Abstract: The trenching plot approach was used to dynamically monitor soil respiration and determine heterotrophic and autotrophic respiration and the controlling factors in a Pinus tabulaeformis plantation in Taiyue Mountain. Results showed that soil temperature and soil moisture displayed obvious seasonal variations. The average soil respiration rate and heterotrophic respiration rate from 2010 to 2011 was 2.71 μmol·m^-2s^-1 and 2.22 μmol·m^-2s^-1, respectively. On average, the heterotrophic respiration rate was 13.7% and 21.1% lower than the soil respiration rate in 2010 and 2011 respectively. Autotrophic respiration rate ranged from 0.01 to 0.89 μmol·m^-2s^-1 with average value of 0.49 μmol·m^-2s^-1 during the two-year experimental period. The relative contribution of autotrophic respiration rate ranged from 0.2% to 37.7% with annual mean contribution of 20.2% to total soil respiration rate. The relationships between soil temperature at different depth (2, 5, 10 cm) and soil respiration rate, and heterotrophic respiration rate could be described by an exponential equation (P<0.001), however, there was no significant correlation between soil moisture at 5 cm depth and soil respiration rate, and heterotrophic respiration rate (P>0.05). Q₁₀ value of heterotrophic respiration rate was higher than that of soil respiration rate by simulating soil respiration rates with soil temperature at 2 cm depth. Two-variable linear/non-linear models using soil temperature and soil moisture at 5 cm depth can well predict soil respiration rate and explain the variations of soil respiration rate and heterotrophic respiration rate. R² values of two-variable fitting models ranged from 0.70 to 0.78.

Key words: Pinus tabulaeformis plantation, heterotrophic respiration rate, autotrophic respiration rate, Q₁₀ value, soil temperature, soil moisture