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).