WOODY SPECIES COMPOSITION, DIVERSITY AND VEGETATION STRUCTURE OF GURUMO WOIDE NATURAL FOREST IN WOLAITA ZONE, SNNPR, ETHIOPIA

Abstract

This study was conducted on Gurumo Woide natural forest in Wolaita Zone, SNNPR, Ethiopia to assess woody species composition, diversity and vegetation structure of the forest. Data were collected systematically along seven transects laid at 300m apart from each other and 20m by 20m twenty-two quadrats established at every 200m interval along the transect. In each major quadrat, five 1m by 1m sub quadrats were established at center and corner for seedlings and saplings assessment. Vegetation classification was performed using XLSTAT version 2015.2.01 software following Ward’s method. Shannon-Wiener diversity and Jaccard’s similarity coefficients were computed for communities. The DBH at the height > 1.3m above the ground was measured using vernier caliper. The height of individuals above the ground was measured by meter tape with the help of standardized long stick marked at 0.5m intervals. Altitude, aspect and coordinate points were measured using GPS. Slope was measured using clinometers. Density, frequency, basal area and IVI were computed. A total of 46 woody species belonging to 43 genera and 26 families were identified. Fabaceae was the species richest family, represented by 13%. The forest composed of 65% trees, 17% trees/shrubs, 13% shrubs and 4% lianas. DBH of all the identified species was classified into four classes. About 87% of the individuals were found in DBH < 6m. Of the 46 species identified, 17.9% was dominated by Syzygium guineense species and 15.4% by Olinia rochetiana species. Of the height of all individuals of species measured, 70% were found in < 5m. Two plant community types were recognized. Community type I had higher species diversity and evenness, 14.9 and 0.8, respectively. Syzygium guineense and Olinia rochetiana were found the densest and most frequent species. About 45% of the total IVI was contributed by dominant species. The general pattern of forest structure showed an inverted J-shape pattern. About 29 (66%), 6 (14%), and 5 (11.4%) species had no seedling, sapling, and matured stages, respectively. All the results of the study indicated that there is a need for effective conservation and participatory forest management in the area. Further studies on land use management system, soil seed bank, seed physiology, floristic study were recommended.