Floristic Composition,Diversity And Endemism Patterns Of Seed Plants In Ethiopia And Eritrea,in The Horn Of Africa

The central task in floristic study is to elucidate and understand the Patterns of plant diversity and the assemblages of floristic systems in particular regions from different perspectives so as to develop and prioritize effective conservation plans especially in tropics where biodiversity is relatively rich but,highly threatened due to climatic change and other anthropogenic driven environmental changes.Ethiopia and Eritrea are among the tropical countries located in the horn of Africa and known for their rich biodiversity resources.However the floristic compositions of their flora had not been clearly known based on the characteristics of its biota.The diversity and endemism patterns of its plant communities also had not been clearly described while at the same time the flora is the most threatened one implying that the study of floristic compositions and the understanding of the spatial patterns of plant diversity are paramount in this region to address such gaps and protect the biodiversity of the region.So in this study we classified the flora of the areas into meaningful floristic units and assessed and mapped the diversity and endemism patterns of plant communities across the region.In order to carry out these,we quantified different diversity measuring metrics and analyzed their patterns at a uniform spatial scale of 0.5°×0.5°grid cells.The flora of the area was quantitatively classified into meaningful floristic units based on the similarity patterns of these 0.5°×0.5°grad cells in terms of their native seed plants taxonomic and phylogenetic ? diversity at the genus,total and endemic species levels.Hierarchical cluster analysis was performed to divide this flora according to the described parameters and ANOSIM(analysis of similarities)was used to evaluate the significance differences between the derived cluster results.The results of the analysis revealed that based on its plant characteristics the flora of Ethiopia and Eritrea can be divided in to two floristic sub-provinces(the south west and the north east),five flora districts and thirteen floristic sub-districts.While the two floristic sub-provinces were found to be more related to the elevation gradients of the region in which the southwest sub-province was almost found to be belonged to the highland parts of the region and the north east sub-province was found to be located in the lowland and warmer parts of the areas,the five floristic districts were found to be more attributed to the variation in plant species compositions and geographical locations among different sites.Our result also showed very variable spatial plant diversity patterns across the region and found that the montane parts of the region are generally the areas of high plant species diversity in the region.Owned to the barriers from the Rift Valley in the region,the species turnover rate between the western and the eastern highlands was found to be very low.Using species weighted endemism index three plant species endemism centres were detected in the flora of Ethiopia and Eritrea including the Simien mountain centres,the east upland show a centre and the Bale mountain centre.The Simien and Bale mountains endemic plant species centres were found to have the highest degree of plant species endemism while the East upland showa centre was the first time to be detected.These centres of unique(endemic)plant species were also found concentrated to the highland parts of the region in the northern,central and south eastern parts Ethiopia.Overall our study has provided a basic scientific frameworks and additional insights to the flora of the region from different perspectives.The obtained results will have a great significance in different aspects.The derived floristic systems provide spatially explicit framework units that help in many broad scale evolutionary and ecological studies as well as in large scale conservation analyses.The mapped diversity patterns and the detected endemism centres help in guiding and planning effective biodiversity conservation programs in the region by specifying potential areas and species of focus for conservation.