Spatial patterns of riparian vegetation community composition and diversity along human- affected East African highland streams

Riparian vegetation, which plays important roles in conservation of regional biodiversity and provision of many environmental services, has been severely degraded in East Africa by human activities. To ameliorate this degradation, more knowledge of the vegetation and factors affecting it is required. Thus, effect of land use on the plant community composition, species richness and diversity patterns were investigated along 18 streams in the Gilgle Gibe River catchment, in south-western Ethiopia, using 100 m(2) plots established along transects on both sides of the streams at 35 sampling locations beside land designated as agricultural, forested, mixed vegetation or eucalyptus plantation. The communities in the plots were surveyed and classified by Two-Way Indicator Species Analysis. In total, 107 vascular plant species belonging to 49 families were recorded. Species richness and diversity were lowest along streams beside agricultural land, which had narrow riparian buffers, and highest along forested streams, which had wider riparian buffers. The communities in the sampling plots were assigned to seven groups. Species richness was positively correlated buffer width (r = 0.74, p < 0.01). The results highlight the human influence on riparian vegetation and the importance of sustainable management that is compatible with its conservation and restoration. However, to address the severity and complexity of forest fragmentation, conservation strategies must embrace a multi-site, contextual approach.