Woody species composition and structure of Kuandisha afromontane forest fragment in northwestern Ethiopia

Abstract

To investigate the woody species composition, diversity and structure of Kuandisha Afromontane forest, vegetation and environmental data were collected from 53 plots of 10 m × 50 m for trees and shrubs and 265 subplots of 2 m × 4 m for seedlings were laid along eight transect lines. The local name, scientific name, abundance, DBH, height and percentage foliage cover of species were recorded. Environmental variables, namely altitude, latitude and longitude as well as disturbance levels were also recorded in each plot. Structure, basal area, importance value index (IVI) and species prioritization were analyzed using spreadsheet programs. Correlation coefficients, frequency, relative frequency, Shannon diversity index, Shannon evenness and vegetation classification were analyzed using an R package. Sixty-six species belonging to 40 families were recorded. Fabaceae was the most diverse family consisting of seven species, followed by Euphorbiaceae and Asteraceae. In terms of habit, 29 species were trees, 28 were shrubs, and 9 were lianas. The overall Shannon diversity index was 2.5. The frequency and relative frequency of woody species with DBH ≥2.5 cm ranged from 1.9 to 92.5 and 0.1 to 5, respectively. Seedling density varied among species ranging from five to 9938 individuals ha−1. The total basal area of woody species having DBH ≥2.5 cm is 15.3 m2 ha−1. The IVI of species ranged from 0.13 for Solanum giganteum Jacq. to 28.4 for Croton macrostachyus Del. The woody vegetation was classified into five community types. Species richness, diversity and evenness of communities were strongly positively correlated. On the other hand, the correlation between disturbance and seedling density, and species richness was strongly negative. Thus, among the recorded woody species, a significant portion was either lacking regeneration or selectively removed for various purposes. The lack of seedlings of those species is mainly attributed to anthropogenic disturbances particularly free grazing. As a result, 14 tree, seven shrub and one liana species were prioritized for conservation and management interventions.