a program driven and sustained by a nonprofit education and conservation organization with staff who have developed expertise in the subject area. University of Maine Wetland Connections Project (Calhoun et al. 2003) Faculty from the University of Maine worked with teachers and students from three high schools to conduct research on forested wetlands including vernal pools. Participating schools were culturally, socioeconomically and geographically diverse and included students from a Native American tribe. Research activities focused on collecting data on hydrology, vegetation communities, and wildlife. Ecological data collected at vernal pools followed methods outlined in Calhoun (2003). Teachers and students presented information on the project at various venues and two of the schools became involved in conservation initiatives to mitigate physical disturbance from ATV and pedestrian traffic they observed near their study wetlands. Vernal Pool Course for Teachers: The Roger Tory Peterson Institute and the State University of New York at Fredonia (Solon Morse and Marc Baldwin, Roger Tory Peterson Institute, personal communication) Coursework for educators is as important as coursework for their students. At least one accredited graduate course has been designed specifically for educators (K–12) seeking to learn more about vernal pools and their application in education. The Roger Tory Peterson Institute in Jamestown, NY, offers a graduate course in education that covers the biology of vernal pools and their use in teaching. The course trains and equips teachers to incorporate field studies of vernal pools in their curriculum through multiple field trips that emphasize the process of inquiry-based learning and scientific methods. The Peterson Institute helps the teachers break down barriers to field studies by making field equipment available on loan. The Institute also provides a Web site through which classes can share data. The strength of the program so far has been its multidisciplinary nature, with teachers developing vernal pool based lessons that can be applied to many grades and in many subject areas, including foreign language studies. These case studies illustrate the many facets vernal pool-based studies might assume, including promoting public awareness, conducting research, applying conservation measures and serving as professional development for educators. Regardless of focus, their success was dependent upon the presence of a highly motivated educator and/or conservation professional, a clear understanding of the objectives, schedule of activities, and availability of resources necessary to complete the project.

SUMMARY Because vernal pools are widespread in the eastern U.S. and Canada, they are ideal outdoor laboratories for engaging students in learning science and local natural history. Often the focus of government conservation efforts, they provide opportunities to involve students in real conservation, and illustrate the application of science

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in a community. Finally, with a growing community of researchers investigating vernal pools, they provide excellent opportunities for partnerships between scientists and educators and their students. The region covered by this book is fortunate in having vernal pools as fascinating small-scale ecosystems as a part of its landscape. The growth in awareness of, and concern for, vernal pools is both a result of significant effort by all of the groups discussed above to involve people in education and local conservation work. This effort will ensure that future generations of conservation-minded citizens will remember how their interest and commitment blossomed with their first experiences amid the egg masses, frog calls and furtive invertebrates of a vernal pool.

ACKNOWLEDGMENTS The authors would like to thank all the educators and researchers who contributed time to this chapter, including Marc Baldwin, Jim Berry, Aram Calhoun, David Celebrezze, Joan Schumaker-Chadde, Betsy Colburn, Chuck Delpier, Laurie Doss, Eileen Fielding, Michael Hayslett, Judy Helgen, Scott Heth and the Sharon Audubon Center, Kim Jensen, Leo Kenney, Roger Lawson, Solon Morse, Damon Oscarson, Pam Snow, Chris Sullivan, and Tom Tyning. This chapter is dedicated to my coauthor, Richard D. Haley, who died in June 2006 following a car accident in Arizona. Richard was a gifted naturalist, educator, and researcher who always instilled a sense of wonder about the natural world in everyone he met. He will be sorely missed by his colleagues.

REFERENCES AAAS (American Association for the Advancement of Science). (1993). Benchmarks for Science Literacy. Oxford University Press, New York. ASNH. (1998). Identification and documentation of vernal pools in New Hampshire. Audubon Society of New Hampshire, Concord, NH. Barstow, D. (1997). The richness of two cultures. In Proceedings of the National Conference on Student and Scientist Partnerships. TERC, Cambridge, MA, pp. 33–37. Bartsch, J. (2001). Community lessons: integrating service-learning into K-12 curriculum. A promising practices guide. Massachusetts Department of Education, Malden, MA. www.doe.mass.edu. Berg, C.A. and Jefson, C. (1998). Top 20 collaborative internet-based science projects of 1998: characteristics and comparisons to exemplary science instruction. Retrieved August 24, 2005 from the World Wide Web http://www.uwm.edu/~caberg/1583.html. Berkowitz, A.R. (1997). A simple framework for considering the benefits of student scientist partnerships. In Proceedings of the National Conference on Student and Scientist Partnerships. TERC, Cambridge, MA, pp. 38–41. Brewer, C. (2002). Conservation education partnerships in schoolyard laboratories: a call back to action. Conservation Biology 16(3): 577–579. Brown, L.J. and Jung, R.E. (2005). An introduction to mid-Atlantic seasonal pools. U.S. Environmental Protection Agency, Mid-Atlantic Integrated Assessment, Fort Meade, MD. EPA/903/B-05/001.

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Calhoun, A.J.K. (2003). Maine citizen’s guide to locating and documenting vernal pools. Maine Audubon Society, Falmouth, ME. Calhoun, A.J.K., Reeve, A., and McGarry, M. (2003). Wetland connections: linking University research initiatives to high school science education. Journal of Geoscience Education 51: 387–397. Calhoun, A.J.K. and Klemens, M.W. (2002). Best development practices: conserving poolbreeding amphibians in residential and commercial developments in the northeastern United States. MCA Technical Paper No. 5, Metropolitan Conservation Alliance, Wildlife Conservation Society, Bronx, New York. Chadde, J.S. and Flaspohler, D. (1999). Amphibian malformation survey of the western upper peninsula using middle/high school classes. Final Report to the Michigan Department of Natural Resources Non-Game Wildlife Fund 1999 Natural Heritage Grants Program, MI. Childress, J. and Hall, J. (1998). Oil spill ecology. The Science Teacher, October 1998, 32–35. Childs, N. and Colburn, E.A. (1993). Vernal pool lessons and activities. Massachusetts Audubon Society, Lincoln, MA. Colburn, E.A. (1997). Certified: a citizen’s step-by-step guide to protecting vernal pools. Massachusetts Audubon Society, Lincoln, MA. Colburn, E.A. (2004). Vernal Pools Natural History and Conservation. McDonald and Woodward Publishing, Blacksburg, VA. Eareckson, L.A. (2002). What do amphibians have to offer? The Science Teacher, May 2002, 48–51. EPA (Environmental Protection Agency). A New England vernal pool through the seasons. U.S. Environmental Protection Agency, Region 1, Office of Ecosystem Protection, Boston, MA. Ernst, J. and Monroe, M. (2004). The effects of environment-based education on students’ critical thinking skills disposition toward critical thinking. Environmental Education Research 10: 507–522. Fisman, L. (2005). The effects of local learning on environmental awareness in children: an empirical investigation. The Journal of Environmental Education 36: 39–50. Gurwick, N.P. and Krasny, M.E. (2001). Enhancing student understanding of environmental sciences research. The American Biology Teacher 63: 236–241. Haley, R.D. (2000). Overcoming barriers to using school nature areas for education. The New England Journal of Environmental Education 13: 7–17. Heyer, W.R., Donnelly, M.A., McDiarmid, R.W., Hayek, L.C., Foster, M.S. (1994). Measuring and Monitoring Biological Diversity: Standard Methods for Amphibians. Smithsonian Institution Press, Washington, D.C. Holloway, S., Rofuth, T.W., Gruner, H., and Mimo, A. (1998). Can applied science in environmental monitoring transform science education? The Educational Forum 62: 354–362. Kenney, L.P. (Ed). (2000). Diving Into Wicked Big Puddles. Vernal Pool Association, Reading, MA. Kenney, L.P. and Burne, M.R. (2000). A Field Guide to the Animals of Vernal Pools. Massachusetts Division of Fisheries and Wildlife Natural Heritage and Endangered Species Program, Westborough, MA, and Vernal Pool Association, Reading, MA. Lewicki, J. (2000). 100 days of learning in place: how a small school utilized “place-based” learning to master state academic standards. Rural School and Community Trust, Washington, D.C. Markham, M.T. (2000). Forestry 101. The Science Teacher, February 2000, pp. 33–37.

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MDIFW (Maine Department of Inland Fisheries and Wildlife). (2005). Vernal pools alive (poster). Maine Department of Inland Fisheries and Wildlife, Augusta, ME. Mitchell, J.C. (2000). Amphibian Monitoring Methods and Field Guide. Smithsonian National Zoological Park, Conservation Research Center. Front Royal, VA. Moss, D.M., Abrams, E.D., and Kull, J.A. (1998). Can we be scientists too? Secondary students’ perceptions of scientific research from a project-based classroom. Journal of Science Education and Technology 7: 149–161. NCMLS (North Carolina Museum of Life Science). (1996a). Sharing science: linking students with scientists and engineers, a survival guide for teachers. North Carolina Museum of Life and Science, Durham, NC. Retrieved October 11, 2005 from the World Wide Web http://www.noao.edu/education/tguides/teatxt.html. NCMLS (North Carolina Museum of Life Science). (1996b). Sharing science with children: a survival guide for scientists and engineers. North Carolina Museum of Life and Science, Durham, NC. Retrieved October 11, 2005 from the World Wide Web http://www.noao.edu/education/tguides/scitxt.html. NRC (National Research Council). (1996). National Science Education Standards. National Academy Press. Washington, D.C. NSRC (National Science Resources Center). (1997). Science for all Children: A Guide to Improving Elementary Science Education in Your School District. National Academy Press, Washington, D.C. Overholt, E. and MacKenzie, A.H. (2005). Long-term stream monitoring programs in U.S. secondary schools. The Journal of Environmental Education 36(3): 51–56. Penuel, W.R., Korbak, C., Lewis, A., Shear, L., Toyama, Y., Yarnell, L. (2003). GLOBE year 7 evaluation: Exploring student research and inquiry in GLOBE. SRI International, Menlo Park, CA. Potter, B. (2001). Vernal pool. In Community lessons: integrating service-learning into K-12 curriculum. A promising practices guide. Bartsch, J. (Ed.) The Massachusetts Department of Education, Learn and Serve America, Massachusetts Service Alliance, Boston, MA. Rao, P., Arcury, T.A., and Quandt, S.A. (2004). Student participation in community-based participatory research to improve migrant and seasonal farmworker environmental health. The Journal of Environmental Education 35: 3–15. Sedlacek, N., Young, J.A., Acharya, C., Botta, D., and Burbacher, T.M. (2005). Linking the classroom to the community. The Science Teacher, April–May 2005, pp. 44–45. Shymansky, J.A., Kyle, W.C., and Alport, J.M. (1983). The effects of new science curricula on student performance. Journal of Research in Science Teaching 20: 387–404. Singletary, J.R. (2000). Sound ecology. The Science Teacher, April 2000, pp. 41–43. Siry, C. and Buchinski, L.C. (2005). A field guide of their own. Science and Children, September 2005, pp. 36–39. Sutherland, W.J. (Ed.). (1996). Ecological Census Techniques: A Handbook. Cambridge University Press, Cambridge. Snow, P., Colburn, B., and Boose, E. (2005). Harvard forest schoolyard freshwater ecology: vernal pool research. Harvard Forest, Petersham, MA. Tomasek, T.M., Matthews, C.E., and Hall, J. (2005). What’s slithering around on your school grounds? The American Biology Teacher 67: 419–425. USGS National Wildlife Health Center (2006). Collection, preservation and mailing of amphibians for diagnostic purposes. Retrieved March 29, 2007 from the World Wide Web http://www. nwhc.usgs.gov/publications/amphibian_research_procedures/specimen_collection.jsp.

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VINS (Vermont Institute of Natural Sciences). (2002). Vernal pools: life in temporary ponds. A unit of environmental citizenship: learning to make informed decisions. Vermont Institute of Natural Science Woodstock, VT. Vierling, K.T., Bolman, J., and Lane, K. (2005). Field ecology in a cultural context. The Science Teacher, March 2005, pp.26–29. Woodhouse, J.L. and Knapp, C.E. (2000). Place-based curriculum and instruction: outdoor and environmental education approaches. ERIC Digest. ED4480122000-12-00, Retrieved October 11, 2005 from the World Wide Web http://www.eric.ed.gov. Zucca, C., Harrison, W., and Anderson, B. (1995). Forest fire ecology. The Science Teacher, May 1995, pp. 23–25.

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Conserving Vernal Pool Habitat through Community Based Conservation Aram J.K. Calhoun and Patti Reilly

CONTENTS Community Based Conservation and Citizen Scientists ......................................321 Can Citizen Science Make a Difference? .............................................................321 Community Based Conservation of Vernal Pool Habitat .....................................324 (1) Organizing a Local Conservation Initiative ........................................324 (2) Engaging and Retaining Citizen Scientists .........................................327 (3) Quality Control of Data.......................................................................329 (4) Conducting the Vernal Pool Inventory and Assessment .....................329 Conservation Recommendations ...........................................................................335 (5) Putting the Data to Work.....................................................................335 Summary ................................................................................................................336 Acknowledgments..................................................................................................336 References..............................................................................................................336

The more clearly we can focus our attention on the wonders and realities of the universe about us, the less taste we shall have for destruction.

These words from Rachel Carson are as relevant today as they were during the mid20th century when she alerted people to the seemingly invisible perils of pesticides in the environment. In Silent Spring (1962) we were asked to consider a spring without the dawn chorus of birds. Forty years later, reports of amphibian declines and increasing incidences of disease suggest that frog choruses may also be in peril (see Collins and Storfer 2003, Muths et al. 2003). Environmental red flags are no

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longer limited to remote tropical mountains or jungles that the average citizen cannot locate on maps (Stuart 2004). We can see the effects of environmental degradation at home. The good news is that although Rachel Carson raised an alarm call, she was optimistic that people could make positive changes. She believed in nurturing the human “sense of wonder” as a first step in developing a conservation ethic in citizens. We believe vernal pools are small (and wondrous) enough that they will capture the interest of local citizens. Spring choruses of wood frogs, salamander courtship dances, and fairy shrimp (a magical name to begin with) can instill a sense of wonder in children and adults alike. The inherent attractiveness and accessibility of vernal pools, coupled with the difficulty in regulating them, suggest community based conservation may be the most effective strategy for conserving these habitats. Community based conservation was a term widely used by environmental groups in the 1980s to describe international attempts to maintain biodiversity in developing countries while taking into account the needs of the local people (Gezon 1997; Brockington 2005). In North America we still tend to think of community based conservation as a paradigm for conserving biodiversity in developing countries where people directly sustain themselves on local resources (Alcorn 1993), yet loss of biodiversity due to land conversion is of increasing concern in our own backyards (Wilcove et al. 2000; Theobald 2003). In the U.S. and Canada, community based conservation is now used in terms of community forestry, grassroots ecosystem management, and collaborative conservation (Moseley 1999; Conley and Moote 2003). Snow (2001) states “collaborative conservation reaches across the great divide connecting preservation advocates and developers, commodity producers and conservation biologists, local residents, and national interest groups to find working solutions to intractable problems that will surely languish unresolved for decades in the existing policy system.” This statement focuses on the conservation process as well as outcomes and recognizes that outcomes will ultimately be identified and realized by the stakeholders. We embrace this community based approach to vernal pool conservation because conserving pools and adjacent terrestrial habitat used by pool-breeding amphibians involves multiple property owners and interests. Given the complexity of vernal pool habitat, and the difficulty of remotely identifying pool functions, involvement of local citizens is essential for effective conservation of pools (Berkes and Folke 2003). The purpose of this chapter is to illustrate how community based conservation using citizen scientists can effectively bring about conservation of vernal pool habitat. We discuss the role citizen science has played historically and how citizen science can advance vernal pool conservation, and we provide the framework for initiating a vernal pool conservation plan (the “how”). An example of a successful community based vernal pool conservation initiative in four New England towns is provided as a case study.

