Tree species composition, structure and regeneration status in Munessa natural forest, Southeastern Ethiopia

Munessa forest is one of the undifferentiated afromontane forests in Ethiopia. The forest has threatened by deforestation, free grazing and illegal logging.  This study aimed to estimate the structure, composition and diversity of tree species and their regeneration status in Munessa natural forest.  Vegetation data were collected from 54 plots of 20 m x 20 m for trees and 162 subplots of 5 m x 5 m for seedlings and saplings that were laid along six parallel transect lines. Vegetation structure, basal area, IVI and species prioritization were analyzed using spreadsheet programs. Correlation coefficients, vegetation classification, frequency, Shannon diversity index and Shannon evenness were analyzed using R software version 3.2.2 for windows 8. A total of 41 tree species belonging to 27 families were recorded. Fabaceae was the most dominant family represented by four species followed by Oleaceae and Rutaceae, each having three species. The hierarchical cluster analysis revealed four community types, of which Syzygium guineense - Croton macrostachyus community type, exhibited the highest species diversity and evenness. The Shannon diversity and evenness index for the entire study area was 2.6 and 0.39 respectively. The correlation between elevation and species richness was negative and insignificant (r = -0.545, p < 0.05). The densities of seedlings, saplings and mature trees were 6,934, 1,686 and 481 individuals ha-1 respectively. This indicated that the regeneration status was significantly lower compared to other similar sites. The total basal area of the forest was 91.75 m2ha-1 and its IVI ranged from 0.62 for Calpurnia aurea to 70.29 for Podocarpus falcatus. The estimated values of population structure and regeneration status of the forest indicated that there was a huge disturbance induced by anthropogenic factor particularly free grazing and tree cutting. Therefore sustainable forest management strategies need to be implemented for sustainable utilization of the forest.