……………………………… The impact of land-use intensification on pollination and seed-dispersal interactions in the wild cherry (Prunus avium L.) ……………………………… Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften vorgelegt beim Fachbereich Biologie der Johann Wolfgang Goethe-Universität in Frankfurt am Main von Nils Breitbach aus Wiesbaden Frankfurt im März 2011 (D 30) vom Fachbereich Biologie der Johann Wolfgang Goethe-Universität als Dissertation angenommen. Dekanin: Prof. Dr. Anna Starzinski-Powitz 1. Gutachterin: Prof. Dr. Katrin Böhning-Gaese 2. Gutachter: Prof. Dr. Ingolf Steffan-Dewenter Datum der Disputation: 14. Februar 2012 To my mother, who always supported me. » Perhaps the most important point is to ensure that science never becomes divorced from the basic human feeling of empathy with our fellow beings. « The Dalai Lama (2005) CHAPTER 3 of this thesis has been published by Springer Berlin / Heidelberg as: Breitbach N., Laube I., Steffan-Dewenter I. & Böhning-Gaese K. (2010): Bird diversity and seed dispersal along a human land-use gradient: high seed removal in structurally simple farmland. Oecologia 162(4): 965–976. DOI: 10.1007/s00442-009-1547-y CHAPTER 4 of this thesis has been published by Springer Berlin / Heidelberg as: Breitbach N., Tillmann S., Schleuning M., Grünewald C., Laube I., Steffan-Dewenter I. & Böhning-Gaese K. (2012): Influence of habitat complexity and landscape configuration on pollination and seed-dispersal interactions of wild cherry trees. Oecologia 168(2): 425–437. DOI: 10.1007/s00442-011-2090-1 CHAPTER 5 of this thesis has been submitted to an international journal of ecology as: Breitbach N., Laube I., Böhning-Gaese K. & Schleuning M. (submitted): Shorter seed-dispersal distances reduce recruitment success in farmland populations of bird-dispersed cherry trees. Contents 1 ZUSAMMENFASSUNG DER ARBEIT __________________________________________ 1 2 GENERAL INTRODUCTION _______________________________________________ 13 2.1 Global change and ecosystem functions ______________________________ 13 2.2 Aim and Structure of the Thesis _____________________________________ 16 CHAPTER 3 BIRD DIVERSITY AND SEED DISPERSAL ALONG A HUMAN LAND-USE GRADIENT: HIGH SEED REMOVAL IN STRUCTURALLY SIMPLE FARMLAND. _______________________ 21 Abstract __________________________________________________________ 22 Introduction ________________________________________________________ 23 Materials and methods _______________________________________________ 25 Study region ___________________________________________________________ 25 Study species __________________________________________________________ 26 Study trees and the structure of habitat and landscape __________________________ 26 Bird community _________________________________________________________ 27 Tree visitors and seed removal ____________________________________________ 29 Spatial effects and confounding variables ____________________________________ 30 Results ___________________________________________________________ 31 Bird community _________________________________________________________ 31 Tree visitors and seed removal ____________________________________________ 33 Discussion ________________________________________________________ 37 Conclusions _______________________________________________________ 42 Acknowledgements _________________________________________________ 42 CHAPTER 4 INFLUENCE OF HABITAT COMPLEXITY AND LANDSCAPE CONFIGURATION ON POLLINATION AND SEED-DISPERSAL INTERACTIONS OF WILD CHERRY TREES. ___________ 43 Abstract __________________________________________________________ 44 Introduction ________________________________________________________ 45 Materials and methods _______________________________________________ 48 Study region ___________________________________________________________ 48 Model system __________________________________________________________ 49 Study trees and structure of habitat and landscape _____________________________ 50 Local bee community ____________________________________________________ 51 Visitation rates of pollinators _______________________________________________ 52 Pollination success ______________________________________________________ 52 Species richness and visitation rates of seed dispersers and seed removal __________ 53 Statistical analyses ______________________________________________________ 54 Results ___________________________________________________________ 55 Local bee community, flower visitors and pollination success _____________________ 55 Comparison between the different functional animal groups ______________________ 58 Discussion ________________________________________________________ 60 Local bee community ____________________________________________________ 