対数正規分布とその応用(第5報) : 混合対数正規分布の択伐林樹高分布への応用

The mixed lognormal distribution, the two-component univariate lognormal mixture distribution,
f(H) = (N_1)/N･1/(√<2π>σ_1H)exp{-(<(log H-μ_1)>^^^2)/(2<σ_1>^^^2)}
+(N_2)/N･1/(√<2π>σ_2H)exp{-(<(log H-μ_2)>^^^2)/(2<σ_2>^^^2)}
was proposed as a mathematical model to describe the height frequency distribution in selection forests. The model was applied to 4 observed height frequency distributions in Ate(Thujopsis dolabrata var. H0NDAI MAKIN0) selection forests. In order to estimate the 6 parameters of the mixed lognormal distribution, the method of momemts estimation was used instead of the graphical techinques. The principle of the method was summarized briefly. The agreement between the observed and the expected frequencies was tested by the chi-square test. The model achieved a good fit to 3 observed height frequency distributions. The mixed lognormal distribution may be useful for analyzing the height frequency distribution of selection forests.