Ecological Factors Affecting the Diversity of Tropical Tree Seedlings C
Total Page：16
File Type：pdf, Size：1020Kb
Louisiana State University LSU Digital Commons LSU Doctoral Dissertations Graduate School 2007 Ecological factors affecting the diversity of tropical tree seedlings C. E. Timothy Paine Louisiana State University and Agricultural and Mechanical College, [email protected] Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_dissertations Recommended Citation Paine, C. E. Timothy, "Ecological factors affecting the diversity of tropical tree seedlings" (2007). LSU Doctoral Dissertations. 2452. https://digitalcommons.lsu.edu/gradschool_dissertations/2452 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Doctoral Dissertations by an authorized graduate school editor of LSU Digital Commons. For more information, please [email protected]. ECOLOGICAL FACTORS AFFECTING THE DIVERSITY OF TROPICAL TREE SEEDLINGS A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Biological Sciences by C. E. Timothy Paine B. A. Dartmouth College 1999 August, 2007 i DEDICATION In memory of my grandfather Hugh R. (Farf) Gibson 1920 – 1999 ii ACKNOWLEDGEMENTS I first want to thank Kyle Harms. My advisor has been consistently kind, considerate, and supportive of my goals. In his gentle way, he has shepherded me away from dozens of unpro- ductive dark alleys, and encouraged me to head out independently toward the edge of scientific knowledge. He is one of a kind. I thank my graduate committee. Discussions with Richard Stevens, Jim Cronin, Jay Geaghan, and Thomas Dean sharpened the arguments forwarded in this dissertation. Their guid- ance has been invaluable. Luis Escobar, James P. Geaghan and Qingfang Wu were generous with their time and knowledge, and helped develop the data analysis. Extensive discussions with Barry Moser, who died unexpectedly in 2006, brought much of statistics into focus for me. I deeply appreciate the efforts of Pamela Weisenhorn, Armando Mendoza, Christina Georghiou, Nataly Hidalgo, Kristen Schmitt, and Cecilia Carrasco, who worked with me as field assistants. All tolerated many hot hours in the muddy, buggy understory. Pamela Weisenhorn, par- ticularly, far surpassed what could be expected from a field assistant. Her eye for detail improved the design and execution of these experiments. I want to thank my friends and labmates at LSU, who have been supportive and wonder- ful, including Heather Passmore, Paul Gagnon, Jonathan Myers, and Adriana Bravo. I owe special thanks to Jane Carlson, who started at LSU with me, and has been my best friend and confidante since the first. Jane Carlson, Jonathan Myers, Heather Jackson, Margaret Metz, Sarahfaye Mahon, and Heather Jackson carefully read drafts of the chapters of this dissertation, and made many sug- gestions that improved it. The errors that remain are my own. iii I appreciate my colleagues and friends from Cocha Cashu. Susan Willson took a chance on me, and introduced me to Cocha Cashu. John Bunce, Varun Swamy, Kyle Dexter, Natalia Quinteros, and Nicole Gibson supported me, and each other, throughout our concurrent Ph.D. investigations in el bosque encantado. Mercedes Foster provided guidance and judgement, and un monton of natural history. Working with seedlings would have been impossible without the plant identification skills shared by her, John Terborgh, Nigel Pitman and Fernando Cornejo. Mac Alford (USM) determined the Casearia sp. nov. used in Chapter 4. I wish to single out Patricia Alvarez for special thanks – her energy, drive, and laughter made life in the jungle exciting and joyous, and made the manuplants.org project possible. I continue to miss Francis Bossuyt and Abbie Sorenson, whose love of all natural things opened my eyes. I thank my family of Paines, Feldermans, Fauses, Gibsons, and others. Their love was unconditional, whether or not they knew what I spent all those years doing in the jungle. More than anything, I thank Sarahfaye Mahon for her incredible support, encouragement, and compan- ionship. Collaboration with Stefan Schnitzer and Walt Carson made possible the experiments described in Chapter 3. Christopher Baraloto and Margaret Metz also kindly shared unpublished results that contributed to the generality of Chapter 3. And collaborating with Harald Beck, who has long been a role model for me, made the mammal-exclosure experiments of Chapter 4 possi- ble. Discussions with him also materially improved Chapter 3. John Terborgh has been extremely generous in sharing unpublished results from his seed-trapping project. These data provided con- text that strengthened all three experiments of this dissertation. I thank Peru’s Instituto Nacional de Recursos Naturales (INRENA) for permission to con- duct research in Manu National Park. This research was supported through a LASPAU fellowship iv from the Organization of American States, a Grant-in-Aid-of-Research from Sigma Xi, and the LSU Biology Graduate Student Association (BioGrads). I particularly appreciate the support of a LSU Board of Regents fellowship, without which this dissertation would not have been possible. v TABLE OF CONTENTS DEDICATION ................................................................................................................................ ii ACKNOWLEDGEMENTS ........................................................................................................... iii LIST OF TABLES ....................................................................................................................... viii LIST OF FIGURES ....................................................................................................................... ix ABSTRACT ................................................................................................................................... xi CHAPTER 1 – INTRODUCTION ..................................................................................................1 PROCESSES THAT LIMIT THE RECRUITMENT OF TROPICAL TREE SEEDLINGS ........................................................................................................................1 LIMITS TO DISPERSAL ........................................................................................2 POST-DISPERSAL LIMITS TO ESTABLISHMENT ............................................5 SITE DESCRIPTION ............................................................................................10 FOCAL SPECIES ..................................................................................................16 DISSERTATION STRUCTURE ...........................................................................16 CHAPTER 2 — WHAT SHAPES TROPICAL SEEDLING COMMUNITY STRUCTURE? SEED DISPERSAL VERSUS ENVIRONMENTAL CONDITIONS ..............................21 INTRODUCTION .................................................................................................21 METHODS ............................................................................................................23 RESULTS ...............................................................................................................31 DISCUSSION ........................................................................................................40 CHAPTER 3 — WEAK COMPETITION AMONG TROPICAL TREE SEEDLINGS: IMPLICATIONS FOR SPECIES COEXISTENCE ..........................................................47 INTRODUCTION .................................................................................................47 MATERIALS AND METHODS ..........................................................................49 RESULTS ...............................................................................................................55 DISCUSSION ........................................................................................................59 CHAPTER 4 — SEED PREDATION BY NEOTROPICAL RAINFOREST MAMMALS INCREASES DIVERSITY IN SEEDLING RECRUITMENT .........................................64 INTRODUCTION .................................................................................................64 METHODS ............................................................................................................66 RESULTS ...............................................................................................................74 DISCUSSION ........................................................................................................81 CONCLUSIONS ...................................................................................................85 vi CHAPTER 5 – CONCLUSIONS ..................................................................................................86 SUMMARY ...........................................................................................................86 SYNTHESIS ..........................................................................................................86 LITERATURE CITED ...................................................................................................................89 APPENDIX 1 – DENSITIES OF SEEDLINGS IN SEED-ADDITION EXPERIMENTS OF CHAPTER 2 ....................................................................................................................107 APPENDIX 2 – LETTERS OF PERMISSION ...........................................................................118