Ecological Role of Altitude on Quantitative Characteristics of Caucasian Oak (Quercus macranthera Fisch. & C.A.Mey. ex Hohen.) Stands in Arasbaran Forest

The Arasbaran vegetation community is an important source of biodiversity and one of the biosphere reserves in the northwest of Iran, which is influenced by different climates and special importance due to variations in altitude. Since an altitude is an environmental characteristic that affects the habitat of plant species, this study aimed to investigate the ecological role of altitude on the quantitative characteristics of caucasian oak trees (Q. macranthera Fisch. & C.A.Mey. ex Hohen.) and determine the best range for the natural growth of this species in Arasbaran forests. Three oak stands were selected in three altitude ranges including low (1200-1400 m a.s.l.), middle (1400-1600 m a.s.l.) and high (1600-1800 m a.s.l.) altitude. At each altitude, three plots were sampled with one-hectare area, and the quantitative characteristics of all trees, including diameter at breast height, basal area and trees canopy diameter were measured. Normality of data was verified by the Kolmogorov-Smirnov test, and the comparison of the mean of the characteristics was done using one-way ANOVA at a probability level of 0.05 and Duncanchr('39')s test. The results showed that there was a significant difference in diameter of the trees, the height of the trees and basal area per hectare among the three altitudes, but density per hectare had a significant difference between the first and second altitudes.  In addition, the canopy coverage had no significant difference among the three altitude ranges. The middle altitude was more favorable condition stand in terms of its quantitative characteristics. Therefore, the results of this study indicated that the middle altitude (1400-1600 m a.s.l.) is a more suitable habitat for caucasian oak species in Arasbaran forests, and doing more protection of the stands in this altitude can be created a seed bank for the production of high quality seedlings and forest plantations in the region.