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COMMUNITY BASED CONSERVATION AND CITIZEN SCIENTISTS Citizen participation is the cornerstone of a democratic society (Arnstein 1969; Sclove 1998), so it is not surprising that citizen engagement in social–ecological issues (after Berkes 2004, humans as part of ecosystems) is burgeoning. Over the past 30 years, since the establishment of statutory environmental standards, public awareness of environmental issues has increased. If we are to maintain ecological services (e.g., clean air and water resources) critical to our long-term health, we can little afford to separate humans from nature in today’s human-dominated world (Sinclair et al. 2000; Kates et al. 2001; Gunderson and Holling 2002) Educating citizens on specific issues is now readily accomplished using the Internet, making even remote participation plausible (Stevenson et al. 2003). Citizens are often motivated to become involved at the local level because today many local governments play a lead role in land-use planning. Community based conservation can be a grassroots catalyst for change as responsible comprehensive plans and municipal ordinances that are attentive to important environmental issues are developed (Chapter 10, Mahaney and Klemens). Scientific personnel working on widespread environmental problems have recognized that an authoritative top–down management framework is ineffective (Ludwig 2001; Berkes 2002). The idea of complementing top–down resource management with a bottom–up participatory approach is an increasingly respected strategy and encourages building partnerships to bridge the gaps between local needs and the agendas of other stakeholders (Johnson 2000; Mackinson 2001; James 2002; Brosius and Russell 2003; Moore and Kuntz 2003). Inclusive, people-oriented, and community based approaches to conservation are in part a reaction to the failures of exclusionary, inflexible regulations (Ludwig 2001; Berkes 2004; Sclove 1998) and are growing in both the U.S. and Canada (Savan and Sider 2003).

CAN CITIZEN SCIENCE MAKE A DIFFERENCE? The term “citizen scientist” (citizens who collect scientific data according to standardized protocols) was coined in the 1990s by Dr. Rick Bonney at Cornell’s Laboratory of Ornithology to acknowledge citizen contributions to science and to engage the public in large bird population monitoring programs (Stevenson et al. 2003). For over 100 years citizens across North America have successfully collected data on natural phenomenon (e.g., flowering phenology, leaf-fall, migration events), documented presence/absence of wildlife (call surveys, tracking) and measured environmental soil, air or water variables (e.g., nitrogen in the water, pollen in the air) (Table 16.1). As environmental issues become increasingly complex (i.e., global warming, tracking population trends in amphibians or neotropical migrant birds), data collection on large spatial and temporal scales is often beyond the reach of individual researchers (see Pattengill-Semmens and Semmens 2003). Decision-makers have traditionally depended on these researchers to provide data to support their policy decisions. Unfortunately, such research may be detached from local specifics,

Keeping Track Monitoring Program (1994)

Cornell Laboratory of Ornithology Programs for Citizen Scientists (e.g., Backyard Bird Count, Birds in Forested Landscapes) Vermont

Audubon Society with partners in Cornell Lab of Ornithology, Bird Studies Canada, Humboldt Institute, and others Canada Wildlife Habitat Canada EMAN TD Friends of the Environment Foundation Canada, Mexico, and U.S.

Citizen tracking of large ranging mammals

The lab is a nonprofit membership institution whose mission is to interpret and conserve the Earth’s biological diversity through research, education, and citizen science focused on birds

Citizen data collection on water quality, frogs, butterflies, air quality for improving communities. Help decision-makers gather as much information as possible to make effective and sustainable choices in planning for our environment

All-day census of early-winter bird populations. Results compiled into the longest running database on trends of early winter bird populations across the Americas

Northeastern U.S.

Appalachian Mountain Club Citizen Science program (2005) Christmas Bird Count (1900)

Citizen Science Canada

To provide teachers, students and community groups with information resources and educational opportunities to conserve, restore and create wetland habitats Citizen monitoring of phenological events, air quality

Purpose

Banrock Station Wetlands Foundation Canada

Region/Partners

www.keepingtrack.org

http://www.birds.cornell.edu/

http:// www.citizenscience.ca/

http://www.audubon.org/ bird/cbc/

http://www.outdoors.org/ conservation/index.cfm

http://www.torontozoo.com/ adoptapond/

Web Site

322

Adopt-a-Pond

Program

TABLE 16.1 Selected Examples of Citizen Science Programs from around the Region

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Wetland Health Evaluation Program (1997)

Vermont Institute of Natural Science (VINS): Citizen Science Programs (1970) Minnesota

U.S. Partners The Nature Conservancy and guidance by the National Marine Fisheries Service Vermont

Canada and US; citizen-based

Canada, Mexico, and U.S.

Citizen monitoring of wetlands. Data are used by the Minnesota Pollution Control Agency to track wetland health throughout the Twin Cities metropolitan area

Long-term monitoring program designed to track the status and trends of frog and toad populations Provides up-to-date information on breeding bird surveys by state and province To educate and enlist divers in the conservation of marine habitats. The REEF Fish Survey Project allows volunteer SCUBA divers and snorkelers to collect and report information on marine fish populations To protect our natural heritage through education and research designed to engage individuals and communities in the active care of their environment

A suite of community-based or “citizen science” monitoring programs

Canadian Nature Federation/University of Guelph/Ecological Monitoring and Assessment Network (EMAN)

North American Amphibian Monitoring Program (1995) North American Breeding Bird Atlas Explorer Reef Environmental Education Foundation (REEF)(1990)

First national ecological measurement and observation system designed to answer regional to continental scale issues developing Citizen Science programs

U.S. nonprofit organization

National Ecological Observatory Network (NEON; ) Citizen Gateway Science (in development) NatureWatch (e.g., IceWatch, PlantWatch, WormWatch, FrogWatch) (1994)

Multiyear citizen odonate atlasing program

Purpose

Maine

Region/Partners

Maine Damselfly and Dragonfly Survey (19992004)

Program

www.mnwhep.org

http://www.vinsweb.org/cbd/ citizensci.html

http://www.pwrc.usgs.gov/ naamp/ http://www.pwrc.usgs.gov/ bba/ http://www.reef.org/index. shtml

http://www.naturewatch.ca/ english/

http://www.neoninc.org

http://mdds.umf.maine.edu/

Web Site

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time-consuming, data-poor and expensive. Citizen scientists provide local knowledge, local perspective on the issues, and the watchdog capacity needed to assess decision performance and evaluate change that directly affects conditions around them. Although there continues to be debate on the scientific merit of such data, in most cases the data collected by citizen science programs have been very credible and used effectively to draw attention to environmental concerns at the community level.

COMMUNITY BASED CONSERVATION OF VERNAL POOL HABITAT There are many challenges to vernal pool conservation at the local level. The current demand for instantaneous data and decision-making is problematic for conservation issues, such as vernal pool protection, that rely on baseline conditions and indicators of long-term change. Additionally, most vernal pools occur on private property (Dahl 2000) where externally imposed conservation may be perceived as a threat to landowner rights. Therefore, conservation at this level requires stakeholder education and involvement from the start. Planning for development and conservation of resources must go hand-in-hand. To date, community based monitoring of vernal pools has been limited in the U.S. and Canada. For example, a U.S. National Directory of volunteer environmental monitoring programs for aquatic resources identified 772 programs in 1998: only nine addressed vegetated wetlands, and even then the focus was on birds. Today citizen-based vernal pool conservation measures range from local road closings during peak amphibian migrations to wetland ordinances (Table 16.2), yet the majority of initiatives focus on public education or monitoring rather than long-term protection of vernal pool habitat. In this section, we provide guidance for communities interested in vernal pool conservation through communitywide planning using data collected by citizen scientists. Even though we cannot provide a cookbook approach to pool conservation, we can identify key steps in the process gleaned from our experience working with local communities. Details of the process and the ultimate implementation of a plan, however, will be shaped by the community itself. It is assumed that the community will have already embraced a goal of improving conservation of pool resources. We have identified five key steps for meeting this goal: (1) organizing a local vernal pool habitat conservation initiative which includes clear targets and a means for assessing success, (2) recruiting and retaining citizen scientists, (3) developing quality control measures to ensure project credibility, (4) conducting a vernal pool inventory and ecological assessment, and (5) putting the data to work. A brief discussion of each is presented below.

(1) ORGANIZING

A

LOCAL CONSERVATION INITIATIVE

First, one must define “local.” For vernal pool issues, the scale (e.g., village, town, municipality, watershed, province) will be dictated by logistical constraints and political realities: how much area can be part of a project and still be effectively

Vermont Department of Fish and Wildlife/Bonnyvale Environmental Education Center Canadian Biosphere Reserves Association with partners Ontario Niagra Escarpment and University of Guelph New Jersey Rutgers University and Conserve Wildlife Foundation Ohio Environmental Council and The Nature Conservancy Ontario, Canada

New York and Pennsylvania Federal, state, and local partners Maine Maine Audubon Soiciety, University of Maine

Jefferson Salamander Monitoring (2003)

New Jersey Fish and Wildlife Vernal Pool Mapping Project (2002)

Ohio Vernal Pool Partnership (2005)

Ontario Vernal Pool Association (2004)

Upper Susquehanna Coalition Vernal Pool Page (1992)

Very Important Pool Program (1999–2004)

Region/Partnership

“Big Night” Salamander Crossings Brigades Project (2002)

Program (Inception)

TABLE 16.2 Examples of Vernal Pool Citizen-Science Initiatives in the Region

Citizen monitoring of vernal pools around the state for five years

To create a database of vernal pools in an effort to better understand their functions

Community-based conservation of vernal pools through education, partnerships, science Promote education, study, and protection of vernal pool habitats

Project to revisit the 1991 Jefferson sites and investigate other potential habitat to identify where Jefferson Salamanders occur along the Escarpment Citizen mapping of New Jersey vernal pools

Citizen crossing guards for amphibians migrating to breeding pools

Purpose

www.maineaudubon.org

http://www.u-s-c.org/ html/vernalpoolpage.htm

http://www.ontariovernalpools. org/

www.ovpp.org

http://www.state.nj.us/dep/ fgw/vpoolart.htm

http://www.escarpment.org/ Monitoring/salamanders.htm

http://www.beec.org/projects.h tml#reptile

Web Site

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surveyed and managed through local conservation strategies? After that question is answered, partners and stakeholders should be identified. Local conservation of vernal pool habitat requires leaders (town or project initiators) who cultivate partnerships and involve stakeholders. Partnerships can open doors to financial support, logistical support, and lend a project broader credibility with the public and potential funders. Stakeholders are all those who might be affected by the conservation planning. These might include state, provincial, or federal agencies, environmental organizations, land trusts, land-use/policy organizations, consultants, developers, scientists, educators, citizens, and resource land owners (after Preisser et al. 2000, and see Rubec 2003). Stakeholders should be involved from the inception of the project. In this way, stakeholders become champions for the initiative and are more likely to “trust” data collected by citizens. Organizers must identify how pool conservation efforts fit into local land-use planning and produce clear objectives/outcomes that can be shared with stakeholders and the media. Once the goal is clear (i.e., identify, survey and map all vernal pools or develop a vernal pool ordinance), organizers must decide what inventory and assessment tools and protocols to use (see Appendix A for examples of Best Management Practice literature and other guides). Also, organizers may decide to include vernal pool resources in existing regional habitat mapping projects (e.g., Beginning with Habitat [Maine], Wildlife Habitat Canada). Having selected a method for vernal pool inventory and assessment, an organizer must then become familiar with the administrative structure of the local government, who should be involved in the project (e.g., town planner or manager, town council) and identify who should be notified about the project (e.g., town council, land trusts, conservation commission; see Vasseur et al. 1997). At this stage, key partners and stakeholders (and eventually landowners with pools) must be educated about the vernal pool resource and may be enlisted to help define the project path. Having the support and trust of local landowners is key to the success of a project. These are developed through informational workshops, presentations to local governing units and project planning meetings. Landowners should be invited to organizational meetings and field visits. Administrative and technical support may be provided by the partners, the municipality, or a combination of both. Administrative duties include providing a clearinghouse for disseminating information to citizen scientists, the public, and stakeholders, and managing the database (including processing citizen data) and mapping of the resource, preferably using a Geographic Information System [GIS]. The town, municipality or administrative unit should then work closely with the partners and citizens to guide the rest of the project. Clear targets should be identified by the project organizers. In this way, partners and stakeholders know what outcomes to expect and citizens have a clear goal to meet. A target may range from mapping all the pools in a town to conserving 20% of all pools in a town to a comprehensive wetland ordinance. Organizers should also put in place a means of assessing success and redressing failures.

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(2) ENGAGING

AND

327

RETAINING CITIZEN SCIENTISTS

A prime objective of local vernal pool initiatives has been to develop an educated citizenry capable of making informed decisions about conserving local vernal pools. To engage citizens, project leaders must clearly communicate the project goal and the means by which to accomplish the goal. Clear organization, standardized protocols and operating procedures and predetermined reporting strategies will ensure that citizen volunteers see progress and feel part of a defined project that has a realistic outcome. Still, people volunteer for a variety of reasons, and it can be challenging to engage and retain citizen scientists. Important issues for citizens are those that directly affect them, their families, or the quality of their community. To engage citizens in giving their time and efforts to vernal pool conservation the message must be enticing and the incentives compelling. We suggest the following approach to encourage engagement: •

•

•

Create an interest by elevating and fostering public awareness to raise “vernal pool literacy.” Within the community, popularize the ecological and educational benefits of vernal pools. For example, an appreciation of vernal pool ecology can be increased through media coverage of amphibian migrations, distribution of visually appealing citizen guides, newspaper articles about vernal pool projects, newsletters, mailings, listserves, phone calls, and presentations (see Appendix A for citizen resources on vernal pools). Instill a sense of ownership and responsibility. Citizens can be inspired by what project leaders say and how they say it. Citizen scientists must feel that their work makes a difference and that they are valued contributors. Convey the concept of a sense of place, how vernal pool wildlife enhances local biodiversity and landscape health (Chapter 15, Gruner and Haley), the vulnerability of vernal pools and their inhabitants, and the ability for citizens to make a difference for future generations through proactive participation. It is important to help the public understand specific human impacts to the vernal pool system (e.g., in watershed terms, “We all live downstream!”). A personal stake will motivate volunteers to actively participate in vernal pool conservation. Provide training for goal-oriented projects. Teach skills needed to achieve the objective through workshops, illustrated manuals, Web-based field guides and protocols. Help the public understand its ability to act and affect change regarding vernal pool conservation through their participation. Provide inspiring examples of citizen projects.

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•

Put on a public face. Publish accounts of the project in local newspapers, brochures, Web sites, and magazines (e.g., NEON Citizen Science Magazine, the Web-based Journal of Citizen Science). Promote a sense of accomplishment and pride to project participants with high profile articles and accounts. Encourage citizen scientists to write letters to the editor, to speak with local reporters about their work, and to host tours of local pools.

