赤水河流域清香木天然群落主要树种生态位研究

为探讨赤水河中段清香木在天然群落中的地位、资源的利用状况以及主要树种间的相互关系，揭示天然群落中清香木的生态适应性，通过野外样地调查及定量分析，以海拔450-930 m不同海拔梯度作为一维资源位状态，研究了群落中19个主要树种的生态位宽度、生态位相似性比例以及生态位重叠特征。结果表明：清香木、铁仔、华西小石积等树种具有较大的生态位宽度，其B（SW）i、 B（L）i分别为0.8592、0.8421、0.8392、0.9323、0.8805和0.8369；生态位相似性大于0.5的种对有25对，占总种对数的14.6％；生态位重叠值大于0.5的种对有49对，占总种对数的28.7％；生态位宽度越大，其树种间生态位相似性比例和生态位重叠值越高，竞争就会更加激烈，反之则低。

Study on the Niche Characteristics of Main Tree Species of Pistacia weinmannifolia Community in Natural Forest along Chishui River

This paper focused on exploring the position of Pistacia weinmannifolia in natural forest along the mid-stream of Chishui River, the use of resources in the community as well as mutual relation among main tree species, and revealling natural communities in the ecological adaptability of Pistacia weinmannifolia, and further study on competition of Pistacia weinmannifolia with other major species.The investigation was carried out in the natural community along Chishui River.By using quantitative methods, we differentiated elevation gradient from 450 m to 930 m as a one-dimensional state resources （ resource position） , and analyzed 19 main tree species in the commu-nity, in terms of characteristics of niche breadth, niche similarity, and niche overlap.The results showed that：Pistacia weinmannifolia, Myrsine africana and Osteomeles schwerinae species had larger niche breadth, among which B（SW）i, and B（L）i were respectively about 0.859 2, 0.842 1, 0.839 2, 0.932 3, 0.880 5, 0.836 9;there were 25 pairs of tree species whose niche similarity value was larger than 0.5, which accounted for total spe-cies logarithm of 14.6 %; and there were 49 pairs of tree species whose niche overlap value was larger than 0.5 , which accounted for total species logarithm of 28.7 %.The larger the niche breadth was, the higher the niche similarity and overlap value of tree species were.Accordingly the competition was more intensive, and vice versa.