60 Visitation rate(s) of pollinators _____________________________________________ 61 Pollination success ______________________________________________________ 62 Comparison between the different functional animal groups ______________________ 63 Conclusions _______________________________________________________ 65 Acknowledgements _________________________________________________ 65 CHAPTER 5 REDUCED SEED-DISPERSAL DISTANCES ARE CONGRUENT WITH LOW RECRUITMENT SUCCESS IN FARMLAND POPULATIONS OF BIRD-DISPERSED CHERRY TREES. _ 67 Abstract __________________________________________________________ 68 Introduction ________________________________________________________ 70 Materials and methods _______________________________________________ 72 Study region ___________________________________________________________ 72 Study species __________________________________________________________ 73 Feeding trials __________________________________________________________ 74 Radio tracking and movement analysis ______________________________________ 75 Dispersal curve estimation ________________________________________________ 77 Seedling establishment and survival ________________________________________ 80 Results ___________________________________________________________ 81 Feeding trials __________________________________________________________ 81 Overall distribution of seed-dispersal distances ________________________________ 81 Habitat preferences of blackbirds ___________________________________________ 82 Habitat-specific seed-dispersal distances ____________________________________ 82 Directed dispersal in forest and farmland _____________________________________ 83 Seedling establishment and survival ________________________________________ 84 Discussion ________________________________________________________ 85 Seed-dispersal distances _________________________________________________ 85 Directed dispersal _______________________________________________________ 86 Seedling recruitment _____________________________________________________ 87 Caveats ______________________________________________________________ 88 Conclusions _______________________________________________________ 89 Acknowledgements _________________________________________________ 90 6 GENERAL CONCLUSIONS _______________________________________________ 91 6.1 Pollination ______________________________________________________ 91 6.2 Seed dispersal __________________________________________________ 92 6.3 Synthesis ______________________________________________________ 94 6.4 Future challenges ________________________________________________ 96 8 INDEX OF TABLES ___________________________________________________ 111 9 INDEX OF FIGURES ___________________________________________________ 113 10 APPENDICES ______________________________________________________ 116 Appendix 1: Control variables – Materials and methods & Results ____________ 116 Appendix 2: Detailed results for the bird counts during the breeding season and the tree observations __________________________________________________ 123 Appendix 3: Categorisation of suitable habitat from CORINE 2006 data of land-use ________________________________________________________________ 127 Appendix 4: Statistical summary of linear regressions and SARs _____________ 128 Appendix 5: Results of trapping _______________________________________ 129 Appendix 6: Statistical summary of AICc calculations from multiple regressions _ 132 Appendix 7: Distribution of regurgitation times (RTs) _______________________ 133 Appendix 8: Categorisation of suitable habitat from ATKIS DLM data of land-use 137 Appendix 9: Individual-based seed-dispersal distances _____________________ 138 Appendix 10: Individual-based habitat-specific seed-dispersal distances for 30 Common Blackbirds ________________________________________________ 143 11 DANKSAGUNG _____________________________________________________ 150 CURRICULUM VITAE ___________________________________________________ 153 Zusammenfassung der Arbeit 1 1 Zusammenfassung der Arbeit Menschliche Aktivitäten beeinflussen beinahe alle Bereiche des Lebens auf der Erde (MEA 2005a; UNEP 2007). Die Zerstörung und Veränderung natürlicher Lebensräume sind als Hauptursache für den weltweiten Biodiversitätsverlust identifiziert (Harrison and Bruna 1999; Dale et al. 2000; Foley et al. 2005; MEA 2005a). Zusammen mit dem Klimawandel wird die Landnutzungsveränderung daher als einflussreichster Aspekt anthropogen verursachten globalen Wandels betrachtet (MEA 2005a). Landnutzungsveränderung schließt sowohl die Umwandlung natürlicher Habitate in Agrarland oder Siedlungen als auch die Landnutzungs- intensivierung in bereits kultivierten Landschaften