Floristic Composition, Structural Analysis and Regeneration Status of Woody Species of Gemechis Natural Forest, West Hararghe Zone, Oromia, Ethiopia

Abstract

The study was conducted on Gemechis natural forest, West Hararghe, Oromia Regional state, Ethiopia with the objective of  determining the floristic composition, structural analysis and regeneration of wood plant species. Systematic sampling was used to collect vegetation data. Accordingly,50 sampling quadrats of 20 m x 20 m were laid along six line transects at every 50 m interval within which five 5 m x 5 m small quadrats were laied to sample woody species with <2cm DBH (diameter at breast height). In each quadrat, all live woody species were recorded with  their number counted and DBH measured for those with DBH>2cm. Fifty one (51) woody species belonging to 50 genera and 34 families were recorded in the forest. The collected specimens were composed of 64.7% of tree, 31.3% shrubs and 3.9% of lianas. The most species rich families were Rosaceae, Lamiaceae and Myrsinaceae. Shannon diversity index and evenness of woody species of the Gemechis natural forest were 3.04 and 0.77, respectively. The total density of woody species recorded in Gemechis forest was 3430 individuals ha^-1. ^.Total basal area of woody species in the study area was 31.12 m²h^-1. The dominant and ecologically most important tree species in Gemechis Forest on the basis of their importance value index( IVI) values were Maesa lanceolata (19.2), Rytigna neglecta (16.9), Maytenus sp. (15.9), Bersama abyssinica (14.2), Argomuellera  macrophyllab (11.7), Dovyalis caffra (10.9), Teclea nobilis (9.24) and Vernonia amygdalina (7.3). Cummulative DBH class distribution showed that large number of individuals fall in lower DBH class, which shows that this vegetations is in a good regeneration status. However, as some species are of irregular population structure and low IVI further study should be conducted to identify factors that negatively affect them. In general, the data from this study showed that the  forest had high species diversity. From the cummulative DBH class distribution of the study area, the number of individuals that fall in lower DBH classes were higher than their number at higher DBH classes which indicate that seedlings and sapling were more in number than the mature/older woody species which suggesting that vegetation of Gemechis forest was generally in a good regeneration status.

Keywords: Basal area, Diameter at breast highest, Gemechis forest, Important value index,  Woody species