Investigation of Changes in Probability Distribution Functions of Diameter, Height and Crown area of Trees Affected by Slope Aspect

Changes in probability distribution functions of diameter, height and canopy area of trees in Arasbaran natural stands were studied in this research. For this purpose, six hectares of pure stands of hornbeam species were selected in a protected area. A total of 625 hornbeams (consist of 262 trees in northwest slopes and 363 tees in northwest slopes) were measured. Beta, Gamma, Lognormal, Normal, Exponential and Weibull distribution functions were fitted to the maximum likelihood method and Kolmogorov-Smirnov and Anderson-Darling tests. The results showed the beta distribution for the diameter characteristic in both slope aspects, the log-normal distribution function in the northwest aspect and the normal distribution in the northen aspect for the tree height characteristic, the gamma and beta functions in the northwest slope, and the beta function in the northeast direction was shown as the most appropriate functions. ANOVA analysis also showed that there were no significant differences between the two slop aspect in terms of tree diameter but there was a significant difference in height and canopy cover and this was the reason for differences in the probability distribution functions.