بررسی ساختار تیپ‌های مختلف جنگلی با استفاده از شاخص های نزدیک‌ترین همسایه(مطالعه موردی: بخش گرازبن جنگل خیرود)

To implement correct management of forest ecosystems, enough information in relation to the structures of tree species is necessary. In this study, the structures of trees species in Fagus, Fagus-Carpinus, Carpinus-Fagus and Carpinus-Quercus types were investigated and compared in Hyrcanian forest. The data used in this study was collected from 239 plots with an area of 1000 m2 in Gorazbon district of Kheyrud forest, and Crancod (ver. 1.3) software was employed to calculate the uniform angle (Wi), Mingling (DMi), DBH dominance (TDi) and Height dominance (THi) indices. The result of uniform angle index showed a random positioning for the trees in the studied types. Also, the result of mingling index showed a low mixture for four studied types. The result of this index indicated an intra-specific competition for Fagus orientalis and Carpinus betulus and an inter-specific competition for other species. The average value of DBH and Height dominance indices showed a relative similarity among the studied types. The result of these indices showed that some species such as Acer velutinum,، Tilia begonifolia and Alnus subcordata are dominant and species including Ulmus glabra and Diospyros lotus are dominated. The comparing of similar species structure showed a non significant difference for positioning, DBH and height dominance features in different types. Also, this comparison showed a significant difference in mingling feature of Carpinus betulus, Fagus orientalis, Acer velutinum, Tilia begonifolia, and also deadwoods in the studied types. The utilized indices in this study had a high ability in the description of forest types' structures and also the ecological features of trees species.