عنوان مقاله [English]
The development stages in the natural forests run very slowly, which are not easy to recognize them within a short period of time. The duration of development of a stand and transition from one stage to another varies among the forest communities. Also the growth characteristics and dynamic of the stands varies in different development stages. This paper aimed to study the diameter and height increment of oriental beech in relation to tree age within the stages. For this purpose, four beech trees in diameter from 15 to 70 cm, were selected and stem analysis were carried out in an interval of 1.4 m logs. The results showed that the diameter increment has no uniform pattern and varies with the age of tree and the development stage of the stand. The diameter and height increment of young beechs are very slow at the early stage of growth (up to the age of 30), which starts to increase later. A beech tree with a diameter of 12 cm could be 30 years old and could reach to a height of 12 m. While, another beech tree with a diameter of 40 cm could be 140 to 150 years old and the total height of such tree could reach to 25 m. The development (successional) cycle of oriental beech in the Caspian region, which occurs with establishing of seedlings within the gaps after falling of old trees and continues up to physiological death of trees, is estimated between 200 and 230 years. At this age the diameter of tree could reach to 70 cm.