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.
