山杨天然林林分结构的研究

本文利用７３块山杨标准地资料，研究分析了山杨天然林的林分结构，验证了ｆ（Ｄ）＝ａＤＢ十Ｋ关系成立，林分直径分布遵从Ｗｅｉｂｕｌｌ分布时，其林分树高分布、年龄分布也遵从Ｗｅｉｂｕｌｌ分布的理论。结果表明，山杨天然林多属单层同龄纯林，且直径结构表现出了很强的规律性；在直径较小的山杨林分中，其直径分布为正偏，峰度较显著。当林分平均直径大于８ｃｍ，其分布为负偏，用Ｗｅｉｂｕｌｌ分布函数拟合时，在年龄较小，林分平均直径小于６ｃｍ时，其形状参数１．５＜Ｃ２；当林分平均直径大于７ｃｍ时，形状参数２＜Ｃ３。

A Study on Structures of Natural Populus Stands

Using seventy.seven plots natural poplar stands,structure of stands are studied and analysed in this paper. The function f(D)=k+αDβ has been tested, the diameter distribution follows weibull distribution, the height distribution and the age distribution follow too. The results have showed single layer and even-age stands in natural poplar stands. The diameter distribution shows evident rules. the mean diameter is smaller in poplar stands,the bia degree of diameter distribution is left, and lepto kurtosis is evident,when the mean diameter of stands>8cm, then the diameter distribution is right, the age is smaller and mean diameter<6cm in stands, using weibull distribution fix, the shape parameter 1. 57cm, 2