中文摘要：

森林生态系统是陆地生态系统中最重要的组成部分之一,是一个重要的碳库,树干呼吸是森林碳平衡的重要组成部分.为了研究哀牢山中山湿性常绿阔叶林的树干呼吸日变化和季节变化规律,以及它们与影响因子的关系,采用CO2红外气体分析法（IRGA）,对哀牢山中山湿性常绿阔叶林3种主要树种（变色锥、黄心树和南洋木荷）的树干呼吸进行为期1a活体原位监测,还监测了干季（4月）和雨季（8月）黄心树和南洋木荷的树干呼吸日变化特征.研究发现,2个树种的树干呼吸、树干温度和空气温度日变化幅度并不大,3种树种的树干呼吸具有相同的季节规律,并且雨季的树干呼吸速率大于干季;不同树种以及同一树种不同径阶对温度的响应不一致;3种树种树干呼吸速率与胸径呈显著的正相关关系（R2=0.216）.

英文摘要：

Forest is an important pool of carbon in the terrestrial ecosystem.Stem respiration is an important part of the carbon balance in the forest stands.The objective of our research is to address the following questions：The daily and seasonal variation of the stem respiration rates,and the relationship between stem respiration rates and the impact factors in a montane evergreen broad-leaved forest.In this study,infrared gas analyzer（IRGA） method was applied to measure the stem respiration by connecting LI-840 CO2 gas analyzer to a custom-built Polyvinyl Chloride（PVC） chamber,the stem respiration rates of three dominant tree species in a montane evergreen broad-leaved forest were measured from February,2009 to January,2010.The daily variation of Machilus bombycina and Schima noronhae was measured in the dry and wet season.The results demonstrated that the stem respiration rate of the tested tree species had an obvious seasonal variation,with the maximum occurred in September.The fluctuation of daily variation of the stem respiration rate,stem temperature and air temperature was not significant.The response of stem respiration to temperature differed among tree species and diameter classes.There was significant correlation between stem respiration and DBH（R2 = 0.216）.