Journal of Rangeland

This study aimed to evaluate the effects of various grazing intensities including non-grazing (as control site), moderate grazing and heavy grazing on aboveground and belowground biomass of Bromus tomentellus in Bijar protected area- Kordestan province. Regression techniques were used to assess the relationships of aboveground and belowground biomass of the species, and one-way ANOVA and Duncan's test were used to compare all the treatments. According to the results, there was a linear relationship between aboveground and underground biomass in the different treatments. Increasing grazing intensity leads to a significant reduction in aboveground, belowground and total biomass of the plant species. The species biomass in moderatly and heavily grazed sites declined 37% and 80% respectively in compare with the control. ‏‏‏‏‏‏The average  total biomass in the control, moderately and heavily grazed sites were estimated 839, 488.75 and 132.88 kg/ha respectively. The relative contribution of aboveground and belowground biomass of the species were decreased and increased respectively as the grazing intensities were increased. The relative contribution of aboveground biomass in the control, moderately and heavily grazed sites were 54.97%, 61.42% and 64.34% respectively. The relative contribution of belowground biomass in the control, moderately and heavily grazed sites were 45.03%, 38.58% and 35.66% respectively. The results of this study highlight the importance of controlling the grazing intensities to prevent soil erosion and losing the valuable plant species.