strstructure and composition of oriental beech stands in the middle stage of ecological succession in the hyrcanain region

this study was designed to investigate the structural characteristics of beech forests in the middle stage of ecological succession. in order to this purpose undisturbed beech stands in kheyroud forest had chosen and three one hectare sampling plot laid out. all of tree species measured with full callipering method and diameter and height of trees were recorded. natural regeneration within one hectare plots was counted and recorded in three different height classes including: i) shorter than 30cm, ii) between 30and 130cm, and iii) taller than 130 cm. vitality and stem form of seedlings and asplings were also recorded as unforked, forked and broom-shaped forms. according to the results, beech stands in this stage of succession are far from typical irregular structure and deficiency of tree number in diameter classes of 10cm and over55cm is obvious. meanwhile stratification of trees in different stand stories within one, two and three hectare area calculated and results revealed 40, 48.5 and 57% of beech trees occupied middle or under story layers, respectively. in hornbeam as second dominant species these amount calculated 42, 54.5 and 42, respectively and for other species 52, 42 and 29% were observed. the ratio of seedlings and saplings number to adult tree species demonstrates that the proportion of hornbeam is relatively high in the middle and under storey and the successional pathway of the studied stands is toward the late stage, where the proportion of