Global metawebs of spider predation highlight consequences of land-use change for terrestrial predator–prey networks

Land-Use Change and Terrestrial Predator–Prey Networks Land-use change, here defined as the conversion of one land-use type into another (e.g., forest to arable land), affects biodiversity and biotic interactions worldwide (Sala et al., 2000). Although there has been large regional variation in the extent of agricultural expansion and abandonment in Europe in the past 50 years (Rabbinge and van Diepen, 2000), there has been a general trend that forest has expanded at the expense of agricultural land (Kankaanpäa and Carter, 2004; Rounsevell et al., 2006). The patterns have been similar in North America the past decades (Smith et al., 2010). Globally, particularly in developing countries, the general pattern has instead been agricultural expansion (Smith et al., 2010), threatening forest ecosystems (DeFries et al., 2010; Lambin and Meyfroidt, 2011; but see Angelsen, 2010). In fact, models predict an increase of cropland between 10 and 25% up to 2050, mainly due to agricultural expansion in developing countries (Schmitz et al., 2014). Natural and semi-natural non-forest ecosystems are primarily threatened by a conversion to pasture land (Schmitz et al., 2014) or by cultivation with biofuels (Havlík et al., 2011). Climate change is an important additional driver of land-use conversion, as the range of crop species contract or expand (Olesen and Bindi, 2002) and as forests adapt to changing climatic conditions (Spittlehouse and Stewart, 2004). In the past, effects of land-use change were often exclusively assessed by their impact on species richness (Tilman et al., 2001). Today, it has increasingly become evident that we need metrics that capture additional features of biological communities to understand consequences of land-use change on ecosystem functions and the provision of ecosystem services (Tylianakis et al., 2007; Diehl et al., 2013). Trophic interactions that link species in food webs are important components that modulate functions provided by biological communities (Laliberté and Tylianakis, 2010; Tylianakis et al., 2010; Thompson et al., 2012). For example, the loss of large apex predators from an ecosystem due to anthropogenic disturbance may cascade through the food chain and lead to drastic effects on primary producers (Estes et al., 2011). Predator populations are often severely affected by anthropogenic disturbances (Attwood et al., 2008). Consequently, the conversion from one major land-use type into another may alter predator–prey interactions (Ives et al., 2005) and the provision of predator-mediated ecosystem services such as the control of agricultural pests (conservation biological control; Barbosa, 1998)