Offer a variety of avenues for involvement and encourage citizen scientists to participate wherever they feel comfortable. Citizens will likely stay with the project if they feel they are having a fulfilling hands-on experience with a biological system and if the research is relevant. Does their work increase knowledge of the resource and direct stewardship of the surrounding environment? Will the collection of data document baseline conditions that may be used to monitor changes over time? And will the results be used in community planning and decision making? The ability to influence policy at the local level and to have a role in making sure the decisions address citizen and stakeholder concerns is a compelling reason to stay involved. More specifically: •

•

Encourage further involvement. Provide opportunities to be actively involved in the field (collecting data) and in the public arena (influencing local or state/provincial policies, laws, and decisions). Encourage citizens to serve on municipal committees or boards responsible for identifying high priority conservation lands or reviewing development activities; help conduct scientific research; write or solicit newspaper or magazine articles about the ecology and conservation of vernal pools; work with youth groups and/or school groups to inventory local pools; and testify before a local, provincial, or state board about the importance of pools. Many citizens in our vernal pool monitoring programs have become active on these fronts. Communicate results and provide feedback. Continually provide citizen scientists, landowners, and stakeholders with documentation of their contributions and appreciation for their efforts. It is critical that volunteers can view data they have collected and visualize the broader impacts of the information they have generated. Landowners should receive a formal letter of acknowledgment and a copy of the data collected from their land. A presentation that includes the results of the project and production of a GIS data layer representing citizen data are effective visual feedback mechanisms. GIS capability is becoming more common in rural towns and will be a powerful tool to most in the future (Chapter 14, Baldwin et al.). Some towns have created Web pages that highlight their vernal pool accomplishments (see Case Study).

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(3) QUALITY CONTROL

OF

329

DATA

Quality control methods for data collected by volunteers are well-developed. Many community based projects adopt protocols used by state or provincial agencies. For example, NatureWatch (activities monitored through partnership with University of Guelph, Nature Canada, and the Ecological Monitoring and Assessment Network [EMAN]) uses EMAN protocols rewritten for lay people. The U.S.-based National Ecological Observatory Network (NEON) Citizen Science Gateway endorses projects that meet set criteria for data collection (IBRCS 2003). Vernal pool monitoring protocols have been developed for monitoring pondbreeding amphibians in the north-central U.S. (see Knutson et al. 2002) and for monitoring wood frog and spotted salamander populations in the northeastern U.S. (see USGS Amphibian Research and Monitoring Initiative [ARMI] egg mass counting protocol and Managers Monitoring Manual for Egg Mass Surveys [http://www.pwrc.usgs.gov/monmanual/techniques/eggmass.htm]). Frogwatch is a community based program in Canada managed by Nature Canada and EMAN. Data sheets and collection protocols are also provided in a number of vernal pool citizen guides (Kenney 1995; Tappan 1997; Calhoun and Klemens 2002; Calhoun 2003). To ensure reliable data, volunteers should be provided with written protocols for each stage of the data collection. Biological assessments should be documented with photographs of indicator species and egg masses. Digital photographs of pools and the immediate surrounding habitat are also useful for creating baseline information that can be used to document changes in pool habitat over time. (All equipment for the monitoring programs should be available to the participants at no cost as an incentive to participate.) To ensure quality data, organizers must invest time in training volunteers in the field. Project leaders must work with volunteers to practice filling out data forms and to locate and count egg masses. Well-trained citizen scientists can collect reliable information on vernal pool breeding fauna (Oscarson and Calhoun 2007). Oscarson and Calhoun (2002) found no statistically significant differences between volunteer and biologist egg mass counts and indicator species identification in his study in southern Maine.

(4) CONDUCTING

THE

VERNAL POOL INVENTORY

AND

ASSESSMENT

Communities may develop their own inventory and assessment criteria or adapt existing ones. Calhoun and Klemens (2002), for example, recommend a tier-rating system for pools based on both pool biological criteria and condition of the adjacent terrestrial habitat (Table 16.3). Pools supporting larger breeding populations of target amphibian species (determined through egg mass counts) and that have a relatively intact adjacent terrestrial habitat are rated as Tier 1, or having the highest priority for conservation. The priority rating system assumes that communities will not be able to conserve every pool and provides planners with a tool to predict which pools may provide the greatest long-term support of pool-breeding amphibians. This model could easily be adapted to community needs. For example, the biological criteria suggest egg mass thresholds for determining biological significance, but egg mass

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TABLE 16.3 Vernal Pool Assessment Sheet VERNAL POOL ASSESSMENT SHEET A. Biological Value of the Vernal Pool (1) Are there any state-listed species (Endangered, Threatened, or Special Concern) present or breeding in the pool? Yes______ No__________ (2) Are there two or more vernal pool indicator species breeding (i.e., evidence of egg masses, spermatophores [sperm packets], mating, larvae) in the pool? Yes______ No__________ (3) Are there 25 or more egg masses (regardless of species) present in the pool by the conclusion of the breeding season? Yes______ No__________ B. Condition of the Critical Terrestrial Habitat (1) Is at least 75% of the land 100 feet from the pool undeveloped? Yes______ No__________ (2) Is at least 50% of the habitat from 100–750 feet of the pool undeveloped? Yes______ No__________ NOTE: For these purposes, “undeveloped” means open land largely free of roads, structures, and other infrastructure. It can be forested, partially forested, or open agricultural land. C. Cumulative Assessment Number of Questions Answered YES in Category A 1–3 1–3 0 1–3

Number of Questions Answered YES in Category B

Tier Rating (I = Highest Priority)

2 1 1–2 0

Tier I Tier II Tier III Tier III

Source: Calhoun et al. 2002. With permission.

numbers may vary regionally (Calhoun et al. 2003). A community may adjust these numbers to reflect existing or proposed state, county, or provincial regulations. Similarly, invertebrate or plant pool indicators could be incorporated into the biological criteria (Chapter 6, Colburn et al.; Chapter 5, Cutko and Rawinski). Disturbance to critical terrestrial habitat should be included in the rating calculations, but again, the nature and thresholds for disturbance can change with the science and may need to be rated relative to other available habitats (Calhoun et al. 2005). For example, in some development situations, it might be appropriate to designate management zones around the pool (see Figure 12.3) that incorporate known terrestrial habitat rather than using concentric circle zoning approach (Chapter 12,

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Windmiller and Calhoun; Baldwin et al. 2006). The key is to base the assessment on the best available science and to tailor it to the goals of the community.

Case Study By Damon B. Oscarson Westchester Land Trust Bedford Hills, NY New England Citizen Scientists Work to Develop Local Vernal Pool Conservation Plans The town of Falmouth, ME, and the towns of Farmington, Simsbury, and Suffield, CT, formed partnerships with the University of Maine and nongovernmental environmental groups to inventory and assess their vernal pool resources. The Connecticut towns established a partnership with the Farmington River Watershed Association (FRWA) and the Metropolitan Conservation Alliance, a program of the Wildlife Conservation Society. The town of Falmouth was assisted by Maine Audubon Society. We selected town planners or members of conservation commissions to coordinate activities and manage volunteers as they were familiar with the town planning processes, active in local conservation, and were willing to recruit and manage volunteers within their town. Potential vernal pools were remotely identified using aerial photography. Landowners were contacted to request permission to gain access to privately owned pools. Local coordinators in each town recruited volunteers by contacting local naturalists and ecologists, educators, and other active members of the community. Volunteer training sessions, which included field visits, were conducted prior to the field season. Identified pools were assigned to each volunteer along with maps, field data sheets and various field guides to assist in pool surveys. A ListServ was created to facilitate communication among volunteers, coordinators, biologists, and principal investigators. Volunteers surveyed vernal pools in early April 2003 in Connecticut and mid-April 2003 in Maine and were required to collect data on pools twice during the season (Figure 16.1). Data on biological value, number of egg masses per breeding amphibian species, state-listed species, and other pool indicators) and the condition of the terrestrial habitat surrounding the pool were gathered in the field. Tier ratings (assigning relative conservation priority) were assigned to each pool surveyed, based on biological value and the condition of the terrestrial habitat reported in the volunteer data sheets. Results Fifty-two volunteers surveyed 382 vernal pools. Of the 382 potential surveyed pools, 262 (69%) were confirmed as vernal pools. Volunteers in this study were able to accurately collect biological and physical data on vernal pools in the field. Data from each pool were entered into a GIS database and delivered to each town (Figure 16.2). All four towns have begun to propose and develop conservation plans and apply conservation mechanisms to protect high priority vernal pools. The Connecticut towns are working to incorporate the vernal pool data along with other biological data sets into a regional ongoing Farmington Valley Biodiversity Project. Results from the Biodiversity Project are being used to identify priority areas within each town to focus conservation efforts, and to guide town planners in how to incorporate the results within the municipal

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FIGURE 16.1 Volunteer field-training session. Damon Oscarson instructs citizen scientists in Connecticut on how to fill out data collection forms.

FIGURE 16.2 Final map of the 2004 vernal pool assessment conducted in one of our study towns in Connecticut. Tier 1 pools are the highest conservation priority based on egg mass abundance and quality of the adjacent terrestrial habitat. Tier 2 and 3 pools are lower priority but may provide restoration opportunities or, in the absence of Tier 1 pools, be critical for conserving pool-breeding species.

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planning and regulatory process. In Maine, the town of Falmouth has recently passed amendments to their Zoning and Site Plan Review Ordinance which includes a Resource Conservation Zoning Overlay District (RCZOD). The new RCZOD covers the remaining undeveloped areas in the town and sets standards for subdivisions to preserve areas on each site which have high natural resource value. These Conservation Subdivisions allow for cluster development and require 50% of the residential area plus the unsuitable area to be set aside for open space preservation. The open space area must contain important conservation areas which include vernal pools and their associated upland habitat mapped by the town. The Falmouth Conservation Commission has also formed a Vernal Pool Subcommittee to discuss and pursue other conservation strategies. The commission has published a vernal pool brochure and created a Web site to educate the public about efforts to protect vernal pools in their town.

Inventory We suggest the following steps for completing a successful vernal pool inventory. Our focus is on conserving vernal pool landscapes and because of this, for the development of guidelines, we have used the life history needs of breeding amphibians that require habitat beyond the pool. Many protections are based on abundance of egg masses and presence of breeding amphibians. Communities wishing to do detailed invertebrate or water chemistry studies will have to develop different protocols in addition to these (see protocols at http://www.anr.state.vt.us/dec/waterq/bassvernal.htm; Burnham and Sorenson 2003). Locate Existing Data Natural resources maps from ENGOs (environmental nongovernmental groups), state or provincial agencies should be reviewed. Data on vernal pools may be available from consulting firms, land trusts, or municipal projects that have identified natural resources for planning purposes. Obtain Recent Aerial Photography and Photointerpret Potential Pools Potential pools should be identified using recent, spring, leaf-off color infrared photography at a scale of 1:4800 or 1:12000 (see Chapter 4, Burne and Lathrop for details). Other types of aerial photographs may be used but are less desirable. Photointerpretation may have to be outsourced if the expertise does not exist at the local level. Protection of vernal pools and most small isolated wetlands is, in part, limited by a resource manager’s ability to map them on a large scale (Grant 2005). As a result, many New England states and New Jersey have started mapping vernal pools and soliciting citizen involvement (Burne 2001; Tappan and Marchand 2004; Lathrop et al. 2005 ). Citizens can improve the accuracy of aerial photointerpretation through local knowledge and with field-verifications. For example, the Rutgers University Center for Remote Sensing and Spatial Analysis (in New Jersey) has developed an interactive Internet mapping site to aid the state and its citizens in conducting surveys (see Lathrop et al. 2005).

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Produce a Master Map of Potential Pools It is critical to have a map of all potential pools within the project area for citizens to view. Each pool should be assigned an identification number. Local knowledge will be invaluable in refining these maps. Determine Ownership of Each Potential Pool Contact the landowner for permission to assess the pool or pools on her or his property. A letter requesting permission for access should include a summary of the project highlighting its benefits to the landowner and the community, an invitation to the owner to attend an informational workshop on the project, and assurance that the property will be undisturbed by the assessment. Even if the pool is on public land, it is best to contact the owner or managers of the lands. Assessment Completing an assessment of the pool resources will require indoor and outdoor citizen-training sessions and a strong volunteer support network. Here is a framework that can be modified according to project goals: 1. Conduct the indoor volunteer training workshop in late winter/early spring. Training should include a presentation on vernal pool ecology, egg mass, amphibian, and invertebrate identification, and should supply protocols for preventing the spread of amphibian diseases (see the Declining Amphibian Populations Task Force code of practice on preventing spread of disease). At this session, volunteers should learn how to fill out data sheets and receive guidance on when and how often to collect data. Details on successful training sessions are discussed in Oscarson and Calhoun (2007), and they include establishing a volunteer electronic list-serve, volunteer access to expert advice throughout the project, and field support. 2. Recruit a volunteer coordinator (either from the municipality or the citizen scientists) who will be responsible for encouraging volunteers, following up on progress made at each sampling period, and for collecting data at the end of the field season. Volunteer coordinators may also solve problems (trouble finding pools, confusion over data). 3. Hold a field-based workshop after the wood frogs have laid eggs (ambystomatid salamanders lay eggs less explosively and should be counted at least two weeks after wood frog counts). During this session, volunteers will gather to determine pool assignments. Only those pools for which access is granted should be inventoried. Usually volunteers are familiar with the town and landowners and will choose pools close to home or associated with people they know. After pool assignments are made, volunteers should inventory a pool with an expert and practice filling out data sheets. Sampling protocols for counting egg masses are published on-line (see USGS, Amphibian Research and Montoring Initiative http://armi.usgs.gov/). This field experience is critical. In addition, it may

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be necessary to have a biologist on call who is willing to assist volunteers in the field as needed. 4. Provide a mechanism for volunteers to include pools that may have been missed through photointerpretation. 5. Enter data into a spreadsheet, calculate assessment ratings, and develop spatial maps using GIS technology. Ideally, data and photos from each pool can be linked to the pool locations using GIS. If GIS is not available, overlay maps can be created.

CONSERVATION RECOMMENDATIONS (5) PUTTING

THE

DATA

TO

WORK

Following inventory and assessment, a community will have a vernal pool data layer to incorporate into its GIS database or other spatial planning tools. We recommend using the data to effect on-the-ground local conservation of vernal pools. Translation of these data into conservation will be as varied as the political units and communities involved, and will range from voluntary adherence to Best Management Practices to local regulation through ordinances (see Colburn 2004). When possible, existing templates should be used to help the group craft a plan. Section III of this book provides detailed information for communities on how to conserve pools once a vernal pool database is in place. Chapter 10 summarizes federal and provincial regulations and local strategies for pool conservation; Chapter 11, Chapter 12, and Chapter 13 discuss specific land-use activities that should and should not occur in vernal pool habitats and suggest management guidelines; and Chapter 14 presents some innovative ideas for applications of spatial modeling tools to conservation planning. Because of local knowledge and interest, conservation planning at the local level can be much more effective with input from citizen scientists than when regulated from afar by a regional, state, or provincial governmental body. How far a community taps into the skills of this work force is dependent upon the community. Completion of the inventory and assessment of vernal pools is a major first step to conservation planning. We emphasize that the vernal pool inventory should be used to identify the characteristics of exemplary pools in your region. Biological and terrestrial conditions may vary from region to region. If communities use a tier-rating system as in Calhoun and Klemens (2002), they should be flexible in their approaches to conservation. For example, if a community has very few Tier 1, or high priority pools, they should look for restoration opportunities and may want to concentrate efforts on some pools with lower priority ratings (restoration examples can be found at the Ohio Vernal Pool Partnership or the Ontario Vernal Pool Association). We cannot provide the formula for effecting conservation in your community, but we do provide an example of a successful project in New England that might provide some inspiration (see Case Study).

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SUMMARY Citizen scientists can be successfully trained to conduct vernal pool inventories and assessments as a baseline for developing local vernal pool habitat conservation plans. The key to successful local initiatives is to engage conservation partners and to include stakeholders in the planning and implementation process. We recognize five key steps to developing local vernal pool resource protection: (1) organizing a local vernal pool habitat conservation initiative (with clear objectives or targets), (2) recruiting and retaining citizen scientists, (3) developing quality control measures to ensure project credibility, (4) conducting the vernal pool inventory and ecological assessment, and (5) putting the data to work. Currently many vernal pool identification resources and informational documents exist (most are also Web-based) making citizen engagement and education a mere matter of exposure. Local protection strategies are more effective and comprehensive than higher level governmental regulations and ultimately will make the conservation of resources part of the economic development and fabric of community life.

