Spatio-Temporal Patterns of Biodiversity and their Drivers - Method Development and Application Dissertation zur Erlangung des akademischen Grades Dr. rer. nat. vorgelegt der Fakultät für Biologie, Chemie und Geowissenschaften der Universität Bayreuth von Herrn Dipl. Ing. Gerald Jurasinski geb. am 24.03.1975 in Quedlinburg Gutachter: 1. Prof. Dr. Carl Beierkuhnlein 2. Bayreuth, den 17.April 2007 Spatio-Temporal Patterns of Biodiversity and their Drivers - Method Development and Application By Gerald Jurasinski Biogeography - University of Bayreuth Germany There never were in the world two opinions alike, no more than two hairs or two grains; the most universal quality is diversity. Michel de Montaigne Contents Contents Summary III Zusammenfassung V Organization of the thesis VII List of Manuscripts and Publications VIII Abbreviations XI 1 Introduction 1 1.1 Motivation 1 1.2 Background 2 1.3 Hypotheses 13 2 Conceptional and methodological contributions 16 2.1 A new terminology for biodiversity 16 2.2 Sampling spatial patterns with hexagonal grids 16 2.3 The coefficient of multi-plot similarity 16 2.4 simba - Similarity analysis for vegetation ecology 18 3 Empirical contributions 19 3.1 Spatial patterns of phytodiversity in a Mediterranean ecosystem 19 3.2 Homogenization of Alpine summits 30 4 Summarizing Discussion 32 4.1 Conceptional issues 32 4.2 Methodological issues 34 4.3 Empirical results 36 4.4 Conclusions and Outlook 40 Acknowledgements 41 References 42 I Contents Appendices 55 Appendix 1 Inventory, differentiation, and proportional diversity – a consistent terminology for quantifying biodiversity. Oikos (submitted) 57 Appendix 2 Hexagonal grids - an alternative for quantifying spatio-temporal patterns of biodiversity. Journal of Biogeography (submitted) 81 Appendix 3 Measuring multi-plot similarity with presence-absence data. Ecology (in preparation) 101 Appendix 3 Spatial patterns of biodiversity - assessing vegetation using hexagonal grids. Proceedings of the Royal Irish Academy - Biology and Environment (2005) 106B: 401-411 123 Appendix 4 Distance decay and non-stationarity in a semi-arid Mediterranean Ecosystem. Journal of Vegetation Science (submitted) 141 Appendix 5 Beyond richness - Upward shift of alpine plants leads to homogenisation of mountain summits. Journal of Vegetation Science (accepted) 171 Appendix 7 simba-Manual (simba - Similarity Analysis for Vegetation Ecology) 185 Appendix 8 Species list recorded through the three years of field-work in Northeastern Morocco 236 Appendix 9 Additional information on climatic characteristics of the Investigation Area in Northeastern Morocco 246 Appendix 10 Patterns of similarity caused by various asymmetric binary similarity coefficients, compared to the respective ternary plots 250 Appendix 11 Curriculum Vitae Gerald Jurasinski 252 Statement 254 II Summary Summary In the light of land use and climate change which rapidly alter landscapes and ecosystems worldwide there is an urgent need for standardized and comparable data in order to detect changes of biodiversity. Therefore, it is paramount to provide methods for the comprehensive assessment and evaluation of biodiversity. These methods are required to be representative as well as pragmatic due to the fact, that there is insufficient time to obtain complete data sets. If biodiversity is lost rapidly at the landscape level, frequent re-investigations have to be done in order to detect and analyze such changes. The central objective of this thesis is the development and evaluation of spatially explicit, widely applicable methods for the assessment and analysis of phytodiversity, encompassing species richness as well as spatial and temporal heterogeneity of diversity. The conceptual perspective on the one hand and the application of the methodology in order to investigate ecological phenomena on the other represent the two foci of the thesis. A review of the terminology of biodiversity - especially ‘beta-diversity’ - reveals a multitude of co-existing concepts. This plethora of definitions hampers application and scientific progress. Thus, a new terminology is proposed, which, compared to Whittaker’s concept of diversity (alpha, beta, gamma), provides less ambiguous terms (inventory-, differentiation-, and proportional diversity). It enables a more direct access to the underlying ecological phenomena and key questions. Hence, it can help to structure the scientific discussion and future research. Spatial patterns of diversity may be best assessed with systematic sampling. However, square sampling grids implemented so far are exposed to the problem of distance decay and deliver indefinite values. Therefore systematic sampling in hierarchically nested equidistant grids is proposed as an appropriate methodology for