Plant Diversity, Vegetation Structure and Relationship between Plant Communities and Environmental Variables in the Afromontane forests of Ethiopia

Abstract

Diversity patterns of vascular plant species were studied along geographical gradients in the Afromontane region of Ethiopia. Vegetation data were sampled from five moist evergreen Afromontane forest fragments, namely Harenna (southeast), Bonga, Maji, Berhane-Kontir and Yayu (southwest). In each forest, quadrats of 20x20 m were laid along transects to collect vegetation data. The patterns of plant diversity were evaluated on the basis of species richness as the total number of species at each site and species change between and within sites and in relation to vegetation structure. Floristic analyses of five Afromontane forests altogether revealed 118 families and 653 vascular plant species, and about 5% of the species were endemic. Species richness and densities vary considerably between the forest sites. The highest beta and gamma diversities were recorded in the Berhane-Kontir forest and the lowest in Bonga. The studied Afromontane forests were floristically different but the common feature of the geographically separated forests is the occurrences of wild coffee populations. Ordination of the study quadrats of the forests forms five groups based on the species composition. Moist evergreen Afromontane forests support a high density of woody plants, which, however, differ between sites. The Ethiopian moist evergreen Afromontane forests are highly threatened due to anthropogenic factors and, thus, need immediate conservation measures. It is recommended that conservation strategies should focus on multiple-sites conservation networking in order to include a range of forests in the conservation system.