عنوان مقاله [English]
Livestock Grazing is as the most effective factor in changing dimensional characteristics and plant biomass in rangelands that affected different aspects of ecosystem production. Regarding to the fact that Artemisia fragranus is the main species of mountainous rangeland in Khoy and the limited quantitative information about the effect of different grazing intensities on structural characteristics, aerial biomass and especially underground biomass is available, so in the present study the effect of different grazing intensities (light, intermediate and heavy) on structural characteristics, aerial and underground biomass was assessed. Therfore, three rangeland sites with various grazing intensities are selected and 60 plots of 1 m2 along 100 m transects were established. Thus, structural characteristics, litter, aerial and undergrlound biomass of Artemisia fragrans were measured in the study sites. To compare the means of dimensions and biomass components of species in three study areas, analysis of variance and multiple Duncan mean comparison test were used. The results proved that there are significant differences among studied parameters (except for collar diameter and collar area) of studied species among three grazing intensities. The most and the lowest means of aerial biomass in 2 places with low and heavy grazing intensity were 18.5 and 42.76 gr. also, the most amount of ground biomass was 32.95gr and the lowest amount of ground biomass was 56.46gr that belong to places with low and high grazing intensity. Calculating of variation percent of the parameters in each sites of moderate and heavy intensity in relation to light grazing showed that all parameters have declined and the most variation percent of study species parameters belongs to heavy grazing site. Generally, decline amount for collar diameter and collar area is the lowest and also for aerial and underground and litter parameters is the highest.