Influence of landscape-scale farming practices on diversity and community weighted mean (CWM) body size of predatory arthropod communities in permanent grasslands

Abstract: Agricultural intensification and landscape simplification are major drivers of
biodiversity loss in permanent grasslands, with profound consequences for predatory arthropod communities and associated ecosystem services. This research investigates how local management practices, landscape heterogeneity, and landscape-scale farming intensity jointly shape both taxonomic and functional dimensions of arthropod diversity. Ground-dwelling predators (spiders, carabid beetles, rove beetles, and chilopods) were sampled in 18 permanent grasslands in northeastern France during spring and autumn. Taxonomic α and β diversity were analyzed alongside functional structure using community-weighted mean body size metrics. Multivariate analyses identified independent gradients of local intensity, land-cover composition, and landscape-wide farming practices. α diversity was primarily driven by
grassland cover in spring and by local nitrogen inputs in autumn. In contrast, β diversity and
species turnover were strongly influenced by landscape-scale farming intensity, indicating
environmental filtering processes. Functional analyses revealed that intensive managed
landscapes, particularly those with high herbicide and fungicide use, favored communities
dominated by larger-bodied predators, leading to functional imbalances. Overall, these findings highlight that agricultural intensification affects not only species composition but also functional traits critical for biological control, underscoring the need to integrate land-use composition and farming intensity into biodiversity-friendly management strategies.