Linking rhizosphere soil microbial activity and plant resource acquisition strategy

Plants live in association with a diversity of soil microorganisms, which are extremely important in affecting plant growth and soil biogeochemical cycling. By adopting plant trait-based approaches, we explored the linkages between rhizosphere soil microbial activity and plant resource acquisition strategy of above- and below-ground across a range of tree species in a subtropical evergreen mixed forest. The microbial activities were represented by diverse extracellular enzymes relevant to carbon, nitrogen and phosphorus cycling and soil organic carbon (SOC) mineralization. At the species level, leaf and root traits were mainly represented by two leading dimensions, that is, the ‘fast-slow’ economics spectrum on which leaf and root traits were well aligned and the orthogonal collaboration gradient in the root. Both extracellular enzymes and SOC mineralization in the rhizosphere varied greatly across plant species. We found that diverse rhizosphere soil microbial activities positively correlated with the classical ‘fast-slow’ conservation gradient of plant resource acquisition (especially above-ground), that is, the rhizosphere soil microbes associated with fast-growing plant species feature higher metabolism than that of slow-growing plant species. In comparison, rhizosphere soil microbial activities were independent of the plant collaboration gradient in the root, and it might be an alternative exploitative strategy in foraging soil nutrients for plants. Synthesis. Our study strengthens the multivariate nature of plant resource acquisition in adapting to above- and below-ground stresses. The findings on the linkages between rhizosphere soil microbial activity and plant resource acquisition strategy have the potential to improve our understanding and prediction of plant species turnover impacts on soil biogeochemical cycles.