Louisiana State University LSU Digital Commons LSU Doctoral Dissertations Graduate School 2005 Effects of hurricanes and fires on southeastern savanna-forest landscapes Heather Alicia Passmore Louisiana State University and Agricultural and Mechanical College, [email protected] Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_dissertations Recommended Citation Passmore, Heather Alicia, "Effects of hurricanes and fires on southeastern savanna-forest landscapes" (2005). LSU Doctoral Dissertations. 805. https://digitalcommons.lsu.edu/gradschool_dissertations/805 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]. EFFECTS OF HURRICANES AND FIRES ON SOUTHEASTERN SAVANNA-FOREST LANDSCAPES 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 Heather Alicia Passmore B.A., Earlham College, 1996 December 2005 DEDICATION In Memory of my Grandfather Dr. Robert Richmond Bryden, Ph.D. 1916-2005 Ecologist, professor and always a wonderful Grandpa ii ACKNOWLEDGEMENTS First and foremost my thanks go to Bill Platt. When I needed it most Bill provided a dichotomous key that led me to his lab. Over the years Bill has offered encouragement and unconditional support through the best and worst times. I count myself lucky to have had the chance to study and work hard with Bill Platt, and I am very glad for the opportunity to continue working with him in the future. Next I want to thank the members of my graduate committee. Dr. Jim Cronin has always provided straight-forward and solid advice on research and teaching. In addition I cannot thank him enough for his time and energy spent on letters of recommendation for grants and postdoctoral positions. Dr. Kam-Biu Liu has been an invaluable and supportive member of my graduate committee since its formation. I am grateful for his input and unique perspective on the ecological effects of hurricanes. I appreciate the patience and thoughtful advice offered by Dr. Barry Moser on all statistical analyses in this dissertation, as well as his willingness to write letters of recommendation. I thank Dr. Lewis Gaston for kindly serving as my dean’s representative. Finally, I would like to thank Dr. Brian Lockhart for his service on my committee and his enthusiastic field assistance on multiple occasions. Other faculty and researchers at LSU have played important roles in my academic development. I would not have come to Louisiana were it not for the support of Dr. Julie Denslow. In addition I have received invaluable help, advice, and letters of support from Drs. Kevin Carman, David Longstreth, Kyle Harms, Loretta Battaglia, Richard Stevens, and Brian Beckage. I am especially thankful for the kindness and patience of Kyle Harms at this time. This research would not have been possible without the cooperation and collaboration of the folks at Camp Whispering Pines. I am greatly indebted to Ranger Larry Ehrlich for his iii unflagging support with the canopy removal and prescribed fire treatments. I would especially like to thank Jean Fahr and the Southeast Louisiana Girl Scout Council for generously providing access to the wonderful field site, the great resources, the comfortable cabins, and the ubiquitous latrines at Camp Whispering Pines during this study. Field work at CWP would have been a much lonelier affair were it not for the loyal canine companionship of Toby (may he rest in peace) and Junior. Many thanks go to the LSU and Tulane undergraduates who have enthusiastically helped with field work and data entry over the years: Walter Simpson, Juan Gonzalez, Uchenna Nweze, Patrick Igbokwe, Holly and Jamie Book and Adrianna Pince. Without help from each of them I would have spent many more hours in the field collecting data and many more hours in front of the computer entering those data. During my years of graduate school I have been fortunate to develop lifelong friendships with many wonderful graduate students. First, I am endlessly grateful for the helpful discussions and logistical support from two old-school members of the Platt lab: Jarrod Thaxton and Paul Gagnon. The seed that started this dissertation was planted by the Hurricane Seminar group of Spring 2000: Charlie Kwit, Jarrod Thaxton, Paul Gagnon, Jennifer Cramer and Sarah Riley. More recently the Dissertation Writing Groups of Daniel Ortiz-Barrientos and Jean Huffman have encouraged and advised in the final stages. Many other dear friends and family have helped me in the field including: Susan Pell, Paul Gagnon, Dan Lane, Jennifer Cramer, Adriana Bravo, Tim Paine, David Brown, Loren Passmore, Hanna Passmore Hobson, and Richard Hobson. At the house on Oleander Street I have had many wonderful housemates starting with Jane Carlson, Ozan Arslan, Daniel Ortiz-Barrientos, Indah Kusuma, Adriana Bravo, and Jonathan Myers. The best officemate ever is Rae Crandall. I will always fondly remember the iv original and final Denslow lab group at LSU: Julie Denslow, Loretta Battaglia, Sandra Guzman, Saara Dewalt, Satya Maliakal Witt, and Krista Farris Lopez. I recognize the support and love from my parents, Bob and Carol, and my siblings Loren & Kusia, Hanna & Richard. I am thankful for my new family of Gagnons, Trojaceks, Winsteads and Benners. Strong foster family support has come from Susan Pell and Ken & Mary Alice Carpenter. I also recognize the special teachers who encouraged curiosity, passion and dedication to explore the natural world: Norm Budnitz, Brent Smith, and Amy Mulnix. One powerful and constant presence through my graduate career has been my Earlham College ’96 Comprehensive Exam Study Group: Katie Goslee, Sankari Muralidharan Wegman, Katy Fullin Reeder, and Angie Messer. More than anything I want to thank my husband Paul for his help and support through the years and his wonderful companionship the last three years (and all the years to come). Finally, a greasy chew bone goes to Pyrocaniac’s Longleaf Kena for the regimented daily structure she demands and for the comedic relief she provides. v TABLE OF CONTENTS ACKNOWLEDGEMENTS........................................................................................................... iii ABSTRACT................................................................................................................................. vii CHAPTER 1 INTRODUCTION.................................................................................................. 1 Conceptual Models of Disturbance Interactions......................................... 3 Experimental Tests of Interactions............................................................. 4 Dissertation Structure................................................................................. 7 2 HURRICANE-FIRE INTERACTIONS IN FORESTED LANDSCAPES IN COASTAL SOUTHEASTERN NORTH AMERICA........................................... 9 Introduction............................................................................................... 10 Background..........................................................................................…. 11 Hypotheses and Predictions...................................................................... 23 Summary..........................................................................………………. 45 3 EFFECTS OF SEQUENTIAL DISTURBANCES ON THE UNDERSTORY OF SAVANNA-FOREST ECOTONE................................................................. 47 Introduction............................................................................................... 48 Methods..................................................................................................... 51 Results....................................................................................................... 62 Discussion................................................................................................. 85 4 CONCLUSIONS.................................................................................................. 93 LITERATURE CITED................................................................................................................. 98 APPENDIX A: TREE SPECIES LIST....................................................................................... 113 APPENDIX B: CANOPY PHOTO ANALYSIS SETTINGS................................................... 114 VITA........................................................................................................................................... 115 vi ABSTRACT Sequential large-scale disturbances may produce interacting effects that differ from those predicted for each disturbance in isolation. These non-additive effects can strongly influence the composition and structure of plant communities. Hurricanes and natural lightning-season fires are large-scale, frequent disturbances in southeastern savanna-forest landscapes. Although interactive effects have been proposed, my research is the first to develop and experimentally test mechanistic hypotheses for hurricane-fire interactions. I develop a predictive conceptual model for interacting disturbances. I propose that hurricane-fire interactions depend on the relative timing of disturbances