Data from: Soil microbial community variation correlates most strongly with plant species identity, followed by soil chemistry, spatial location and plant genus

Soil ecologists have debated the relative importance of dispersal
limitation and ecological factors in determining the structure of soil
microbial communities. Recent evidence suggests that "everything is
not everywhere", and that microbial communities are influenced by
both dispersal limitation and ecological factors. However, we still do not
understand the relative explanatory power of spatial and ecological
factors, including plant species identity and even plant relatedness, for
different fractions of the soil microbial community (i.e. bacterial and
fungal communities). To ask whether factors such as plant species, soil
chemistry, spatial location, and plant relatedness influence rhizosphere
community composition, we examined field-collected rhizosphere soil of
seven congener pairs that occur at Bodega Bay Marine Reserve, CA, USA. We
characterized differences in bacterial and fungal communities using
Terminal-Restriction Fragment Length Polymorphism. Plant species identity
was the single best statistical predictor of both bacterial and fungal
community composition in the root zone. Soil microbial community structure
was also correlated with soil chemistry. The third best predictor of
bacterial and fungal communities was spatial location, confirming that
everything is not everywhere. Variation in microbial community composition
was also related to combinations of spatial location, soil chemistry, and
plant relatedness, suggesting that these factors do not act independently.
Plant relatedness explained less of the variation than plant species, soil
chemistry, or spatial location. Despite some congeners occupying different
habitats and being spatially distant, rhizosphere fungal communities of
plant congeners were more similar than expected by chance. Bacterial
communities from the same samples were only weakly similar between plant
congeners. Thus, plant relatedness might influence soil fungal, more than
soil bacterial, community composition.