Regulatory Effects of Soil Microbes and Soil Properties on Ecosystem Multifunctionality Differ Among Grassland Types in the Qinghai-Tibetan Plateau

Alpine steppe (AS), alpine meadow (AM), and alpine swamp meadow (ASM) are the principal grassland types on the Tibetan Plateau, which not only contribute to the maintenance of local ecosystem functions but also play a crucial role in global ecological processes. Soil microbial communities act as indispensable linchpins in modulating ecosystem functions. However, there is still a lack of general understanding about the regulatory mechanisms of soil fungi and bacteria with their multidimensional attributes on ecosystem multifunctionality (EMF) in different grassland types. Here, we comprehensively investigated the relative impacts of microbial diversity, community composition, network complexity, as well as the soil environmental factors on EMF in the three grassland types. Our results indicated that EMF was positively regulated by soil bacterial community composition, particularly the phyla Proteobacteriota and Verrucomicrobiota in AS. Additionally, both fungal diversity and network complexity exhibited significant positive correlations with EMF, with fungal network complexity identified as the primary driver of EMF in AM. Notably, the EMF in ASM was predominantly affected by soil moisture, rather than soil microbial community attributes. This study provides comprehensive evidence on the regulatory mechanisms of soil microbial and environmental factors in the EMF of different grassland types. These findings have significant implications for maintaining the ecosystem multifunctionality of specific grassland types.