Soil microbial gene abundance rather than diversity and network complexity predominantly determines soil multifunctionality in Tibetan alpine grasslands along a precipitation gradient

The relationship between biodiversity and ecosystem functioning has mainly focused on plant communities, with comparably little known about soil microbial-driven ecosystem functions. Climate change severely threatens soil microbial roles, but how soil microbial communities determine soil multifunctionality under climate change is poorly understood. Here, we evaluated the effects of diverse bacterial and fungal properties, including microbial gene abundance, diversity and network complexity, on soil multifunctionality (nine soil functions) across a 3000 km transect along a natural precipitation gradient in Tibetan alpine grasslands. Variation partitioning analyses were performed to disentangle the relative importance of bacterial and fungal properties to the variation of soil multifunctionality. Moreover, structural equation modelling was adopted to explore the influencing pathways of precipitation-induced changes in plant and edaphic factors to soil microbial properties and, consequently, soil multifunctionality. Soil multifunctionality was positively associated with bacterial and fungal gene abundance, diversity and network complexity. Microbial gene abundance was the more important driver influencing soil multifunctionality than microbial diversity and network complexity. In addition, microbial gene abundance was mainly determined by precipitation-induced changes in soil pH. Meanwhile, the effects of bacterial properties on soil multifunctionality were much larger than those of fungi. Soil multifunctionality was closely associated with different bacterial (cellulolysis, ligninolysis, nitrogen reduction, denitrification and nitrate fixation etc.) and fungal (soil saprotrophs, arbuscular mycorrhizal and plant pathogens etc.) functional guilds, which exert vital regulations on an array of soil biogeochemical cycling processes. Our results provide the large-scale evidence of the relative contribution of soil microbial gene abundance, diversity and network complexity to the variation of soil multifunctionality in alpine grasslands with changing precipitation, which is pivotal for understanding microbial roles in modulating and predicting soil multifunctionality under future precipitation changes.Read the free Plain Language Summary for this article on the Journal blog. Read the free Plain Language Summary for this article on the Journal blog.image