林木直径分布的研究

<正> 林木株数依直径的分布(以下简称直径分布)是研究林木及其材种结构的基础,是了解营林措施合理性的重要手段之一;但由于直径分布受多种因素影响,变化多端,近百年来对此虽作过大量研究,发表了数以百计的论文,但尚未取得完全令人满意的结果。 迄今对直径分布的研究,大致分为分布规律和分布函数两个方面。前者着重从生物学角度说明直径分布规律;后者着重探讨分布的数学表达形式。欧、美、日、苏等国从1898年到现在已正式发表的直径分布函数式已有20多种。本文主要以β_1—β_2场作为检验分布函数适应性的理论基础,并用实验数据对普遍认为较好的5种分布函数作了比较,对其中适应性较广的β分布作了改进,发展了矩解、似然解和偏峭解;并借助多元分析,初步分析了影响林木直径分布的因子。研究对象既包括林分也包括大地域。

A STUDY OF THE DISTRIBUTION OF DIAMETER OF WOOD

The distribution of diameters of wood is the most simple and effective factor in the depiction of a stand of trees and the most important factor in forest resource inventories, but attempts undertaken in the study of diameter distributions have not been very successful so far.Beta, SB, Weibull, lognormal, Gamma and normal distributions are discussed in terms of their flexibility on the skevvness squared (B1)-kurtosis (B2) plane. Five kinds of distributions have been drawn up on the basis of the data gathered from the stands and forests in broad areas and the Beta distribution gives the best performance in terms of its applicability to various sample distributions. Moment estimators, maximum livelihood estimators and estimators usi ig skewness and kurtosis for the Beta distribution are given. The estimators using skewness and kurtosis are most desirable.