Influences of Tree Species and Canopy Cover on Aboveground Biomass Yield and Ground Cover of Herbaceous Plants in Eastern Oromia, Ethiopia

The study was conducted at Keramile protected open forest of Goro-gutu district, Eastern Ethiopia, with the objective to examine the effects of tree species on the above ground aboveground biomass yield and ground cover of the herbaceous plants. Three tree species, Podocarpus falcatus and Juniperus procera from indigenous and Cupressus lusitanica from exotic tree species were used. Twenty large trees from each tree species, a total of 60 trees were selected purposively and 480 samples (four quadrats under and outside canopy in four directions for each tree) of herbaceous plants were collected. The results of the current study showed that tree species, canopy cover and their interactions had significant (P<0.05) influence on herbaceous plant above ground aboveground biomass yield and ground cover. The herbaceous plants differed in terms of above ground aboveground biomass yield and ground cover between the three tree species and canopy types. The herbaceous plant above ground aboveground biomass yield and ground cover were significantly (P<0.05) higher under P. falcatus than to J. procera and C. lusitanica trees, while no significant differences were (P>0.05) found between J. procera and C. lusitanica trees. The above ground aboveground biomass yield and ground cover obtained outside canopy was significantly higher than under canopy cover of the three tree species examined. The overall result showed that tree canopy cover strongly decreased aboveground biomass yield (P<0.0001) and ground cover (P<0.0001) of the herbaceous plants. The increased above ground aboveground biomass yield and ground cover of herbaceous plants in the outside canopies in the current study indicates that the presence of these tree species in the study area could increase the vulnerability of the herbaceous plant community to future disturbances, such as climate events. Generally, tree species, canopy cover and their interaction had negative impact on ground cover and aboveground biomass yield of herbaceous plant, in Keramile protected open forest, Goro-gutu district, eastern Ethiopia. Therefore, integrated forest and herbaceous plant management and conservation is crucial in Keramile protected open forest, Goro-gutu district, eastern Ethiopia and areas receiving similar practice.