RANGELAND CONDITION ASSESSMENT AND EVALUATION OF CHEMICAL COMPOSITION OF SELECTED BROWSE SPECIES IN DASSENCH DISTRICT OF SOUTH OMO ZONE, SOUTH-WESTERN ETHIOPIA

Abstract

Rangeland is the primary source of livestock feed, on which the livelihood of pastoralists depends. This study intended to fill the scientific information gap in the Dassench districts of the South Omo Zone, aiming to investigate the range condition and evaluate the chemical composition of selected browse species.Vegetation and soil conditions were studied from quadrats established along two transects. 5, 4, and 3 quadrats of 400m2 /transectwere laid along a 15km gradient (5km, > 5 km-10 km, and > 10 km-15 km) from the watering point for vegetation analysis. A total of 90 sampling units of 1m2 quadrats (30 quadrats per grazing type) were used to study the herbaceous plant. A total of 54 quadrats were taken for basal cover, litter cover and soil condition assessment. The effects of grazing types on range condition scores and browse nutrient content were analyzed using the analysis of variance (ANOVA). A total of 33 herbaceous species, which included 23 grass species, 1sedge, 3 legumes, and 6 forbs were recorded. Aristidaadscensionsis, Aristidahirtglama, and Cynodondactylonwere among the dominant and common grasses in heavy grazing type, while A. adscensionsis,A. hirtglama, and Echinocholoacolonumwere some of the common and dominant grass in moderately grazing type. The light grazing type was also dominated by Cenchrus ciliaris, Cynodondactylon, and Aristidasomalensis.Of 22 woody species identified, the common and dominant woody species in the heavily grazing type were Solanum spp., C. rotundifolia and B. boxifolia. In the same way,Solanum spp.,Acacciareficiens, and Acacia Senegal were common in moderate grazing types. In the light grazing type, the common and dominant species were Solanum spp., AcacciaOerfota, and A. Senegal. The mean condition scores of woody species density in the three grazing types were significantly different at (P≤0.05). The light grazing type has significantly (P≤0.05) the highest condition score than the other two grazing types. The basal and litter cover, soil compaction and grass species composition were significantly (P≤0.05) the highest among the three grazing types. The light grazing area had the highest (P≤0.05) DM biomass of total grass, highly, and intermediately desirable grass (75.45±3.06, 36.14±3.46 and 25.49±3.47) than the other two grazing types respectively. The light grazing type provides significantly (P≤0.05) the highest total DM biomass than the other two grazing types. Dry matterbiomass of Zyzyphusmauritiana was the highest (220.89kg) in a heavily grazed area.Browse species investigated showed relatively high fodder value of Crude Protien contents (19.05, 19.63, and 18.16%) for Acaccia. senigal, Acacciatortilis, and Z. mauritiana respectively. The result of the study indicated that there was a reduction in rangeland productivity, a change in vegetation cover, declining in highly palatable perennial grasses and an increase in less palatable annual grass species. Thus, the majority of studied rangeland has classified under the poor range condition class. Henceforth, it is recommended, to train the pastoral communities on proper rangeland management and improvement methods appropriate to the areaand to develop watering points throughout the rangeland.