Anagallis arvensis. Atlas des plantes de France, A. Masclef (1891) ZENTRUM FÜR BIODIVERSITÄT UND NACHHALTIGE LANDNUTZUNG SEKTION BIODIVERSITÄT, ÖKOLOGIE UND NATURSCHUTZ – CENTRE OF BIODIVERSITY AND SUSTAINABLE LAND USE – SECTION: BIODIVERSITY, ECOLOGY AND NATURE CONSERVATION Effects of different energy cropping systems on plant diversity in Central German agricultural landscapes Dissertation zur Erlangung des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakultäten der Georg-August-Universität Göttingen vorgelegt von Charlotte Seifert aus Paderborn Göttingen, August 2014 Referent/In: Prof. Dr. Christoph Leuschner Korreferent/In: Prof. Dr. Erwin Bergmeier Tag der mündlichen Prüfung: 03.09.2014 Wheat field in Central Germany. Picture by Charlotte Seifert, August 2012. Ein Weizenfeld Weil es die Ähre verschmäht, sich mit der Farbe zu zieren, Hat die Natur ihr den Mohn dicht an die Seite gestellt; Jener hat sie die Kraft vertraut, den Menschen zu nähren, Diesem verlieh sie den Reiz, welcher sein Auge erfreut. Jene frage drum nicht: Wo sprießen dir nützliche Körner? Oder diesen: Wo trägst du den erquicklichen Schmuck? Wenn die eine uns fehlte, so könnten wir freilich nicht leben, Aber wir möchten es nicht, wäre der and’re nicht da! Christian Friedrich Hebbel (1813-1863) German poet and dramatist Impressions from an extensively managed field margin near Göttingen in Lower Saxony in June 2012. Pictures by Caroline Focke. Table of contents List of tables .......................................................................................................................................... V List of figures ....................................................................................................................................... VI Appendices ......................................................................................................................................... VII Abbreviations and acronyms .............................................................................................................. IX Chemical elements ............................................................................................................................... XI Units ...................................................................................................................................................... XI Unit prefixes ....................................................................................................................................... XII Acknowledgements ........................................................................................................................... XIV Summary ........................................................................................................................................... XVI Zusammenfassung ......................................................................................................................... XVIII CHAPTER 1 INTRODUCTION ........................................................................................................... 1 1.1 Research context ........................................................................................................................ 1 1.1.1 Plant diversity in agricultural landscapes ............................................................................ 1 1.1.1.1 Arable plant assemblages as a mirror of agricultural land use practices ......................... 1 1.1.1.2 The role of arable plants in agroecosystems .................................................................... 3 1.1.1.3 Current conservation status ............................................................................................. 3 1.1.2 Energy cropping .................................................................................................................. 5 1.1.2.1 Contribution to the total energy supply ........................................................................... 5 Global importance of bioenergy .................................................................................................. 5 Bioenergy in the European Union ............................................................................................... 5 The case of Germany –‘Energiewende’ ...................................................................................... 6 1.1.2.2 Conversion technologies and biomass feedstocks ........................................................... 7 Solid biofuels ............................................................................................................................... 7 Biomass for anaerobic digestion ................................................................................................. 8 Biomass for liquid transport fuels ............................................................................................... 9 1.1.2.3 Environmental impacts of energy cropping................................................................... 10 Direct impacts on biodiversity................................................................................................... 10 Direct impacts on the abiotic environment and soil organic matter cycles ............................... 12 Indirect impacts ......................................................................................................................... 14 1.2 The study areas ........................................................................................................................ 15 1.2.1 Location, geology and climate .......................................................................................... 15 1.2.2 Land use history ................................................................................................................ 18 1.2.3 Energy cropping in the study areas.................................................................................... 20 1.3 General description of the applied methods.......................................................................... 22 II 1.3.1 Vegetation sampling .......................................................................................................... 22 1.3.2 Soil sampling and analyses ................................................................................................ 23 1.3.2.1 pH .................................................................................................................................. 23 1.3.2.2 Effective cation-exchange capacity (ECEC) and base saturation .................................. 23 1.3.2.3 C/N-ratio and soil organic matter content ..................................................................... 23 1.3.2.4 Plant-available phosphorus ............................................................................................ 24 1.3.3 Measuring PAR transmissivity .......................................................................................... 24 1.3.4 Data analysis ...................................................................................................................... 25 1.3.4.1 General comments on the statistical approaches used ................................................... 25 1.3.4.2 Variation partitioning .................................................................................................... 26 1.4 General objectives and outline of the chapters ..................................................................... 27 1.5 References ................................................................................................................................ 29 CHAPTER 2 ARABLE PLANT DIVERSITY ON CONVENTIONAL CROPLAND – THE ROLE OF CROP SPECIES, MANAGEMENT AND ENVIRONMENT ............................................ 37 Abstract ................................................................................................................................................ 37 2.1 Introduction ............................................................................................................................. 38 2.2 Methods .................................................................................................................................... 41 2.2.1 Study areas ........................................................................................................................ 41 2.2.2 Sampling design ................................................................................................................ 42 2.2.3 Sampling of arable weed assemblages .............................................................................. 42 2.2.4 Soil sampling and analyses ................................................................................................ 42 2.2.5 Derivation of environmental, management and spatial variables ...................................... 43 2.2.5.1 Management variables ................................................................................................... 43 2.2.5.2 Environmental variables ................................................................................................ 45 2.2.5.3 Spatial factors ................................................................................................................ 45 2.2.6 Statistical analyses ............................................................................................................. 45 2.2.6.1 Model selection and variation partitioning .................................................................... 45 2.2.6.2 Comparisons