Improving insect conservation values of agri-environment schemes through diversified seed mixtures

Abstract

To counteract ongoing biodiversity declines, many European countries have implemented agri-environment schemes (AES) such as ecological focus areas (EFAs), the efficiency of which is often questioned due to low levels of habitat quality. We established new grasslands (NG) using a more diverse seed mixture specifically adapted to mimic low-intensity meadows occurring in our study region in Lower Austria. We compared abundance, species richness, species assemblages and β diversity of solitary bees, bumblebees, syrphids, butterflies, orthopterans, true bugs and cicadas in currently subsidized legume-grass mixtures targeted at supporting pollinators (SG), old grasslands (OG) and NG over a two-year period. Bees, bumblebees and syrphids clearly profited from NG in terms of abundance and species richness, while SG were significantly less attractive. Butterflies were most abundant in OG and significantly less attracted to both SG and NG. True bugs were particularly attracted to NG and SG. However, we did not find any preference in cicadas. Orthopteran species richness was similar in all three types, but individual numbers were significantly lower in NG than in OG. OG and NG supported highly distinctive species assemblages. For solitary bees, syrphids, true bugs and cicadas distinctiveness of sites (β diversity) was more decisive for overall diversity than local diversity. We urge policy makers to put more effort into the establishment of EFAs by using high quality seed mixtures of regionally adapted species and increased plant diversity. Furthermore, preserving permanent grasslands, which support different sets of insect assemblages, should be focused as well to maximize biological conservation value.