the assessment of spatial patterns in vegetation. A new coefficient of multi-plot similarity is developed for the analysis of pattern diversity. For the first time this allows the calculation of similarity between one and many plots while taking species identity into account. It performs superior to all other tested coefficients in detecting vegetation hotspots and gradients. The multi-plot similarity coefficient provides a promising tool for ecological research as well as for nature conservation and monitoring. The developed equidistant sampling grid has been applied in a case study in Northeastern Morocco to investigate the drivers of spatial patterns of biodiversity. The nested equidistant sampling grid with hexagonal plots allows for a detailed evaluation of different aspects of biotic diversity on landscape scale. However, while disturbances play an important role in shaping the emergent patterns of species distribution, the long time disturbance regime, manifested in the coarse vegetation structure, plays an even more important role. Most notably, the relationships between spatial patterns of biodiversity and its drivers vary with III scale and exhibit considerable non-stationarity. This has important implications for ecological research. When the relation between pattern and process is under study, the sampling design should address scale issues and enable to study the variation of the relations with scale and extent. The methodology developed for the comparison of multiple plots has been applied to a data set of vegetation on Alpine summits to evaluate whether the upward shift of mountain plants causes homogenization of the summits. The analysis reveals that this indeed is the case: The increase in species richness on the summits is accompanied by a decrease in differentiation diversity. In the context of this thesis it is to state, that the heterogeneity concept may provide an interesting tool for the evaluation of actual ecological research questions as well as for nature conservation and monitoring. IV Zusammenfassung Zusammenfassung Landnutzungsveränderungen und Klimawandel führen weltweit zu einer rapiden Veränderung von Landschaften und Ökosystemen. Es werden dringend standardisierte und vergleichbare Daten benötigt, um den damit einhergehenden Verlust von Biodiversität zu erfassen. Daher ist es überaus wichtig, Methoden für eine umfassende Erfassung und Bewertung von Biodiversität zur Verfügung zu stellen. Aufgrund der Geschwindigkeit des Biodiversitätsverlustes sollten diese ebenso repräsentativ wie pragmatisch sein. Wenn Biodiversität auf Landschaftsebene verloren geht, müssen Aufnahmen häufig wiederholt werden, um diese Veränderungen erfassen und analysieren zu können. Das Hauptziel dieser Arbeit ist die Entwicklung und Evaluierung räumlich expliziter, übertragbarer Methoden zur Erfassung und Analyse pflanzlicher Vielfalt. Dies schließt Artenreichtum ebenso ein wie die räumliche und zeitliche Heterogenität der Artenzusammensetzung. Die konzeptionelle Erarbeitung einer Methodik sowie ihre Anwendung zur Untersuchung ökologischer Fragestellungen bilden die zwei Schwerpunkte dieser Arbeit. Eine Bewertung der bestehenden Terminologie zur biologischen Vielfalt - insbesondere bezüglich des Begriffes beta-Diversität - macht deutlich, dass eine Vielzahl konkurrierender Konzepte existiert. Diese Fülle an Definitionen verhindert die Anwendung sowie den wissenschaftlichen Fortschritt. Daher wird eine neue Terminologie vorgeschlagen, welche - im Gegensatz zu Whittakers Konzept der Vielfalt (mit den Begriffen alpha-, gamma- und beta-Diversität) - klarere Begriffe zur Verfügung stellt (Erfassungs-, Unterscheidungs- und Verhältnis-Diversität). Sie ermöglicht eine direktere Erfassung der zugrundeliegenden ökologischen Phänomene und Fragestellungen was wiederum eine effiziente Strukturierung zukünftiger Forschung und Diskussionen ermöglicht. Räumliche Muster der Vielfalt können am ehesten mit systematischem Sampling erfasst werden. Allerdings sind rektanguläre Raster - wie sie bisher angewendet worden - nicht unproblematisch. Einerseits wird dabei die Veränderung der Ähnlichkeit von Erfassungsflächen mit der Entfernung zwischen ihnen nicht berücksichtigt. Andererseits ergeben sich uneindeutige Ähnlichkeitswerte. Daher wird das systematische Sampling in hierarchisch geschachtelten, equidistanten Rasterflächen vorgeschlagen. Es scheint eine geeignete Methode zur Untersuchung räumlicher Muster in der Vegetation zu sein. Zur Analyse von Vielfaltsmustern wird ein neuer Koeffizient der Multi-Plot-Diversität vorgestellt. Zum ersten Mal ist damit die simultane Berechnung der Ähnlichkeit zwischen einer und mehreren Erfassungsflächen unter Berücksichtigung der Identitäten der Arten auf allen betrachteten Flächen möglich. Er erlaubt