ACKNOWLEDGMENTS We acknowledge all the dedicated citizen scientists who have participated in vernal pool conservation projects throughout our region and who have been the inspiration for this chapter. We also acknowledge the many partners dedicated to wetland conservation and citizen science and education who have worked with the authors including the Farmington River Watershed Association, Maine Audubon Society, Science Center of Connecticut, the Metropolitan Conservation Alliance, the towns of Falmouth, ME, and Farmington, Suffield, and Simsbury, CT. Special thanks to Hank Gruner, Michael Klemens, Damon Oscarson, and Sally Stockwell for their leadership and dedication to community based conservation. We also thank Dr. Stockwell for her thoughtful review of this manuscript.

REFERENCES Alcorn, J.B. (1993). Indigenous peoples and conservation. Conservation Biology 7: 424–426. Arnstein, S.R. (July 1969). Ladder of citizen participation. AIP Journal 216–224. Baldwin, R., Calhoun, A.J.K., and deMaynadier, P.G. (2006). Conservation planning for amphibian species with complex habitat requirements: a case study using movements and habitat selection of the wood frog (Rana sylvatica). Journal of Herpetology 40: 443–454. Berkes, F. (2002). Cross-scale institutional linkages: perspectives from the bottom up. In Ostrom, E., Dietz, T., Dolsak, N., Stern, P.C., Stonich, S., and Weber, E.U. (Eds.). The Drama of Commons, National Academy Press, Washington, D.C., pp. 291–321. Berkes, F. (2004). Rethinking community based conservation. Conservation Biology 18: 621–630. Berkes, F. and Folke, C. (Eds.) (2003). Navigating Social-Ecological Systems: Building Resilience for Complexity and Change. Cambridge University Press, Cambridge.

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Brockington, D. (2005). Politics and ethnography of environmentalisms in Tanzania. African Affairs 105/481: 97–116. Brosius, J.P. and Russell, D. (2003). Conservation from above: an anthropological perspective on transboundary protected areas and ecoregional planning. Journal of Sustainable Forestry 17: 39–66. Burne, M.R. (2001). Massachusetts Aerial Photo Survey of Potential Vernal Pools. Natural Heritage and Endangered Species Program, Department of Fisheries and Wildlife. Westborough, MA. Burnham, D. and Sorenson, E. (2003). Vermont Wetlands Bioassessment Program: An Evaluation of the Chemical, Physical, and Biological Characteristics of Seasonal Pools and Northern White Cedar Swamps. Final Report. Vermont Department of Environmental Conservation and Vermont Department of Fish and Wildlife, Nongame and Natural Heritage Program, Waterbury, VT. Calhoun, A.J.K. and Klemens, M.W. (2002). Best Development Practices: conserving poolbreeding amphibians in residential and commercial developments in the northeastern United States. MCA Technical Paper No. 5, Metropolitan Conservation Alliance, Wildlife Conservation Society, Bronx, New York. Calhoun, A.J.K., Walls, T., McCollough, M., and Stockwell, S. (2003). Developing conservation strategies for vernal pools: a Maine case study. Wetlands 23: 70–81. Calhoun, A.J.K., Miller, N.A., and Klemens, M.W. (2005). Conserving pool-breeding amphibians in human-dominated landscapes through local implementation of Best Development Practices. Wetlands Ecology and Management 13: 291–304. Carson, R. (1962). Silent spring. Houghton Mifflin, Boston, MA. Colburn, E.A. (2004). Vernal Pools: Natural History and Conservation. McDonald and Woodward Publishing, VA. Collins, J.P. and Storfer, A. (2003). Global amphibian declines: sorting the hypotheses. Diversity and Distribution 9: 89–98. Conley, A. and Moote, M.A. (2003). Evaluating collaborative natural resource management. Society and Natural Resources 16: 371–386. Dahl, T.E. (2000). Status and trends of wetlands of the conterminous United States 1986–1997. U.S. Fish and Wildlife Service, Office of Biological Service, Washington, D.C. Gezon, L. (1997). Institutional structure and the effectiveness of integrated conservation and development projects: case study from Madagascar. Human Organization 56: 462–470. Grant, E.H.C. (2005). Correlates of vernal pool occurrence in the Massachusetts, USA landscape. Wetlands 25: 480–487. Gunderson, L.H. and Holling, C.S. (2002). Panarchy: Understanding Transformations in Human and Natural Systems. Island Press, Washington, D.C. IBRCS [Infrastructure for Biology at Regional to Continental Scales Working Group.] (2003). Rationale, blueprint, and expectations for the National Ecological Observatory Network. IBRCS White Paper, American Institute of Biological Sciences. James, S.M. (2002). Bridging the gap between private landowners and conservationists. Conservation Biology 16: 269–271. Johnson, M.D. (2000). A sociocultural perspective on the development of U.S. natural resource partnerships in the 20th century. USDA Forest Service Proceedings, RMRS-P-13. Kates, R.W., Clark, W.C., Corell, R., Hall, J.M., Jaeger, C.C., Lowe, I., McCarthy, J.J., Schellnhuber, H.J., Bolin, B., Dickson, N.M., Faucheux, S., Gallopin, G.C., Grübler, A., Huntley, B., Jäger, J., Jodha, N.S., Kasperson, R.E., Mabogunje, A., Matson, P., Mooney, H., Moore, B., III, O’Riordan, T., and Svedin, U. (2001). Sustainablility science. Science 292: 641–642.

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Kenney, L.P. (1995). Wicked Big Puddles: A Guide to the Study and Certification of Vernal Pools. Reading Memorial High School-Vernal Pool Association, Reading, MA. Knutson, M.G., Lyon, J.E., and Parmelee, J.R. (2002). Resources for monitoring pondbreeding amphibians in the northcentral USA in Farm ponds as critical habitats for native amphibians: final report. Submitted to the Legislative Commission on Minnesota Resources by U.S. Geological Survey Upper Midwest Environmental Sciences Center, La Crosse, WI. Lathrop, R.G., Montesano, P., Tesauro, J., and Zarate, B. (2005). Statewide mapping and assessment of vernal pool: a New Jersey case study. Journal of Environmental Management 76: 230–238. Ludwig, D. (2001). The age of management is over. Ecosystems 4: 758–764. Mackinson, S. (2001). Integrating local and scientific knowledge: an example in fisheries science. Environmental Management 27: 533–545. Moore, E.A. and Koontz, T.M. (2003). A typology of collaborative watershed groups: citizenbased, agency-based, and mixed partnerships. Society and Natural Resources 16: 451–460. Moseley, C. (1999). New Ideas, Old Institutions: Environment, Community, and State in the Pacific Northwest. Ph.D. dissertation, Yale, New Haven, CT. Muths, E.E., Corn, P.S., Pessier, A.P., and Green, D.E. (2003). Evidence for disease-related amphibian decline in Colorado. Biological Conservation 110: 357–365. Oscarson, D. and Calhoun, A.J.K. (2007). Developing vernal pool conservation plans at the local level using citizen scientists. Wetlands 27: 80–95. Pattengill-Semmens, C.V. and Semmens, B.X. (2003). Conservation and management of the reef volunteer fish monitoring program. Environmental Monitoring and Assessment 81: 43–50. Preisser, E.L., Kefer, J.Y., Lawrence, J.D., and Clark, T.W. (2000). Vernal pool conservation in Connecticut: an assessment and recommendations. Environmental Management 26: 503–513. Rubec, C.D.A. (compiler). (2003). Wetland stewardship in Canada. Contributed papers from the conference on Canadian wetlands stewardship. Report No. 03-2. North American Wetlands Conservation Council, Ontario, Canada. Savan, B. and Sider, D. (2003). Contrasting approaches to community based research and a case study of community sustainability in Toronto, Canada. Local Environment 8: 303–316. Sclove, R.E. (1998). Better approaches to science policy. Science 279: 1283. Sinclair, A.R.E., Ludwig, D., and Clark, C.W. (2000). Conservation in the real world. Science 289: 1875. Snow, D. (2001). Coming home: an introduction to collaborative conservation. In Brick, P., Snow, D., and Van de Wetering, S. (Eds.). Across the Great Divide: Explorations in Collaborative Conservation and the American West. Island Press, Covelo, CA, pp. 1–11. Stevenson, R.D., Haber, W.A., and Morris, R.A. (2003). Electronic field guides and user communities in the ecoinformatics revolution. Conservation Ecology 7: 3. [online] URL: http://www.consecol.org/vol7/iss1/art3. Stuart, S.N. (2004). Status and trends of amphibian declines and extinctions worldwide. Science 306: 1783. Tappan, A. (Ed.) (1997). Identification and Documentation of Vernal Pools in New Hampshire. New Hampshire Fish and Game Department, Nongame and Endangered Species Program, Concord, NH.

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Tappan, A. and Marchand, M. (2004). Identification and Documentation of Vernal Pools in New Hampshire (2nd ed.). New Hampshire Fish and Game Department, Nongame and Endangered Wildlife Program. Concord, NH. Theobald, D.M. (2003). Targeting conservation action through assessment of protection and exurban threats. Conservation Biology 17: 1624–1637. Vasseur, L., LaFrance, L., Renaud, D., Morin, D., and Audet, T. (1997). Advisory committee: a powerful tool for helping decision makers in environmental issues. Environmental Management 21: 359–365. Wilcove, D.S., Rothstein, D., Dubow, J., Phillips, A., and Losos, E. (2000). Leading threats to biodiversity: what’s imperiling U.S. species. In Stein, B.A., Kutner, L.S., and Adams, J.S. (Eds.). Precious Heritage: The Status of Biodiversity in the United States. Oxford University Press, Oxford, pp. 239–254.

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APPENDIX 16.1 INFORMATIONAL RESOURCES FOR CITIZEN SCIENTISTS AND MUNICIPALITIES ENGAGED IN VERNAL POOL CONSERVATION PLANNING VERNAL POOL CITIZEN GUIDES* Brown, L.J. and Jung, R.E. (2005). An introduction to Mid-Atlantic seasonal pools. U.S. Environmental Protection Agency, Mid-Atlantic Integrated Assessment, Ft. Meade, MD. EPA/903/B-05/001. Burne, M.R. (2001). Massachusetts Aerial Photo Survey of Potential Vernal Pools. Natural Heritage and Endangered Species Program, Department of Fisheries and Wildlife. Westborough, MA. Calhoun, A. (2003). Maine Citizen’s Guide to Locating and Describing Vernal Pools. 3rd ed. Maine Audubon Society, Falmouth, ME. Calhoun, A.J.K. and deMaynadier, P. (2003). Forestry habitat management guidelines for vernal pool wildlife in Maine. Maine Department of Inland Fisheries and Wildlife. Wildlife Conservation Society Technical Paper No. 6 Rye, New York. Calhoun, A.J.K. and Klemens, M.W. (2002). Best Development Practices for pool-breeding amphibians in commercial and residential developments. Wildlife Conservation Society Technical Paper No. 5. Rye, New York. Colburn, E.A. (Ed.) (1997). Certified: A Citizen’s Step-by-Step Guide to Protecting Vernal Pools. 7th ed. Massachusetts Audubon Society, Lincoln, MA. Donahue, D.F. (1997). Guide to the Identification and Protection of Vernal Pool Wetlands of Connecticut. Connecticut Forest Stewardship Program, CT. Kenney, L.P. (1995). Wicked Big Puddles: A Guide to the Study and Certification of Vernal Pools. Reading Memorial High School—Vernal Pool Association, Reading, MA. Marchand, M.N. (Ed.) (2004). Identification and Documentation of Vernal Pools in New Hampshire, 2nd ed. NH Fish and Game Department, Nongame and Endangered Species Program. Stone, J.S. (1992). Vernal Pools in Massachusetts: Aerial Photographic Identification, Biological and Physiographic Characteristics, and State Certification Criteria. M.S. thesis. University of Massachusetts, Amherst, MA. Tesauro, J. (2004). New Jersey’s vernal pools. New Jersey Division of Fish and Wildlife, Endangered and nongame species program. http://www.njfishandwildlife.com/epsp/ pdf/vernalpool03.pdf.

SELECTED FIELD GUIDES

TO

VERNAL POOL FAUNA

Bishop, S.C. (1969). Handbook of Salamanders: The Salamanders of the United States, of Canada, and of Lower California. Comstock Publishing Associates, Ithaca, New York. Conant, R. and Collins, J.T. (1998). A Field Guide to Reptiles and Amphibians: Eastern and Central North America. 3rd ed. Peterson Field Guide Series. Houghton Mifflin Co., New York. Cook, F.R. (1967). An analysis of the herpetofauna of Prince Edward Island. National Museum of Canada Bulletin 212. * Many resources are available online.

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Cook, F.R. (1984). Introduction to Canadian Amphibians and Reptiles. National Museum of Natural Sciences, Ottawa, Ontario, CA. DeGraaf, R.M. and Rudis, D.D. (1983). Amphibians and Reptiles of New England: Habitats and Natural History. University of Massachusetts Press, Amherst, MA. Gilhen, J. (1983). The Amphibians and Reptiles of Nova Scotia. Nova Scotia Museum, Halifax, NS, Canada. Gorham, S.W. (1970). The amphibians and reptiles of New Brunswick. New Brunswick Museum, Saint John, NB, Canada. Hunter, M.L., Jr., Calhoun, A.J.K., and McCollough, M. (Eds.). (1999). Maine Amphibians and Reptiles. University of Maine Press, Orono, ME. Kenney, L.P. and Burne, M.R. (2000). Field Guide to the Animals of Vernal Pools. Massachusetts Division of Fisheries and Wildlife, Natural Heritage and Endangered Species Program and Vernal Pool Association, Westborough, MA. Klemens, M.W. (1993). Amphibians and reptiles of Connecticut and adjacent regions. State Geological and Natural History Survey, New York. Massachusetts Audubon Society. (1995). Pondwatchers: Guide to Ponds and Vernal Pools of Eastern North America. Lincoln, MA. www.umassextension.org. Wright, A.H. and Wright, A.A. (1949). Handbook of Frogs and Toads of the United States and Canada. Comstock Publishing Associates, Ithaca, New York.

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Section IV Index

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Index Note: Italicized page numbers refer to tables and illustrations.

