Floristic Composition and Structural Analysis of Komto Afromontane Rainforest, East Wollega Zone of Oromia Region, West Ethiopia

Abstract

ABSTRACT This study was conducted on Komto Forest in East Wollega Zone, Oromia National Regional State, west Ethiopia with the objective of determining the floristic composition, vegetation structure, community type and regeneration status for some tree species in the forest. Systematic sampling method was used to collect vegetation data. Accordingly, 53 quadrats each with 400 m2 (20 m X 20 m) for woody species and subplots of 1 m X 1 m within the main plots for herbaceous plants were laid along line transects radiating from the peak of Komto Mountain in 8 directions. All plots (quadrats) were laid at a distance of 200 m along the transect lines. For seedlings, the main quadrats were divided into subplots of 10 m X 10 m (100 m2) to make seedling counting easier. In each of these quadrats, all vascular plant species were collected and brought to ETH for identification. In addition, vegetation parameters such as DBH, height and seedling and sapling density of woody species including location and altitude of each quadrat were recorded. Vegetation classification was performed using PC-ORD software packages. Sorensens’s similarity coefficient and Shannon-Wiener diversity index were also used to detect similarities among communities and to compute species richness and evenness between the plant communities respectively. A total of 180 species in 151 genera and 66 families were identified from the forest out of which 31 were new records from Wollega (WG) floristic region for the flora of Ethiopia and Eritrea. Fabaceae and Asteraceae are the dominant familes in terms of species richness. Furthermore, 18 endemic species some of which are under the Red Data List of IUCN were also identified. In this study, four plant communities were identified and described. Structural analysis of some selected tree species revealed different population pattern. Generally, the forest was dominated by small sized trees and shrubs indicating that it is in the stage of secondary regeneration. Phytogeographical comparison of Komto Forest revealed the highest similarity with moist montane forests which asserts that Komto Forest is one of the moist montane Forests in Ethiopia. Studies on the structure and regeneration of the forest indicated that there are species that require urgent conservation measures. Therefore, based on the results of this study, detailed ecological studies in relation to various environmental factors such as soil type and properties, ethnobotanical studies to explore indigenous knowledge on the diverse uses of plants, and sound management and monitoring as well as maintenance of biodiversity that promote sustainable use of the forest and its products are recommended.