Structural analysis of Combretum-Terminalia mixed Acacia vegetation in Ilu Gelan District, West Shewa Zone, Oromia Region, Central Ethiopia

Vegetation of two distinct sites known as Dirki and Jato was studied in Ilu Gelan District, West Shewa Zone of Oromia Region, 195 km west of Addis Ababa, to make a structural analysis on the component plant species comprising the Vegetation. The systematic sampling method was used to collect vegetation data from 54 (20 m × 20 m) plots. To collect data for herbaceous plants, five 1 m × 1 m subplots were laid in each of the main plot, where four were at the corners and one at the center. Diameter at breast height was measured for woody species taller than 2 m while height and cover/abundance values were visually estimated. Shannon - Wiener Diversity Index was used to calculate species diversity, richness and evenness of the plant communities whereas Soresen’s Similarity ratio was used to measure the similarity between the Vegetation and four other related vegetation sites studied earlier in different study areas. One hundred six species were used for the structural analysis of the Vegetation studied. Agglomerative Cluster Analysis revealed three plant community types from the study area. Total density and basal area calculated for woody species were 5,145.83 individuals ha-1 and 18.96 m2 ha-1 respectively. Population structure and regeneration status of selected woody species were assessed and results revealed that some species had regeneration problems and need management measures.