COMPARISON OF PLANT SPECIES DIVERSITY IN THE AFRO-ALPINE ZONE OF BALE AND SIMEN MOUNTAINS

摘要: The Great Rift Valley bisects the highlands of Ethiopia into the eastern and western massifs. Among the number of high mountains in the surrounding escarpments, two are protected and designated as National Parks: Simen and the Bale Mountains National Parks, which are also located in either side of the Great Rift Valley. The montane moorlands, the montane grasslands and the woodlands are major ecoregions in the mountains. Above 3500 meters elevation lie the high Ethiopian montane moorlands. The present study aims at comparing the plant species diversity between plant communities of the two Mountains. Data collection was done during the successive field works that held between 2007 and 2009. Systematic sampling was performed in each mountain from three different habitats, each having four replicates of plots. In addition to the three commonly used diversity indices (species richness, Shannon entropy and Gini-Simpson index) the method of rarefaction was applied to avoid the sample size biases in estimating species richness. Chao 2 index was also used to compute quadrat richness. Though Bale Mountains is larger in size and expected to harbor more numbers of afro-alpine plant species than Simen Mountains, the present study revealed out that the reverse is true. The most likely explanation to such a result may be variation in the topography and biogeographic history of the mountains.