ECOLOGICAL STUDY OF THE WOODY VEGETATION OF GOBELLE VALLEY OF BABILE ELEPHANT SANCTUARY, OROMIA REGIONAL STATE, EASTERN ETHIOPIA

Abstract

An ecological study of the natural vegetation was carried out in Gobelle Valley of the BES, to identify and document the list of woody species, and to analyze diversity, richness, evenness, population structure, and regeneration status of woody species. Vegetation data were collected from 60 quadrats of 20 x 20 m (400 m2) laid systematically at every 100m along 3 transects. Vegetation parameters such as diameter at breast height (DBH), richness, evenness and density of woody species (i.e. shrubs and trees) were recorded, and all the collected vascular plant species were brought and deposited to HU Herbarium. Different diversity indices were used to analyze vegetation data. Shannon Weiner Diversity Index and Biodiversity Professional Software Version 2 were used to determine species diversity and evenness. A total of 58 plant species in 36 genera and 18 families were identified from the study area. The Shannon-Wiener Diversity index (H') and evenness values of Gobelle valley vegetation were 3.05 and 0.75, respectively. The collected species were composed of 44.8 % trees, and 55.2% shrubs. Fabaceae was represented by the highest number of species 15 (26%). A total basal area of 22.38 m2/ha, and a density of 34687 individuals ha-1 were calculated for woody species (5159.6trees and29738.7shrubs) individuals ha-1. The highest impact of invasive species was imposed from Lantana camara which had a density of 1,828 individual’s ha-1.Furthermore, 3 endemic species which are under the Red Data List of IUCN were also identified and requires close attention to conserve them in situ. Generally, the forest was dominated by the small sized trees and shrubs indicating that it is in the stage of regeneration. The existence of strong anthropogenic disturbance in the sanctuary calls for an immediate intervention to conserve and ensure sustainable biodiversity of the study area.