Dataset-GCB.xlsx

Abstract: Microbial necromass carbon (MNC) is an important contributor to stable soil organic carbon pools and is regulated by plant root traits and microbial community characteristics. Mean air temperature in the Tibetan Plateau (TP) is predicted to increase between 1.5 and 2.9°C by the end of 21st century, and how the accumulation and persistence of soil MNC will vary under different warming scenarios still poorly understood. We conducted an eight-year field warming experiment, simulating warming at 0 ℃, 0.4 ℃, 1.5 ℃, 2.0 ℃, and 2.5 ℃ above ambient temperatures in a high-altitude alpine meadow ecosystem. We found that low-level warming generally enhanced bacterial necromass carbon (BNC), fungal necromass carbon (FNC), and total MNC compare with high level warming in soil layers between 0-30 cm. Different warming treatments did not significantly affect the ratios of MNC or BNC to soil organic carbon (SOC) across depths. Structural equation modeling analysis demonstrated that the effect of plant root traits on MNC persistence strengthened with warming intensity, while the influence of microbial community characteristics waned as warming increased. Overall, our study provides novel evidence that the major determinants of MNC production and stabilization may vary with warming magnitude in alpine meadows. Differences in potential responses of microbial residue C to warming should be considered in global C-cycling models to more accurately predict future feedbacks between climate and soil C stocks.