Effect of grazing intensification on dung beetle biodiversity-ecosystem functioning relationship in a biogeographical context

Landscape modification and intensification of farming practices generally reduce species richness and functional diversity, although with some exceptions and regional differences. We assessed the relationship between grazing intensity, climate, biodiversity, and ecosystem functioning on global pasturelands, a human-modified ecosystem distributed worldwide. Specifically, we studied the determinants of several aspects of dung beetle (Coleoptera: Scarabaeoidea) diversity (abundance, species richness, and functional diversity) and their consequences on the provision of dung removal, a key ecological function associated with several ecosystem services, including nutrient cycling, bioturbation, and secondary seed dispersal. To do this, we performed paired field experiments using a standardized protocol in pasturelands of 38 localities scattered worldwide, albeit with better coverage of the Americas and Europe. These experiments compared the variation in dung beetle diversity and dung removal rates between pastures subject to low and high cattle stocking rates as a measure of management intensity. Species richness was significantly higher in low-intensity pastures, but abundance, dung removal and functional diversity showed no overall differences between low- or high-intensity pastures. However, dung removal increased with species richness across sites, while functional diversity consistently enhanced the provision of this ecosystem service in low-intensity pastures. This implies that, despite intensified cattle stocking rates, ecosystem services related to decomposition and nutrient cycling can be maintained when a diverse dung beetle assemblage inhabits human-modified landscapes. Therefore, actions to maintain functional diversity and fragments managed extensively at the landscape level will improve biodiversity conservation, enhance matter and energy cycles, and maximize ecosystem service delivery in pasturelands.