中文摘要：

依托西双版纳热带雨林通量站、西双版纳橡胶林通量站、哀牢山亚热带常绿阔叶林通量站和元江干热河谷通量站，利用设置在不同森林生态系统的开路涡度相关系统的碳通量数据，配合常规气象观测系统的光合有效辐射数据，使用MichaelisMenten方程，比较分析了不同生态系统的光合作用光响应参数。研究发现，在4种森林生态系统中，西双版纳橡胶林生态系统的最大光合速率（Pmax）和昼间呼吸速率（Rd）呈现最大值，表现出单一人工林较强的光合潜力和较大的呼吸速率；在4种森林生态系统中，哀牢山亚热带常绿阔叶林的表观量子效率（α）最大，显示了哀牢山亚热带森林生态系统在低光环境下具有非常强的光能利用效率；而元江稀树灌草丛光合作用光响应参数数值均最小，其季节动态呈较好的单峰型；西双版纳热带雨林光合作用光响应参数数值均介于西双版纳橡胶林与元江稀树灌草丛之间。结果表明：不同森林生态系统光合作用光响应参数与温度、土壤含水量具有相似的季节动态，均为雨季大，干季小，环境因子影响着生态系统的光合与呼吸季节动态。在4种森林生态系统中，光合作用光响应参数与碳汇效应有着较好的相关关系，显示光合作用光响应参数可以较好地指示森林生态系统的碳汇效应。研究结果可为森林生态系统碳汇效应的深入研究提供基础数据。

英文摘要：

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 （Pmax） and ecosystem daytime respiration （Rd） 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.