In order to explore the photosynthetic characteristics of tropical montane rain forest tree species at differ-ent successional stages on Hainan Island, the diurnal variations of the seedling' s photosynthesis of three representa-tive tree species ( Endospermum chinense in the primary successional stage, Elaeocarpus dubius in the middle succes-sional stage and Parakmeria lotungensis in the old growth stage) in four relative irradiance levels were studied by the pot experiments. Endospermum chinense had the strongest ability of leaf temperature controlling, which showed lower leaf temperature than Elaeocarpus dubius and P. lotungensis in the diurnal changes. Elaeocarpus dubius had the highest photosynthetic physiology plasticity. Elaeocarpus dubius was similar to Endospermum chinense on photosyn-thetic rate and lower than P. lotungensis on leaf temperature under sunny days, whereas it didn' t differ significantly with P. lotungensis on photosynthetic rate and leaf temperature under cloudy days. Endospermum chinense and P. lotungensis had higher water use ability than Elaeocarpus dubius, which showed lower stomatal conductance and transpiration rate and higher water use efficiency. Endospermum chinense had higher photosynthetic capacity, which showed higher photosynthetic rate than P. lotungensis. The differences of plant species on photosynthesis capacity, leaf temperature control ability, photosynthetic physiology plasticity and water use ability had important effects on succession of plant community.%为研究海南岛热带山地雨林不同演替阶段植物的光合特性,比较了不同光梯度下3个典型树种幼苗在晴天和阴天时的光合生理日变化过程.先锋种黄桐有最强的叶温控制能力,日变化中叶温低于中期种显脉杜英和顶极种乐东拟单性木兰.中期种显脉杜英有最高的光合生理可塑性,晴天时,显脉杜英净光合速率与黄桐差异不显著,叶温低于乐东拟单性木兰；阴天时,净光合速率和叶温与乐东拟单性木兰差异不显著.与显脉杜英相比,黄桐和乐东拟单性木兰的水分利用能力高,气孔导度、蒸腾速率低,水分利用效率高；黄桐的光合能力高,净光合速率比乐东拟单性木兰高.植物在光合能力、叶温控制能力、光合生理可塑性和水分利用能力上的差异对植物群落的演替有重要影响.
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