بررسي رابطه بين ويژگي هاي كمي و كيفي توده هاي جنگي طبيعي راش با عوامل رويشگاه (منطقه اسالم )

An Evaluation of Relationship between Quantitative and Qualitative Characteristics and Site Factors in the Natural Beech (Fagus orientalis) Stands in Asalem

To find the effect of important site variables on quantitative and qualitative changes in natural beech stands in Asalem, method of principle component analysis (PCA) was used.Jn this area ten sites consisting of 242 sample plots were investigated. Based upon and by employing Braun-Blanquet combined scale and TWJNSPAN classification, 8 vegetation groups were distinguished. After determining vegetation groups, the groups were analyzed using principle component analysis (PCA). Twenty five variables in the 8 vegetation groups including: features of forest stand, physiographic factors and some soil characteristics were analyzed. The results showed that organic matter, nitrogen (in second and sixth groups) and altitude factor (in fifth and eighth groups) were important indices that affect the variations between groups. The features of the first axis were the most important factors on variations between groups. The obtained results also showed that the studied variations on the right of first axis were indices of productivity and the mentioned axis factors may affect the variations between groups. Finally, the results indicated that the most variations were at the sixth group which had the most egen vector and was situated on the productivity axis. Therefore, site vaiations on this axis exerted the most effect on the quantitative and qualitative characteristics of the sixth group. All studied sample plots in this group were situated toward north at 1000-1200 above sea level. The sites situated in this group consisted of deep soil, more moisture and high silt. The forest stands that were situated in this group enjoyed a more suitable condition as compared to other groups.