Some quantitative indicators and leaf pigment content of old beech in the pure and mixed stand (Case study: Asalem- Nav forests of Guilan)

The beech (Fagus orientalis Lipsky) is one of elite and extremely valuable species in the forests of northern Iran, which examining the quantitative indicators in both pure and mixed stand can be characterized the recovery or destruction of a forest population. In order to, after the jungle cruise and field study in Asalem-Nav forests, a pure and mixed stand of parcel 319 with an area of 54 acres that have similar conditions were examined. Then 30 poles of old beech trees with a diameter of more than one meter were selected randomly and some of quantitative and qualitative characteristics were measured. The results showed there was no significant difference between beeches of two stands about the diameter at breast height, total height, trunk length and percentage of trunk length slenderness. Also, Qualitative variables of crown symmetry in both symmetric and asymmetric, trunk twisting in three modes (Lack of twisting, sensible twisting to the right, A subtle twisting to the left), mode of branching on beech tree trunk with divisions of branchless, low-branching and high branching have significant differences at the 95% probability level. Furthermore, allelopathic performance of a variety of tree species in the adjacent beech mixed stand led to a significant reduction in the content of photosynthetic pigments chl.a, chl.a+b and carotenoids. Whereas flavonoid concentration in the mixed stand indicated a considerable increase compared to the pure population. Thus, it can be concluded that some quantitative traits in the same ecological conditions are not affected by the adjacent species of beech. The results also indicated that the percentage of symmetry in the crown of the trees in pure stand is more but the high average of the tree length and asymmetry crown in mixed stand can due to the existence of other species and compete for more light.