University of Miami Scholarly Repository Open Access Dissertations Electronic Theses and Dissertations 2010-04-08 Seed Dynamics and Seedling Establishment of Woody Species in the Tropical Savannas of Central Brazil (Cerrado) Ana A. Salazar Parra University of Miami, [email protected] Follow this and additional works at: https://scholarlyrepository.miami.edu/oa_dissertations Recommended Citation Salazar Parra, Ana A., "Seed Dynamics and Seedling Establishment of Woody Species in the Tropical Savannas of Central Brazil (Cerrado)" (2010). Open Access Dissertations. 371. https://scholarlyrepository.miami.edu/oa_dissertations/371 This Open access is brought to you for free and open access by the Electronic Theses and Dissertations at Scholarly Repository. It has been accepted for inclusion in Open Access Dissertations by an authorized administrator of Scholarly Repository. For more information, please contact [email protected]. UNIVERSITY OF MIAMI SEED DYNAMICS AND SEEDLING ESTABLISHMENT OF WOODY SPECIES IN THE TROPICAL SAVANNAS OF CENTRAL BRAZIL (CERRADO) By Ana A. Salazar Parra A DISSERTATION Submitted to the Faculty of the University of Miami in partial fulfillment of the requirements for the degree of Doctor of Philosophy Coral Gables, Florida May 2010 ©2010 Ana A. Salazar Parra All Rights Reserved UNIVERSITY OF MIAMI A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy SEED DYNAMICS AND SEEDLING ESTABLISHMENT OF WOODY SPECIES IN THE TROPICAL SAVANNAS OF CENTRAL BRAZIL (CERRADO) Ana A. Salazar Parra Approved: ________________ _________________ Guillermo Goldstein, Ph.D. Terri A. Scandura, Ph.D. Professor of Biology Dean of the Graduate School ________________ _________________ David Janos, Ph.D. Leonel Sternberg, Ph.D. Professor of Biology Professor of Biology ________________ Carol C. Baskin, Ph.D. Professor of Biology and of Plant and Soil Sciences University of Kentucky SALAZAR PARRA, ANA A. (Ph.D., Biology) Seed Dynamics and Seedling Establishment (May 2010) of Woody Species in the Tropical Savannas of Central Brazil (Cerrado). Abstract of a dissertation at the University of Miami. Dissertation supervised by Professor Guillermo Goldstein. No. of pages in text. (180) Studies of seed dynamics and seedling establishment at the community level in savanna ecosystems are scant, particularly in the tropical savannas of Central Brazil. The Brazilian savannas (cerrado) have the largest diversity of plant species among Neotropical savannas. Cerrado vegetation exhibits consistent changes in tree density and tree size along shallow topographic gradients. Vegetation types differ from closed savannas with high tree density, and a nearly continuous canopy cover in the uppermost portions, to open savannas with scattered short trees in the low portions of the topographic gradients. Whether or not dynamics of seeds and seedlings of woody species are consistent with variations in tree density and tree canopy cover across the cerrado landscape has not been determined, but could potentially influence such spatial patterns of tree density and canopy cover. The main objective of this study was to evaluate seed dynamics (i.e., seed rain, soil seed banks, and seed characteristics) and seedling establishment of woody species in three major cerrado vegetation types (closed, intermediate and open savannas) which differ in tree canopy cover and tree height. These vegetation types are located along topographic gradients of approximately 30 m in elevation and 1000 m in length. I conducted field work from June 2005 to August 2008 at the Instituto Brasileiro de Geografia e Estatística (IBGE) reserve, a field experimental station located 35 Km south of Brasilia, Brazil (15˚ 56’ S, 47˚ 63’ W, altitude 1100 m). I established permanent plots in each of the three vegetation types to assess seed rain, seed limitation, seed predation, and seed removal. I also quantified density and composition of the soil seed bank in each vegetation type and studied seed characteristics (i.e., kind of dormancy, moisture content, longevity) of 14 common cerrado woody species. In the field, I quantified establishment of woody seedlings in fire-protected savannas as well as in accidentally burned and frequently burned savannas. In the greenhouse I performed experiments to evaluate the effect of litter cover and light level on seedling emergence of 9 common cerrado woody species. Finally, I evaluated the effect of pulses of heat on seed germination of 5 common cerrado woody species under controlled conditions. The overall results of this study show that regardless of tree canopy cover, cerrado vegetation types are limited in seeds and seedlings of woody species, but these limitations are higher in open than in closed savannas. Most woody