Agri-environmental schemes promote ground-dwelling predators in adjacent oilseed rape fields: diversity, species traits and distance-decay functions

1. Rising demands for agricultural products and high environmental costs of intensive agriculture reinforce the need for ecological replacements in agricultural management. In Europe, agri-environmental schemes (AES) are implemented to enhance species richness and provision of ecosystem services, but the effectiveness of different AES types and the spatial extent of possible beneficial effects are little understood. In this study we assessed the effects of different AES types on diversity, species traits and distance-decay functions of ground- dwelling predators in adjacent crop fields. 2. On 31 study sites with winter oilseed rape (OSR) adjacent to four types of AES differing in management intensity and habitat age we recorded ground-dwelling predators (carabid beetles, staphylinid beetles and spiders) during OSR growth from April to July. Effects of the AES on species richness, activity densities and different traits of these taxa were examined with transects of pitfall traps running ...