BIOINVENT: Effect of grassland management on soil microbial community structure along a North-South European transect

A North-South European transect was established, comprising five countries, to determine the relative influence of geography and agricultural management on the permanent grassland soil microbiome. Each country was divided into two regions of differing growth conditions; favorable (FR) and less favorable (LFR). Soil samples of two grasslands management intensities (MI); intensive (INT) and extensive (EXT), were taken from all regions (223 sites in total). The fungal internal transcribed spacer region and the bacterial 16S rRNA gene were PCR amplified as community marker genes, and Illumina Miseq sequence analysis was conducted to construct operational taxonomic units (OTUs). Across the transect, Country was the stronger driver of both fungal and bacterial community structure. There was also a significant influence of MI at the transect level, with the fungal and bacterial community structure being significantly different in EXT compared to INT. Interestingly, MI had a comparable influence to Country on fungal community structure at this level. An effect of MI on various measures of the soil microbiome (i.e., OTU richness, relative abundance of fungal and bacterial phyla, management-associated indicator OTUs) was also seen at the regional level. Most notable, was the higher fungal OTU richness in EXT grasslands in half of the regions. The effects, however, were not consistent across all regions. These results detail how EXT grasslands provide a distinct habitat for soil microorganisms, particularly the soil fungi, and highlights the importance of their preservation at the European scale.