Arable field cover
Arable field cover had a negative effect on wild bee species richness and abundance supporting previous studies that show negative effects of land use intensification on local pollinator diversity in agricultural landscapes (Senapathi et al. 2017). Hoverflies were, in contrast to wild bees, positively affected by the cover of arable fields, indicating that dry grasslands surrounded by a high share of arable fields, have a higher hoverfly species richness and abundance. Although this positive effect seems counterintuitive at first sight, similar observations were made for agricultural fields and flower strips (Brandt et al. 2017, Haenke et al. 2009, Gabriel et al. 2010). Since hoverflies are highly mobile, they may be attracted by specific habitats, if the landscape offers no food resources (Haenke et al. 2009). As a result, hoverflies may accumulate on dry grasslands with a high proportion of arable field cover. Under this consideration, the observed ‘positive’ effect of arable field cover on hoverfly diversity indicates simply a limitation (and concentration) of food resources within the whole landscape (Haenke et al. 2009). In summary, our study demonstrates that arable field cover is an important predictor for pollinators that affect both guilds contrastingly not only in agricultural ecosystems (e.g. Brandt et al. 2017), but also in (semi-) natural habitats that present ‘biodiversity hotspots’ in Central Europe (Habel et al. 2013).