Warming-induced response of microbial diversity and functions regulated microbial necromass and soil multifunctionality

Abstract

Microbial necromass has been proved to be an important source of stable soil organic carbon (SOC), responding sensitively to global climate warming. Nevertheless, how the response of the soil microbial community to warming influences microbial necromass and ecosystem multifunctionality remains unclear. Here, amino sugars (ASs) were investigated as biomarkers of microbial necromass to evaluate bacterial and fungal necromass in a 60-day indoor warming incubation experiment, as well as the contribution of bacterial and fungal necromass to SOC. And amplicon sequencing and a high-throughput qPCR-based chip were integrated the changes in soil microbial community composition of whole, abundant, and rare taxa, as well as microbial traits (diversity, functional genes). The results showed that warming altered soil microbial community compositions, especially fungi. Under warming, bacterial necromass C and its contribution to SOC increased, while vice versa for fungi. The changes in microbial necromass C were closely associated with increasing C degradation gene abundance, such as cellulose, hemicellulose, and chitin degradation genes. Warming slightly increased soil ecosystem multifunctionality in relation to soil carbon cycling, associated with soil microbial diversity. Rare taxa diversity broadly promoted most single functions and multifunctionality. The impacts of different microbial taxa diversity on multifunctionality were broadly following the order: fungi > bacteria, abundant taxa > whole taxa > rare taxa. Simultaneously accounting for the effects of warming on multiple biotic and abiotic factors, multifunctionality and the contribution of microbial necromass to SOC were driven by nitrogen content, pH, soil microbial biomass, and diversity. Therefore, this study emphasized the crucial roles of microbial diversity, and microbial functions in regulating soil organic carbon pools and soil carbon cycling functions under global climate warming.