Plant diversity is more important than soil microbial diversity in explaining soil multifunctionality in Qinghai-Tibetan plateau wetlands

The Qinghai-Tibetan Plateau harbors rich and diverse wetlands that provide multiple ecological functions simultaneously. Although the relationships between biodiversity and wetland functioning have been well studied in recent decades, the links between the multiple features of plant and microbial communities and soil multifunctionality (SMF) remain unknown in the high-altitude wetlands that are extremely sensitive to human disturbance. Here, using the single function, averaging, weighted, and multiple-threshold methods, we calculated the SMF of Qinghai-Tibetan wetlands based on 15 variables associated with soil nutrient status, nutrient cycle, and greenhouse gas emission. We then related SMF to multidimensional (species, phylogenetic, and functional) diversity of plants and soil microorganisms and microbial network modules. The results showed that plant diversity explained more variance in SMF than soil microbial diversity, and plant species richness and phylogenetic distance were positive predictors of SMF. Bacterial network modules were more positively related to SMF than fungal network modules, and the alpha diversity of bacterial network modules contributed more to SMF than the diversity of the whole bacterial community. Pediococcus, Hirsutella, and Rhodotorula were biomarkers for SMF and had significant relationships with nitrogen mineralization and greenhouse gas emissions. Together, these results highlight the importance of plant diversity and bacterial network modules in determining the SMF, which are crucial to predicting the response of ecosystem functioning to biodiversity loss under intensifying anthropogenic activities.