Ground beetles communities, diversity, biomass and traits in wooded pastures of Jura mountains

Wooded pastures combine trees and pastures in an integrated land resulting from traditional silvopastoral practices. With their sparse tree cover, wooded pastures are expected to represent an ecotone between open area pastures and forests with potentially high species diversity, although this remains to be tested for animal groups including ground beetles. In this study, we aimed to characterise and compare species communities, diversity indices, biomass and ecological traits of ground beetles in wooded pastures, forests and non-wooded pastures. Pitfall traps were set up in 29 study sites located in the Swiss Jura mountains. Ground beetle communities in wooded pastures largely encompass those in open pastures and forests, although some species are found only in forests or open areas. Wooded pastures and open pastures have an equivalent species diversity level, which is significantly higher than the one in forests. Ground beetle diversity is positively correlated with the existence and surface of Biodiversity Promotion Areas. Areas with high tree cover (70–100%) favour brachypterous and hygrophilic species, whereas areas with reduced tree cover (0–20%) favour xerophilic and winged species. Ground beetles' size and biomass increase with tree cover. Wooded pastures are an important ecotone, ensuring a gradual change of land use systems between open areas and forests, where a wide range of species from both land use systems are found. This semi-natural habitat plays an important function in the conservation of ground beetles.