Impact of land use on assemblages of carabid beetles (Coleoptera: Carabidae) in Zambia Dissertation Zur Erlangung des Doktorgrades der Naturwissenschaften (Dr. rer. nat.) Dem Fachbereich Biologie der Philipps-Universität Marburg vorgelegt von Donald Chungu aus Mwense/Sambia Marburg an der Lahn, December 2014 ContentContent Vom Fachbereich Biologie der Philipps-Universität Marburg als Dissertation am 1st December 2014 angenommen. Dekan: Prof. Dr. Monika Hassel Erstgutachterin: Prof. Dr. Roland Brandl Zweitgutachter: Prof. Dr. Nina Farwig Tag der Disputation: 8th December 2014 2 ContentContent Erklärung Hiermit versichere, dass ich meine Dissertation mit dem Titel ‘Impact of land use on assemblages of carabid beetles (Coleoptera: Carabidae) in Zambia’ selbständig und ohne unerlaubte Hilfe angefertigt habe und mich keiner als der von mir ausdrücklich bezeichneten Quellen und Hilfen bedient habe. Diese Dissertation wurde außerdem in der jetzigen oder einer ähnlichen Form noch bei keiner anderen Hochschule eingereicht und hat noch keinen sonstigen Prüfungszwecken gedient. Marburg an der Lahn, December 2014 Donald Chungu 64 Table of contents 1 General introduction 1 Biodiversity in Africa 2 Land use a nd species assemblages 3 Pollution and species assemblages 7 The s tudy area 9 Dissertation outline and objectives 11 References 15 2 Plantations of non-native trees decrease richness and change composition of carabid assemblages in Zambia 24 Abstract 25 Introduction 26 Materials and Methods 28 Results 33 Discussion 37 Acknowledgements 42 References 43 3 Agriculture ecosystems reduce body size of carabid species 54 Abstract 55 Introduction 56 Methods 59 Results 64 Discussion 69 Acknowledgements 73 References 74 4 Heavy metal concentrations in carabids reveal differential response of species to contamination along a Cu-Pb pollution gradient in Zambia 83 Abstract 84 Introduction 85 Methods 88 Results 90 Discussion 95 Acknowledgements 98 References 99 5 Summary 107 6 Deutsche Zusammenfassung 113 7 Appendices 120 8 Curriculum Vitae 129 9 Acknowledgements 134 1 General introduction 1 Chapter 1: General introduction Biodiversity in Africa Africa harbors diverse habitats ranging from tropical rainforests to deserts: The continent includes some of the driest deserts (e.g. Sahara and Kalahari deserts), largest tropical rainforests (e.g. Ituri forest) and highest mountains in the world (e.g. Kilimanjaro mountain; UNEP 2002). Based on these habitat diversity and historical reasons (Heywood 1995; Oba 2014), Africa possesses a unique flora and fauna with even large genetic breaks within the continent (see Cape Flora) and between the main land and the adjacent islands like Madagascar (Myers 1990; Goldblatt 1997). Of the 25 global biodiversity hotspots, a total of five are found in Africa (Koppler et al. 2002). Tropical forests are the most diverse and the most ecologically complex of all terrestrial ecosystems, probably sustain over one-third of all species (Raven 1980; Wilson 1992) and play a disproportionately large role in global carbon and energy cycles (Detwiler 1988; Le Quere et al. 2014). Due to their heterogeneity, greater variety of microhabitats, a greater range of microclimates and increased resource spectrum, tropical forests accommodate a rich diversity of invertebrates as well as vertebrates (Huston 1993; Townsend et al. 2008). It has been estimated that tropical forests in Africa cover 520 million hectares and constitutes more than 17% of the world’s forests stretching from western Africa through central to southern Africa (Achard et al. 2002; Klopper et al. 2002). Recent evidence suggests that the earth is undergoing a period of substantial decreases in biodiversity and mass extinction of 2 Chapter 1: General introduction species (Myers & Knoll 2001; Butchart et al. 2010; Uchida & Ushimaru 2014), which threaten ecosystem processes and therefore also ecosystem services (Heywood 1995; Bihn et al. 2010) and the welfare of humans (Balmford & Bond 2005). Due to population explosion and urbanization, tropical forests have been extensively modified and are shrinking at an unprecedented rate (Matson et al. 1997). As a consequence, Africa had lost 39 million hectares of tropical forest during the 1980s and another 10 million hectares by 1995 (UNEP 2002), and the continent’s large and diverse biological heritage has been exposed to greater risk. Most studies on biodiversity loss have focused on mammals (Dirzo & Raven 2003; Gonzalez 2013), birds (Gregory et al. 2005; de Lima et al. 2013; Boyer & Jetz 2014) and plants (Wood et al. 2013; Newbold et al. 2014). However, the decline and extinction rates of insects, which comprise the majority of terrestrial biodiversity, are inadequately quantified and poorly understood, especially so