COMPARISON OF WOODY SPECIES DIVERSITY, POPULATION STRUCTURE AND PROVISIONING ECOSYSTEM SERVICES ALONG DISTURBANCE REGIME IN BABILE ELEPHANT SANCTUARY, ETHIOPIA

Abstract

The study was conducted at Babile Elephant Sanctuary (BES), to identify and document the list of woody species, and to analyze diversity, richness, evenness and population structural status of woody species and importance of provisioning ecosystem services. The diversity of plant species and population structure of woody species were analysed from 60 quadrats, each with 20 m x 20 m for trees and 5 m x 5 m for shrubs and climbers, using systematic sampling methods with three levels of disturbances regime, namely, low disturbed (LD), moderately disturbed (MD) and heavily disturbed (HD) sites. Vegetation parameters such as diameter at breast height (DBH), richness, evenness and density of woody species were recorded. Ecosystem Services (ESs) were identified using questionnaires surveys from 110 households in three villages lies inside and adjacent to BES by random sampling method. The importance attributed to each ES was evaluated using a descriptive rank analysis. Ordered logistic regressions were used to test whether and how socioeconomic factors influenced the importance attributed to ESs. The most used services were determined, based on the percentage of respondents uses a particular service. Shannon Weiner Diversity Index was used to analysis vegetation data. A total of 61 woody species belonging to 38 genera, and 29 families were identified in study sites. Fabaceae was represented by the highest number of species (14 species = 22.90). Population density of vegetation was significantly higher in the MD site, followed by the LD site. The total basal area of LD, MD and HD were 27.2, 19.8 and 11.2 m2/ha, respectively. LD site had significantly (P= 0.04) highest Shannon’s diversity index value (3.21) than the others two disturbance levels. Fodder, fuelwood, and construction were ranked the most important and used ESs. Age and gender, significantly played important roles in people's perceptions towards the importance of ESs. This result suggests that the consequence of human induced disturbance on woody species diversity and natural forest ecosystem services appeared to be negative depending on the type and intensities of the disturbances.