桤木幼龄林直径结构规律分析

he research of diameter structure regularity is the basis work of forest scientific management.In this paper, the data based on six sample plot of the young alder farmland to forest land, analyzed the diameter structure regularities. Used four distribution functions to fit to its diameter structure, and take chi-square test. By the fitting result and chi-square test results, the young alder in the Western HuNan fit Normal distribution and Weibull distribution, doesn't fit the lognormal and gamma distribution. Used Richards model and Logistic model and Cubic equation to fit cumulative percentage and relative diameters, the results show that Richards model and Logistic model are better than Cubic equation and it has more biologically significance.