in Africa (Dunn 2005; Thomas 2005; Runge et al. 2014). Land use change and species assemblages The major drivers underlying the potential loss of biodiversity are land use change and climate change (Fig. 1.1; Sala et al. 2000; Thomas et al. 2004; Foley et al. 2005). Climate change is already affecting species distributions and traits around the world (Thomas et al. 2004; Zeuss et al. 2014) and is projected to have considerable further impacts this century (Gitay et al 2002; Thomas et al. 2004). Nevertheless, 3 Chapter 1: General introduction land use change remains to be the dominant driver of biodiversity loss over the next century (Souza et al. 2014; Riordan & Rundel 2014). For instance in Europe, land use change has been identified as the principle driver of butterfly declines (Asher et al. 2001; Van Dyck et al. 2009) and population decrease in birds (Gregory et al. 2005). Fig. 1.1: Major biodiversity threats; land use and climate change are the dominant threats to biodiversity. Source: Sala et al. (2000). Agriculture is a dominant and socioeconomically important land use in Africa and elsewhere (Heywood 1995; Halada et al. 2011). However, agricultural expansion generally reduces habitat area, quality and heterogeneity through the interlinked impacts of increased agrochemical use, changes in tillage or grazing practices and is widely recognized as a major driver of biodiversity decline (Benton et al. 2003; Tscharntke et al. 2012). Another form of land use that is increasingly 4 Chapter 1: General introduction becoming a common feature in many African countries are plantations of non- native tree species and is regarded as a strategy to alleviate the critical shortages of fuel-wood and timber (Evans & Turnbull 2004). Plantation forestry often creates artificially homogenous forests with one or few tree species with individuals of the same size and age. Homogeneous forests have relatively few available niches and have been reported to support fewer species (Stephens & Wagner 2007; Bremer & Farley 2010). These plantations are also characterized by special silvicultural treatments, use of fire and chemicals and constant soil cultivation (Evans & Turnbull 2004; Chungu et al. 2010) which may also threaten native biodiversity (Heywood 1995; Tscharntke et al. 2012). Although plantations can be managed to maximize species diversity in some cases (Pawson et al. 2008; Brockerhoff et al. 2008), they are unlikely to attain the biodiversity levels of natural forest (Sloan et al. 2014) and should not be regarded as an alternative to natural forests but rather as complementary to them (Heywood 1995). Beside its influence on species richness, land use change is often suggested as the source of variation in species assemblages at both local and regional scales (Huston 1993; Myers & Knoll 2001; Adams 2010), and has contributed significantly to the decline of sensitive species including carabid beetles in many parts of the world (Brooks et al. 2002; Kotze & O’Hara 2003; Vanbergen et al. 2010). Carabid beetles are widely distributed, are taxonomically well known, with relatively stable systematics, and their ecology has been widely studied (Lövei & Sunderland 1996; Homburg et al. 2014). Carabid beetles are especially important in five major 5 Chapter 1: General introduction different ways. (i) Experimental evidence suggests that carabid beetles may potentially serve as keystone indicators (Kotze et al. 2011). (ii) Carabids are sensitive to anthropogenic induced conditions, such as pesticide use in agro- ecosystems or contamination of soils by heavy metals (Menalled et al. 2007; Butovsky 2011). (iii) Carabid assemblages host numerous species that are characteristic of particular habitat types or successional stages, which makes them promising bioindicators (Lövei & Sunderland 1996). (iv) Carabids may function as early-warning signalers, as suggested by recent studies linking climate and carabid distributions (Gómez et al. 2014; Pozsgai & Littlewood 2014). (v) Carabids reflect natural and human-caused disturbances and management (Lövei & Sunderland 1996). Current theory, e.g. the habitat templet theory (Townsend et al. 1997), predicts that abiotic factors act like filters, sorting organisms with unique trait combinations appropriate for specific habitat conditions (Keddy 1992; Statzner et al. 2004; Berg et al. 2010). Consistent with this theory, land use change is likely to affect the assemblage of species in communities. Body size is one of the most fundamental properties of an organism and correlates with host range, metabolism and extinction risk (Blackburn & Gaston 1994; Brändle et al. 2000; Woodward et al. 2005). Body size has been used to quantify energy transfer, biogeochemical cycling in ecosystems and division of resources