Ground beetles (Coleoptera: Carabidae) in enthropogenic grasslands in Germany: effects of management, habitat and landscape on diversity and community composition

Grasslands are of great importance for the conservation and maintenance of biodiversity in agricultural landscapes. In order to sustain grasslands and their associated biodiversity, we need to widen our knowledge of the role of grassland management and the amount of grassland cover in a landscape. The aim of our study was to correlate the variability of community composition and diversity of carabid beetles in anthropogenic grasslands with management, habitat conditions, landscape composition and plant species richness. Since the condition of grassland biodiversity is often solely evaluated on the basis of species richness of vascular plants, we also wanted to assess whether plants could indicate the diversity of carabid beetles in grasslands. Therefore, we sampled carabid beetles on 29 grassland sites with low to high management intensity and a great variation of abiotic conditions in Central Germany. The diversity of carabid beetles was the highest in grasslands of medium management intensity and was positively affected by a high cover of crops in the surrounding landscape. Both the landscape and soil moisture had an impact on activity density of carabids but depended on the trophic group of the beetles. There was no connection between plant species richness and carabid diversity. The results of our study suggest that plant species richness as a sole indicator of grassland biodiversity might not be sufficient. Nevertheless, moderate management intensity which supports high plant species richness can also increase carabid diversity. We therefore conclude that moderate management intensity is crucial to provide highest biodiversity of carabid beetles in grasslands. Due to landscape effects on carabid communities, we suggest that besides management of single fields, the composition and structure of the whole landscape should be taken into consideration in order to sustain a rich species pool of carabid beetles in agricultural landscapes