Abstract:Soil respiration is an important process of carbon cycle in terrestrial ecosystem. Accurate estimation of soil respiration is of great significance for estimating terrestrial carbon sinks and carbon sources. The semi-mechanistic models of soil heterotrophic respiration and soil autotrophic respiration were developed for the winter wheat-summer maize rotation cropland through in situ observations of soil respiration and its components in a typical cropland in the North China Plain. The results showed that the soil heterotrophic respiration model for the winter wheat-summer maize cropland could be expressed by a function of soil temperature and soil moisture. In the soil heterotrophic respiration model, the effect of soil temperature on soil heterotrophic respiration was described by the Arrhenius equation, and the effect of soil moisture on soil heterotrophic respiration was described by the quadratic equation of symmetric inverted parabola appropriately. Based on the validation by the filed observation, the values of R2 and RMSE for the soil heterotrophic respiration model were 0.68 and 0.52 μmol m-2 s-1, respectively. The soil autotrophic respiration model consisted of two modules: the maintenance respiration module and the growth respiration module. In the maintenance respiration module, maintenance respiration was expressed by a function of soil temperature and leaf area index; in this function, the effect of soil temperature was described by the Van't Hoff exponential equation, and the effect of leaf area index was described by the Michaelis-Menten equation. In the growth respiration module, growth respiration was expressed by a linear function of the difference between gross primary production and maintenance respiration. The structures of soil autotrophic respiration models were the same for winter wheat and summer maize while the parameters for the soil autotrophic respiration models were quite different between the two crops. Based on the validation by the filed observation, the values of R2 and RMSE for the soil autotrophic respiration model of winter wheat were 0.64 and 0.50 μmol m-2 s-1, respectively; and the values of R2 and RMSE for the soil autotrophic respiration model of summer maize were 0.67 and 0.37 μmol m-2 s-1, respectively. This study demonstrated that developing soil heterotrophic respiration model and soil autotrophic respiration model separately could more accurately simulate the seasonal and interannual variations of soil respiration compared with using total soil respiration model. The soil heterotrophic respiration model and soil autotrophic respiration model developed in this study can provide a method for better estimating soil respiration in the winter wheat-summer maize rotation cropland ecosystem in the North China Plain.