TECHNISCHE UNIVERSITÄT MÜNCHEN Lehrstuhl für Vegetationsökologie Fire in subtropical grasslands in Southern Brazil: effects on plant strategies and vegetation dynamics Alessandra Fidelis Vollständiger Abdruck der von der Fakultät Wissenschaftszentrum Weihenstephan für Ernährung, Landnutzung und Umwelt der Technischen Universität München zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaften genehmigten Dissertation. Vorsitzender: Univ.-Prof. Dr. J. Schnyder Prüfer der Dissertation: 1. Univ.-Prof. Dr. J. Pfadenhauer 2. Univ.-Prof. St. I. Higgins, Ph.D., Goethe Universität Frankfurt am Main 3. Prof. V. De Patta Pillar, Ph.D., Universidade Federal do Rio Grande do Sul, Porto Alegre / Brasilien (schriftliche Beurteilung) Die Dissertation wurde am 30.07.2008 bei der Technische Universität München eingereicht und durch die Fakultät Wissenschaftszentrum Weihenstephan für Ernährung Landnutzung und Umwelt am 25.11.2008 angenommen. __________________________________________________________________________ CONTENTS ACKNOWLEDGMENTS i PREFACE iii INTRODUCTION 1 CHAPTER 1: Fire behaviour in Brazilian Campos grasslands (Fidelis, A., Cartay-Delgado, M.D., Blanco, C., Müller, S.C., Pillar, V.D. & Pfadenhauer, J.) 15 CHAPTER 2: Bud bank and belowground organs: their importance for vegetation regeneration in Brazilian Campos grasslands (Fidelis, A., Appezzato-da-Glória, B., Müller, S.C., Pillar, V.D. & Pfadenhauer, J.) 35 CHAPTER 3: Population biology and regeneration of forbs and shrubs after fire in Brazilian Campos grasslands (Fidelis, A., Müller, S.C., Pillar, V.D. & Pfadenhauer, J.) 57 CHAPTER 4: What matters for vegetation regeneration? Seedlings or resprouters? An example from Brazilian Campos grasslands (Fidelis, A., Müller, S.C., Pillar, V.D. & Pfadenhauer, J.) 79 CHAPTER 5: Short-term changes caused by fire and mowing in Brazilian Campos grasslands (Fidelis, A., Blanco, C., Müller, S.C., Pillar, V.D. & Pfadenhauer, J.) 103 CONCLUSIONS 131 SUMMARY 143 __________________________________________________________________________ _______________________________________________________________Acknowledgements ACKNOWLEDGEMENTS First of all, I am greatly thankful to Prof. Jörg Pfadenhauer for his trust on my ideas, on my project and on me. I learned a lot with our discussions about grasslands, as well as with his lectures and I am thankful to all the “Gutachten” that he had written to me, so I could get financial support for my PhD. His enthusiasm about vegetation science and mostly about grasslands “infected” me and helped me to choose the next steps in my scientific career. Danke für die Unterstützung! My other supervisor, Prof. Valério Pillar supported me during my stay in Rio Grande do Sul and therefore, I am very thankful. He always received me with “open arms” in his laboratory and let me join all interesting discussions and projects about conservation of Campos. Obrigada por acolher esta paulista no seu laboratório! I thank Sandra Müller (my third dear supervisor) for receiving me in her home and laboratory and helping me organizing fire experiments and field work. Thanks for your patience and all discussions about my thesis. Especial thanks for helping me with plant identification! Obrigada pelo carinho e amizade! Especial thanks for my “guard angels”. In Brazil: Carolina Blanco and Letícia Dadalt. Not only for the support during field work and the time during my PhD (both in Porto Alegre and in Freising), but also for always listening to me when I needed the most. Obrigada queridinhas pelo carinho, horas de descontração e principalmente pela amizade! In Germany: Maria Dolores Cartay Delgado for her help with the fire experiments, but mostly for her friendship and support during the last years in Germany. Gracias por tudo, amiga! I also would like to thank KAAD for the PhD scholarship. Especially I thank Brigitte Ebertseder for her support during my stay in Freising. Danke! Thanks to Fazit Stiftung and the Technische Universität München for the financial support for the last field trip to Brazil. I also thank EMBRAPA, especially Pedro Trindade for financially supporting part of my project. Obrigada! Thanks to Prof. Beatriz Appezzato da Glória for receiving me so kindly in her laboratory and helping with the belowground organs and the analyses of the bud bank! Obrigada pela ajuda! I am also greatly thankful to Ilsi Boldrini, who always helped with plant identification and literature about the Campos. Obrigada queridinha! Thanks to Michaela Bücherl and Ingrid Kapps, who were taking care of me during this difficult phase of the PhD with nice food and coffee breaks! Vielen Dank! I am also thankful to all my colleagues from the Lehrstuhl für Vegetationsökologie. Especial thanks to Daniela Röder, Kathrin Kiehl, Harald