Abstract: A sample plot survey was used to investigate the communities of Picrasma quassioides, and the habitat characteristics, species composition, floristic composition and species diversity were analyzed. The results showed that 255 species in 207 genera and 85 families of vascular plants were found in 10 plots, and there are abundant species in the P. quassioides community. The main dominant families were Euphorbiaceae, Fabaceae, Gramineae, Moraceae, etc. The floristic types of seed plants in the community were divided into 14 types, with pantropic and tropical Asian elements as the main components, with tropical elements accounting for 72.73% of the total genera, and the community had obvious tropical properties. The community was divided into four types. P. quassioides grew vigorously in community Ⅱ and community Ⅳ, and was the dominant species in the tree layer. Community Ⅱ and community Ⅳ were the ideal habitat. The Margalef index, Shannon Wiener index and Pielou index showed that the shrub layer was larger than the tree layer. The three diversity indexes of tree and shrub layer in community Ⅱ were the highest, while Margalef species richness index of tree layer in community Ⅳ was the higher, while Shannon-Wiener diversity index was the lowest. The root budbreak ability of P. quassioides is stubborn, and the closure measures have positive significance for the restoration of P. quassioides population. The results can provide basic information for the protection and cultivation of P. quassioides resources.

摘要： 采用样地调查法调查苦树Picrasma quassioides群落，以分析其生境特征、物种组成、区系成分、群落类型和物种多样性。结果表明，苦树群落物种组成丰富，10个样地共有维管植物85科207属255种，主要优势科为大戟科、豆科、禾本科、桑科等。苦树群落种子植物分为14个区系类型，以泛热带和热带亚洲成分为主，热带成分占总属数的72.73%，具明显的热带区系特点；群落划分为4个类型，苦树在群落Ⅰ和群落IV中生长旺盛且为优势种，是苦树的理想生境。调查样地内Margalef指数、Shannon-Wiener指数、Pielou指数均表现为灌木层>乔木层；群落Ⅱ乔木层和灌木层的3个多样性指数均最高，群落Ⅳ乔木层Margalef物种丰富度指数较高而Shannon-Wiener多样性指数最低。苦树根系萌芽力强，封禁措施对苦树居群恢复具有积极意义。

关键词: 苦树, 群落类型, Shannon-Wiener指数, Margalef指数, Pielou指数