Impacts of Grazing on Herbaceous Plant Species Diversity and Biomass Production in Borana Rangeland, Southern Ethiopia

The study was carried out in three districts of Borana Zone, Oromia regional state, to determine the impacts of grazing on vegetation structure and herbaceous biomass yield of Borana rangelands under traditional enclosure and continuous grazing rangeland types at the end of the main rain season. Within both rangeland types of each district, three plots of 20 m x 20 m were placed at 200 m intervals, with a transect used to collect data on the herbaceous plant community by randomly throwing seventeen quadrats (1 m x 1 m) in the main plot. The vegetation diversity, richness, and density evenness were analyzed by General Linear Model (GLM) procures, and LSD was used for mean comparison. The herbaceous ground cover was a significant difference (P < 0.05) between rangeland use types. Additionally, a significant difference was seen (P<0.05) in the richness, evenness, and diversity of herbaceous species in connection with the various research locations and rangeland use types. The higher relative frequency of perennial grass and palatable species was recorded in the enclosure range land use types. Additionally, a significant difference was seen (0.05) in the richness, evenness, variety, and density of herbaceous species in connection with the various research locations and rangeland use types. On average, continuous grazing rangeland use types had the least amount of very desired herbaceous species (16.22 %), while the Arero and Yabello enclosures had the highest percentage (56.52 %). The results indicate that overgrazing is the main factor in the decline of the diversity and biomass yield of herbaceous plant species in both grazing use types of study sites, while traditional enclosure is better than continuous grazing rangeland use types.