Abstract
Climate warming affects the carbon cycle of northern peatlands through temperature rises and a changing carbon availability. To clarify the effects of elevated temperature and labile carbon addition on SOC mineralization, as well as their microbial driving mechanisms, topsoil (0-10 cm) and subsoil (10-20 cm) were collected from a peatland in the Great Hing'an Mountains and incubated with or without 13C-glucose at 10 °C and 15 °C for 42 days. The results showed that 5 °C warming significantly stimulated SOC mineralization along with NH4+-N and NO3--N content increases, as well as a decrease in invertase and urease activities. Glucose addition triggered a positive priming effect (PE) in the early stage of the incubation but changed to a negative PE in the late stage of the incubation. Glucose likely regulates carbon dynamics by altering fungi: bacteria, soil invertase, and β-glucodase activities, and MBC, DOC, NH4+-N contents. Glucose addition increased fungal abundance in 0-10 cm at 10 °C and 15 °C, and 10-20 cm at 10 °C, respectively, but significantly decreased fungal abundance in 10-20 cm at 15 °C. Glucose addition decreased bacterial abundance in 0-10 cm at 10 °C but increased bacterial abundance in 10-20 cm soil at 10 °C, and in 0-10 and 10-20 cm soils at 15 °C, respectively. Glucose addition significantly decreased the fungi: bacteria ratio in 0-20 cm soils at 15 °C. In addition, Q10 was significantly positively correlated with the changes in soil DOC, NH4+-N contents, invertase, and β-glucosidase activities, while negatively correlated with fungi: bacteria and urease activities after 5 °C of warming, and glucose addition significantly increased the Q10. Labile carbon may decrease carbon losses in northern peatlands that inhibit warming-induced carbon emission increase, thus partially buffering soil carbon content against change.