Soil Nutrient Composition in Afromontane Forests of Northern Ethiopia

Deforestation in the northern highlands of Ethiopia has left 35,000 forest fragments ranging in size from 3 to 300 ha (Bongers et al 2006). Deforestation produces edges which increase disturbance within the forest such as decreased water availability and increased light. To determine the degree of these edge effects and the nutrient status of these forests, I analyzed the nutrient composition of soils along a gradient from pasture, exterior forest, interior forest and canopy. I examined two forests at different elevations: Bahir Dar (1800 m) and Debre Tabor (2800 m). Deforestation had a strong, negative effect on soil nutrients. The pasture soils had the lowest % nitrogen, % phosphorus and % carbon in comparison to the other habitats. It also had a significantly lower pH. Isotope signatures and bulk density were also significantly impacted. Pasture soils surprisingly had the lowest C:N ratio due to its minimal carbon stocks. Differences in elevation did not significantly impact the effect of deforestation upon the soil. The differences in pasture soils properties and nutrient composition indicate that deforestation has a significant, negative effect on soil fertility and health