Biodiversity and Multitrophic Interactions in Changing Terrestrial
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Biodiversity and multitrophic interactions in changing terrestrial ecosystems o Kumulative Habilitationsschrift zur Erlangung der venia legendi für das Fach Ökologie von Christoph Scherber Angefertigt am Department Nutzpflanzenwissenschaften Abteilung Agrarökologie Georg-August-Universität Göttingen Vorgelegt der Fakultät für Agrarwissenschaften der Georg-August-Universität Göttingen Im Juli 2011 Table of Contents Table of Contents Chapter 1 ����������������������������������������������������������������������������������������������� 5 An introduction and overview Chapter 2 ���������������������������������������������������������������������������������������������� 25 Biodiversity, belowground interactions, and invasion resistance published as: Scherber C, Mwangi PN, Schmitz M, Scherer-Lorenzen M, Beßler H, Engels C, Eisenhauer N, Migunova VD, Scheu S, Weisser WW, Schulze ED, Schmid B (2010) Biodiversity and belowground interactions mediate community invasion resistance against a tall herb invader. Journal of Plant Ecology 3:99-108 Chapter 3 ���������������������������������������������������������������������������������������������� 37 Plant functional identity and herbivore performance published as: Specht J, Scherber C, Unsicker S, Köhler G, Weisser WW (2008) Diversity and beyond: plant functional identity determines herbivore performance. Journal of Animal Ecology 77:1047–1055. Chapter 4 ���������������������������������������������������������������������������������������������� 49 Effects of plant diversity on multitrophic interactions published as: Scherber C et al. (2010) Bottom-up effects of plant diversity on multitrophic interactions in a biodiversity experiment. Nature 468:553-556 Chapter 5 ���������������������������������������������������������������������������������������������� 85 Effects of climate change on herbivore performance in preparation for publication as: Scherber C, Gladbach DJ, Andersen KS, Christensen S, Michelsen A, Albert KR, Mikkelsen TN, Beier C (2011) Effects of warming, drought and elevated CO₂ on performance of an insect herbivore in heathland. 2 Table of Contents Chapter 6 �������������������������������������������������������������������������������������������� 101 Effects of climate change on above-belowground interactions in preparation for publication as: Stevnbak K, Scherber C, Gladbach D, Beier C, Mikkelsen TN, Christensen S (2011) Climate change disrupts interactions between above- and belowground organisms in a field experiment. Chapter 7 �������������������������������������������������������������������������������������������� 117 Effects of arable fields on multitrophic interactions in wild plants published as: Gladbach DJ, Holzschuh A, Scherber C, Thies C, Dormann CF, Tscharntke T (2011) Crop-noncrop spillover: arable fields affect trophic interactions on wild plants in surrounding habitats. Oecologia 166:433-41. Chapter 8 ������������������������������������������������������������������������������������������� 135 Scale effects in biodiversity and biological control accepted for publication as: Scherber C, Lavandero B, Meyer KM, Perovic D, Visser U, Wiegand K, Tscharntke T (2012) Scale effects in biodiversity and biological control: methods and statistical analysis. Book chapter in: Gurr GM, Wratten SD, Snyder WE (eds.) Biodiversity and Insect Pests: key issues for sustainable management. Wiley Blackwell, to appear in print 2012. Chapter 9 �������������������������������������������������������������������������������������������� 153 Effects of tree diversity on beetle communities published as: Sobek S, Steffan-Dewenter I, Scherber C, Tscharntke T (2009) Spatiotemporal changes of beetle communities across a tree diversity gradient. Diversity and Distributions 15: 660–670 3 Table of Contents Chapter 10 ������������������������������������������������������������������������������������������ 179 Effects of tree diversity on herbivory, herbivores and predators published as: Sobek S, Scherber C, Steffan-Dewenter I, Tscharntke T (2009) Sapling herbivory, invertebrate herbivores and predators across a natural tree diversity gradient in Germany’s largest connected deciduous forest. Oecologia 160:279–288. Chapter 11 ������������������������������������������������������������������������������������������ 195 Effects of tree diversity on true bugs (Heteroptera) published as: Sobek S, Goßner M, Scherber C, Steffan-Dewenter I, Tscharntke T (2009) Tree diversity drives abundance and spatiotemporal β-diversity of true bugs (Heteroptera). Ecological Entomology 34: 772–782. Chapter 12 ������������������������������������������������������������������������������������������ 215 Effects of tree diversity