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分析了黑石顶森林群落各高度层光合有效辐射（ＰＡＲ）的季节变化、昼夜变化、垂直空间方面的变化规律及其对植物光合作用的影响．研究表明，光量子通量密度（ＰＦＤ）从群落第一层至第四层呈指数形式减少，群落第四层常小于１．０ｍｏｌ·ｍ－２·ｄ－１．群落中植物叶片净光合作用速率（ＮＰＲ）是：第一层＞第二层＞第三层＞第四层，同一高度层植物叶片ＮＰＲ比较接近，但也存在物种间的差异．ＰＦＤ是影响植物光合作用的最主要因子，第一层植物接受充足的ＰＦＤ，能进行有效的光合作用，群落内部各层的ＰＦＤ不能满足植物光合作用的需要，叶片随ＰＦＤ的增加而同步增加．冬季ＰＦＤ较小时第四层植物的净光合作用时常为负值．群落中叶面积指数为５～７，并随季节的变化而变化．群落的光量子利用效率以第四层植物最高，第一层植物最低，第二三层植物的光量子利用效率相差不大
The seasonal variation, diurnal variation and vertical spatial variation of photosynthetically active radiation (PAR) at different heights in Heishiding forest community were analyzed and their effects on plant photosynthesis were analyzed. The results showed that the photon flux density (PFD) decreased exponentially from the first layer to the fourth layer of the community, and the fourth layer of the community was always less than 1.0mol · m-2 · d-1. The net photosynthesis rate (NPR) of plant leaves in the community was as follows: the first layer> the second layer> the third layer> the fourth layer. The NPR of the plant leaves at the same height was similar, but there were also inter-species differences. PFD is the most important factor that affects plant photosynthesis. The first layer of plant receives enough PFD to carry out effective photosynthesis. The PFD of various layers within the community can not meet the needs of plant photosynthesis, and the number of leaves increases synchronously with the increase of PFD. The net photosynthesis of plants in the fourth layer is often negative when winter PFD is small. The leaf area index of the community is 5 ~ 7, and changes with the seasons. The highest light quantum efficiency of the community was the highest in the fourth plant, the lowest in the first plant, and no significant difference in the light quantum efficiency of the second three plants