Diversity, disturbances and endemism of plants in Dens Natural Forest of Ankober District, Ethiopia

Abstract

The population pressure on the vegetation of Ethiopia is not only declining the diversity, but also decreasing the endemism and forest resources by degrading land and causing the invasion of alien species. The current study was carried out to assess the diversity, endemism, and threats of Dens natural forest, which covers a total of 107 hectares. A total of 65 (20m x 20m) quadrats were laid in seven-line transects thrown from the edge of the forest using the systematic sampling method for trees and shrubs, and 325 sub-plots (1m x 1m) for herbaceous species were established at the four corners and at the center of the main quadrat. Among the five communities identified, community type 3 (Croton macrostachyus - Maytenus arbutifolia) had the highest species richness (89 species), diversity (H’=3.85) and species evenness (J=0.856). Community type 5 (Bersama abyssinica - Allophylus abyssinicus) had the least species richness (75 species), but its species diversity (H’ = 3.58) was higher than community type 2 (Podocarpus falcatus - Croton macrostachyus) (H’ = 3.54) because of higher equitability. Among the 129 plant species of Dens Forest, 10 plant species (7.8%) were identified as endemic to Ethiopia. Firewood collection (22.5%), collection of woods for house construction (21.8%) and farm instrument preparation (21.1%) were severe anthropogenic activities in the forest. Even though the endemism in Dens natural forest is lower, the diversity of Dens forest is the highest when compared with other forests.