Woody Species Composition in Relation to Spatial and Environmental Gradients in Acacia-Commiphora Vegetation Ecosystem of Ethiopia

Abstract

Woody species composition at local scale has been studied well in the tropics. However, how the species composition is related to the spatial and environmental gradients was poorly studied. Here, we examined the effects of the topographic aspects and altitude gradient on the species composition across four sites of Acacia-Commiphora woodland and bushland ecosystem. We collected data on the number of species, number of individuals, dbh and total height for those dbh was ≥ 2.5cm from ten quadrates (size: 50 × 50 m each) along transect of about 2kms laid out in each four sites. Altitude was taken with handheld GPS (Garmin GPSMAP 60CSx) and topographic aspects were recorded for each quadrate. The species composition was dissimilar among the four sites, across altitudinal gradients and topographic aspects. Here, the majority of the rare species are specific to each site, for example, Olea europea is the rare species in site (A) but not recorded in the rest of the three sites. Our overall results underscore the importance of considering the spatial scales and environmental variables in designing conservation methods. Nevertheless, identifying the biotic attributes driving the species composition in the ecosystem envisages further studies.