Modelling diameter distributions of scots pine stands in kastamonu region

In this study, it was aimed to model diameter distributions of pure Scots pine (Pinus sylvestris L.) stands in Kastamonu region and to investigate the effects of stand characteristics such as number of trees, mean diameter, stand density, site class, crown closure, life phase and stand type selection on the most appropriate distribution function. As the study material, 890 sample plots data obtained from the General Directorate of Forestry archives were used. Beta, Gamma-2p, Gamma-3p, Johnson SB, Lognormal-2p, Lognormal-3p, Normal, Weibull-2p and Weibull-3p probability density functions were used to model the diameter distributions. Kolmogorov-Smirnov (KS), Anderson-Darling (AD), Chi-square (X2) and Error Index (e) criteria were used in determining the success of probability density functions and determining the most appropriate function. The functions were ranked according to these criteria for each sample plot. The effects of various stand characteristics on the selection of the most suitable function were determined by Kruskal-Wallis and Chi-square tests. As a result of comparisons according to statistical criteria, Johnson SB probability density function was determined as the most successful function in all criteria. While there were significant differences in the success of probability density functions in terms of number of trees, mean diameter, crown closure, life phase and stand type, they did not show any difference in stand density and site classes. In conclusion, Johnson SB probability density function was found to be the most successful function in modeling the diameter distributions of pure Scots pine stands in Kastamonu region and Johnson SB function can be used for diameter distribution models for these stands which differ in various features.