| Abstract |
A problem in the expression of diameter distribution of plantations using only the Weibull parameters a, b and c was examined. First, it was shown that the scatter of diameters could not be evaluated ...exactly using only parameter b. Therefore, to solve this, a simple calculating method of a standard deviation and variation coefficient of diameters using the Weibull parameters b and c was devised. From examples taken from application, it became clear that differences in the scatter of diameter distributions, where parameter b was nearly the same and c was greatly different, could be evaluated precisely by comparison of standard deviation and variation coefficient calculated using the above method. Furthermore, when comparing of some diameter distributions in which parameter b was different, it was shown that difference in the scatter of diameters must be evaluated using standard deviation and variation coefficient. From the viewpoint of forest management technology, it is very important to ascertain the scatter of diameters with regard to plantations. Therefore, the simple method of calculating standard deviation and variation coefficient of diameters proposed in this study should be utilized effectively in study of forest management technology of plantations using the Weibull distribution.
人工林の直径分布をワイプルパラメータa，b，cのみで表現するさい，直径のバラツキが，尺度のパラメータbのみで正確に判断できない欠点があった．本研究は，この欠点を解決するために，先ず，パラメータb，cを用いて直径の標準偏差，変動係数を簡単に計算する方法を提案した．次に，本方法により計算した標準偏差，変数係数を比較すれば，パラメータbがほぼ同じでcが著しく異なる直径分布のバラツキの違いが正確に判断できることを，三つの応用例を示すことにより明らかにした．さらに，パラメータbが異なる直径分布を比較するさいにも，一つの応用例から，直径のバラツキの差は，標準偏差，変数係数を用いて検討しなければならないことを指摘した．森林施業の立場からみると，直径のバラツキの程度を知ることは重要である．したがって，今回提案されたパラメータb，cを用いた直径の標準偏差，変動係数の簡単な計算法は，今後のワイプル分布を用いた人工林の施業技術の研究に有効に利用できるものと考えられる．show more
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