[Factors influencing the variability in soil heterotrophic respiration from terrestrial ecosystem in China]

Soil heterotrophic respiration is one of the key factors for estimating ecosystem carbon balance. Measurement data of soil heterotrophic respiration from terrestrial ecosystem in China were collected. Climate data (annual precipitation and annual mean air temperature) and relevant environmental factors (e. g. tree age) were also collected. Results indicated that the relationship between heterotrophic respiration and soil respiration could be explained by a power function. Heterotrophic respiration increased with the increase of soil respiration. The power function explained 73% of the variability (R2 = 0.730, P < 0.001) in heterotrophic respiration. The linear equation could be used to explain the relationship between heterotrophic respiration and annual precipitation/mean annual air temperature. The logarithmic regression equation could be employed to describe the relationship between the ratio of heterotrophic respiration to soil respiration and annual precipitation/mean annual air temperature. The ratio of heterotrophic respiration to soil respiration increased with the increase of tree age; a power function could be used to explain the relationship between the ratio of heterotrophic respiration to soil respiration and tree age. Further investigation showed that the relationship between measured annual heterotrophic respiration and modeled heterotrophic respiration by using an empirical model could be described by a linear function, indicating that the empirical model well fitted the variability in heterotrophic respiration.