Floristic composition, structure and regeneration status of woody plant species in Northwest Ethiopia

Abstract

Most of the natural forests in Awi Zone of Northwest Ethiopia exist as patches due to increasing human disturbance. The Bradi forest in this zone was assessed for its floristic composition, structure and regeneration status of woody plant species to better understand the natural dynamics and suggest appropriate conservation strategies. A total of 60 quadrats (20mx20m) were established along transect lines running parallel to each other using systematic sampling for vegetation sampling. Height and diameter at breast height (DBH) were measured for those woody plant species >2 m in height and >2 cm in DBH. Seventy-one woody plant species that belong to 64 genera and 40 families were identified, of which 36 (50.7%), 13 (18.3%), 13 (18.3%) and 9 (12.7%) were trees, lianas, shrubs and trees/shrubs, respectively. A total of 1838 stems ha−1 with DBH >2 cm and height >2 m were recorded. Albizia shimperiana, Paveta abyssinica, Croton macrostachyus, Discopodium penninervium, Teclea nobilis were the most abundant and frequently-occurrring species in the forest. The forest had a Shannon species diversity index score of 3.84 and an evenness of 0.89. Furthermore, the forest had an average basal area of 90.03m2/ha. Woody species with high basal area value such as Ekebergia capensis, A. shimperiana, Prunus africana, and C. macrostachyus were found to have greater importance value index (IVI). According to the DBH and height class distribution, the forest had an inverted J-shaped distribution pattern. However, analysis of regeneration status at species level revealed that 27.5%, 10%, 40% and 22.5% of the woody plants had good, fair, poor regeneration and not regenerating, respectively. This calls for enrichment planting and area exclosures of the study forest.