Strikingly high effect of geographic location on fauna and flora of European agricultural grasslands

Abstract

Wild bees, spiders, earthworms and plants contribute considerably to biodiversity in grasslands and fulfil vital ecological functions. They also provide valuable services to agriculture, such as pollination, pest control and maintenance of soil quality. We investigated the responses of wild bees, spiders, earthworms and plants to geographic location, agricultural management and surrounding landscape variables using a dataset of 357 grassland fields within 88 farms in six European regions. Regions and taxonomic groups were selected to have contrasting properties, in order to capture the multiple facets of European grasslands. Geographic location alone had a dominant effect on the fauna and flora communities. Depending on the taxonomic group, various agricultural management and surrounding landscape variables alone had an additional significant effect on observed species richness, rarefied species richness and/or abundance, but it was always small. Bee species richness and abundance decreased with increasing number of mechanical operations (e.g. cutting). Observed spider species richness and abundance were unrelated to measured aspects of agricultural management or to surrounding landscape variables, whereas rarefied species richness showed significant relations to nitrogen input, habitat diversity and amount of grassland habitats in the surroundings. Earthworm abundance increased with increasing nitrogen input but earthworm species richness did not. Observed plant species richness decreased with increasing nitrogen input and increased when there were woody habitats in the surroundings. Rarefied plant species richness decreased with mechanical operations. Investigating multiple regions, taxonomic groups and aspects of fauna and flora communities allowed identifying the main factors structuring communities, which is necessary for designing appropriate conservation measures and ensuring continued supply of services.