Investigating mechanisms maintaining plant species diversity in fire prone Mediterranean-type vegetation using spatially-explicit simulation models PhD Thesis Alexandra Esther Department of Plant Ecology and Nature Conservation University of Potsdam 2010 Investigating mechanisms maintaining plant species diversity in fire prone Mediterranean-type vegetation using spatially-explicit simulation models DISSERTATION zur Erlangung des akademischen Grades "doctor rerum naturalium" (Dr. rer. nat.) in der Wissenschaftsdisziplin "Naturschutz und Ökologie" eingereicht an der Mathematisch-Naturwissenschaftlichen Fakultät der Universität Potsdam von Alexandra Esther Potsdam, Januar 2010 This work is licensed under a Creative Commons License: Attribution - Noncommercial - No Derivative Works 3.0 Germany To view a copy of this license visit http://creativecommons.org/licenses/by-nc-nd/3.0/de/ Published online at the Institutional Repository of the University of Potsdam: URL http://opus.kobv.de/ubp/volltexte/2010/4463/ URN urn:nbn:de:kobv:517-opus-44632 http://nbn-resolving.org/urn:nbn:de:kobv:517-opus-44632 TABLE OF CONTENTS 1 ZUSAMMENFASSUNG................................................................................................ 4 2 SUMMARY .................................................................................................................... 6 3 GENERAL INTRODUCTION....................................................................................... 8 3.1 MOTIVATION....................................................................................................... 8 3.2 POTENTIAL COEXISTENCE MECHANISMS ................................................ 10 3.3 ASSESSING COEXISTENCE MECHANISMS WITH MODELS .................... 12 3.4 STUDY SIDE – ENEABBA ................................................................................ 13 3.5 OBJECTIVES OF THE THESIS ......................................................................... 15 3.6 STRUCTURE OF THE THESIS ......................................................................... 16 4 HOW IMPORTANT ARE TRADE-OFFS IN EXPLAINING COMMUNITY STRUCTURE AND PLANT RICHNESS? ................................................................. 17 4.1 ABSTRACT ......................................................................................................... 17 4.2 INTRODUCTION................................................................................................ 17 4.3 METHODS........................................................................................................... 19 4.3.1 Life history traits ......................................................................................... 20 4.3.2 Processes...................................................................................................... 22 4.3.3 Simulations.................................................................................................. 24 4.4 RESULTS............................................................................................................. 25 4.4.1 Population level experiments....................................................................... 25 4.4.2. Community level experiments.................................................................... 25 4.5 DISCUSSION....................................................................................................... 31 4.5.1. Trade-off mediated species diversity: empirical vs. theoretical studies ..... 31 4.5.2. Dominance and influence of ‘super-types’................................................. 32 4.6 CONCLUSION .................................................................................................... 33 4.7 APPENDIX .......................................................................................................... 34 1 4.7.1. Model parameters ....................................................................................... 34 4.7.2. Equations in Model..................................................................................... 35 4.8 LINK TO THE NEXT CHAPTERS .................................................................... 37 5 ASSESSING THE IMPORTANCE OF SEED IMMIGRATION ON COEXISTENCE OF PLANT FUNCTIONAL TYPES IN A SPECIES-RICH ECOSYSTEM .............. 38 5.1 ABSTRACT ......................................................................................................... 38 5.2 INTRODUCTION................................................................................................ 39 5.3 METHODS........................................................................................................... 41 5.3.1 Model description........................................................................................ 41 5.3.2 Model structure............................................................................................ 42 5.3.3 Processes...................................................................................................... 44 5.3.4 Simulations.................................................................................................. 49 5.4 RESULTS............................................................................................................. 51 5.4.1 Effects of seed immigration on number of coexisting PFTs ....................... 51 5.4.2 Effects of seed immigration on diversity..................................................... 52 5.4.3 Effects of seed immigration on trait distribution......................................... 53 5.5 DISCUSSION....................................................................................................... 57 5.6 APPENDIX .......................................................................................................... 60 5.6.1 Seed immigration rates depending on scenario and level............................ 60 5.7 LINK TO THE NEXT CHAPTER....................................................................... 60 6 SENSITIVITY OF PLANT FUNCTIONAL TYPES TO CLIMATE CHANGE: CLASSIFICATION TREE ANALYSIS OF A SIMULATION MODEL.................... 62 6.1 ABSTRACT ......................................................................................................... 62 6.2 INTRODUCTION................................................................................................ 62 6.3 METHODS........................................................................................................... 64 6.3.1 Plant Functional Type model....................................................................... 64 6.3.2 Processes...................................................................................................... 66 2 6.3.3 Simulation experiments ............................................................................... 69 6.4 RESULTS............................................................................................................. 73 6.4.1 Consequences of climate change on seed dispersal..................................... 73 6.4.2 Consequences of climate change on community pattern............................. 77 6.5 DISCUSSION....................................................................................................... 78 6.5.1 Consequences of climate change on populations ........................................ 78 6.5.2 Consequences of climate change on community patterns ........................... 79 6.6 APPENDIX .......................................................................................................... 82 6.6.1 Species list with nomenclature following Paczkowska and Chapman (2000) .......................................................................................................... 82 7 GENERAL DISCUSSION............................................................................................ 83 7.1 Potential coexistence mechanisms: low-dimensional trade-offs and seed immigration .......................................................................................................... 83 7.2 Impact of climate change on plant functional types and community structure .... 85 7.3 Model limitations.................................................................................................. 86 8 FUTURE RESEARCH ................................................................................................. 88 9 REFERENCES.............................................................................................................. 90 10 DANKSAGUNG......................................................................................................... 102 3 1 ZUSAMMENFASSUNG Feuer geprägte, mediterrane Vegetationstypen, wie sie im Mittelmeerraum und Süd- West Australien zu finden sind, gelten als globale „hotspots“ für Pflanzendiversität. Um sicher zu stellen, dass Managementprogramme zum Erhalt dieser hoch diversen Pflanzengesellschaften zielgerichtet beitragen, ist ein profundes Verständnis der wesentlichen Koexistenzmechanismen notwendig. In der aktuellen Literatur werden verschiedene Mechanismen diskutiert. Das Ziel meiner Doktorarbeit ist es, die Bedeutung der Mechanismen für den Erhalt der artenreichen, feuergeprägten Vegetation anhand eines Modells systematisch zu untersuchen. Das von mir dafür entwickelte Modell ist räumlich- explizit, stochastisch und regel- und individuenbasiert. Es ist unter Zuhilfenahme von Daten zu Populationsdynamiken parametrisiert, die über 18 Jahre im Mediterranen Buschland von Eneabba Westaustraliens gesammelt wurden. Anhand von 156 Arten sind sieben