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本试验根据100块标准地的实测资料,应用Weibull分布函数分析了河北省油松(人工林)、华北落叶松(人工林)、山杨、白桦和柞栎等5个主要树种的林分直径分布。用最大似然法则求解Weibull分布函数的参数。拟合结果:尺度参数b值基本上在3～10之间,形状参数c值均在1～3之间,参数的变动系数Cv(b)为17％～28％,Cv(c)为12％～17％.据此,5个树种的直径分布均应属于正偏的山状分布类型。且X~2检验结果表明,使用Weibull分布函数拟合以上树种的直径分布效果良好。
Based on the measured data of 100 standard plots, the distribution of stand diameter of five major tree species, Pinus tabulaeformis (Pinus tabulaeformis) plantation, Larix principis-rupprechtii (Plantation), Populus davidiana, Betula platyphylla and Quercus variabilis in Hebei Province was analyzed by Weibull distribution function . Solving the parameters of Weibull distribution function with maximum likelihood rule. The fitting results: the scale parameter b value is basically between 3 and 10, the shape parameter c value is between 1 and 3, the coefficient of variation coefficient Cv (b) is 17% -28%, Cv (c) is 12 % ~ 17% .Accordingly, the diameter distribution of the five tree species should belong to the type of mountain distribution. The results of X ~ 2 test show that the distribution of diameters of the above species is well fitted by Weibull distribution function.