INTEGRATING COMPLEX ECOLOGICAL INFORMATION TO DEVELOP A MANAGEMENT PLAN FOR CHINESE TALLOW (SAPIUM SEBIFERUM L. ROXB.) IN SOUTH GEORGIA by CHERYL MARIE MCCORMICK (Under the Direction of C. RONALD CARROLL) ABSTRACT Managing pernicious invasive plant species is an essential component of maintaining biodiversity and restoring natural ecosystem structure and function. Chinese tallow (Sapium sebiferum L. Roxb.) is recognized as one of the most aggressive invaders of southeastern US wetland and coastal habitats. However, effective management of S. sebiferum is often obstructed by a lack of scientific information for management strategies, conflicting objectives, and a paucity of funding. The first chapter is a comprehensive management plan for S. sebiferum, and includes a description of the biology and ecology of S. sebiferum and its history in the southeastern US. It provides a comprehensive overview of treatment methods for the species, including each method's advantages and disadvantages, timing, and case studies involving management of S. sebiferum on public lands. In Chapter Two, I analyze the effects of feral hog (Sus scrofa L.) rooting behavior on S. sebiferum seedling recruitment and survivorship in island vs. mainland habitats as a function of hog density. I discuss the implications of tallow population regulation by hogs, and associated challenges to agencies mandated to eliminate both of these deleterious exotic species. My analysis indicates that at high densities of feral hogs such as occur on Ossabaw Island, feral hog rooting significantly increases the mortality of Chinese tallow seedlings; whereas at low densities such as occur in mainland ecosystems, there is little impact. In Chapter Three, I present a scientific approach for prioritizing management objectives through the application of generalized linear models to predict seed crop quality based on morphological seed traits in 16 populations of S. sebiferum in mainland, coastal, and island habitats in south Georgia, USA. Based on analyses of generalized linear models (GLMs), I conclude that the use of such models to accurately predict seed crop quality of S. sebiferum populations is an ineffective tool for assisting land managers in developing priorities for tallow control. However, this technique does appear to be useful in identifying very high- and low- priority populations for management. The goal of this body of research is to merge sound science with judicious management strategies, resulting in effective conservation practices. INDEX WORDS: Chinese tallow, Sapium sebiferum, management plan, invasive species, feral hog, rooting, Sus scrofa, Ossabaw Island, bottomland hardwood swamp, seed traits, generalized linear models, generalized linear mixed models INTEGRATING COMPLEX ECOLOGICAL INFORMATION TO DEVELOP A MANAGEMENT PLAN FOR CHINESE TALLOW (SAPIUM SEBIFERUM L. ROXB.) IN SOUTH GEORGIA by CHERYL MARIE MCCORMICK B.A., State University of New York at Plattsburgh, 1994 M.A., The University of Georgia, 1998 A Dissertation Submitted to the Graduate Faculty of The University of Georgia in Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY ATHENS, GEORGIA 2007 © 2007 Cheryl Marie McCormick All Rights Reserved INTEGRATING COMPLEX ECOLOGICAL INFORMATION TO DEVELOP A MANAGEMENT PLAN FOR CHINESE TALLOW (SAPIUM SEBIFERUM L. ROXB.) IN SOUTH GEORGIA by CHERYL MARIE MCCORMICK Major Professor: C. Ronald Carroll Committee: Laurie Fowler Carl F. Jordan Kathleen C. Parker Rebecca R. Sharitz Electronic Version Approved: Maureen Grasso Dean of the Graduate School The University of Georgia [May, August, or December] [Year of Graduation] DEDICATION This work is dedicated to my grandfather, Francis G. McCormick (1920-1984), who inspired me to be inquisitive about the world and who instilled within me the values of unwavering loyalty, solid character and love of one’s family. In his understated and gentle manner, he embodied the guiding principles upon which I have humbly attempted to live my life. Rarely a day passes when I do not wonder whether “Poppy” would be proud of this small accomplishment on my part, and of the manner in which I’ve chosen to express joy, creativity and intellectual expression through my vocation. “What is a scientist after all? It is a curious man looking through a keyhole, the keyhole of nature, trying to know what's going on” - Jacques Yves Cousteau iv ACKNOWLEDGEMENTS It has been an honor and a privilege to work under the direction of Ron Carroll, who has provided countless hours of invaluable mentoring, keen insight, and pragmatic management on this project. Ron will always be one of my greatest professional inspirations. Thank you, Ron, for everything. My deepest gratitude to Rebecca Sharitz, for whose endless patience and