Assessment of impact of ecological elevation on grass species diversity in Yabello Rangeland, Southern Ethiopia

Elevation has great impact on species’ diversity; it creates ecologically diverse vegetation. Studying species’ richness patterns at different scales is very important both for ecological explanations and effective conservation design. In this study, grass vegetation data were collected using systematic sampling methods. 18 transects and 54 quadrants were laid, with 6 transects and 18 quadrants from each selected study kebele having 1 × 1 m2 for grass. In each quadrant, the level of impact for each threatening factor was evaluated and a total of 26 grass species were recorded. The data were analyzed using SPSS and the average species’ composition was assessed in relation to topographic variables. There was upper elevation observed in both richness and diversity of plant species compared to the others with significant P<0.05. Grazing intensity also has significant impact on both species’ diversity, density and area coverage. This shows that the area heavily grazed had less diversity richness and coverage compared to the less grazed (p<0.001) area. From the data we can summarize that anthropogenic, topographic and climate factors were the leading causes of the overall shift of plant community structure in the study area.   Key words: Elevation, grazing intensity, grass composition, Kebele.