Albrecht and Gerhard Overbeck. Danke! Thanks to Michael Jeschke, Ingrid Kapps and Andrea Skiba for reviewing my summary in German. _______________________________________________________________________ i _______________________________________________________________Acknowledgements I am thankful to all my colleagues from the Laboratory of Quantitative Ecology for receiving so well and helping me sometimes with the field work. Exceptional thanks to my “estagiários” Marcel Tust and Maximiliano Oliveira for taking all soil samples and helping me in the field, even when it was very hot! Obrigada pela ajuda e pelo carinho de todos. I cannot forget the support from my dear friends during this journey: Fernanda, Letícia, Christian (amigos de Freising), Tiago & Roberto (meus médicos e amigos de plantão), Ronaldo (meu consultor para assuntos técnicos e motivador nas horas difíceis), Andrea (pelas horas e história divertidas em Porto Alegre), Christian, Romi & Ká (pelas horas divertidíssimas na Alemanha), Ari e Luiz (pela amizade e pelo apoio de sempre). And all other dear friends, who always were there for me and know who they are. I thank my family, José Carlos, Giovanna, Graziela e Bruno for the support during all these years of Germany. Obrigada por tudo e principalmente por aguentarem as saudades! I dedicate this thesis to all “gaúchos", who know how important the Campos are and still fight against the rapid change of traditional land use (cattle grazing). To the “gauchos”, who fight for the conservation of their traditions and the conservation of the beautiful Campos. I hope you still can see the horizon for many, many years! _______________________________________________________________________ ii _____________________________________________________________________Preface PREFACE The thesis is written as a cumulative PhD thesis. Chapters 1 to 5 are independent papers that were and will be submitted for publication in different scientific journals. Moreover, an introduction and a conclusion with an integrating discussion join considerations of the different chapters. In order to facilitate reading, tables and figures were inserted into the text. References about papers in preparation were referred according to the chapter. References in text and in the bibliography were all formatted in the same way. Enumeration of tables and figures was conducted separately for each chapter. In addition to English and German summaries, a summary in Portuguese was written at the end of the thesis, briefly presenting the contents of each chapter. _______________________________________________________________________ iii INTRODUCTION (Morro Santana, Porto Alegre) “…A comienzos de primavera la pampa se muestra en todo su esplendor cuando florecen centenares de especies de gramíneas, semejando la estepa un mar de pasto policromo que se agita a impulsos del viento…” (Cabrera & Willink 1973) ________________________________________________________________________________________ Introduction Campos grasslands in southern Brazil: a present and past overview Grasslands comprise one-fourth of total vegetation of Earth’s plant cover (Kucera 1981), covering African savannas, steppes and prairies from North America, South America and Eurasia, and other partly anthropogenic meadows and pastures (Jacobs et al. 1999; Kucera 1981). They are often controlled by climate and biogeochemical factors, playing an important role on the global carbon cycle (Parton et al. 1996) and supporting a high variety of herbivores and other animal species (Jacobs et al. 1999). Floristic diversity of grasslands varies broadly (Sala et al. 2001). Some grassland physiognomies are within ecosystems considered to be hotsposts of biodiversity, such as the Cerrado vegetation (Myers et al. 2000). In South America a large spectrum of grassland physiognomies can be found: from Pampas, situated mostly in Argentina and with high plant diversity, between 32° and 38°S (Bredenkamp et al. 2002) until the Andean alpine formations like the Llanos with a poorer flora (Barthlott et al. 1996). The tropical savannas, as described by Sarmiento ("tropical vegetation where certain forms of grasses dominate and where seasonal droughts and frequent fires are normal ecological factors", 1984), cover large areas of South America, from Venezuela until the northern part of south Brazil. In Brazil, grassland physiognomies are represented in all biomes in more or less extent (Fig 1., see new vegetation classification, IBGE 2004).. Unfortunately, due to anthropogenic pressure, the areas of natural grasslands have decreased in the last decades. The Cerrado biome, the savanna physiognomies still have ca. 24% (grasslands and shrublands, MMA 2007), whilst the Mata Atlântica biome has less