Self-pruning and its relation to trees structural attributes in Oriental beech (Fagus orientalis L.) forest stand (Case study: Beech forest of Alandan, Mazandaran)

The wood quality in forest trees largely depends on their self-pruning and forest management pays attention to the pruning factor to achieve high quality of wood products. Therefore, this study aimed to determine the relationship between self-pruning index in Oriental beech trees and some of their structural attributes. For this purpose, 186 beech trees were randomly selected in Alandan, Sari and the self-pruning index along with other structural features were measured. The correlation results showed that there is a significant positive correlation between self-pruning index with DBH, crown length, area and crown volume and also a significant negative correlation with symmetry and crown ratios. No significant difference was observed in the height classes of beech trees in terms of self-pruning index (Sig.=0.164). The highest mean value of the pruning index belongs to the class of 75-46 cm in diameter (Sig.=0.002). The analysis of variance results showed that the highest mean value of the index was present in the groups of three trees. With increasing the stubbiness ratio, the self-pruning index increased (p=0.009). A significant interaction was observed between stubbiness ratio with crown length, crown area and volume, DBH and height of beech trees in site. In general, the results showed that self-pruning in large-sized beech trees was performed according to forest conditions and this important index was related to the structural attributes of trees such as height, DBH, surface area and volume of the crown and it is also necessary to consider the pruning of forest trees in intermediate-cutting operations to increase the wood quality.