Study on the main forest community and species diversity of the _natural forest types in upstream Heihe river, Shaanxi | 陕西黑河上游主要天然林类型及物种多样性特征研究

chinois. 通过对陕西黑河上游植物群落的系统调查及物种多样性的定量分析，揭示该区森林群落的分布类型及物种多样性特征，为今后该区植物群落特征及结构研究奠定基础。采用双向聚类法中的TWINSPAN软件包对陕西黑河上游森林群落进行分类，以Margalef物种丰富度指数、Shannon-Weiner指数、Simpson指数和Pielou均匀度指数为指标，对群落不同层次及群落之间的物种多样性进行分析。将研究区24个样地划分为10个群落类型；各群落结构中不同层次间的物种多样性有明显差异，草本层物种多样性大于乔木层和灌木层；各个群落类型的物种多样性大小顺序为白桦+太白杨混交林＞油松+锐齿槲栎混交林＞华山松林＞华榛+青杨混交林＞油松+山杨混交林＞山榆林＞八角枫林＞锐齿槲栎林＞山杨林＞油松林；24个样地内共有植物237种，分别隶属于65科、150属。人为干扰、林下环境的异质性以及物种的生物学特性，都可能造成植物群落内部各层次以及各群落类型间物种多样性的差异；干扰、环境异质性以及物种生物学特性均是复杂的科学问题，是较多因子综合作用的表现。

anglais. Through the systematic investigation of plant communities and species diversity quantitative analysis in the study area, the study revealed the distribution of forest community types and species diversity characteristics, which provided theoretical basis to study plant community character and structure. The forest community was classified by two-way TWINSPAN, and the Shannon-Weiner index, Simpson, Pielou index and evenness index were applied to analyze the community diversity. The 24 plots in the research area can be divided into 10 community types; the species diversity is distinctly different between the different layers of community structure, the species diversity of herb layer is bigger than tree layer and shrub layer; the order of the community diversity is Betula platyphylla+ Populus purdomii＞Pinus tabulaeformis+Quercus aliena var. acuteserrata＞Pinus armandi＞Corylus chinensis+Populus cathayana＞P.tabulaeformis+ Populus davidiana＞Ulmus bergmanniana＞Alangium chinense＞Q. aliena var. acuteserrata＞P. davidiana＞P. Tabulaeformis. There are 237 species, belonging to 65 families, 150 genera, in 24 plots. Interference, environmental heterogeneity of undergrowth and biological characteristics of species may cause the difference of species diversity between plant communities and layers within each community. However, interference, environmental heterogeneity and biological characteristics are complex scientific problems, and they are integrated performance of many factors affection.