©2013 Lea R. Johnson ALL RIGHTS RESERVED
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©2013 Lea R. Johnson ALL RIGHTS RESERVED LONG-TERM OUTCOMES OF ECOLOGICAL RESTORATION AND MANAGEMENT IN URBAN FOREST PATCHES by LEA R. JOHNSON A dissertation submitted to the Graduate School-New Brunswick Rutgers, The State University of New Jersey In partial fulfillment of the requirements For the degree of Doctor of Philosophy Graduate Program in Ecology and Evolution Written under the direction of Dr. Steven N. Handel And approved by ________________________ ________________________ ________________________ ________________________ New Brunswick, New Jersey May, 2013 ABSTRACT OF THE DISSERTATION LONG-TERM OUTCOMES OF ECOLOGICAL RESTORATION AND MANAGEMENT IN URBAN FOREST PATCHES By LEA R. JOHNSON Dissertation Director: Dr. Steven N. Handel Urbanization transforms ecological systems, altering soils, hydrology, climate, species pools, and landscape patterns. Municipalities are turning to ecological restoration of urban forests to provide essential ecosystem services. This dissertation examines long- term effects of ecological restoration of forest patches invaded by woody invasive plants within urban park natural areas in New York City, New York, USA. I compared invaded sites where restoration was initiated 15-20 years prior with similarly invaded urban park forests that had not been restored. Significantly lower invasive species abundance, more complex vertical forest structure, and greater native tree recruitment indicated that invasive species removal followed by planting resulted in divergent successional trajectories and achievement of the central goals of the restoration. However, regenerating species indicated novel future assemblages, and restored sites varied in degree of reinvasion. To examine sources of this variability and test the importance of ii management effort to success of ecological restoration in urban forest remnants, I compared plant communities, management records, indicators of disturbance, and site characteristics among and between restored and unrestored invaded patches and a less-disturbed urban forest remnant. Differences among restored plant communities were associated with total restoration effort and with soil surfaces impacted by urban conditions, indicating the importance of urban context and ongoing management effort to outcomes of ecological restoration in urban areas. To examine these soil effects and to test whether impacts of urbanization on soils affect long-term outcomes of ecological restoration in urban forest patches, I compared plant community composition of restored, unrestored and less-disturbed sites with soil physical and chemical characteristics and urban soil classification maps. No single soil impact dominated effects on plant community composition, but all sites were impacted by anthropogenic factors known to reduce plant growth, change distributions of soil biota, and alter nutrient cycles. I present an urban perspective on the use of succession theory in ecological restoration and introduce adaptive successional phasing as a tool, emphasizing site-specificity, long- term processes, and the importance of the urban environment’s effects on soils, species pools and disturbance regimes, and suggest that native species persisting and thriving in cities should be used in urban ecological restoration. iii ACKNOWLEDGEMENTS This undertaking has been a collaboration involving a great number of people who have shared their time, expertise and thoughtful advice. Steven Handel has advised and supported me throughout the process in too many ways to count. I’ve had the support of an excellent committee, who have given me useful feedback along the way. Joan Ehrenfeld, who helped me to make the connections that began this project, inspired me with her rigor and passion for good science. Steve Clemants was always available to talk in the early phases of this research, and connected me with the good people of the Brooklyn Botanic Garden. I have often wished for both their advice as the project has unfolded. I’ve enjoyed having the opportunity to step out of the thicket and discuss the bigger picture with Steward Pickett. Both Steward and Rich Pouyat were part of laying the groundwork for this study with their early work on urban-rural gradients in New York City, and this research owes much to their contributions to the study of urban systems. Rich has been an invaluable source of expertise on soils in cities. Claus Holzapfel has patiently helped me with analysis of voluminous data, and I’ve enjoyed being an ancillary member of his lab group. Collaboration with the New York City Department of Parks and Recreation’s Natural Resources Group, Prospect Park Natural Resources, New York Botanical Garden, Brooklyn Botanic Garden, New York City Soil Survey, and the Natural Resources