Converting arable land into flowering fields changes functional and phylogenetic community structure in ground beetles

Abstract

Agri-environmental schemes aim to promote biodiversity in agricultural landscapes. However, knowledge about the impact of these measures on diversity components beyond species richness, especially for non-target species and their ecological functions, is still very poor. Here, we investigated the response of ground beetle communities to the conversion of arable land into flowering fields, which are primarily installed to counteract pollinator loss in agricultural landscapes. We are focusing on the relationship between biodiversity components and the evolutionary relationship among functional groups.Land-use conversion from arable land to flowering fields has changed the phylogenetic community composition of ground beetles towards a phylogenetically clustered community. This is due to an increase in closely related medium-sized herbivorous species and a decrease in evolutionarily distinct small carnivorous species. Phylogenetic clustering did not result in a reduction of functional richness, but it increased the number of unique trait combinations of species within the local communities. This suggests a low ecological redundancy among herbivorous species. Because species richness, functional richness and phylogenetic diversity were unaffected by conversion, phylogenetic community structuring was predominantly driven by species turnover rather than by numerical changes.Flowering fields can act as refuges for herbivorous carabids that potentially affect the surrounding agricultural landscape by providing important ecosystem services such as weed control. To understand the impact of habitat transformation on carabid biodiversity, it was more informative to relate response traits to phylogenic and functional diversity than to use single diversity measures such as species richness. This conclusion might also apply to many other taxa.