Litter quality modifies soil organic carbon mineralization in an ecological restoration area

Soil organic carbon (SOC) mineralization impacts the loss and accumulation of carbon (C) in crucial ways. However, it is still unclear how exactly litter quality regulates the SOC mineralization process and SOC stock. We conducted a laboratory incubation experiment under different temperatures, that is 10 degrees C, 20 degrees C, 30 degrees C, and 40 degrees C, and moisture, that is 5%, 10%, and 20% regimes, as well as a control (CK), and different litter qualities, that is, Artemisia ordosica, Caragana korshinskii, and Eragrostis minor. This was conducted in soil from a revegetated area in the Tengger Desert, northern China. We investigated the impacts of litter addition on SOC mineralization by considering the chemical properties of litter, temperature, and soil moisture, as well as the cumulative CO2-C emissions (CCE), maximum rate (MR), potential mineralizable C (C-0), priming effect (PE), temperature sensitivity (Q(10)), moisture sensitivity (MS), and SOC stock. Litter addition increased the CCE, MR, C-0, and MS but decreased the Q(10), and the effects of different litter qualities on CCE, MR, C-0, MS, and Q(10) differed significantly. The SOC mineralization rate increased with increasing temperature and moisture and was also accelerated by the interactions between temperature and moisture. The total C and lignin contents of litter were the key factors that governed SOC mineralization. Litter addition had a positive PE on SOC mineralization, and high-quality litter with low C:N ratio (A. ordosica and C. korshinskii) increased the PE compared with low-quality litter with high C:N ratio (E. minor). The PE also decreased with increasing temperature and moisture. Litter addition resulted in an acceleration of the loss of SOC mineralization, and an increase in the SOC mineralization response toward moisture but reduced the SOC mineralization response toward temperature, whereas litter quality was inversely correlated with the SOC stock. Therefore, the input of low-quality litter will decrease the loss of mineralized SOC caused by PE and diminish the accumulation of SOC in the revegetated regions. These findings may provide a reasonable litter management model to promote the stability of soil C pool in arid revegetated areas.