Grassland soil microbiome

Soil microbial diversity and community composition are shaped by biotic and abiotic factors linked to land management, topographic position, and vegetation. To disentangle and quantify the effects of these drivers we sequenced fungal and bacterial communities from bulk soil of two Swedish grasslands with differing land-use history. Each grassland included both an upper and a lower catenary position, and samples were collected from four soil depths ranging from the surface to below the rooting zone. Fungal communities were identified using PacBio sequencing of ITS2, and for bacterial communities we used Illumina sequencing of 16S. We hypothesized that differences in plant species richness and plant functional group composition between the study sites would drive the variation in soil fungal and bacterial community composition and correlate with microbial diversity, and that microbial biomass and diversity would decrease with soil depth following a decline in resource availability. This study was also the pre-treatment sampling of a field experiment including drought, compost addition, and drought + compost addition treatments, starting in 2019.