镇沅县思茅松天然林分非空间结构特征分析

以云南省镇沅县思茅松天然林为研究对象，选取云南省森林资源连续清查中的14块标准典型固定样地数据，采用分布函数和株数累积分布拟合分析思茅松天然林分直径结构，对思茅松林分的直径分布、树种组成及优势树种等进行综合分析，探讨思茅松天然林分的非空间结构规律。研究结果表明，思茅松天然林分直径分布服从韦伯分布，直径变动幅度较大，且小径阶树木株数最多，随着直径的增大，林木株数开始急剧减少，当直径达到一定值时，株数减少幅度渐趋平缓。各龄组的偏度系数均为正值，径阶分布曲线均为左偏；除近熟林外，其他龄组的峰度系数均为正值，径阶分布曲线均为尖顶峰。研究区内思茅松天然林分的树种组成相对单一，虽有一些其他伴生树种，但数量很少，思茅松所占比例最大，为68.66%，相对多度为68.73%，相对显著度为78.15%，相对频度为13.48%，重要值为53.45%。伴生树种主要有红木荷、南烛、麻栎和茶梨等。

Non Spatial Structure Characteristics of Pinus kesiya Natural Stand in Zhenyuan County

Taking Pinus kesiya natural forest in Zhenyuan County of Yunnan Province as the research object, the data of 14 typical fixed sample plots in the continuous inventory of forest resources in Yunnan Province were selected, and the diameter structure of Pinus kesiya natural forest was analyzed by fitting the distribution function and cumulative plant number distribution. The diameter distribution, tree species composition and dominant tree species were comprehensively analyzed, and the non spatial structure law of Pinus kesiya natural forest was discussed. The results showed that the diameter of Pinus kesiya natural stand obeyed Weibull distribution, which changed greatly, and the number of trees in the small diameter class was the largest. With the increase of the diameter, the number of trees began to decrease sharply, and when the diameter reached a certain value, the reduction of the number of trees gradually flattened. The skewness coefficient of each age group was positive, and the diameter class distribution curve was left biased; except for near mature forest, the kurtosis coefficients of other age groups were positive, and the diameter class distribution curve was sharp peak. The tree species composition in the study area was relatively single, only had a small amount of other associated tree species. Pinus kesiya accounted for the largest proportion of 68.66%, with relative abundance of 68.73%, relative significance of 78.15%, relative frequency of 13.48%, and importance of 53.45%. Associated tree species mainly included Schima wallichii, Vaccinium bracteatum, Quercus acutissima and Anneslea fragrans.