Assessing The Impact Of Exotic Tree Plantation On Local Plant Species Diversity: The Case Of Abba Jote Forest, Jeldu Distirct Western Shewa Zone, Oromia Regional State, Central Ethiopia.

Abstract

The highlands of Ethiopia have undergone drastic forest loss and habitat degradation leaving fragmented by virtue of threatened exotic plantation. This study was conducted on impacts of exotic tree plantation on local species diversity in Jeldu district, Abba Jote Forest, West Shewa Zone, Ethiopia. The aim of this study was to examine the composition, distribution and impacts of exotic woody plants on vegetation dynamics inside Abba Jote Forest. All data were analysed using JMP-14 software. Purposive sampling method was employed to collect vegetation data from different plots of size 20m x 20m plots. These Result revealed that higher number of species richness’ (27) was recorded in Grevillea robusta plantation followed by 14 species richness in Eucalyptus plantation. Fewer species richness (only 4) was recorded in Cupressus lusitinica plantation in the study area district. A total natural regeneration of species plants with different growth habits (trees, shrubs) was recorded. Shannon-Weiner diversity index (4.27) lowest evenness (0.79) was maximum in Grevillea robusta plantation whereas Cupressus lustinica plantation has the lowest Shannon-Weiner diversity index of (1.3) and the highest evenness of (0.94). The result indicates that the larger number of indigenous tree species grow under Grevillea robusta than the others. This asserts that Grevilla robusta has little impact on local species diversity than Eucalyptus globulus and Cupressus lustinica plantations. Hence,Grevillea robusta plantations can be used to foster natural forest rehabilitation in the study area. Grevillea robusta facilitate regeneration of indigenous woody species in the study area may be by reducing soil erosion and ameliorating the microclimate of plantation sites. Since, plantations with different exotic tree species impacts effect on the understory native species composition, diversity, density, and, remarkable impact on belowground native species concerned should raise community awareness’ about exotic plants species. Therefore, to increase community awareness about the ecological impacts of different exotic tree species such as Grevillea robusta to foster natural forest regeneration, reduce soil erosion, and improve microclimate conditions.