热带季节雨林优势树种叶片和冠层尺度二氧化碳交换特征

Characteristics of CO_2 exchange at leaf and canopy levels in tropical seasonal rain forest of Xishuangbanna.

采用叶室法和涡度相关法分析了西双版纳热带季节雨林优势树种绒毛番龙眼和大叶白颜树冠层及其叶片在不同季节的CO2交换量，并拟合得到主要特征值．结果表明：以叶室法测得的两树种冠层最大净光合速率（Pmax A）为雨季〉雨季末〉雾凉季〉干热季，叶片暗呼吸速率（Rd）为雨季〉雨季末〉干热季〉雾凉季；以涡度相关法得到的两树种冠层最大净光合速率（Pmax B）为雨季〉雨季末〉雾凉季〉干热季，而冠层呼吸速率（Re）则是雨季〉干热季〉雾凉季〉雨季末．两种方法得到的不同季节植物冠层最大净光合速率相差0．9～2．0μmol·m^-2·s^-1．

By the methods of chamber-based and eddy covariance measurements, the CO2 exchange of dominant tree species Pometia tomentosa and Gironniera subaequalis at leaf and canopy levels in the tropical seasonal rain forest of Xishuangbanna was measured in different seasons of 2004. The results showed that for the two tree species, the maximum net photosynthesis （Pmax A ） of canopy based on chamber-based measurement ranked in the order of rainy season （RS） 〉 end of rainy season （ERS） 〉 foggy-cool season （FS） 〉 dry-hot season （ DS）, and the dark respiration rate （ Rd ） of leaf was RS 〉 ERS 〉 DS 〉 FS. The Pmax B based on eddy covariance measurement was in the same order as that based on chamber-based measurement, while the canopy respiration rate （Re ） was RS 〉 DS 〉 FS 〉 ERS. The maximum net photosynthetic rate of canopy in different seasons measured by the two methods had a comparatively small difference, ranging from 0. 9 to 2. 0 μmol·m^-2·s^-1.