Investigation on the relationship between vegetation characteristics and topographic factors in utilization units of mountainous rangelands of Vaz, Mazandaran

In mountainous rangelands, there is a complex combination of factors such as topography, vegetation growth stages and water distribution which affect grazing distribution. This research was conducted to investigate the effect of topography on vegetation of summer rangelands of Vaz, Mazandaran province. Five utilization units were selected on the basis of field survey and identifying homogenous grazing units. Key areas were obtained in each unit and sampling was done randomly. Size of the quadrates was 1m2 and the number was calculated by statistical method. In each quadrate, yield was measured by clip and weigh method and utilization rate was determined using height to weight ratio (based on dry weight). Vegetation cover percentage was also recorded. Finally, comparison of plant characteristics in utilization units was performed by SPSS in a completely randomized design with unequal replications. Then, correlation coefficient between each of the independent variables (slope, aspect and height) and dependent variables (yield, canopy cover percentage and utilization) was determined. Also, the most effective factor and interaction effects of independent variables were obtained by stepwise multiple regression analysis. Results showed that slope and aspect had the most correlation with livestock utilization respectively, but no relationship was found for elevation while it affected yield and canopy cover.