A Acadian-Appalachian Conifer Seepage Forest, 85 Actual habitat value, 287 Adaptations, flora, 82 Adirondack Mountains, 283 Aerial photography, see also Mapping community based conservation, 333 limitations, 55 mesofilter conservation, 6 Agricultural practices, chemical contamination, 221 Agrostis stolonifera, 86 Algae, chemical compounds, 220 Allegheny Plateau region, 77 Alpha diversity, 3 Altosid, 221 American black duck (Anas rubripes), 177, 181 American Ornithologist Union, 170 American toad (Bufo americanus), 110, 130 Amphibian distribution patterns, 129, 131–132 Amphibian Malformation Surveys case study, 313 Amphibian Research and Monitoring Initiative (ARMI), 329 Amphipods, common invertebrates, 112 Analog photography, 57–58 Animals (live), handling and keeping, 305–307 Anomola, 114–115 Anostraca, 112 Anthropogenic effects, 6, 25, see also Human landscape Anticosti Island, Quebec, 23 Appalachian Mountains, 13 Aquatic beetles, 117–118 Aquatic earthworms, 106 Aquatic insects, 117–119 Aquatic vegetation, 75 Arachnids, 106 Asian forests, 283 Assessment community based conservation, 329–331, 334–335 data accessibility, 207 Vernal Pool Assessment Sheet, 330

Atlantic Atlantic Atlantic Atlantic

Canada Conservation Data Centre, 83 Coastal Plain Northern Pondshore, 85 salmon (Salmo salar), 6 white cedar (Chamaecyparis thyoides), 22, 86 At-risk plant species, 74 Avoidance strategy, 242–243, 243 Avoidance vs. compensation, 205

B Baccillus thuringiensis var., 123, 216, 221, 259 Baldwin studies, 281–294 Balsam fir (Abies balsamea), 264 Barratt's sedge (Carex barrattii), 85 Barred owls (Strix varia), 177 Basins characteristics, 37–38 flora, 79 managed forest relationships, 257–260 Basommatophora, 116 Bats, 180, 181, 182, see also specific type Bears, 180 Beavers (Castor spp.), 4, 158 Beetles, 46 Beggar-tick (Bidens discoidea), 79–80 Beginning with Habitat, 326 Bell studies, 281–294 Belted kingfisher (Ceryle alcyon), 177 Best Management Practices (BMPs) community based conservation, 326 managed forests, 268 urbanization, 242, 246 voluntary adherence to, 335 Beta diversity, 3 Big brown bat (Eptesicus fuscus), 180 Biodiversity, 2–3 Biogeography importance, 77–78 Biological landscape defined, 282 landscape species approach, 283–286 Biological setting flora, 71–88 invertebrates, diversity and ecology, 105–123 pool-associated amphibians, 149–163 pool-breeding amphibians, 127–142 reptiles, birds, and mammals, 169–183

345

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vernal pool importance, 169–183 Birds, see also specific type American Ornithologist Union, 170 biodiversity, 2 connectivity and dispersal, 45 Cornell's Laboratory of Ornithology, 321 habitat associations, 170 vernal pool importance, 176–177, 178–179 wetland-terrestrial connectivity, 46 Bivalvia, 116 Black-and-white warblers (Mniotilta varia), 177 Black bear (Ursus americanus), 180 Blackbird, 177 Black spruce (Picea mariana), 264 Blanding's turtle (Emydoidea blandingii) conservation implications, 181 edge-related effects, 240 pool importance, 171, 174 regional conservation, 208 road mortality, 239 Blue-spotted salamander (Ambystoma laterale), 260–261 BMP, see Best Management Practices (BMPs) Bogs conservation implications, 26 depressions, 21 flats, 24 substrate, 80 Bog turtle (Glyptemys muhlenbergii), 174, 205 Boom or bust population dynamics, 135 Boone studies, 213–225 Borrow pits, 86 Boston-Washington corridor, 235 Brackish marshes, 18 Brevicaudata, 112–113 Brooks studies, 31–50 Brown frog (Rana arvalis), 159 Bullfrog (Rana catesbiana), 122, 258 Burne studies, 55–66 Butterflies, 86 Buttonbush (Cephalanthus occidentalis) adaptations, 82 biogeography, 77 classification, 75 hydroperiods, 79

C Caddisflies biodiversity, 2 community ecology, 110 diversity and ecology, 106 invertebrates, diversity and ecology, 117 wetland-terrestrial connectivity, 47

Calhoun studies, 233–246, 319–336 California evapotranspiration, 36 genetic diversity, 83 hydrologic connectivity, 70 land trusts, 204 precipitation, 33 urbanization, 235 vertebrates, 170 California tiger salamander (Ambystoma californiense), 152 Canada community based conservation, 326 conservation and educational organizations, 234 conservation implications, 83 conservation policy, 195–197 depressions, 20 flats, 24 land development, 48 urbanization, 235 Canada Ocean Act, 195 Canada Wildlife Act, 195, 196 Canadian Environmental Assessment Act, 195, 196 Canadian National Vegetation Classification (CNVC), 75 Canadian Shield, 13, 21 Canadian Wetland Inventory, 55, 195 Cane toad (Bufo marinus), 152 Canopy amphibian distributional patterns, 129, 132–134, 134 closure, flora, 79 extinction-recolonization, 158 managed forest relationships, 260–263 Cape Cod, Massachusetts, 35 Carbaryl, 259–260 Carolina bays biogeography, 77 evapotranspiration, 36 precipitation, 33 vertebrates, 170 Carson, Rachel, 319–320 Case studies community based conservation, 331–332, 332 educational opportunities, 311–314 remote and field identification, 63, 63–64, 65 Castor canadensis, 4 Catchment morphology, 37–38 Catskill Mountains, 23 Cattails (Typha spp.), 86 Census population size, 153, 156 Chamaecyparis thyoides, 22 Chemical contamination

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Index agricultural practices, 221 complicating factors, 222–223 conservation recommendations, 223–224 contaminants and effects, 215–217 forest management practices, 217–220, 218–219 fundamentals, 213–215, 224–225 mosquito control, 218–219, 220–221 sources, 217–223 urban development, 221 water quality, 259–260 Chemicals, 123 Chorus frog (Pseudacris triseriata), 135, 141 CIR, see Color infrared (CIR) photography Citizen-driven certification process, 64 Citizen guides, 340 Citizen science approach community based conservation, 321, 322–323, 324, 327–328 National Ecological Observatory Network (NEON) Citizen Science Gateway, 329 New England case study, 331–332, 332–333 programs, 322–323 region initiatives, 325 survey techniques, 62 vernal pool advantages, 4–5 Clam shrimp, 106, 112–113, 113 Classification anthropogenic effects, 25 conservation implications, 25–26 depressions, 15, 20–23, 22 flats, 23–24 flora, 73–77 fundamentals, 11–12, 26 geologic history, 12–13 geomorphic setting, 20–25 hydrogeomorphic basis, 14, 18 hydrogeomorphic setting, 18–25 hydrologic dynamics, 38 physical setting, 11–26 regional variations, 13–14, 15–17 riverine, 17, 24–25 slopes, 16, 23 water, 60 Clean Water Act (CWA) Canada regulations, 196 conservation implications, 83 federal regulations, 197–198 regulations, 201 Clearcutting birds, 176 managed forests, 260–261, 261 Climate change, 49 Coarse-filter ecosystems, 5–6

347 Coarse woody debris (CWD), 265, 266–267 Colburn studies, 105–123 Coleoptera, 117–118 Color infrared (CIR) photography, 57, 64 Commission errors, 60–61 Common frog (Rana temporaria), 156, 159 Common invertebrates, 112–120 Common reed (Phragmites australis), 86 Community-based conservation aerial photography, 333 assessment, 329–331, 330, 334–335 case study, 331–332, 332 citizen scientists, 321, 322–323, 324, 327–328 conservation recommendations, 335 data, 329, 335 fundamentals, 319–320, 336 inventory, 329–334 local initiatives, organizing, 324, 326 map production, 334 New England citizen scientists case study, 331–332, 332 photography and photointerpretation, 333 Community dynamics, 136–137 Community ecology, 110, 111, 112 Compensation vs. avoidance, 205 Complexity, managed forests, 255–256 Complicating factors, chemical contamination, 222–223 Coniferous swamp pools, 75 Connecticut bats, 181 biogeography, 77 edge-related effects, 240 extinction-recolonization, 158 flats, 23 hydroperiods, 132 inventory, 208 regulations, 201–202 spatial ecology, 139 zoning, 207 Connectivity, hydrology and landscape, 39–41, 40–41 Conservation, community based aerial photography, 333 assessment, 329–331, 330, 334–335 case study, 331–332, 332 citizen scientists, 321, 322–323, 324, 327–328 conservation recommendations, 335 data, 329, 335 fundamentals, 319–320, 336 inventory, 329–334 local initiatives, organizing, 324, 326 map production, 334 New England citizen scientists case study, 331–332, 332

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ownership determination, 334 photography and photointerpretation, 333 Conservation and valuing biodiversity, 2–3 ecosystem conservation, 5–7 ecosystem processes, 3–4 fundamentals, 1–2, 7 keystone ecosystems, 4 social values, 4–5 Conservation implications classification, 25–26 flora, 83–86 hydrology and landscape connectivity, 47–49 pool-associated amphibians, 161–163 pool-breeding amphibians, 139, 140, 141 vernal pool importance, 181–182 Conservation opportunities, urbanizing, 241 Conservation planning, informational resources, 340–341 Conservation policy Canada, 195–197 conservation recommendations, 209–210 fundamentals, 193–195, 194, 210 United States, 197–209 Conservation recommendations chemical contamination, 223–224 community based conservation, 335 conservation policy, 209–210 invertebrates, diversity and ecology, 121–123 landscape species approach, 293–294 managed forests, 265–273 professional, 310–311 remote and field identification, 65–66 Contaminants and effects, 215–217 Copepoda, 114 Copepods, 106, 114 Copper-bellied watersnake (Nerodia erythrogaster), 174, 176 Core authentics, 309 Cornell's Laboratory of Ornithology, 321 Cranberries (Vaccinium spp.), 80 Cranberry bogs, 26, see also Bogs Crayfish, 46, 112 Creating vernal pools, 244–245 Creeping rush (Juncus repens), 79 Creeping St. John's-wort (Hypericum adpressum), 85 Critical habitats, 284–286 Crustaceans, 112–115, 114 Culiseta melanura (mosquito), 119, see also Mosquitoes Cutko studies, 71–88 CWA, see Clean Water Act (CWA) CWD, see Coarse woody debris (CWD) Cypress pond ecosystems, 36–37

precipitation, 33

D Damselflies, 106, 118 Data existing, 333 quality control, 329 United States, conservation policy, 208–209 using, 335 Declining Amphibian Populations Task Force, 334 Deforestation, hydrology, 258–259 Deleterious allele, 153, 156 deMaynadier studies, 253–274 DEP, see Department of Environmental Protection (DEP) Department of Environmental Protection (DEP), 64 Deposition, 12 Depressions geomorphic settings, 15, 20–23, 22 managed forests, 269–271 Diceros bicornis, 6 DigitalGlobe Quickbird satellite, 58 Digital orthophotography, 59 Digital orthophoto quarter quadrangle (DOQQ) imagery, 58 Digital photography, 58 Diptera, 118–119 Direct loss, 235–236, 236–237 Dispersal, see also Migration; Movement; Urbanization definition, 153 invertebrates, diversity and ecology, 109–110 landscape connectivity, 43, 44–46, 45 population and genetic linkages, 151–156 Distributional patterns, 131–134 Distributions, diversity and ecology, 107–108 Disturbed vernal pools, 86 Diversity, multiple scales, 82–83 Diving beetles, 46, 110 DOQQ, see Digital orthophoto quarter quadrangle (DOQQ) imagery Doyon Elementary School case study, 312–313 Dragonflies community ecology, 110, 112 diversity and ecology, 106 flora/fauna relationships, 86 invertebrates, diversity and ecology, 118 wetland-terrestrial connectivity, 47 Drift, 152, 153, 155, 156–157 Duckweeds (Lemma spp.), 80 Dwarf burhead (Echinodorus tenellus), 85

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Index Dynamics hydrology, 36, 38–39, 39 population, 42–47

E Eastern Eastern Eastern Eastern Eastern

box turtle (Terrapene carolina), 173 chipmunk (Tamias striatus), 180 equine encephalitis (EEE), 119 hemlock (Tsuga canadensis), 79 newt (Notopthalmus viridescens), 239, 256 Eastern ribbonsnake (Thamnophis s. sauritus), 175–176 Eastern spadefoot toad (Scaphiopus holbrookii), 132, 255 Ecological Gifts Program, 204 Ecological impact considerations, 304–305 Ecological Monitoring and Assessment Network (EMAN), 329 Ecosystem-centric strategy, 5 Ecosystem conservation, 5–7 Ecosystem-focused approach, 5 Ecosystem persistence, 241 Ecosystem processes, 3–4 Edge-related effects, 240 Education, public, 123 Educational opportunities Amphibian Malformation Surveys case study, 313 case studies, 311–314 conservation professional recommendations, 310–311 Doyon Elementary School case study, 312–313 ecological impact considerations, 304–305 field study program considerations, 301–307 fundamentals, 299–301, 314–315 Harvard Forest Schoolyard Freshwater Ecology case study, 313 legal issues, 307 live animals, handling and keeping, 305–307 Marvelwood School case study, 313 Michigan middle and high schools case study, 313 Nessacus Middle School case study, 312 partnerships, 307–310, 308 Reading Memorial High School case study, 312 relationship building, 310–311 Roger Tory Peterson Institute case study, 314 safety, 302, 304 science education organization recommendations, 311

349 scientist recommendations, 310–311 State University of New York at Fredonia case study, 314 teacher recommendations, 311 University of Maine Wetland Connections Project case study, 314 Vermont Institute of Natural Science, 313–314 Educational organizations, 310 EEE, see Eastern equine encephalitis (EEE) Effective population size, 153, 156 Eleocharis microcarpa, 45 EMAN, see Ecological Monitoring and Assessment Network (EMAN) Endangered species, 178–179, 204 ENGOs, see Environmental nongovernmental groups (ENGOs) Enhancement of habitat, 244 Environmental nongovernmental groups (ENGOs), 333 Environmental Protection Act, 196 EPA, see U.S. Environmental Protection Agency (EPA) Erosion, glacial processes, 12 Estuarine fringe, 18 ET, see Evapotranspiration (ET) Eubalaena glacialis, 6 Europe, community ecology, 110 Evapotranspiration (ET) canopy, 133 depressions, 21 flats, 23–24 hydrologic budget, 36, 36 Existing data, 333, see also Data Explanatory classification system, 14, 18 Extinction fish species, 136–137 managed forests, 254 metapopulation theory, 42, 43, 44 Extinction-recolonization dynamics pool-associated amphibians, 158–161, 160–161 Exurban growth, 285, 286–287

F Fairy shrimp (Eubranchipus spp.) biodiversity, 2 connectivity and dispersal, 45 distributions and life cycles, 107 diversity and ecology, 106, 112, 113 life history strategies, 108–109 water quality, 259 False hop sedge (Carex lupuliformis), 85 False positives and negatives, 60

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Faunal association relationship, 85–86 Fear of takings, 205–206 Featherfoil (Hottonia inflata), 2, 72 Federal environmental laws, see Regulations Federal Geographic Data Committee, 76 Federal level policy, 197–201 The Federal Policy on Wetland Conservation, 195, 196 Fertilizers, 216, 220 Fidelity to ponds, 256–257 Field guides, 340–341 Field identification, 61–65, see also Remote and field identification Field study program considerations animals, handling and keeping, 305–307 ecological impact considerations, 304–305 fundamentals, 301–302 legal issues, 307 NRC content standards, 304–305 safety, 302, 304 Fine-filter ecosystems, 5 Fingernail clams (Sphaerium spp.) biodiversity, 3 connectivity and dispersal, 45 diversity and ecology, 106 invertebrates, diversity and ecology, 116 life history strategies, 108 Fisheries Act, 195, 196 Fitness, 153, 156 Flats, geomorphic setting, 23–24 Flatworms, 106, 110 Flexibility, 208 Floodplains hydrologic connectivity, 41 riverines, 24–25 state heritage classifications, 77 Flora adaptations, 82 basin size, 79 biogeography importance, 77–78 Canadian National Vegetation Classification, 75 canopy closure, 79 classification, 73–77 conservation implications, 83–86 disturbed vernal pools, 86 diversity, multiple scales, 82–83 faunal association relationship, 85–86 fundamentals, 71–73, 72, 74, 87–88 genetic diversity, 83 hydroperiod, 78–79 invasive plant species, 86, 87 National Vegetation Classification, 76 natural communities and systems, 85 physical factors importance, 77–82

rare ecological associations and systems, 85 rare plants, 74, 84–85 state heritage classifications, 76–77 substrate, 79–80 surrounding vegetation, 80 types, 73–77 U.S. National Wetlands Inventory, 75 zonation, 80–81, 81 Focal landscapes gap analysis, 290–291 landscape species approach, 283, 289–291, 290–292 wood frog (Rana sylvatica), 292 Forest management practices, 217–220, 218–219, see also Managed forests Fossaria modicella (snails), 108 Four-toed salamander (Hemidactylium scutatum), 86 Fredonia, New York, 314 Free-living flatworms, 115 Frogs, see also specific type community ecology, 110 connectivity and dispersal, 44–45 conservation implications, 139, 141 dispersal distances, 153–154 drift and inbreeding, 156 ecology and conservation, 128 habitat enhancement and aesthetics, 122 migration distances, 140 protection zone, 271 Fungi, 6

