Impacts of contrasting conservation grazing management on plants and carabid beetles in upland calcareous grasslands

Abstract

Abstract Calcareous grassland is among the most species rich and diverse habitat in Europe, but has faced decline due to agricultural intensification and abandonment. In recent years, conservation organisations have changed grazing practices in this habitat in an attempt to maintain characteristic vegetation. However, there has been little consideration of the effects of changes in grazing practices on invertebrate communities or their relationship with plant communities. This study determines the impacts of commonly used grazing practices in internationally rare upland calcareous grasslands on vegetation and on carabid beetles, a diverse group that is known to respond to environmental change. Typical conservation management regimes (light cattle grazing, light sheep grazing and ungrazed), established for over ten years, were examined in three regions of Britain. Carabid beetles were sampled using pitfall traps from late April – early September 2013 and per cent cover of plant species was recorded in 2 m × 2 m quadrats paired with pitfall traps sequentially throughout the sample period. Plant and beetle species composition differed significantly between regimes, as did plant species richness where ungrazed sites had significantly fewer species than sheep or cattle grazed sites. In contrast, beetle species richness did not differ by grazing type. Three beetle species were significantly associated with grazing management regimes: Carabus arvensis with light cattle grazing, and Carabus violaceaus and Synchus vivalis with light sheep grazing, the former two having undergone major population declines in the UK. Grazing regime affects both plant and carabid beetle communities and is important in supporting distinct species compositions as well as rare and declining species. Carabid beetles did not always respond in the same way as plants to grazing regime, suggesting that conservation managers should exercise caution when using plant species composition or broad measures of plant diversity to indicate biodiversity value, identify priority habitats or select grazing regimes to support a particular habitat condition.