The effects of disturbance on the population structure and regeneration potential of five dominant woody species - in Hugumburda-Gratkhassu National Forest Priority Area, North-eastern Ethiopia

摘要

Vast areas of forests in North-eastern Ethiopia have been replaced by cropland, shrub land or grazing areas. Thus, information about how vegetation composition and structure varies with disturbance is fundamental to conservation of such areas. This study aimed to investigate the effects of disturbance on the population structure and regeneration potential of five dominant woody species within forest where local communities harvest wood and graze livestock. Vegetation structure and environmental variables were assessed in 50 quadrats (20mx20m). In most of both disturbed and undisturbed treatments, Juniperus procera was the highest contributor to the basal area of the forest, while that of Olinia rochetiana was the lowest. Analysis of population structure showed high density at lower Diameter at Breast Height (DBH) and low density at higher DBH classes. Undisturbed forest treatments had 84% canopy cover, 22m mean vegetation height and a density of 1320 trees of dominant species and 1024 seedlings/saplings ha(-1). In disturbed habitats, canopy cover (73%), mean vegetation height (18m) and density of dominant trees and saplings were significantly lower than in undisturbed habitats. Thus, to ensure species, survival and maintain species diversity managed use of the protected area is essential.