G Gap analysis, 289–291, 290–292 Gartersnakes (Thamnophis spp.), 175–176 Gastropoda, 116 Gastrotrichs, 106 Gene flow, 153, 239–240 Generalists, 173–174, 178–179 Genetic diversity, 83 Genetic drift, 152, 153 Genetic linkages and population conservation implications, 161–163 drift, 153, 155, 156–157 extinction-recolonization dynamics, 158–161, 160–161 fundamentals, 149–150 inbreeding, 153, 155, 156–157 local adaptation, 158–161, 160–161 physical setting, 150–155, 151, 153, 155 population organization, 150–156, 151, 153, 155 Genetic neighborhood, 153

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Index Geographically isolated wetlands, 32 Geographic information systems (GIS), 56, 62 Geologic history, 12–13 Geomorphic setting, 20–25 Geomorphology, 18 Giant tube-casemaking caddisflies (Ptilostomis spp. and Banksiola spp.), 110 Gibbs studies, 149–163 GIS, see Geographic information systems (GIS) Glossy buckthorn (Rhamnus frangula), 86 Glyphosate, 220, 259 Goldenrod (Euthamia tenuifolia), 73 Google Earth, 58 GPS equipment, 62–63 Grackles (Quiscalus spp.), 177 Graminoids, 75 Gray fox (Urocyon cinereoargenteus), 180 Great blue heron (Ardea herodias), 177, 199 Great Lakes, 14, 23, 26 Great laurel (Rhododendron maximum), 80 Great Plains, 170 Green darner (Anax junius), 118, see also Damselflies; Dragonflies Green frog (Rana clamitans), 131–132, 258 Green heron (Butorides virescens), 177 Groundwater budget, 33–35, 34 Gruner studies, 299–315 Guidelines, managed forests depression, 270–271 life zone, 273 protection zone, 271–272 Gypsy moth (Lymantria dispar), 216

H Habitat community based conservation, 324–335, 325 enhancement and aesthetics, 121–122 value, 287 Habitat Management Guidelines (HMGs), 268, 274 Hairy-tailed mole (Parascalops breweri), 180 Haley studies, 299–315 Hard-copy photography, 58–59 Harvard Forest Schoolyard Freshwater Ecology case study, 313 Harvest operations, 269–273, 270 Hawks (Buteo spp.), 177 Heath shrubs, 80 Hemiptera, 118 Hemlock looper (Lamdina fiscellaria fiscellaria), 216 Herbicides, 259 Herons, 177, 181, 199

351 Herrington's fingernail clam (Sphaerium occidentale), 116, see also Fingernail clams (Sphaerium spp.) Hessel's hairstreak butterfly (Callophrys hesseli), 86 Histosols, 24 Hog-nosed snake (Heterodon platirhinos), 175 Hollands studies, 11–26 Homozygosity, 153, 156 Horsehair worms, 106 Hottonia inflata, 2 Houlahan studies, 253–274 Human landscape, see also Anthropogenic effects defined, 282 landscape species approach, 283, 285, 286–287 Human-modified landscapes chemical contamination, 213–225 community based conservation, 319–336 conservation policy, 193–210 educational opportunities, 299–315 landscape species approach application, 281–294 managed forests, 253–274 urbanizing, 233–246 Hunter studies, 1–7 Hydraulic conductivity, 34–35 Hydrodynamics, 18 Hydrogeomorphic basis, 14, 18 Hydrogeomorphic (HGM) approach, 18 Hydrogeomorphic position, 18 Hydrogeomorphic setting, 18–25 Hydrologic budget, 33–36, 34 Hydrologic impacts, 47–49 Hydrology, managed forests, 258–259 Hydrology and landscape connectivity basin morphology, 37–38 catchment morphology, 37–38 climate change, 49 connectivity, 39–41, 40–41 conservation implications, 47–49 dispersal, 43, 44–46, 45 dynamics, 36, 38–39, 39 evapotranspiration, 36, 36 fundamentals, 31–32, 50 groundwater, 33–35, 34 hydrologic budget, 33–36, 34 hydrologic impacts, 47–49 land development, 48 loss of landscape, 45, 49 metapopulation theory, 42, 43, 44 population dynamics, 42–47 precipitation, 33 surface water, 35 timber harvesting, 47–48

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wetland-terrestrial connectivity, 46–47 Hydroperiods amphibian distributional patterns, 132 flora, 78–79 fundamentals, 33 habitat enhancement and aesthetics, 122 hydrologic dynamics, 38 Hydroregimes, 33, 38

I Illinois, 14 Image availability, 58 Impacts, minimizing, 243–246, see also Urbanization Importance, vernal pools birds, 176–177, 178–179 conservation implications, 181–182 fundamentals, 169–170, 182–183 generalists, 173–174, 178–179 lizards, 174–176, 175, 178–179 mammals, 177–181, 178–179 reptiles, 170–176 snakes, 174–176, 175, 178–179 specialists, 171–173, 173 turtles, 170–174, 171 Inbreeding, 153, 155, 156–157 Income Tax Credit Act of Canada, 195 Indiana lizards and snakes, 174 regulations, 201 surficial geology, 14 Indiana myotis (Myotis sodalis), 181 Informational resources, 340–341 Informed development, 208–209 Initiatives, organizing locally, 324, 326 Inland Wetlands and Watercourses Act of 1972, 202 In-lieu fee programs, 246 Insects, see also specific type connectivity and dispersal, 45 diversity and ecology, 106 mesofilter conservation, 6 Intermittent connections, 40–41 Interpretation, survey techniques, 59–61 Invasive plant species, 86, 87 Inventory community based conservation, 329–334 urbanizing, 242 U.S. conservation policy, 207–209 Invertebrates aquatic beetles, 117–118 aquatic insects, 117–119 caddisflies, 117

chemicals, 123 clam shrimp, 112–113 common invertebrates, diversity and ecology, 112–120 community ecology, 110, 111, 112 conservation recommendations, 121–123 copepods, 114 crustaceans, 112–115, 114 damselflies, 118 dispersal, 109–110 distributions, 107–108 dragonflies, 118 education, public, 123 fairy shrimp, 112 fingernail clams, 116 free-living flatworms, 115 fundamentals, 106–107, 107, 123 habitat, enhancement and aesthetics, 121–122 large crustaceans, 112–114, 113 life cycles, 107–108 life history strategies, 108–109 molluscs, 115–116 mosquitoes, 119, 122–123 oligochaetes, 115 ostracodes, 114 pesticides, 123 protection efforts, 121 public education, 123 small crustaceans, 114–115 snails, 116 tadpole shrimp, 114 true bugs, 118 true flies, 118–119 water fleas, 114–115 water mites, 120, 120 worms, 115 Ipswich, Massachusetts, 312–313 Isopods, 112 Issues, key, xix–xx Italian agile frog (Rana latastei), 159

J Jefferson salamander (Ambystoma jeffersonianum), 180, 264–265

K Karst ponds, 37 Kentucky, 110, 175 Kettle depressions, 21–22 Keystone ecosystems, 4 Klemens studies, 193–210

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Index Koi (Cyprinus carpio), 122 K-selected perennials, 82

L Labrador, 131, 196 Lacustrine fringe, 18 Laevicaudata order, 112–113 Lake Hitchcock, 23 Lakes, classification, 18 Land development, 48 Landscape, 6, 282 Landscape approaches, 26 Landscape connectivity, loss of, 45, 49 Landscape species approach, 287–288, 288 conservation approach, 283–284 conservation recommendations, 293–294 critical habitats, 284–286 defined, 282 exurban growth, 285, 286–287 focal landscapes, 289–291, 290–292 fundamentals, 281–283, 282, 294 gap analysis, 289–291, 290–292 human landscape, 285, 286–287 movement, 284–286 relevance, 293 target landscape identification, 285, 287–288, 288 threat analysis, 287–288, 288 Land trusts, 204 Large crustaceans, 112–114, 113 Late-Wisconsin glaciation, 12 Lathrop studies, 55–66 Leatherleaf (Chamaedaphne calyculata), 80 Leeches, 106, 110 Legal issues, 307, see also Regulations Leibowitz studies, 31–50 Levins metapopulation, 46 Life cycles invertebrates, diversity and ecology, 107–108 pool-breeding amphibians, 128–130 Life history strategies, 108–109 Life zone, managed forests, 272–273 Litter, managed forests, 264–265 Little brown bat (Myotis lucifugus), 180 Live animals, handling and keeping, 305–307 Livestock grazing, 6 Living Landscapes Program, 283 Lizards, 174–176, 175, 178–179 Local adaptation, 158–161, 160–161 Local extinction metapopulation theory, 42, 43, 44 wood frogs, 136 Local initiatives, organizing, 324, 326

353 Local level regulation, 203–209 Long Island, 141 Long sedge (Carex folliculata), 77 Loss of landscape connectivity, 45, 49 Lower New England regions, 77

M Mahaney studies, 193–210 Maine biogeography, 77–78 birds, 177 community based conservation, 326 data quality control, 329 distributional patterns, 131 disturbed pools, 86 floristic diversity, 82 gap analysis, 289, 290 landscape species approach, 284, 286, 288, 290–291 land trusts, 204 managed forests, 254 morphological attributes, 37 raccoons, 180 rare plants, 83 regulations, 201–202 road mortality, 238 snakes, 176 state heritage classifications, 76 turtles, 171 Maine case study, conservation policy, 202–203 Maine case study, landscape species approach biological landscape, 284–286 critical habitats, 284–286 exurban growth, 285, 286–287 focal landscapes, 289–291, 290–292 fundamentals, 284, 285 gap analysis, 289–291, 290–292 human landscape, 285, 286–287 movement, 284–286 relevance, 293 target landscape identification, 285, 287–288, 288 threat analysis, 287–288, 288 Malathion, 221 Mammals biodiversity, 2 habitat associations, 170 vernal pool importance, 177–181, 178–179 wetland-terrestrial connectivity, 46 Managed forests basics, 254–255 basin relationships, 257–260 canopy relationships, 260–263

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clearcutting, 260–261, 261 coarse woody debris, 265, 266–267 complexity, 255–256 conservation recommendations, 265–273 depressions, 269–271 floor relationships, 263–265, 266–277 fundamentals, 273–274 guidelines, 268–273 harvest operations, 269–273, 270 hydrology, 258–259 life zone, 272–273 litter, 264–265 partial harvesting, 261–263, 262–263 physical integrity, 257 preharvest planning, 268–269 protection zone, 271–272 vernal pool relationships, 257–265 water quality, 259–260 Management guidelines, managed forests depression, 270–271 life zone, 273 protection zone, 271–272 Management rationale, managed forests depression, 269 life zone, 272 protection zone, 271 Managers Monitoring Manual for Egg Mass Surveys, 329 Mandate issues, 206–207 Many fruited false-loosestrife (Ludigia polycarpa), 85 Mapping, see also Aerial photography geomorphic settings, 20 production, 334 responsibility for, 55 site-based, 293 survey techniques, 63, 63–64, 65 Marbled salamander (Ambystoma opacum) ecology and conservation, 130 managed forests, 256 water quality, 259 Maritime Provinces depressions, 20–21 land development, 48 landscape species approach, 284 Marsh pools, 75 Marvelwood School case study, 313 Maryland, 77, 235 Masked shrew (Sorex cinereus), 180 Massachusetts bats, 181 conservation implications, 26 depressions, 22 hydrologic dynamics, 38 interpretation, 59

invasive plant species, 86 mapping, 64 morphological attributes, 37 precipitation, 33 rare plants, 83 regulations, 201–202 remote sensing, 57 shrews, 180 snakes, 176 state heritage classifications, 76 targeted surveys, 56 turtles, 171 urbanization, 236–237, 241 Massachusetts case study survey techniques, 63, 63–64, 65 United States, conservation policy, 200–201 Massachusetts fern (Thelypteris palustris), 77 Massachusetts Natural Heritage Program, 150 Meadow voles (Microtus pennsylvanicus), 180 Mermaid weed (Proserpinaca palustris), 82 Mesofilter conservation, 6 Metals, effects, 216 Metamorphosis conservation implications, 139 ecology and conservation, 128–130 protection zone, 271 Metapopulation theory, 42, 43, 44 Methoprene, 221 Michigan amphibian malformation case study, 313 bats, 180 depressions, 20 lizards and snakes, 175 regulations, 201 surficial geology, 13 Micropools, 41 Microsatellite marker, 153, 160 Midges, 110 Midwestern states, 21, 235, see also specific states Migration, 151–156, 153, 286, see also Dispersal; Movement; Urbanization Migratory bird rule, 199 Migratory Birds Convention Act, 195 Migratory breeders, 46–47 Mink (Mustela vison), 180 Minnesota birds, 176 depressions, 20, 22 groundwater, 35 regulations, 198, 201 snakes, 176 surficial geology, 13–14 tadpole shrimp, 114 timber harvesting, 48 Mississippi, 33

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Index Mitchell studies, 169–183 Mitigation banks, 246 Mixed canopy pools, 75 Models, urbanizing, 246 Moisture, see Precipitation Mole salamanders (Ambystoma spp.) clearcutting, 260 coarse woody degree, 265 habitat enhancement and aesthetics, 121 life zone, 272 managed forests, 255 protection zone, 271 urbanization, 235, 239 Molluscs community ecology, 110 diversity and ecology, 106 invertebrates, diversity and ecology, 115–116 Monitoring opportunities, 242 Moose (Alces alces), 2, 181 Moroccan water frogs (Rana saharica), 152 Mosquitoes chemical contamination sources, 218–219, 220–221 community ecology, 110 control, 21, 218–219, 220–221 diversity and ecology, 106 eastern equine encephalitis, 119 invertebrates, diversity and ecology, 119, 122–123 life history strategies, 109 Mosquitofish (Gambusia spp.), 220 Movement, see also Dispersal; Migration; Urbanization barriers, urbanization, 239–240 ecology, managed forests, 256–257 landscape species approach, 284–286 Mudpuppy (Necturus maculosus), 128

N NAD83, see North American Datum of 1983 (NAD83) Nanticoke River, 235 Narrow-leaved fragrant goldenrod (Euthamia tenuifolia), 73 National Air Photo Library, 58 National Digital Orthophoto Program (NDOP), 58 National Ecological Observatory Network (NEON) Citizen Science Gateway, 329 National Marine Fisheries Service, 198 National Parks Act, 195, 196 National Science Education Standards, 302, 305 National Vegetation Classification (NVC), 76, 85

