Quantitative characteristics and structure of tree species in two different conservation situations in Arasbaran forests

Analysis of the structure of tree species provides a complete information on species diversity, composition, spatial distribution in mixed natural forests. It helps to better understanding of many ecological and silvicultural issues in order to optimal management of the ecosystem. The main objective of this research is to investigate the differences and similarities of sites with different conservation history (Kalale and Vaygan Sites with a long-term conservation history and Kuran Sites with a short-term conservation history) in terms of diversity and composition of the tree structure in Arasbaran forests. For this purpose, nine hectares with one-hectare sample plot were inventoried with full-callipering method. The measured characteristics were type of species, distance and azimuth of each tree from the last tree, diameter at breast height (DBH), tree height. The spatial pattern of trees was determined by the modified K-Ripley function. Based on the results, 14 species were observed in the three study areas. Four species of hornbeam (68 %), maple (8 %), yew (7 %) and persian oak (2.5 %) composed of about 88% of the total density of trees. Kalale site (15.29 m2) and Kuran (0.26 m2) had the highest and lowest basal-area per hectare, respectively. Kalale and Vaygan sites had a wide range of diameter classes in comparison with the Kuran site. L function showed that almost all species had cluster distribution and only hornbeam had a random distribution in Kuran site. Therefore, every intervention in order to tending reclamation andenrichment of the studied stands should be based on making species mixture and keeping clustered spatial pattern and also it should be avoided pure species reforestation to ensureboth biodiversity and sustainability of stands