on trap-nesting bees, wasps and their natural enemies published as: Sobek S, Tscharntke T, Scherber C, Schiele S, Steffan-Dewenter I (2009) Canopy vs. understory: Does tree diversity affect bee and wasp communities and their natural enemies across forest strata? Forest Ecology and Management 258: 609–615 General discussion and Conclusions ������������������������������������������� 225 Summary ��������������������������������������������������������������������������������������������231 Acknowledgements ������������������������������������������������������������������������� 233 Bibliography ������������������������������������������������������������������������������������ 235 4 Chapter 1 An introduction and overview 5 An introduction and overview of this thesis 1 General Introduction 1.1 Components of global change We are all living in a changing world - rapid hu- Since the onset of the 18th century, human societies man global population growth, expansion and glo- have passed through several phases of industrial balization of the economy, increasing global trade, revolutions (Spilhaus 1970), all of which created revolutions in communication technology, as well their own impacts on the environment (Ellis 2011). as political changes, are just some of many possible In general, such transitions are characterized by indicators of change (Martino and Zommers 2007). abrupt changes in technology, communicaton or However, population and economic growth don´t mobility, followed by increases or decreases in come without costs - in particular, growth always human population growth rate (Meyer and Turner requires resources, and resource demand has been 1992). increasing dramatically over the last decades. Over the last decades, it has become clear that some For living organisms, and the ecosystems which of these anthropogenic impacts have now reached they are part of, some types of human activities are a global dimension, affecting components of the more influential than others. One major type of hu- Earth system as a whole (Zavaleta and Heller 2009), man activity is land-use, that is, the way in which commonly referred to as “global change” or “global man transforms land cover for various (often agri- changes” (Turner et al. 1990). cultural) purposes. Global change may, for example, comprise processes Understanding the effects of land-use on life on such as (i) increasing atmospheric concentrations Earth is therefore one important aim of this thesis. of CO2 (carbon dioxide); (ii) anthropogenic changes The following subsections shall introduce some of in biogeochemical cycles, or (iii) land-use change the basic concepts, and may serve as an overview of (Vitousek, 1994). The term “global change” may what will be covered in later chapters of this thesis. have two distinct meanings. On the one hand, “global” may refer to the spatial scale of operation of a process; for example, an event happening very locally may have direct consequences on a global scale. On the other hand, “global” may also mean an accumulation of localized changes (Figure 1, p. 6; for details, see Turner et al. 1990). In this thesis, some of these components of global change will be experimentally manipulated on a local scale, to study global change effects on ecosystems. In particular, we study the effects of Regional pathways to global change Cumulative Source + [......] n (intra-regional) Impact Systemic Source Impact (regional to global) Figure 1: Pathways to global change. Global change may be either (i) a cumulative process, where individual sources have regional impact, and only have a cumulative effect on the Earth system, or (ii) a more direct process, where a single regional event has direct global conse- quences. Modified from Turner et al. 1990. 6 An introduction and overview of this thesis rising atmospheric CO2, warming and increased how changes in biodiversity at one trophic level are drought on a heathland ecosystem (Chapter passed on to adjacent levels (Cardinale et al. 2006), 5, page 85; Chapter 6, page 101). It has and how biodiversity change affects different types been shown that increasing concentrations of of interactions. In this thesis, we address these issues atmospheric CO2 may affect plant productivity, by experimentally manipulating plant biodiversity, nitrogen cycling (e.g. via changes in plant nitrogen and studying responses of organisms and processes demand) and trophic interactions (e.g. via changes in a multitrophic context (Chapter 4, page 49). in survival, growth and reproduction of herbivores). We investigate these mechanisms using two types 1.2.2 Effects of biodiversity on biological of insect herbivores (Chapter 5, page 85 and invasions Chapter 6, page 101). Biological invasions have been recognised as an 1.2 Global losses of biodiversity important cause of biodiversity