Assessment of Vegetation Composition and Productivity of Rangeland as Affected by Altitude and Grazing Pressure in Kuraz District of South Omo Zone, South Western Ethiopia

Abstract

The study was conducted in Kuraz district of south Omo Zone, South nation nationalities and people regional state of Ethiopia (SNNPRS), with the objectives of identifying effect of altitude and grazing pressure on vegetation composition and biomass yield of rangeland. Accordingly, a total of 19, 1, 2, 7 and 21 species of grasses, legumes, sedges, other herbaceous plant and woody species were identified in the district, respectively. A. adscensionsis, C. dactylon and S. consililis were the common/dominant species in the communal grazing lands, whereas A. hirtglama, E. choloacolonum, P. geminatum and S. spicatus were common/dominant species in the riverside. In the enclosure grazing sites, E. ch.roxbarghiana, C. dactylon and P. maximum and S. pyramidalis were the common and/or most frequent species. Furthermore, Acacia. sengal, A. mellifer, A. seyel, C. glondelosa and G. erythraea were the common and/or dominant woody species in the communal grazing area, whereas A. seyel, G. erythraea, A. senegal and A. millefera in the riverside. G. villosa, C. africanus, A. oerfota and Mede (local name) were the common and/or dominant species in the enclosure. Almost all the plant species existed in both altitudes. The mean woody density in communal, riverside and enclosure sites of the study district were 2,175, 1963.7 and 1725.5 plants per hectare, respectively. Thus, the wood species density indicated that communal and riverside grazing sites have shown higher number of woody vegetation than enclosure. Total dry matter biomass (DM), DM of grass, and DM of highly desirable grass species were significantly (P<0.05) higher in enclosure (1042, 832 kg/ha and 362 Kg/ha) followed by communal (756.5, 412.5 kg/ha and 47kg/ha) and riverside (621, 355 kg/ha and 50.5 kg/ha). The study indicated that as there was bush encroachment in the study district which resulted in decrease of palatable herbaceous species. Hence, there has to be different interventions on rangeland management practices like bush clearing, paddocking and rotational grazing.

Keywords: Biomass, grazing, herbaceous composition, chemical composition, invaders