In this study, carbon dioxide (CO₂) fluxes were continuously measured using the openpath eddy co-variance systems at four forest ecosystems sites (including Xishuangbanna tropical rain forest, Xishuangbanna rubber plantation, Ailaoshan subtropical evergreen broadleaved forest and Yuanjiang savanna ecosystem). Photosynthetically active radiation (PAR) was calculated using the routine meteorological measurement system, and the net ecosystem exchange (NEE) lightresponse curve fitted parameters were calculated using the MichaelisMenten equation. The highest maximum photosynthesis rate (P_max) and ecosystem daytime respiration (R_d) were observed at Xishuangbanna rubber plantation, indicating a strong photosynthetic potential and respiration rate in manmade monoculture system. Ailaoshan subtropical evergreen broadleaved forest exhibited the highest apparent quantum yield (α), which indicated the greatest efficiency of ecosystem light use under low light conditions. Yuanjiang savanna ecosystem showed the lowest NEE lightresponse curve fitted parameters and their seasonal variations displayed a definite unimodal curve. NEE lightresponse curve fitted parameters of Xishuangbanna tropical rain forest were lower than those of Xishuangbanna rubber plantation and higher than those of the Yuanjiang savanna ecosystem. All NEE lightresponse curve fitted parameters of the four forest ecosystems had similar seasonal dynamics with higher value during rainy season than that during dry season in relation to the temperature and moisture conditions. There were consistent relationships between NEE lightresponse curve fitted parameters and carbon absorbing efficiency in the four forest ecosystems. NEE lightresponse curve fitted parameters had an indicative function of carbon sequestration capacity in this study. The results of this study provide a basis for further study on carbon sink capacity of different forest ecosystems.