Plant Communities and Diversity along Altitudinal Gradients from Lake Abaya to Chencha Higlands

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Addis Ababa University


Vegetation-environment relationships have been investigated in the study. Community transition and species diversity are affected among others by environmental heterogeneity. Multivariate numerical techniques were adopted to identify communities. The resemblance function for the identification of communities was similarity ratio, while correlation coefficient was used to identify species groups. Shannon-Wiener diversity index and Jaccard’s community coefficient were computed to measure species diversity in a community and community transitions respectively. One-way analysis of Variance (ANOVA) was used to test the differentiation of communities due to environmental factors such as soil properties, slope and aspect. The results helped to identify five plant communities and seven species groups. Statistical analysis indicates that the differentiation of communities might partly be explained by the variation of soil properties and topographic features at p<0.05 level of significance, excepting Cation exchange capacity. Community’s grade gradually along altitudinal gradients as indicated by the high community coefficients 0.52, 0.53 and 0.16 (Table 1 and 2) in between adjacent communities. Shannon- Wiener diversity index revealed that species diversity and richness is high in communities 1, 2 and 3 at 1250-1800m altitudinal ranges. The high species diversity and richness could be due to environmental heterogeneity, which are associated with the effect of altitude. These communities are found in steep slopes and in areas of human settlement nearby where disturbance of the vegetation is observed. Therefore, conservation of these vegetation types should be given priority concern for the conservation of biodiversity in the study area



Geography and Environmental Studies