Distribution and Importance Value Index of Woody Species Under Different Successional Stages at Jello-Muktar Dry Afromontane Forest, South-eastern Ethiopia

Abstract

The study was carried out at 8°55’N-9°05’N latitude and 40°50’E-40°51’E longitude, South-Eastern Ethiopia at Jello-Muktar dry afromontane forest to assess variations in distributions and Importance Value Index of woody species under three successional stages. We laid out a total of 90 sample plots for the three suceestional stages. For each successional stage, three sites were selected each with 10 sample plots. The average distance between the plots was 200 m and each plot have radius of 30m. In each plots, identification, counting and measurement of diameter at breast height (DBH) of all trees and shrubs (DBH≥ 10cm) was conducted. Analysis of The Importance Value Index (IVI) at different successional stages and sites was based on the frequency, density and dominance of each species at different successional stages. The result showed a gradual increase in the total number of trees and shrub species from the ES to the IS and MS succession and species of mature forests were present throughout the chrono-sequences of all stages. Species of Vernonia amygdalina, Juniperus procera, Olea africana, Olea capensis, Hagenia abyssinica, Prunus africana, Rosa abyssinica, Discopodium penninervium and Premna resinosa were found in all successional stages. In the ES succession, Vernonia amygdalina was the highest in terms of its IVI of 36.58 followed by Vernonia auriculifera (31.66) and Hagenia abyssinic (30.28). Species of Hagenia abyssinica had the highest IVI of 67 and 23 in IS and MS successions respectively. There must be conservation strategies and priorities for those species that occurred only once in one of the sites and species with low IVI in addition to the dominant ones.