Woody species Composition, Vegetation Structure and Regeneration Status of Aziga Mountain Natural Forest in Angacha District, Kambata Tambaro Zone, SNNPRS, Ethiopia

Abstract

This study was conducted on Aziga Mountain Natural Forest in Angacha District; Kambata Tembaro Zone of SNNPRS. The objective of this study was to investigate the floristic composition, vegetation structure, and regeneration status of woody species. A systematic sampling method was used to collect woody vegetation data from 27 plots 20 m×20 m sample plots which were established at 40 m intervals in alternate directions along the transect, laid at 400m apart. Within the main plots, five (four at the corner and one at the center) 5 m×5 m sub-plots were laid to collect saplings and seedlings data. Woody species data of Shrubs, Lianas and Trees were analyzed by using the Shannon diversity Index, Height and DBH of all identified woody species heights taller than 1.5m and thicker than 2.5cm were measured for vegetation structure analysis. A total of 47 woody plant species belonging to 29 families and 44 genera were identified. Of the all collected woody species, 24(51.06%) were trees, 19(40.43%) shrubs and 4(8.51%) were lianas. Of the all 29 families, the family Fabaceae was the most species-rich family represented by four species (8.7%), followed by families Lamiaceae and Apocynaceae represented by three species each. Total density and basal area calculated for all woody species were 1376 individuals/ha and 14.3m²/ha, respectively. The most of the tree densities were distributed in lower diameter (DBH) and height classes and proceeding with decreasing degree of individuals towards the higher DBH classes and height classes, it shows an inverted J-shape distribution. The most important (dominant) woody species with the highest(IVI) values were Croton macrostachyus (25.47),Cordia africana (23.814),Olea europaea subsp.cuspidata(20.44),Juniperus procera(17.68),Hagenia abyssinica(15.8),Acacia abyssinica(14.34),Millettia ferruginea subsp.ferruginea(13.78) and Dombeya torrida(13.2).Analysis of regeneration status of all woody species in study forest showed that seedling >sapling> mature trees implying the forest is at good regeneration status. But large size trees in the forest were under threat due to anthropogenic disturbances for different purposes. To reduce this threat and to use the forest sustainably, participatory forest management is required.