Contribution of root traits to variations in soil microbial biomass and community composition

It is well known that plant root-microbe interactions are critical drivers of ecosystem processes such as soil carbon and nutrient cycling; however, considerable uncertainties exist about how root chemical and morphological traits influence soil microbial community composition. We used 13 tree species grown in field monocultures in subtropical China to explore the ecological linkages between leaves, leaf litter, and root chemical and morphological traits associated with plant growth and nutrient-acquisition strategies, as well as soil microbial biomass, the fungi to bacteria (F/B) ratio, and Gram-positive to Gram-negative bacteria (GP/GN) ratio. The combination of above- and belowground traits captured a greater proportion of variations in soil microbial biomass and community composition than did aboveground traits alone. Individually, root traits explained more variations of the F/B and GP/GN ratios than did the individual effects of aboveground leaf or leaf litter traits. All distinct microbial biomass groups and F/B ratios decreased with the specific root length, whereas the F/B ratio increased, and the GP/GN ratio decreased with root tissue density. Our study highlighted the importance of the functional traits of plant roots in determining the microbial biomass and community composition in forest ecosystems. The combination of leaf and root traits may improve our understanding of the mechanisms that underly plant-microbe interactions toward the sustainable management of forest ecosystems.