Abstract: To improve our understanding of the responses of soil temperature and soil heterotrophic respiration to global warming in forest ecosystem, we simulated the change trend of soil temperature of subtropical evergreen broadleaved forest in Ailao Mountains using the observed soil temperature data from 1986 to 2013, and computed the time required for a 2 ℃ increase in soil temperature. We conducted a soil warming experiment in a subtropical evergreen broadleaved forest in Ailao Mountains. We compared field observations from trenching (NR) and trenching with soil warming (SW) from 2011 to 2013 with simulation results obtained from the WNMM model using future climate data under SRES A2 and B2 scenarios. We found that the soil temperature at 5 cm depth was significantly increased by 0.224 ℃·10 a^-1 in the last 30 years, and thus it would spend 90 years to increase 2 ℃. The apparent respiration temperature sensitivity index (Q₁₀) was 5.17 and 4.50 under the NR and SW treatments, respectively. Based on the Q₁₀ value, under a 2 ℃ increase in soil temperature, soil heterotrophic respiration under the NR treatment was 14.6% higher than that of the SW treatment. The WNMM model was able to simulate soil water content (P<0.001) and soil temperature (P<0.001) after calibration and validation. By the end of 2100, soil heterotrophic respiration under the NR treatment would be 10.2% and 9.8% higher than that under the SW treatment under SRES A2 and B2 scenarios, respectively, and the soil heterotrophic respiration under the NR and SW treatments would be 7.0% and 6.6% higher under the SRES A2 scenario than under the SRES B2 scenario, respectively. These results indicated that field experiments on soil warming were important for understanding the responses of soil heterotrophic respiration to global warming, and should not be replaced by model simulation in that the latter will overestimate soil heterotrophic respiration.

Key words: continuous cropping, nutrition medium, biochar,  , becterial community structre.