Shifts in prokaryotic communities under forest and grassland within a tropical mosaic landscape

The Anthropocene is linked to massive land use changes as a result of human activity. While aboveground changes in biodiversity are well documented, the effects on belowground microbial communities are less understood, yet could impact on many ecosystem functions. Here we aimed to identify differences in belowground microbial diversity between forest and grassland sites in a humid tropical mosaic landscape in Papua New Guinea. Using DNA-based amplicon sequencing targeting the 16S rRNA gene, prokaryotic community composition was assessed from surface soil samples. The composition of prokaryotic communities (beta diversity) differed between forest and grassland sites despite maintaining similar richness (alpha diversity) levels. Changes in community structure were small at higher taxonomic levels, but strong at the operational taxonomic unit (OTU) level but for a small subset of taxa. Changes in community composition between sites (based on Bray-Curtis distance) reflected a large rearrangement with species assemblage (OTU) differing by 68%. The results suggest that ecosystem change in this landscape leads to ecological filtering and selection at lower, but not higher taxonomic levels.