Explaining the variation in the soil microbial community: do vegetation composition and soil chemistry explain the same or different parts of the microbial variation?

To assess whether vegetation composition and soil chemistry explain the same or different parts of the variation in the soil microbial community (SMC). The above and below-ground communities and soil chemical properties were studied along a successional gradient from moorland to deciduous woodland. The SMC was assessed using PLFAs and M-TRFLPs. Using variance partitioning, Co-Correspondence Analysis (CoCA) and Canonical Correspondence Analysis (CCA), the variation (total inertia) in the SMC was partitioned into variation which was uniquely explained by either plant composition or soil chemistry, variation explained by both soil chemistry and plant composition, and unexplained variation. Plant community composition uniquely explained 30, 13, 16 and 20% of the inertia and soil chemistry uniquely explained 5, 18, 9 and 9% of the inertia in the archaeal TRFLPs, bacterial TRFLPs, fungal TRFLPs and all PLFAs, respectively. For the first time, variance partitioning was used to include data from a CoCA; although the current limits of such an approach are shown, this study illustrates the potential of such analyses and shows that soil chemistry and plant composition are, in substantial amounts, explaining different parts of the variation within the SMC. This marks an important step in furthering our understanding of the relative importance of different drivers of change in the SMC.