Study of Age Effects on Growth of Beech Trees in Lomir Forest, Guilan

Oriental Beech forests have economic and ecological importances in Hyrcanian zone in the north of Iran. Therefore qualitative and quantitative controls of the stands are essential in management of these forests. This study was aimed for determining the effect of age on growing variables of beech trees in Lomir forest in Asalem, Guilan Province. In this study, 179 Beech trees were selected based on diameter classes (5 cm). The relationships between tree age and growing variables of beech trees were tested by regression analysis. The results of this study indicated that tree age-diameter (=0.93) and tree age-height (=0.77) relationships were described using Power model. Volume growth was fitted by power model with the adjusted coefficient of determination of 0.92 (=0.92). The S-curve model gave the best result for relationship between age-crown diameter (=0.78) and age-bark thickness (=0.80). But the tree artificial form factor is not affected with increasing tree age. These results indicated that diameter and height trends of annuall increment are negative in final periods of tree life. But volume trend of annual increment always is positive. The results of this research could be a guideline for foresters to manage forest economically.