施肥对高寒草甸土壤有机碳激发效应及净碳平衡的影响

he inputs of exogenous substrate affect the priming effect, which jointly influence the dynamics of soil organic carbon (SOC), but the mechanism is complex. In this study, we investigated the effects of fertilization (CK, N, P and NP) on priming effect of SOC and net carbon balance in alpine meadows by adding labelled glucose. The results indicated that fertilization significantly decreased the cumulative mineralization of SOC, and the accumulative mineralization of soil C treated with N、P and NP was 16%、19%、32% lower than CK treatment, respectively; inputs of exogenous organic C caused positive priming effect for all treatments, with the magnitude of P > CK > NP > N. However, the cumulative priming amount under P treatment was about twice that of other treatments. The glucose-C remained in the soil was higher than the SOC loss caused by priming in all fertilization treatments, which led to a positive net C balance with the order of NP > N > P > CK. In conclusion, the net C balance suggested that fertilization would increase SOC content in the short term, but the accumulated C in soil could be easily decomposed and would continue to accelerate the decomposition of SOC. Therefore, priming effect need to be further explored on longer time scales.