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应用2003年11月~2004年10月晴好天气涡度相关通量观测资料,对西双版纳热带季节雨林CO2交换的日变化和季节变化进行分析。结果表明:雾凉季、干热季和雨季的净生态系统CO2交换(NEE)均呈现出单峰型曲线的日变化趋势,昼间其变化规律较强,夜间呈波动状态。昼间NEE(取绝对值)雾凉季和雨季均显著大于干热季;夜间NEE雨季显著大于干热季,而干热季显著大于雾凉季。光合有效辐射是影响NEE日变化的主要因素,但不是造成季节差异的主要因素;饱和水汽压差和气温对NEE的季节差异有较大贡献。另外,应用Michaelis_Menten模型对昼间不同饱和水汽压差和气温下NEE对光合有效辐射的响应进行分析,结果表明:各季节较高饱和水汽压差下的表观最大光合速率(Pmax)、表观暗呼吸速率(Re)比较低饱和水汽压差下的Pmax、Re大,而表观光量子产额(α)则相反。各季节较高气温下的Re比较低气温下的Re大;雾凉季气温的差异对Pmax和α的影响较小;干热季和雨季较高气温下的α较小。
The daily and seasonal variations of CO2 exchange in the tropical seasonal rainforest in Xishuangbanna were analyzed using observation data of the correlation between the fluency of sunny weather and November 2003 to October 2004. The results showed that the diurnal variation trend of net ecosystem CO2 exchange (NEE) in dry season, warm dry season and rainy season all showed a single peak curve, with a strong variation during the day and a fluctuating pattern at night. The daytime NEE (absolute) foggy season and rainy season were significantly greater than the dry-hot season; NEE rainy season was significantly greater than the dry-hot season at night, while the dry-hot season was significantly larger than the foggy season. Photosynthetically active radiation is the main factor affecting diurnal variation of NEE, but it is not the main factor causing the seasonal difference. Saturated vapor pressure and temperature have a greater contribution to the seasonal difference of NEE. In addition, the Michaelis-Menten model was used to analyze the response of NEE to photosynthetically active radiation at different saturated vapor pressures and air temperatures at daytime. The results showed that the apparent maximum photosynthetic rate (Pmax) Dark respiration rate (Re) Pmax, Re is greater than that of the lower saturated vapor pressure difference, while the apparent light quantum yield (α) is opposite. Re in each season was higher than that in low temperature. The differences in temperature between foggy and cool season had little effect on Pmax and α, and α in high temperature in dry season and rainy season was smaller.