Composition and structure of woody plant communities as a function of altitude and human degradation in Afromontane moist evergreen forests SW Ethiopia

Abstract

Tropical moist evergreen forests provide key ecosystem services for human wellbeing. However, due to human pressure, Afromontane forests have lost much of their natural species composition and structure. In this study, vegetation surveys were carried out with the aim of investigating woody species composition and structure and their drivers of degradation in SW Ethiopia. Woody plant species were identified, forest structure measured and environmental variables determined in 75 plots across four forest patches along an altitudinal gradient. The result shows that the remaining patches still have 63 woody species from 36 families. Our results showed the presence of three plant communities: a first mid-elevation degraded mountain forest community, a second mid-elevation more intact community and a third higher elevation degraded cloud forest community. The Shannon diversity index of the second community was significantly higher than the first and the third community. Exotic tree planting and charcoal production were important determinants of the first community composition. Despite their socioecological importance, the expansion of exotic tree planting showed to be a major threat for natural forest ecosystem. In the study area, intervention is needed to maintain the ecological balance between plantation and natural forest.