Conservation Service have made this research possible. Tim Wenskus of the New York City Parks Department’s Natural Resources Group started it all by wanting to know what had happened to NRG’s earliest restorations. He helped me to find records, suggested people to talk to, and shared his wealth of knowledge of both New York City’s wild lands iv and their management. Katerli Bounds, Michael Feller, Craig Mandel, Minona Heaviland, Chisato Shimada, Richard Love, Ellen Pehek, Brady Simmons, Susan Stanley, and other members of the Natural Resources Group have likewise been generous with their time and expertise. They answered my many questions, helped me to find interns and make maps, and put up with me piling boxes of old files under the desks. Jessica DiCicco, Anne Wong, and John Jordan at Prospect Park shared their knowledge of Brooklyn’s forest. Jessica DiCicco and Tim Wenskus deserve special thanks for helping me to decode four-letter codes for hundreds of species. Jessica Arcate Schuler of New York Botanical Garden made it possible to extend the study to include the Thain Memorial Forest. I am grateful to Steve Glenn, Gerry Moore and Paul Harwood of the Brooklyn Botanic Garden for poring over many bicycle-loads of specimens, and for sharing both pleasant lunches under the magnolias and their botanical expertise. Rich Shaw of NRCS and the New York City Soil Survey has likewise been generous with his time, and his interest in the project made the soil metals analysis possible. Thanks to Edwin Muniz for doing the metals analysis. The physical undertaking of sampling required a hale and hearty crew willing to withstand summer heat and head boldly into two-meter-high thickets of Rosa multiflora. The generous support of the Center for Urban Restoration Ecology, Timon McPherson at The New School, Matt Palmer at Columbia University, and New York City Parks NRG provided me with an excellent core crew of students and volunteers, for which I am very grateful. Eric Berger worked with me during two years of summer sampling. His calm, patience and sense of humor in the most ridiculous physical conditions were a gift. Thanks to the Columbia Earth Institute, Natalia Rossi was an important part of the early data organization and site location process. New School interns Leila Mougoui-Bakhtiari, v Tom McPartlon, Jason Sohn-Greenberg, Stephen Toriello and Hsiaolan Mu did excellent work, supported by regular volunteers Mustafa Ali, Lisa Kozlowski, Josephine Decker, and Rita Suri who gave their time to the project. Many friends, students and curious people also volunteered, representing professions from poet to programmer and sousaphonist to social worker. Thanks to Bruno Soria, Clement Courtial-Filhol, Corwin Zelazny, Douglas Manson, Gabriel Willow, James Knox, Joe Keady, Jooyoung Oh, Judy Shatzky, Karla Sosa, Kathleen Kerwin, Kevin Eng, Laura Vuksinich, Leslie Wacker, Mark Krawczuk, Michal Krol, Thomas Dunn, Will Smith, Zach Schulman, and Zane Mackin for giving time and a bit of blood to the mosquitoes and rose thorns. Thanks to Lisa Bentson for flying out from New Mexico for the final week of sampling. I am fortunate to have been part of the program in Ecology and Evolution, and I thank the people who have taught, tested, encouraged, and sparred with me at Rutgers. Marsha Morin saved me from the perils of bureaucracy on many occasions, and Marcie Anzsperger at CTAAR taught me to create and use databases. I enjoyed many afternoon tea breaks with David Ehrenfeld, who has been a source of encouragement through the harder times. I thank my labmates and fellow residents of Plant Physiology Elena Tartaglia, Carrie Norin, Shannon Galbraith-Kent, Amy Karpati, Belen Sanchez Humanes, Christina Kaunzinger and Myla Aronson for sharing the long journey and helping in ways large and small. Finally, I thank my family, especially Ginny Johnson, William Gonzales, Niki Johnson, and Ralph Johnson, and my family of friends for their love and support. Jenny Smith and Michele Hardesty deserve special mention and a cake. Last but not least, I would like to thank Adam Mumford for being. vi Any omissions here are certainly due to the effects of the dissertation on the author and not lack of gratitude. This work is dedicated to Joan Ehrenfeld, Steve Clemants, Harris Wulfson, Carisa Williams Joseph and Gwendolyn Griffiths Johnson. Their memories inspire me. vii TABLE OF CONTENTS ABSTRACT OF THE DISSERTATION ............................................................................ ii ACKNOWLEDGEMENTS ............................................................................................... iv LIST OF TABLES .......................................................................................................... xii LIST OF FIGURES ......................................................................................................