Population Structure of Woody Plant Species at Jello-Muktar Dry Afromontane Forest, South-Eastern Ethiopia

Abstract

There is limited quantitative information with regard to the vegetation structure in South-eastern Ethiopia. This study was therefore carried out to determine the density, DBH, Basal area and height distributions of woody plant species at Jello-Muktar dry afromontane forest. Systematic sampling design was used to collect vegetation data in total of 90 circular sample plots of each 30cm radius. In each plot all woody plants which are ≥2 cm diameter at breast height and height > 1m were identified, measured and recorded. Analysis of Size class distribution was performed for height (100 cm and above) and diameter classes (2 cm and above) and BA of each woody plant species with DBH ≥ 2 cm was computed The study revealed that more than 93% of the individuals had the DBH class distribution of more than 40.01 cm DBH. The DBH class distribution showed an inverted J-shape curve with the presence of more individuals in the lower DBH classes which is an indication of the active regeneration. The basal area in this study ranged from 10.9 m ²/ha for DBH class 1 to 59.02 m ²/ha for DBH class 11. The total basal area was found to be 245.65m² and there was a J-shape curve relationship between DBH class and basal area class distribution. About 89 % of trees and shrubs had heights of more than 5m tall but only 3.45% the total individuals recorded were more than 30m. The population structure of the entire forest showed higher stem densities in the Lower diameter classes and progressively declining stem densities with increasing Diameter classes. Study of woody plant species population structure is an invaluable strategy for planning management actions and also helps in identifying the status of the forest stand with regard to its rate of disturbance. Hence it is better to manage those parts of forest stands with less number of individuals through enrichment planting of indigenous tree species.

Keywords: DBH, basal area, height, DBH class, height class, dry afromontane, woody

DOI: 10.7176/JNSR/13-5-03

Publication date:March 31^st 2021