The effect of grazing intensity on palatability classes and life form of plant species in semi-arid regions

Considering previous studies which showed no significant relation between the distance from water point and total vegetation cover, in current research plant species were classified based on life forms (shrub, bush, perennial grass, perennial forbs and annual forbs) and palatability classes (,  and ). One way ANOVA was applied to determine the variations with distance from water point 8 main directions. Results showed that 8 main directions had no significant effect on vegetation cover and palatability classes of studied life forms. While life forms and palatability classes had different reactions to grazing according to the distance from water point. As shrubs, bushes, perennial grasses and palatability class  increased and annual forbs and palatability class  decreased with distance from water point. Perennial forbs and palatability class  had uniform distribution. Using results of Duncan multiple range test a critical area was determined at 400 m distance from water point. In the mentioned critical area, shrubs and bushes showed a decrease in vegetation composition while annual forbs increased. Palatability class  also was eliminated in this area. According to the variations in perennial grasses and palatability class, very sensitive to grazing, it can be concluded that grazing intensity had been very severe at a distance of 800-1000 m from water point.