Application of probability distributions in order to fit canopy classes of Quercus brantii trees, Case Study: Dalab forests of Ilam

Determining the fitting pattern of canopy classes in Zagros forests shows that at different times, the overall status of these forests from the destruction process and ecological sequence points of view. The aim of this research was to investigate crown canopy classes probability distribution of Quercus persica trees in Dalab forests of Ilam. For this purpose, an area of 37.2 hectares in Ilam forests was selected, and based on systematic random pattern 37 transects with fixed length were measured. Finally, the numbers of 209 trees were selected. Exponential, Gamma, Normal and Log-normal probability distribution functions were fitted to crown canopy classes. Characteristics of distribution function by using of maximum likelihood method was estimated. Actual probability and probability which derived from functions was compared using Kolmogorov-Smirnov and Anderson-Darling tests. Results of fitting tests and P-P plots showed that Normal distributions is the best probability distributions for modeling distribution in crown canopy classes of oak trees.