Abstract: Rhizospheric and non-rhizospheric soils and the absorption, transition, and storage roots were sampled from the midsubtropical Pinus massoniana and Castanopsis sclerophylla forests to study the CO₂ fluxes from soil mineralization and root decomposition in the forests. The samples were incubated in closed jars at 15 ℃, 25 ℃, 35 ℃, and 45 ℃, respectively, and alkali absorption method was applied to measure the CO₂ fluxes during 53 days incubation. For the two forests, the rhizospheric effect (ratio of rhizospheric to non-rhizospheric soil) on the CO₂ flux from soil mineralization across all incubation temperature ranged from 1.12 to 3.09, with a decreasing trend along incubation days. There was no significant difference in the CO₂ flux from soil mineralization between the two forests at 15 ℃, but the CO₂ flux was significantly higher in P. massoniana forest than in C. sclerophylla forest at 25 ℃ and 35 ℃, and in an opposite pattern at 45 ℃. At all incubation temperature, the CO₂ release from the absorption root decomposition was higher than that from the transition and storage roots decomposition, and was smaller in P. massoniana than in C. sclerophylla forest for all the root functional types. The Q₁₀ values of the CO₂ fluxes from the two forests were higher for soils (1.21-1.83) than for roots (0.96-1.36). No significant differences were observed in the Q₁₀ values of the CO₂ flux from soil mineralization between the two forests, but the Q₁₀ value of the CO₂ flux from root decomposition was significantly higher in P. massoniana than in C. sclerophylla forest. It was suggested that the increment of CO₂ flux from soil mineralization under global warming was far higher than that from root decomposition, and for P. massoniana than for C. sclerophylla forest. In subtropics of China, the adaptability of zonal climax community to global warming would be stronger than that of pioneer community.