Simulation of carbon flux of forest ecosystem by Biome-BGC and MODIS-PSN models

An approach was used to incorporate the forest carbon flux for Qilian Mountains by ecological-process-based model (Biome-BGC), and remote-sensing-based model (MODIS-PSN). The calibration phase, aiming at setting the ecophysiological parameters to effectively simulate the daily GPP behavior of the Qilian Mountains, was proceeded by adjusting the 8 day GPP outputs obtained from Biome-BGC using the optimized MODIS-PSN algorithm and the observations. The results showed that the optimized MODIS-PSN could describe the GPP behavior faithfully comparing to the eddy covariance-observed GPPs, with R²=0.77, RMSE=6.219gC/m²/8d. After validation, the calibrated Biome-BGC has been proved to estimate the performances of daily GPP behavior effectively comparing to the eddy covariance-observed GPPs, especially in summer and winter (with R²= 0.76, RMSE= 1.3115gC/m²/d), which illustrated that the combination of Biome-BGC and optimized MODIS-PSN could express the carbon fluxes well over the Qilian Mountains.