How do soil microbes exert impact on soil respiration and its temperature sensitivity?

Understanding how soil microorganisms influence the direction and magnitude of soil carbon feedback to global warming is vital to predict future climate change. Although microbial activities are major contributors to soil respiration (R-S) and its temperature sensitivity (Q(10)), the mechanisms underpinning microbial influence on R-S and Q(10) remain unclear. Coupling variation partitioning analysis (VPA), correlation analysis and multiple stepwise linear regression analysis, we illustrate that bacteria mainly affect R-S and its temperature sensitivity (Q(10)) by shifting bacterial community composition (denoted by principal coordinates analysis). We also found that soil water content (SWC) and available nutrient (AN) were the factor key to changing bacterial community composition (P < 0.05). Co-occurrence network demonstrated that Mod 0 ecological cluster composed of copiotrophic taxa groups was significantly associated with R-S and Q(10) (P < 0.01, R > 0.5), including Proteobacteria, Actinobacteria, and Bacteroidetes. Illuminating the mechanisms underpinning the influence of soil microbes on R-S and Q(10) values is fundamental to understanding mechanistic soil-climate carbon cycles.