资源环境科技发展态势分析平台

Diffuse radiation can promote the vegetation photosynthesis. Radiation use efficiency (RUE=GPP/PAR) simulated by TEC, VPM, EC-LUE, and DTEC models were against the measured RUE from FLUXNET under different bins of diffuse photosynthetically active radiation fraction (FDIFF_PAR) in this study. Our results showed that the observed RUE increased linearly with FDIFF_PAR. The differences of RUE between the first bin and other bin (RUE_bin) from two big-leaf models were underestimated when the FDIFF_PAR is higher than 0.5 except in evergreen broadleaf forests and RUE_bin from the DTEC model was overestimated when the FDIFF_PAR is higher than 0.7. The role of temperature and vapor pressure deficit (VPD) in the diffuse radiation effects on vegetation photosynthesis was underestimated in EC-LUE, TEC, VPM. Although many studies applied LUE models to assess the effects of diffuse radiation on vegetation photosynthesis, our results suggested that these models were needed to be improved.