后河自然保护区珍稀濒危植物群落乔木层结构特征

对1hm^2固定样地内的亚热带常绿落叶阔叶混交林乔木层树种的胸径级结构和高度级结构以及按径经对乔木树种多样性和均匀度进行了研究。结果显示；群落内乔木树种数和个体数堕落有径级和高度级增加呈下降趋势。树种数和个体数之间存在显著正相关关系。胸径面积之和随胸径级增加呈波动状态，而随高度级的增加呈先升后降的变化。群落的多相关性一指数和均匀度指数都较高，群落内优势种明显，各种的多度差异较小，群落结构较为稳定，其中珍稀植物在各个胸径级和高度级内的树种数和个体数都较高，群落的更新良好。幼苗补充充足，珍稀树种幼苗丰富度和多度较高。

The Characteristics of Tree Layer Structure of the Rare Plant Community in Houhe Nature Reserve

The research was made on the structures of the size class and height class of the tree layer species of the subtropical mixed evergreen and deciduous forest in a fixed quadrat of one ha. and working out the tree species diversity and evenness of the arbors according to the size class. The results showed that the tree species numbers and individual numbers of the arbors in the community declined as the growing of the size class and the height class, and there was a remarkable positive correlation between the tree species number and individual number. The sum of basal area at DBH (Diameter at breast height) fluctuated as the increase of size class, though it produced a curve which is composed of a former ascending part and a latter descending part as the increase of the height. The diversity index and evenness of the community were relatively high, so there were no distinct dominant populations in the community. The abundances of each species varied slightly, therefore the community has a steady structure. The rare plants of the community had both a relatively high tree species number and individual number. The seedlings of the arbors abound in the community especially the seedlings of the rare and endangered plant species, the community is in a good state of regeneration. Finally, the tree layer can be divided into three parts.