Institute of Botany, Chinese Academy of Sciences, China (People's Republic)
Soil microbial communities are essential in regulating ecosystem functions and services in terrestrial ecosystems. However, the importance of soil bacterial and fungal communities as predictors of multiple soil functions (i.e. soil multifunctionality) in grassland ecosystems has not been studied systematically. Here, we measured soil microbial diversity and biomass, microbial community composition, and multiple soil functions in diverse grasslands including meadow steppe, typical steppe, desert steppe, alpine meadow, and alpine steppe, spanning a 3,500 km northeast–southwest transect in China. The random forest algorithm was adopted to determine the importance of climatic, altitude, geographical location, plant, edaphic and microbial predictors in driving soil multifunctionality. Structural equation models were employed to examine the direct and indirect effects of those predictors on soil multifunctionality. Our results demonstrated that soil fungal diversity, dominant bacterial taxa (phyla Actinobacteria and Proteobacteria), and microbial biomass are important predictors for maintaining soil multifunctionality of grassland ecosystems. Importantly, the direct positive effects of these predictors were maintained after accounting for multiple predictors. Furthermore, our results extend the view of fungal taxonomic diversity (richness of species) to phylogenetic diversity (presence of different evolutionary lineages) as important predictors of soil multifunctionality. Our study provided strong empirical evidence that soil multifunctionality was driven by different facets of the bacterial and fungal communities in the grassland ecosystems. In particular, our results highlighted that any loss of fungal diversity and dominant bacterial taxa might reduce soil multifunctionality, exacerbating ecosystem functions and services such as soil fertility, production, fiber, food, human welfare, and climate mitigation in grassland ecosystems.
