Over the last century, human disturbance plays an important role in the change of global climate and environment and consequently, the loss of global species diversity. Unsustainable use of forest resources is causing dramatic changes in the forest communities and poses a serious threat to biodiversity worldwide. Plant species diversity is an index reflecting the complexity and stability of forest community function. The effect of human disturbance on forest community can be directly reflected by the change of community structure and diversity. We hypothesize that community structure and plant species diversity varies with the different densities of human disturbance. In order to investigate the influences of different disturbances (slight disturbance and severe disturbance) on the characteristics of species composition and diversity ofPinus massoniana plantation in Jiangyou district, Sichuan Province, a field investigation was conducted. The species richness indexD, Shannon-wienner indexH, Simpson indexH′, Pielou indexJsw are adopted to evaluate the level of species diversity inPinus massoniana community. The results were as following, (1) 124 species, belonging to 56 families and 105 genera were found in 8 plots with a total area of 3200 m2. The number of species in different layer decreased with the increase of disturbance intensity. (2) In terms of the community structure, different densities of human disturbance leads to different community structure. The diameter class was normally distributed with severe disturbance and the peak value 26 was found in diameter classⅥ(7 cm≤DBH<9 cm). The diameter class was not normally distributed with slight disturbance and the peak value 43 was found in diameter classⅦ(13 cm≤DBH<15 cm). The height class was similar to the diameter class under both slight and severe disturbance. Individuals under slight disturbance were mainly distributed in small and medium height class (3≤H<17), and individuals under severe disturbance were mainly distributed in medium and high height class (H≥13). As presented, the distribution of individuals under severe disturbance was relatively not even among different diameter and height classes and the low vertical diversity and instability of community structure were reflected. (3) Influenced by human disturbance, the richness indexD, Shannon-wienner indexH and Pielou indexJsw decreased and the Simpson indexH′ increased with the increase of disturbance intensity, and a negative relation between human disturbance and species diversity was dedicated.%物种多样性是群落功能复杂性和稳定性的重要量度指标，人为干扰对森林群落的影响可以通过群落结构和物种多样性的变化而直接显现，不同干扰强度下的森林群落结构和物种多样性特征不同。采用典型样地法，对比研究两种人为干扰强度（干扰强和弱）对江油地区的马尾松(Pinus massoniana)人工林群落的物种组成、群落结构和物种多样性的影响，采用物种丰富度指数D值、Shannon-wienner指数H值、Simpson优势度指数H′值和均匀度指数Jsw值来综合衡量群落的物种多样性水平。结果表明，（1）在总面积3200 m2的8个样地中记录到124个物种，隶属于105属56科，干扰强的群落各层次物种数均低于干扰弱的群落。（2）不同强度人为干扰下马尾松人工林的群落结构不同，干扰弱的群落径级结构呈近正态分布，在径级Ⅵ（7 cm≤d<9 cm）处出现数量的峰值26株，群落结构较稳定；干扰强的群落径级结构不呈正态分布，在径级Ⅶ(13 cm≤d<15 cm)处出现峰值43株。干扰弱和干扰强的群落高度级结构与其径级结构具有相似性，干扰弱的群落的个体主要集中在低中高度级（3≤H<17）；干扰强的群落的个体数在各高度级分布不均匀，主要分布在中高高度级（H≥13）；干扰强的群落的个体数在各径级和高度级分布相对不均匀，群落结构趋于不稳定。（3）人为干扰对马尾松人工林群落造成负面影响，随着人为干扰强度的增加，物种丰富度指数D值、Shannon-wiener多样性指数H值、均匀度多样性指数Jsw值降低，Simpson优势度指数H′值增大，物种多样性呈下降趋势。
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