Abstract

Tropical Afromontane forests are among the most species-rich ecosystems on earth and comprise exceptional species richness and high concentrations of endemic species. The natural forest of Agama, an Afromontane forest, was studied with the objectives of determining its species composition, diversity and community types. Systematic sampling design was used to collect vegetation data. Soil samples were taken from each relevé at a depth of 0 to 30 cm and soil pH, sand, clay and silt were analyzed. The plant communities’ classification was performed using the hierarchical cluster analysis. We evaluated species richness, eveness (Pielou J’ index) and diversity (Shanon-Wiener index). Sorensens’s similarity ratio was used to compare Agama forest with other similar forest in Ethiopia. A total of 162 plant species, 130 genera and 70 families were recorded from which Acanthaceae and Rubiaceae were the richest families. Furthermore nine endemic plant species were identified. In this study, four plant community types were identified and described.  Post-hoc comparison of means among the community types showed that altitude was differed significantly between community types, indicating altitude is the most important factor in determining community type. Phytogeographical comparison of Agama Forest with other vegetation using Sorensens’s similarity ratio revealed the highest similarity with Masha and Godre forest. In conclusion Agama forest presents high richness, diversity and endemism, with different plant communities according to altitude. Thus conservation of plant biodiversity is highly recommended.

Key words: Diversity, altitude, phytogeography, richness, endemism.