355 National Wetlands Inventory (NWI), 55, 57, 75 Native Plant Society of California, 245 Natural communities and systems, 85 Natural Heritage and Endangered Species Program (NHESP), 64 Natural history, 255–257 Natural Resources Canada, 254 Natural Resources Protection Act, 202 Nature Canada, 329 NatureServe, 83, 85 NatureWatch, 329 Neighboring habitat loss, 237–238 Nematodes, 6 Nessacus Middle School case study, 312 Netherlands, 239 Netted chain fern (Woodwardia aereolata), 83 Neutral genetic marker, 153, 160 New Brunswick forest litter, 264 landscape species approach, 284 managed forests, 254 New Brunswick Wetlands Conservation Policy, 196 New England aerial photography, 333 citizen scientists case study, 331–332, 332 conservation and educational organizations, 234 depressions, 20–21 flats, 23–24 forest land ownership, 274 land development, 48 land trusts, 204 managed forests, 254 mapping, 55 regulations, 198 remote sensing, 57 surficial geology, 13 targeted surveys, 56 urbanization, 235 New England Wild Flower Society, 85 Newfoundland, 13, 196 New Hampshire bats, 181 regulations, 201 state heritage classifications, 77 vegetation classification, 75 New Hampshire Natural Heritage Inventory, 75 New Jersey aerial photography, 333 birds, 177 conservation implications, 141 depressions, 20 land development, 48 migration and dispersal, 151

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pool importance, 174 rare plants, 83 regulations, 201–202 remote sensing, 58 surficial geology, 13 survey techniques, 62 targeted surveys, 56 New Jersey rush (Juncus caesariensis), 73 Newts, 130, 239, 256 New York Adirondack Mountains, 283 conservation and educational organizations, 234 depressions, 20–21 rare plants, 83 regulations, 201 state heritage classifications, 76 surficial geology, 13–14 New York fern (Thelypteris novae-boracensis), 80 NHESP, see Natural Heritage and Endangered Species Program (NHESP) Nitrate fertilizers, 220 Nonbreeding migrants, 46 No net loss local regulation, 203–204 Nova Scotia, 197 unavoidable impact mitigation, 243 North American Datum of 1983 (NAD83), 58 North Carolina Museum of Life Science, 311 Northeastern North America, glaciated, xvii–xix, xviii Northern Myotis spp., 180 Northern right whale (Eubalaena glacialis), 6 Northern watersnake (Nerodia sipedon), 175 North Lake Eyre (Australia), 6 Notostraca, 114 Nova Scotia landscape species approach, 284 rare plants, 83 regulations, 196–197 NRC content standards, 302, 303–304 NVC, see National Vegetation Classification (NVC)

O Odonata, 118 Ohio flats, 24 lizards and snakes, 175 Ohio Vernal Pool Partnership, 335 regulations, 201 surficial geology, 14 Oligochaetes, 115

Omission errors, 60–61 Ontario depressions, 21 Ontario Vernal Pool Association, 335 road mortality, 239 surficial geology, 13 Ontario Vernal Pool Association, 209 Opossums, 180 Organic soils, 24 Ostracodes community ecology, 110 diversity and ecology, 106 invertebrates, diversity and ecology, 114 Outbreeding depression, 153, 156 Outdoor laboratories, vernal pools as Amphibian Malformation Surveys case study, 313 case studies, 311–314 conservation professional recommendations, 310–311 Doyon Elementary School case study, 312–313 ecological impact considerations, 304–305 field study program considerations, 301–307 fundamentals, 299–301, 314–315 Harvard Forest Schoolyard Freshwater Ecology case study, 313 legal issues, 307 live animals, handling and keeping, 305–307 Marvelwood School case study, 313 Michigan middle and high schools case study, 313 Nessacus Middle School case study, 312 partnerships, 307–310, 308 Reading Memorial High School case study, 312 relationship building, 310–311 Roger Tory Peterson Institute case study, 314 safety, 302, 304 science education organization recommendations, 311 scientist recommendations, 310–311 State University of New York at Fredonia case study, 314 teacher recommendations, 311 University of Maine Wetland Connections Project case study, 314 Vermont Institute of Natural Science, 313–314 Owls, 177, 181

P Painted turtle (Chrysemys picta), 173, 238 Paleozoic Era, 13–14

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Index Palustrine systems, 75 Partial harvesting, 261–263, 262–263 Partnerships, 307–310, 308 Passenger pigeon (Ectopistes migratorius), 254 Paton studies, 169–183 Pauli studies, 213–225 PCBs, effects, 216 Peatlands, 24, see also Bogs Pennsylvania basin size and canopy closure, 79 biogeography, 77 birds, 177 disturbed pools, 86 hydroperiods, 78 land development, 48 partial harvesting, 262 raccoons, 180 rare plants, 83 regulations, 198, 201 state heritage classifications, 76 substrate, 80 surficial geology, 14 vegetation classification, 75 zonation, 81 Perennial inlets, 39 Periglacial climate, 12–13 Permanent surface-water connections, 39–40 Pesticides effects, 215 invertebrates, diversity and ecology, 123 potential, 218–219 PEt, see Potential evapotranspiration (PEt) Philopatry, 256–257 Photography and photointerpretation, 57, 333 Physical factors importance, 77–82 Physical integrity, managed forests, 257 Physical setting classification, 11–26 hydrology and landscape connectivity, 31–50 pool-associated amphibians, 150–155, 151, 153, 155 remote and field identification, 55–66 Pine flatwood ecosystems, 33 Place-based education, 300, see also Outdoor laboratories, vernal pools as Plains gartersnake (Thamnophis radix), 175 Planning challenges and solutions, 207–209 Plant species, common, 91–104 Pleistocene Epoch, 13 Plymouth gentian (Sabatia kennedyana), 72–73 Podocopida, 114 Policy Directive for Development in Wetlands, 196 Polished tadpole snail (Aplexa elongata), 116, see also Snails Pondweeds (Potamogeton spp.), 80, 82

357 Pool-as-population, 161 Pool-associated amphibians, see also specific type conservation implications, 161–163 drift, 153, 155, 156–157 extinction-recolonization dynamics, 158–161, 160–161 fundamentals, 149–150 inbreeding, 153, 155, 156–157 local adaptation, 158–161, 160–161 physical setting, 150–155, 151, 153, 155 population organization, 150–156, 151, 153, 155 Pool-breeding amphibians amphibian distribution patterns, 129, 131–132 canopy, 129, 132–134, 134 community dynamics, 136–137 conservation implications, 139, 140, 141 distributional patterns, 131–134 fundamentals, 127–128, 129, 141–142 hydroperiod, 132 life cycle, 128–130 population dynamics, 134–136 spatial ecology, 137–139, 138 Pool-breeding amphibians, landscape species approach biological landscape, 284–286 conservation approach, 283–284 conservation recommendations, 293–294 critical habitats, 284–286 exurban growth, 285, 286–287 focal landscapes, 289–291, 290–292 fundamentals, 281–283, 282, 294 gap analysis, 289–291, 290–292 human landscape, 285, 286–287 movement, 284–286 relevance, 293 target landscape identification, 285, 287–288, 288 threat analysis, 287–288, 288 Population and genetic linkages conservation implications, 161–163 drift, 153, 155, 156–157 extinction-recolonization dynamics, 158–161, 160–161 fundamentals, 149–150 inbreeding, 153, 155, 156–157 local adaptation, 158–161, 160–161 physical setting, 150–155, 151, 153, 155 population organization, 150–156, 151, 153, 155 Population bottleneck, 153, 157 Population dynamics, 42–47, 134–136 Population organization, 150–156, 151, 153, 155 Potential evapotranspiration (PEt), 36 Prairie potholes

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evapotranspiration, 36 groundwater, 35 precipitation, 33 vertebrates, 170 Pre-Cambrian rocks, 13 Precipitation climate change, 49 depressions, 21 flats, 23–24 hydrologic budget, 33 Predaceous diving beetles, 46, 109, 117, 122 Preharvest planning, 268–269 Preservation of habitat, 244 Prince Edward Island, 196 Project SEARCH, 309 Protection efforts, 121 Protection levels, 287 Protection zone, 271–272 Ptilostomus spp., 2 Public awareness, 327, 328 Public education, 123

Q Quebec biogeography, 77 conservation recommendations, 223 depressions, 21 slopes, 23 surficial geology, 13

R Raccoons (Procyon lotor), 180, 182, 240 Raithel studies, 169–183 Rana sylvatica, 2 Rare ecological associations and systems, 85 Rare plants, 74, 84–85 Rawinski studies, 71–88 Reading Memorial High School case study, 312 Recolonization, 42, 43, 44 Redback salamander (Plethodon cinereus), 128, 260 Red fox (Vulpes vulpes), 180 Red maple (Acer rubrum) biogeography, 77 depressions, 22 fundamentals, 72 zonation, 81 Red maple swamp pools (Acer rubrum), 75 Red-spotted newt (Notophthalmus viridescens), 130 Reed canary grass (Phalaris arundinacea), 86

Reed studies, 105–123, 149–163 Regional approaches, 26 Regional scale, 208 Regional variations, 13–14, 15–17 Regulations Canada, 195–197 conservation recommendations, 209–210 fundamentals, 193–195, 194, 210 United States, 197–209 wetland policies, xii–xiii Reilly studies, 319–336 Relationship building, 310–311 Relevance, 293 Remote and field identification analysis techniques, 59–61 case study, 63, 63–64, 65 conservation recommendations, 65–66 errors discussion, 60–61 field identification, 61–65 fundamentals, 55–56, 66 image availability, 58 interpretation, 59–61 Massachusetts case study, 63, 63–64, 65 remote sensing, 57–58 survey techniques, 57–65 Remote sensing, 57–58, 64 Reptiles, see also specific type biodiversity, 2 fundamentals, 170 generalists, 173–174, 178–179 lizards, 174–176, 175, 178–179 snakes, 174–176, 175, 178–179 specialists, 171–173, 173 turtles, 170–174, 171 vernal pool importance, 170–176 Rescue effects, spatial ecology, 137 Restoration of habitat, 244 Rheinhardt studies, 11–26 Rhode Island birds, 177 drift and inbreeding, 157 groundwater, 35 hydroperiods, 78 regulations, 201 road mortality, 239 state heritage classifications, 76 urbanization, 237, 241 Ringed-boghaunter dragonfly (Williamsonia lintneri), 86 Riverine climate change, 49 geomorphic settings, 17, 24–25 hydrologic connectivity, 41 National Wetland Inventory, 75 Road mortality, 238–239

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Index Roads, hydrology, 258 Roger Tory Peterson Institute case study, 314 Rotifers, 106 Roundworms, 106 Royal fern (Osmunda regalis), 72 R-selected annuals, 82 Rusty willow (Salix cinerea spp.), 86 Rutgers University Center for Remote Sensing and Spatial Analysis, 333 Ruts, forest floor, 258, 272, see also Skid trails

S Safety, field studies, 302, 304 Salamanders, see also specific type chemical compounds, 219–220 common, 129 community ecology, 110 connectivity and dispersal, 44–45 conservation implications, 141 dispersal distances, 153–154 ecology and conservation, 128, 130 flora/fauna relationships, 86 genetic diversity, 152 habitat enhancement and aesthetics, 121 migration distances, 140 partial harvesting, 262 population dynamics, 135, 149 urbanization, 234 wetland-terrestrial connectivity, 47 Salt marshes, 18 Sanderson studies, 281–294 Satellite images, 55–56, see also Aerial photography; Mapping Scarification, 272, see also Ruts, forest floor Schools, 311, see also Educational opportunities Science education organization recommendations, 311 Scientist recommendations, 310–311 Sciomyzid fly larvae, 108 “Seasonally flooded” terminology, 75 “Semi-permanently flooded” terminology, 75 Semlitsch studies, 127–142 Sensitive fern (Onoclea sensibilis), 77 Shading, 133 Sheep laurel (Kalmia angustifolia), 80 Short-tailed shrew (Blarina brevicauda), 180, 265 Shrews, 180, 182 Shrub swamp pools, 75 Silent Spring, 319 Site-based mapping, 293 Skelly studies, 127–142 Sketch mapping, 59, 62 Skid trails, 25, see also Ruts, forest floor

359 Skunks, 180 Slender marsh-pink (Sabatia campanulata), 85 Slopes, 16, 23 Small crustaceans, 106, 114–115 Small-fruited spike-rush (Eleocharis microcarpa), 45 Smoky shrew (Sorex fumeus), 180 Smooth alder (Alnus serrulata), 83 Snails, see also specific type community ecology, 110 distributions and life cycles, 108 diversity and ecology, 106 invertebrates, diversity and ecology, 116 life history strategies, 108 Snakes, see also specific type conservation implications, 181 vernal pool importance, 174–176, 175, 178–179 wetland-terrestrial connectivity, 46 Snapping turtle (Chelydra serpentina) generalists, 173 handling, 307 road mortality, 238 Snow melt, 49 Social values, 4–5 Soils, forest, 258 Solid Waster Agency of Northern Cook County vs. U.S. Army Corps of Engineers (SWANCC), 195, 199–201, 209 Sources, chemical contamination agricultural practices, 221 complicating factors, 222–223 forest management practices, 217–220, 218–219 mosquito control, 218–219, 220–221 urban development, 221 Spatial distribution interfaces, 3 Spatial ecology, 137–139, 138 Specialists, 171–173, 173 Species at Risk Act, 195 Species-centric strategy, 5 Species-focused approach, 5 Species of concern, 178–179 Speckled alder (Alnus incana), 77 Sphagnum spp., 80 Spiders, 106 Spinicaudata, 112–113 Spotted salamander (Ambystoma maculatum) clearcutting, 260 coarse woody degree, 265 community ecology, 110 ecology and conservation, 130 forest litter, 264 gap analysis, 291 life zone, 272

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pool fidelity, 256 protection zone, 271 road mortality, 239 snakes, 176 spatial ecology, 138 urbanization, 234, 238 Spotted turtle (Clemmys guttata) conservation implications, 181 edge-related effects, 240 pool importance, 171–174 regional conservation, 208 Spring peeper (Pseudacris crucifer), 135, 256 Spruce (Picea spp.), 79 Spruce budworm (Choristoneura fumiferana), 216, 260 Standards inadequacy, 205 Star-nosed mole (Condylura cristata), 180, 182 State heritage classifications, 76–77 State level regulations, 201–203, 287 State University of New York at Fredonia case study, 314 Stereo viewing, 59 Stinkpot (Sternotherus odoratus), 174 Stocking predators, 122 Stream flow, 49, see also Riverine Streamside salamander (Ambystoma barbouri), 159 Strip-cutting, 259 Striped skunks (Mephitis mephitis), 180 Students, 4, see also Educational opportunities Substrate, 79–80, 122 Surface water, 35 Surrounding vegetation, 80 Surveys analysis techniques, 59–61 case study, 63, 63–64, 65 conservation recommendations, 65–66 errors discussion, 60–61 field identification, 61–65 fundamentals, 55–56, 66 image availability, 58 interpretation, 59–61 Massachusetts case study, 63, 63–64, 65 remote sensing, 57–58 survey techniques, 57–65 Survey techniques analysis techniques, 59–61 errors discussion, 60–61 field identification, 61–65 image availability, 58 interpretation, 59–61 Massachusetts case study, 63–64, 63–64 remote sensing, 57–58, 61–65 Swale zones, 41 Swamp cottonwood (Populus heterophylla), 85

SWANCC (Solid Waster Agency of Northern Cook County vs. U.S. Army Corps of Engineers), 195, 199–201, 209 Sweet pepperbush (Clethra alnifolia), 83

