The effect of different grazing intensities on aerial biomass, underground biomass of two species including Agropyron libanoticum and Festuca ovina in southeastern rangelands of Sabalan Mountain

     This study was conducted to assess the effects of different grazing intensities on the biomass amount of Agropyron libanoticum and Festuca ovina in summer rangelands of southern Sabalan, Ardabil province. After determining three sampling areas as different livestock grazing treatments (light, moderate, and heavy grazing), plant sampling was performed by a random-systematic method in 25 plots along 600-m transects. A linear regression was used to determine the relationship between aerial and underground biomass. To assess the effects of different grazing intensities on biomass of these species a one-way ANOVA and Tukey test were used. The results showed that there was a significant relationship between aerial and underground biomass of two species in different treatments. Moreover, increasing the livestock grazing intensity resulted in a significant decrease in the aerial and underground biomass and total biomass of both species. In addition, increasing grazing intensity leads to decreasing aerial biomass in moderate and heavy grazing treatments compared to the light grazing intensity (26.31% and 42.24, , for Festuca ovina, respectively, and 22.04% and 48.76% for Agropyron libanoticum, respectively. Increasing grazing intensity leads to decreasing underground biomass in moderate and heavy grazing treatments compared to the light grazing intensity (25.14% and 42.75 for Festuca ovina, respectively, and 9.39% and 35.30% for Agropyron libanoticum, respectively. Generally, grazing intensity reduced the aerial and underground biomass of Agropyron libanoticum and Festuca ovina.Therefore, grazing control in rangeland management is necessary to prevent the destruction of these species.