中文摘要：

物种多样性是群落功能复杂性和稳定性的重要量度指标,海拔高度是影响物种多样性的重要因素.该实验采用典型样地法,在800～900 m（低海拔）和1 100～1 200 m（高海拔）2个海拔高度分别取4个20 m×20 m的样地,对江油地区的杉木人工林群落结构和物种多样性进行研究,采用物种丰富度指数（D）、Shannon-Wienner多样性指数（H）、Simpson优势度指数（H ）和均匀度指数（Jsw）来综合衡量不同海拔杉木人工林群落的物种多样性.结果表明：（1）组成江油杉木人工林的物种共计205种,分属66科177属;低海拔地区乔木7种,灌木54种,草本47种;高海拔地区乔木10种,灌木60种,草本41种.（2）低海拔和高海拔的木本植物组成无明显差异,草本层的物种组成有明显差异.（3）群落各层次的物种多样性指数在低海拔和高海拔都表现为：灌木层＞草本层＞乔木层,乔木层的各项指数最低;物种多样性指数随海拔升高在特定区间内表现出一定规律性,D、H和Jsw值总体上呈高海拔＞低海拔,H＆#39;则相反,表明高海拔杉木人工林物种多样性和物种在群落中分布的均匀度都有增加的趋势,这与高海拔受人为干扰较轻以及环境因子的变化等密切相关.

英文摘要：

Plant species diversity is an index reflecting the complexity and stability of forest community function. Altitude is a prominent factor affecting plant species diversity. In order to investigate the influences of different altitudes on the characteristics of species composition and diversity of Cunninghamia lan- ceolata plantation in Jiangyou district, Sichuan Province, we conducted a field investigation. Four sample plots were selected in high and low altitude,respectively. The species richness index（D）,Shannon-wienner index（H） ,Simpson index （H＇） and Pielou index（Jsw） were adopted to evaluate the level of species diversity in C. lanceolata plantation. The results indicated that： （1）A total of 205 species belonging to 66 families and 177 genera were found in this study area. 7 trees,54 shrubs,47 herbs and 10 trees,60 shrubs,41 herbs were included in low and high altitude, respectively. （2）In terms of species composition, the high and low altitude contained similar woody plants. （3）The species diversity at both low altitude and high altitude in different layers of these communities was in a decreasing order of herb layershrub layertree layer. Species diversity index showed regularity in certain range along with the increasing of altitude. The species D, H and Jsw were demonstrated as high altitude）low altitude while the Hr was converse. An increasing trend in species diversity and evenness of species distribution at high altitude was found, which may be re- lated to the slight human disturbance and variable environmental factors.