Revegetation enhances soil organic carbon mineralization and its temperature sensitivity in the Tengger Desert, North China

Abstract

Revegetation plays a critical role in the soil organic carbon (SOC) cycle, especially in desert regions. However, the effects of this restoration practice on SOC mineralization are poorly understood, which inhibit the accurate estimation of SOC sequestration. In this study, SOC mineralization rates in revegetated sites along a chronosequence in the Tengger Desert were investigated by the incubation method, and the relationships between SOC mineralization rate and the temperature (T) and soil moisture (SM) of incubation, soil properties and vegetation characteristics were analyzed. The results showed that SOC mineralization rates and its temperature sensitivity (Q10) significantly increased after revegetation. The maximum CO2-C emission rates (MR), cumulative CO2-C emissions (CCE), potentially mineralizable SOC (C0) and Q10 increased by 0.04–5.62, 0.78–4.88, 0.94–4.04 and 0.37–0.47 times in 64 years following revegetation, respectively, while the proportion of C0 to total SOC (C0/SOC) decreased by 2.12–7.22 times. T and SM and their interaction had significant influences on MR, CCE, C0 and C0/SOC, while SM had no significant effect on Q10. The stepwise multiple linear regression analysis showed that the SOC mineralization rate had greater R2 with stand age and smaller R2 with SM, indicating that the SOC mineralization was mainly regulated by the stand age. The SEMs indicated that the soil properties were the main direct factors affecting SOC mineralization. The RDA indicated that soil AP, C:N ratio and T were the key factors controlling SOC mineralization during the revegetation process. Our findings indicated that long-term revegetation in desert regions enhanced SOC transformation and its temperature sensitivity, but decreased the percentage of CO2-C loss from soil, thus leading to SOC accumulation.