百山祖两种阔叶木本植物的光合蒸腾作用特性研究

利用Li-6400便携式光合测定仪分别对凤阳山—百山祖国家级自然保护区阔叶混交林中2种常见木本植物尖萼紫茎（Stewartia acutisepala）和小叶白辛树（Pterostyrax corymbosus）的光合蒸腾特性进行了研究，并应用相关性分析与逐步回归分析法就上述植物各生理生态因子对净光合速率（P_n）和蒸腾速率（T_r）的影响进行了分析。结果表明:（1）尖萼紫茎的P_n主要影响因子是水分利用率（WUE）、太阳辐射（PYR），而小叶白辛树的主要影响因子则是胞间CO₂摩尔分数（C_i），PYR，且在P_n日变化过程中，尖萼紫茎的值始终大于小叶白辛树，可以判断尖萼紫茎的光合作用比小叶白辛树要强；（2）影响尖萼紫茎T_r的主要因子是气孔导度（G_s）及光合有效辐射（PAR），影响小叶白辛树的主要因子则是G_s、空气相对湿度（RH），而据T_r日变化可发现尖萼紫茎的蒸腾作用强于小叶白辛树；（3）对2种植物WUE的分析可知，尖萼紫茎的碳水平衡性优于小叶白辛树。且总体而言，在该生境中，制约尖萼紫茎光合蒸腾作用的因子比小叶白辛树少。因此，尖萼紫茎对该生境适应性优于小叶白辛树，分布更为广泛。

Study on Photosynthesis-transpiration Characteristics of Two Broadleaf Woody Plant Species in the Forests of Baishanzu

Photosynthesis and transpiration play the significant roles in the evaluation of ecological benefits from a forest ecosystem. In order to determine their photosynthesis and transpiration characteristics at canopy level, this paper conducted some measurements with Li-6400 portable photosynthetic apparatus on two typical tree species in the forest ecosystem of Fengyang Mountain. Results show that the main factors influencing P_n of Stewartia acutisepala were WUE and PYR, meanwhile, the main factors influencing P_n of Pterostyrax corymbosus were C_i and PYR. In the process of daily variation of P_n, the value of Stewartia acutisepala was always higher than Pterostyrax corymbosus. It can be judged that the photosynthesis of Stewartia acutisepala was stronger than Pterostyrax corymbosus. Additionally, the main factors influencing T_r of Stewartia acutisepala were G_s and PAR, while the main factors influencing T_r of Pterostyrax corymbosus were G_s and RH. According to daily variation of T_r, the transpiration of Stewartia acutisepala was stronger than Pterostyrax corymbosus. According to the analysis of WUE, the carbon water balance ability of Stewartia acutisepala was better than Pterostyrax corymbosus. Therefore, the adaptability of Stewartia acutisepala to this habitat was superior to Pterostyrax corymbosus, and the former was more widely distributed.