species do not form persistent soil seed banks along cerrado vegetation types because their seeds are short-lived, predated and quickly removed from the ground. In addition, dispersal season and dormancy appear to control timing of germination at the onset of the rainy season to ensure survival of seedlings in the field. In the absence of fire, establishment of woody seedlings is higher in closed than in open savannas because canopy cover mitigates the stressful environmental conditions of open savannas and thus facilitates establishment of woody seedlings. As a result, closed savannas are likely to maintain higher density of woody elements over time than open savannas. In burned savannas, however, species composition of woody and herbaceous seedlings is significantly affected because establishment of seedlings of woody and herbaceous species decreases but vegetative reproduction increases. This dissertation study indicates that interactions of early life- history stages of woody species with environmental and disturbance factors appear to play a more significant role in maintaining woody cover variations along cerrado topographic gradients than previously recognized. Dedication I would like to dedicate this dissertation to my family, my husband and my father’s memory. My family gave me the strength and resilience to complete this dissertation despite the difficulties. My husband assisted me with lab and field work. His unconditional love, daily support, encouragement, and blind faith helped me complete this dissertation. My father taught me the importance of discipline to achieve major goals. iii Acknowledgments I am grateful to my advisor Dr. Guillermo Goldstein for his guidance, time, support, and encouragement throughout all my years as a graduate student at the University of Miami (UM). I am also grateful to my committee members Drs. David Janos, Leonel Sternberg and Carol C. Baskin, for all their help, comments and suggestions on how to improve this dissertation. I also thank my previous advisors in Colombia, Claudia Ramírez Sandoval and Maria Susana Carrizosa, who not only got me interested in seed biology and taught me some techniques I was able to use in this dissertation, but also encouraged me to continue a career in science. I am very grateful to my husband Daniel Ramírez for all his support throughout all my years as a graduate student. This dissertation is the result of a team-work effort. He not only assisted me with home duties, field and laboratory work, but also gave me a lot of help in improving my English writing. I couldn’t have had a better field assistant and a better partner. I will be forever grateful for all his support, help and love. I am extremely grateful to my mother Elena Parra Lleras, my uncle Ernesto Parra Lleras, and my aunt Gloria de Parra for their unconditional support, patience and love. I also thank my brothers Julio, Bernardo and Mario for their encouragement and good cheer all along. I greatly thank the staff of The Reserva Ecológica do IBGE for their logistic support and the IBGE herbarium staff, in particular Maria Aparecida da Silva for helping me to identify plant specimens. I thank Drs. Augusto C. Franco and M. Haridasan for their great help and support that allowed me to carry out field work in Brazil. iv I am thankful to Randol Villalobos, Catarina Cartaxo, Mariana Saraceno, and Marina Scallon not only for assisting me in the field, but also for their friendship. I thank Randol Villalobos, Lucero Sevillano, Floria Mora-Kepfer, Catalina Aristizábal, Eric Manzane, David Matlaga, Tanya Hawley, Frans Juola, Naveen Wijesena, Bhagya Janananda, Robert McEderry, and Amartya Saha for their friendship and support at the University of Miami. I am also extremely grateful to Simone Cappellari, Imma Oliveras, Sybil Gotsch and Erica Geiger for their friendship, help and support in Brazil. I thank Rafael La Rota, Ana Cifra, Maria Hernandez, and Luis Parra for their support, encouragement and friendship through these years. They have been like my family in Miami since my arrival. I also thank each of the members of the “Mycorrhiza Discussion Group for all of their comments on my dissertation, and for giving me great feedback on how to improve my dissertation seminar. I am very thankful to Orou Gaoue, David Matlaga, and Lucero Sevillano for providing statistical guidance. Finally, I thank the National Science Foundation (Biocomplexity project), in particular its principal investigator, Dr. Fernando Miralles-Wilhelm, for allowing my participation in his project and for funding a large part of my field work. I also thank UM Center for Latin American Studies, UM Jerry Curtis Scholarship, UM Kushlan- Frohring Graduate Research Support Fund, and UM College