Trait composition and functional diversity of spiders and carabids in linear landscape elements

Schirmel J, Thiele J, Entling MH, Buchholz S

Zusammenfassung

Agricultural intensification is a cause of global biodiversity decline. Seminatural linear landscapeelements (LLE) within agricultural landscapes can considerably mitigate these declines, but their effectson functional properties of biodiversity are poorly known. We analyzed trait composition and functionaldiversity (functional dispersion) of spiders and carabids in woody and herbaceous LLE. We expected thatspecies assemblages of woody LLE are more diverse and K-selected compared to herbaceous LLE, and thateffects of environmental parameters vary between LLE types. We selected 58 LLE in an agriculturallandscape in Northwest Germany. We sampled carabids and spiders by pitfall trapping and measuredlandscape connectivity, landscape-wide land-use diversity, local land-use diversity, and local plantrichness as explanatory variables. The trait composition of arthropods in woody LLE was more K-selected(lower dispersal ability, a higher food specialization or trophic level) than in herbaceous LLE. Moreover,spider functional diversity was higher in woody LLE. Spider functional diversity and proportion ofpredatory carabids in woody LLE increased with increasing connectivity of the habitats. In contrast, inherbaceous LLE local plant richness and landscape-wide land-use diversity were most important driversfor spider and carabid diversity and traits. Our results show that species richness and functional diversityof spiders and carabids were differently affected by landscape and local factors. Therefore, theimportance of landscape connectivity was higher in woody LLE, suggesting that their inhabitants aremore sensitive to habitat fragmentation than the highly mobile generalist species living in herbaceoushabitats.