Short-term Effects Of Grazing Systems and Grazing Intensities On Standing Crop and Vigor of Bromus tomentellus M. R. Moghaddam!

Sort-term effects (one grazing season) of rotation and continuous grazing systems as well as heavy, medium and light grazing intensities on standing crop and vigor of Bromus tomentellus Pasture was studied in Homand Abesard Range Research Station. The treatments in each system were analysed while taking in to account a randomized complete block design. A comparison of the two systems was made using t-test. Sangesari race sheep was employed as the grazer animal. One handred stands were sampled in each grazing intensity for parameters of standing crop and vigor. The results showed that the rotation of grazing system had more negative effects on the parameters. In both grazing systems, the parameters decreased when the grazing intensities were increased. The standing crop and vigor in treatments and control differed significantly. The variations in plant height and stalk were the same as variations in standing crop. Except for differences of heavy and medium treatments in continuous system, -the differences in" treatments of grazing intensities and control in both systems were significant