           !  "# $% &% !% ’ # !% ( Plant Diversity along Altitudinal Gradients in the Eastern Escarpment of the Rift Valley of Northern Ethiopia: Key for Conservation Priorities Ermias Aynekulu Center for Development Research (ZEF), University of Bonn, Walter-Flex-Str. 3, 53113, Bonn, Germany. Email ermias8@yahoo.com Abstract The forests of the mountainous landscapes of the northern Ethiopian highlands, which once were characterized by high plant diversity, have been degraded and fragmented for decades. Although forest and biodiversity conservations are major development priorities in northern Ethiopia, it has been difficult to implement conservation strategies at regional level due to reasons like land-use conflicts. The aim of this study thus was to identify the priority areas for biodiversity conservation. We measured data on the floristic and structural composition of vascular plants using twenty nine plots (2500m 2 ) with 100m altitudinal intervals, using two transects taken along the eastern escarpment the Rift Valley of northern Ethiopia ranging from 1000 to 2740m above sea level. In both sites, we found that the species richness of vascular plants increases steadily with increasing altitude up to 2000m and declines after that. The minimum species richness is 2 species per plot at the lower altitude whilst the maximum is 45 species per plot obtained between 1900 and 2100m. Hence, the altitudinal zone between 1900 and 2100m can be considered as a priority zone for biodiversity conservation. Such species- rich zones may serve as a habitat and corridor for birds and wild life and is an important seed source for vegetation restoration activities which are widely undertaken on the degraded sites of northern Ethiopia. Keywords: Dessea forest, species richness, altitudinal zone, corridor, land use, northern Ethiopia 1 Introduction Studying plant species distribution in response to environmental factors helps to generate information for a better understanding of ecological processes and in managing ecosystems. Altitude is a major environmental variable that controls the distributions of plant communities