Investigation of production and consumption of two species of Bromus tomentellus Boiss. and Festuca ovina L. in different grazing intensities in the mountain rangelands

Since the amount of species production and consumption varied at different grazing intensities, this study was conducted to determine the amount of production and consumption of Bromus tomentellus and Festuca ovina species in mountainous rangelands of Chaharbagh. Three sites with different grazing intensities (exclosure, moderate grazing and high grazing intensity) were considered and species production and consumption were measured at the end of grazing season. Five transects of 100 m were applied for each sites. Then, two random points were selected in each transect and sampling were carried out from 5 plants near these points. The growth values of plant inside the exclosure for the current year considered as the average production of the species. The difference between the mean biomass of plant inside the exclosure, and other sites, was evaluated as the amount of livestock consumption of the species. Thus, percentage of consumption (rate of utilization) of each species was obtained by dividing the amount of species usage in each site by the amount of production inside the exclosure. T-test was used to determine the differences of biomass of each site with the exclosure and also to compare the amount of species usage at different grazing intensities. Results showed that the highest density and production of B.tomentellus and F.ovina were 19000 stand per ha, 76 gr per stand and 25000 stand per ha, 50 gr per stand, respectively for exclosure site and the lowest density and production for high intensity grazing site. Most consumption rate of B.tomentellus and F.ovina species was observed in high and moderate intensity grazing sites, respectively. Due to the higher consumption of Br. tomentellus Compared to other species, conservation measures should focus more on this species.