Microbial richness and composition independently drive soil multifunctionality

Soil microbes provide multiple ecosystem functions such as nutrient cycling, decomposition and climate regulation. However, we lack a quantitative understanding of the relative importance of microbial richness and composition in controlling multifunctionality. This knowledge gap limits our capacity to understand the influence of biotic attributes in the provision of services and functions on which humans depend. We used two independent approaches (i.e. experimental and observational), and applied statistical modeling to identify the role and relative importance of bacterial richness and composition in driving multifunctionality (here defined as seven measures of respiration and enzyme activities). In the observational study we measured soil microbial communities and functions in both tree- and bare soil-dominated microsites at 22 locations across a 1200 km transect in southeastern Australia. In the experimental study we used soils from two of those locations and developed gradients of ...