gentle encouragement I am forever indebted. It was a great honor to be mentored by a true paragon of wetlands research. Kathy Parker is a personal hero whose boundless energy, sharp, “big picture” intellect, and endearing personality inspires me in all realms of my life. All aspects of my work have greatly improved for her contribution. A special thanks to Laurie Fowler, who exudes positive energy and wisdom and without whom I am convinced the state of environmental policy in the State of Georgia would simply collapse. I have been inspired by the pragmatic, grounded research of Carl Jordan, whose logic, wisdom and cordiality I always appreciated. Thank you, Dr. Jordan for your review of my research; and for giving Institute graduate students the run of your farm. Lastly, Jim Hamrick elevated my research to levels I never imagined, through his high expectations, scientific rigor, and tremendous breadth and depth of plant ecology and genetics. Working with Jim was a professionally expansive and often very humbling experience. I am undoubtedly a higher-caliber scientist now than I was prior to working in your lab. I would like to extend my gratitude to the Georgia Department of Natural Resources for providing funding that made this research possible. Mike Harris, Todd Holbrook, Jim Simmons, Andy Meadows, William “Darryl” Hartley, and Mark Dodd all ensured that my experiences on Ossabaw were positive, both personally and professionally. v My sincerest thanks go to Andrew Grosse and Jason Norman, without whose assistance throughout many seasons of field work on Ossabaw, I could not have sustained the data collection efforts. Their deep commitment to and passion for their vocation, coupled with an insatiable inquisitiveness about the natural world and determination to produce results of the very highest caliber, commands my respect and admiration. I consider each to be finest example of undergraduate student achievement that UGA has to offer, and the very brightest students with whom I have had the pleasure to work. Though his influence appeared in the “11th hour”, Jim Sulentich, Executive Director of the Santa Lucia Conservancy, gave me one very compelling reason to complete my work. His good humor, gentle encouragement, and mastery in mentoring have already left an indelible mark on my professional career. Thanks, Jim. I reserve my deepest expression of gratitude to Eleanor “Sandy” West (aka, “Moose”), the Grande Dame of Ossabaw Island, who made an indelible impression on me from our first introduction. I have never met a more passionate, hilarious, quirky, well-read, refined, intelligent woman. The years I spent on Ossabaw at “The Main House” were some of the most memorable and treasured in my life. Words cannot adequately express my gratitude to you for your irrepressible love of Ossabaw and all of its creatures, great and small. Thank you, Mrs. West, for giving us this unspoiled jewel. My greatest learning experience came from you. vi TABLE OF CONTENTS Page ACKNOWLEDGEMENTS.............................................................................................................v LIST OF TABLES....................................................................................................................... viii LIST OF FIGURES ..................................................................................................................... xiii CHAPTER 1 CHINESE TALLOW (SAPIUM SEBIFERUM L.ROXB.) MANAGEMENT PLAN .............................................................................................................................1 2 EFFECTS OF FERAL HOG (SUS SCROFA L.) ROOTING ON CHINESE TALLOW (SAPIUM SEBIFERUM L. ROXB.) SEEDLING SURVIVORSHIP IN A SOUTHEASTERN BARRIER ISLAND AND BOTTOMLAND HARDWOOD SWAMP .................................................................87 3 USING GENERALIZED LINEAR MODELS TO PREDICT SEED TRAITS OF CHINESE TALLOW (SAPIUM SEBIFERUM L. ROXB.), AN INVASIVE SUBTROPICAL TREE.............................................................................................126 vii LIST OF TABLES Page Table 1.1: Chemicals derived from various plant tissues of Chinese tallow and their Medicinal properties ......................................................................................................................77 Table 1.2: Generalist fungal pathogens associated with Chinese tallow.......................................78 Table 1.3: Insect herbivores documented to consume Chinese tallow (Source: Zhang and Lin, 1994; translated from Chinese to English and provided courtesy of Dr. William E. Rogers, Texas A&M University, 2002).........................................................................................79 Table 1.4: Herbicides for preventing sprouting