T Tadpole shrimp, 106, 113, 114 Taking, fear of, 205–206 Target landscape identification, 285, 287–288, 288 Teachers, 309–311, see also Educational opportunities Tebufonozide, 220, 259–260 Tennessee, 177 Terraserver, 58 The Federal Policy on Wetland Conservation, 195, 196 Threatened species copper-bellied watersnake (Nerodia erythrogaster), 176 eastern ribbon snake (Thamnophis s. sauritus), 175 types, 178–179 United States, conservation policy, 204 Three-angled spikebrush (Eleocharis tricostata), 85 Three-nerved joe-pye weed (Eupatorium dubium), 83 Tibbetts, Elizabeth, xv Tiger salamanders (Ambystoma tigrinum), 141, 176 Timber harvesting, 47–48 Timber management, 6 Timber wolf (Canis lupus), 254 Toads, see also specific type common, 129 community ecology, 110 conservation implications, 141 dispersal distances, 153–154 ecology and conservation, 128 Toothed planorbid (Planorbula armigera), 116, see also Snails Traffic intensity, 239 Tree removal, 258 Trichoptera, 117 Triclopyr, 220, 259 True bugs, 118 True flies, 118–119 Turbellaria orders, 115 Turtles, see also specific type habitat associations, 170 handling, 307 road mortality, 238

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Index urbanization, 234 vernal pool importance, 170–174, 171 wetland-terrestrial connectivity, 46

U Unavoidable impact minimization, 243–246 United States, conservation policy assessment data accessibility, 207 assessment standards inadequacy, 205 avoidance vs. compensation, 205 challenges and solutions, 204–205, 207–209 compensation vs. avoidance, 205 cross-purposes of mandates, 206–207 data, 208–209 endangered species, 204 fear of takings, 205–206 federal level, 197–201 flexibility, 208 informed development, 208–209 inventory, 207–209 local level, 203–209 Maine case study, 202–203 mandate issues, 206–207 Massachusetts case study, 200–201 over-reliance, regulations, 205 planning challenges and solutions, 207–209 regional scale, 208 standards inadequacy, 205 state level, 201–203 SWANCC, 199–201 taking, fear of, 205–206 threatened species, 204 Universal Transverse Mercator (UTM), 58, 62–63 University of Guelph, 329 University of Maine Wetland Connections Project case study, 314 Urbanization avoidance strategy, 242–243, 243 BMP models, 246 chemical contamination sources, 221 conservation opportunities, 241 conservation recommendations, 241–246 direct loss, 235–236, 236–237 ecosystem persistence, 241 edge-related effects, 240 enhancement, 244 fundamentals, 233–234, 246 gene flow barriers, 239–240 impact of, 235–240 in-lieu fee programs, 246 inventory, 242 land development, 48 minimize strategy, 242–243, 243

361 mitigation banks, 246 models, 246 monitoring opportunities, 242 movement barriers, 239–240 neighboring habitat loss, 237–238 preservation, 244 restoration, 244 road mortality, 238–239 unavoidable impact minimization, 243–246 vernal pool creation, 244–245 U.S. Army Corps of Engineers (the Corps), 195 U.S. Environmental Protection Agency (EPA) conservation implications, 83 distributional patterns, 132 regulations, 198 U.S. Fish and Wildlife Service, 55, 75, 198 U.S. Geological Survey (USGS), 58 U.S. National Science Education Standards, 302, 305 USGS Amphibian Research and Monitoring Initiative (ARMI), 329 UTM, see Universal Transverse Mercator (UTM)

V Value of habitat, 287 Valuing and conservation biodiversity, 2–3 ecosystem conservation, 5–7 ecosystem processes, 3–4 fundamentals, 1–2, 7 keystone ecosystems, 4 social values, 4–5 Vectobac, 221 Vectolex, 221 Vegetation, see Flora Vermont basin size and canopy closure, 79 bats, 181 birds, 177 chipmunks, 180 coarse woody debris, 265 floristic diversity, 82 forest litter, 264 Jefferson salamander (Ambystoma jeffersonianum), 180 regulations, 201 shrews, 180 state heritage classifications, 76 wood frogs, 180 Vermont Institute of Natural Science, 313–314 Vernal pools assessment sheet, 330 at-risk plant species, 74

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Science and Conservation of Vernal Pools in Northeastern North America

biodiversity, 2–3 boundaries, 60 creation, 244–245 ecosystem processes, 3–4 fundamentals, xi–xiii, xvi–xvii hydrologic role, 4 keystone ecosystems, 4 literacy, 327 managed forest relationships, 257–265 nonnative plants, frequent, 87 plant species, common, 91–104 social values, 4–5 types, 19 values of, 2–5 Vernal pools, importance birds, 176–177, 178–179 conservation implications, 181–182 fundamentals, 169–170, 182–183 generalists, 173–174, 178–179 lizards, 174–176, 175, 178–179 mammals, 177–181, 178–179 reptiles, 170–176 snakes, 174–176, 175, 178–179 specialists, 171–173, 173 turtles, 170–174, 171 Vernal pools, outdoor laboratories Amphibian Malformation Surveys case study, 313 case studies, 311–314 conservation professional recommendations, 310–311 Doyon Elementary School case study, 312–313 ecological impact considerations, 304–305 field study program considerations, 301–307 fundamentals, 299–301, 314–315 Harvard Forest Schoolyard Freshwater Ecology case study, 313 legal issues, 307 live animals, handling and keeping, 305–307 Marvelwood School case study, 313 Michigan middle and high schools case study, 313 Nessacus Middle School case study, 312 partnerships, 307–310, 308 Reading Memorial High School case study, 312 relationship building, 310–311 Roger Tory Peterson Institute case study, 314 safety, 302, 304 science education organization recommendations, 311 scientist recommendations, 310–311 State University of New York at Fredonia case study, 314

teacher recommendations, 311 University of Maine Wetland Connections Project case study, 314 Vermont Institute of Natural Science, 313–314 Virginia bats, 181 biogeography, 77–78 hydroperiods, 78 zonation, 81 Virginia opossum (Didelphis virginiana), 180

W WAAS-enabled GPS, 62–63 Wading birds, 177 Water beetles and bugs, 106 Watercourse and Wetland Alteration Regulation, 196 Water fleas (Daphnia pulex) diversity and ecology, 106 invertebrates, diversity and ecology, 114–115 life history strategies, 108 Water mites, 106, 120, 120 Water quality, 259–260 Water Resources Act, 196 Water shrews (Sorex palustris), 180 Water willow pools (Decadon verticillatus), 75 Weeks studies, 105–123 Westford, Massachusetts, 237–238 West Nile virus (WNV), 119 West Virginia, 77 Wetland Alteration Approval, 196 Wetland Conservation Policy for Prince Edward Island, 196 Wetlands Conservancy Mapping program, 64 Wetlands Protection Act, 202 Wetland-terrestrial habitat, 46–47, 237–238 White-footed mice (Peromyscus leucopus), 180 White Mountain National Forest, 264 White-tailed deer (Odocoileus virginianus), 181 Wildlife Conservation Society's Living Landscapes Program, 283 Wild turkey (Meleagris gallopavo), 254 Windmiller studies, 233–246 Wisconsin bats, 180 depressions, 20, 22 distributional patterns, 131 flats, 23 mink, 180 regulations, 198, 201 surficial geology, 13–14 wood frogs, 180 Wisconsin Sand Plain, 23

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Index WNV, see West Nile virus (WNV) Wood duck (Aix sponsa), 177, 181 Wood frog (Rana sylvatica) biodiversity, 2 birds, 177 chipmunks, 180 clearcutting, 260 community dynamics, 136 community ecology, 110 distributional patterns, 131–132 focal landscape layer, 292 gap analysis, 291 landscape species approach, 284 life zone, 272 pool fidelity, 256 protection zone, 271 road mortality, 239 snakes, 176 turtles, 173

363 urbanization, 234–235, 238 wetland-terrestrial connectivity, 47 Woodland jumping mice (Napaeozapus insignis), 180 Woodland pools, 77 Wood turtle (Glyptemys insculpta), 171, 174, 240 Worms, 106, 110, 115

Y Yale Myers Forest, 132

Z Zonation, 80–81, 81 Zooplankton, 3, 130, 219–220

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a

b

c

COLOR PLATE 1 A comparison of commonly available aerial photographs for one locality in Massachusetts, U.S.A. (a) Color infra-red (CIR) film; (b) true-color digital orthophoto; and (c) black and white film emulsions. Scale is approximately 1:12,000.

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a

b

COLOR PLATE 2 Color infrared digital ortho quarter quadrangle (DOQQ) with National Wetland Inventory polygons (a) and USGS topographic map (b) for a selected southern New Jersey coastal plain vernal pool complex. Blue arrow indicates a vernal pool that is part of a palustrine forested wetland (PFO1); orange arrow indicates a vernal pool in an upland setting.

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COLOR PLATE 3 True-color aerial photograph of a site in Massachusetts where intensive ground-truthing using calling and transect surveys identified significant errors of omission. Photo-interpreted potential vernal pool data are in red (N = 11), and field-verified pools in yellow (N = 34). Omission errors were created by low topographic relief that limited cues to basin presence, conifer stands that created shadow and obstructed views of the ground and water surfaces, and small pool size.

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COLOR PLATE 4 A “classic” vernal pool in an upland depression. This vernal pool setting is easily recognized in the spring, but can be difficult for the untrained eye to discern in late summer when it may be dry. This northern New England pool is surrounded by softwood forest; pools in similar geomorphic settings in southern New England often occur in hardwood forests. (Photo: Aram Calhoun.)

COLOR PLATE 5 Vernal pools often are embedded in larger forested wetlands such as this red maple (Acer rubrum) swamp. It is common for pools in northern New England and Atlantic Canada to occur in extensive softwood-dominated forested wetlands including spruce-fir flats. (Photo: Robert Bryan.)

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COLOR PLATE 6 Vernal pools located in floodplain forests may provide foraging and resting habitat for reptiles of conservation concern in the Northeast including ribbon snakes (Thamnophis sauritus) and wood turtles (Glyptemys insculpta). Intermittent spring flooding may introduce fish, but this is a temporary phenomenon. (Photo: Phillip deMaynadier.)

COLOR PLATE 7 Vernal pools may occur in all freshwater wetland classes, including shrub and emergent dominated wetlands. This moss (Sphagnum spp.) carpeted pool provides ideal breeding habitat for the rare ringed boghaunter dragonfly (Williamsonia lintneri). Winterberry (Ilex verticillata), speckled alder (Alnus incana), highbush blueberry (Vaccinium corymbosum), and buttonbush (Cephalanthus occidentalis) are common vernal pool shrubs in these systems. (Photo: Phillip deMaynadier.)

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COLOR PLATE 8 Following a brief appearance in breeding pools in the spring, spotted salamanders (Ambystoma maculatum) spend most of their adult life in the surrounding upland forest where they find refuge under logs, leaf litter, and inside small mammal burrows. (Photo: www.patrickzephyrphoto.com.)

COLOR PLATE 9 One of the earliest pool-breeding amphibians in our region is the secretive blue-spotted salamander (Ambystoma laterale). Look for this species, and the closely related Jefferson salamander (A. jeffersonianum), crossing roads on their way to breeding pools on rainy nights in early spring. Throughout much of the Northeast, polyploid hybrids (animals with more than two sets of chromosomes) of Jefferson and blue-spotted salamanders are more common than either parental species. (Photo: Leo P. Kenney.)

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COLOR PLATE 10 The last amphibian to breed in our region’s vernal pools is the marbled salamander (Ambystoma opacum). Following late summer or fall courtship in the upland area surrounding a pool, females lay up to 200 eggs in a small depression at the bottom of a dry basin. The adult female often stays with her eggs, offering protection from predation and desiccation, until fall rains inundate the pool basin and nest chamber. (Photo: www.patrickzephyrphoto.com.)

COLOR PLATE 11 Wood frogs (Rana sylvatica) are among a small number of northern amphibians capable of producing high levels of glucose in the liver, which functions as an antifreeze compound. Freeze resistance is an important adaptation for a species that overwinters above ground (under leaf litter or in shallow burrows), and whose distribution extends as far north as the Arctic Circle. (Photo: Megan Gahl.)

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COLOR PLATE 12 Colorful and charismatic, spotted turtles (Clemmys guttata) are closely associated with vernal pools in the Northeast where they spend considerable amounts of time foraging, searching for mates and, in deeper, persistent pools, overwintering. (Photo: Phillip deMaynadier.)

COLOR PLATE 13 Blanding’s turtles (Emydoidea blandingii) are recognizable by their highly domed shell and bright yellow throat. Challenging the conservation of this species in the Northeast is the large number of small wetlands and vernal pools individual turtles often weave together in an activity area. Long-distance upland movements place Blanding’s turtles at elevated risk of road kill, predation, and illegal collection. (Photo: Leo P. Kenney.)

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COLOR PLATE 14 Fond of tadpoles and frogs and adept at swimming, ribbon snakes (Thamnophis s. sauritus) are one of the most frequently encountered snakes at vernal pools in our region. Care is needed to distinguish this species from the easily confused eastern garter snake (Thamnophis s. sirtalis), which is also commonly found foraging and basking along the edges of vernal pools. (Photo: Joseph Mitchell.)

COLOR PLATE 15 Eastern garter snakes (Thamnophis s. sirtalis) are just one of the many common forest predators attracted to vernal pools because of the tremendous biomass of frogs, salamanders, and other prey species produced annually from these ecosystems. This individual is predating an adult spotted salamander (Ambystoma maculatum) near the edge of a seasonal wetland. (Photo: Chris Franklin/CELT.)

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COLOR PLATE 16 Some examples of the great variety of invertebrates commonly found in vernal pools. From top to bottom: Left: Phantom midge larva (Uniramia, Insecta, Diptera, Chaoboridae, Chaoborus sp.) — the shiny round air chambers allow the larvae to control their buoyancy. Small (recently hatched) swimming mayfly nymph (Uniramia, Insecta, Ephemeroptera, Baetidae) — although diverse in streams and ponds, only a few mayfly species occur in vernal pools. Water flea carrying eggs (Crustacea, Branchiopoda, Anomola, Daphniidae) — many pool inhabitants prey on these filter feeders. Cyclopoid copepods (Crustacea, Copepoda, Cyclopoida, Cyclopidae) — tiny but fierce predators, some species control mosquito populations. Right: Amphipod (“scud”) (Crustacea, Malacostraca, Amphipoda, Crangonyctidae) on caddisfly case (Uniramia, Insecta, Trichoptera, Limnephillidae) — the tan, round balls are fairy-shrimp eggs incorporated into the case by the caddisfly larva. Flatworm (Platyhelminthes, Turbellaria, Tricladida) — these cryptic animals are important cold-water predators. Female fairy shrimp (Crustacea, Branchiopoda, Anostraca, Chirocephalidae, Eubranchipus sp.) — species identification requires examination of male antennae. All are at approximately the same scale. (Photos © Judy M. Semroc. Used by permission.)

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COLOR PLATE 17 Following a brief period of breeding in vernal pools, adult salamanders and frogs migrate significant distances into the surrounding forest where they remain largely unseen and unheard for most of the year. Emerging metamorphs disperse into the same forest habitat later in the season, generally in mid- to late summer and fall. The values reported below each species contour line are mean and maximum distances reported from the literature for relatively better-studied pool-breeding taxa of the Northeast. Migration distances are reported in feet (versus meters) to facilitate comparison with the limited wetland protection standards required by most local and federal governments. Readers are referred to Chapter 7, Table 7.2 (Semlitsch and Skelly), for a comprehensive summary of migration distances for pool-breeding amphibian specialists of northeastern North America. (Schematic by Matt Burne and Phillip deMaynadier.)

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COLOR PLATE 18 An example of ecologically sensitive forest management around a vernal pool located in a mature mixed forest. Implementation of the vernal pool Habitat Management Guidelines (HMGs; Chapter 13, deMaynadier and Houlahan) requires decreasing timber harvest intensity with increasing proximity to high value pools hosting breeding indicator species. HMG zones are drawn to scale. (Drawing by Mark McCollough. Reprinted from Calhoun and deMaynadier 2004, with permission from the Metropolitan Conservation Alliance.)