بررسي تاثير عوامل تخريب (چراي دام و جنگل نشينان ) در تغيير جوامع گياهي جنگلهاي چلاو آمل

Consideration on the effect of degradation causes (live stock grazing and forest villagers) on the change of vegetation and plant elements of Chelave forests

In this study, the plant association as well the antheropogenic impacted area such as grazing and vegetation types were considered. The study carried out in 2500 hectare of Chelave forests of Amol city. These forests located at 800m to 1900m above sea level, here, traditional animal husbandry has experienced since some decade ago. plant associations were identified, carried out by using Braun-Blanquet method. 65 sample plots (Releve) were selected, using the piant form and slope factors. Six associations and two subassociations, as well as one variant were recognized. Vegetation types and elements at the degrated forests and the cattle resting areas were also recognized. By comparing the natural forest associations with the impacted forest considered that a great change has occured within the targeted forests and some invasive woody species such as Crataegus ambigua, Mespilus germanica and Prunus avium has increased and Ihe number of climax species decreased. Hence the main composition of the forest association was changed. By comparing of diversity indices of the sites in Chelave, it was found that, in spite of the expection, the wood species have had more diversity rather than original plant associations in disturbed forests. It could be occured because of appearance of pioneer and invasive species and more uniformity in the distribution of individuals among above mentioned species.