Positive effects of fungal β diversity on soil multifunctionality mediated by pH in the natural restoration succession stages of alpine meadow patches

[Display omitted] •The most crucial limiting factors were soil pH and moisture in the natural restoration succession stages of degraded patches.•Soil moisture affects pH and mediates the microbial diversity–multifunctionality relationships.•Fungal β diversity and multifunctionality showed a positive correlation.•Bacterial α diversity and multifunctionality were negatively correlated. It is important to have a deep understanding of microbial diversity–multifunctionality relationships. Studies on α diversity of microorganisms have been reported extensively, but the different microbial species of diversity at β scale is still unclear. In this study, we selected bare patches (BP), vegetated patches (VP) and healthy alpine meadows (AM) of different degradation severity in different restoration succession stages to investigate the microbial α and β diversity (bacteria and fungi), and soil multifunctionality (i.e. plant aboveground biomass, belowground biomass, soil organic carbon, total nitrogen, total phosphorus, ammonium nitrogen, nitrate nitrogen, and available phosphorus) to analyze the relationship between each other. The results show that the most crucial limiting factors were soil pH and moisture in the natural restoration succession stages of degraded patches, and soil moisture affects pH and mediates the microbial diversity–multifunctionality relationships. Fungal β diversity and multifunctionality were positively correlated, bacterial α diversity and multifunctionality were negatively correlated. Soil pH not only directly impacts on multifunctionality, but also indirectly affects multifunctionality by influencing bacterial α and fungal β diversity. These results indicate that fungal β diversity can positively predict soil multifunctionality, and is the key mediator of soil pH and multi-functionality. Our findings highlight the potential of fungal β diversity to improve soil multifunctionality in the natural restoration succession stages of degraded meadow patches.