Plant communities and their species diversity in the semi-arid rangelands of Borana lowlands, southern Oromia, Ethiopia

Abstract

Plant community types and botanical composition of herbaceous and woody plants in the Borana lowlands were investigated by multivariate methods (TWINSPAN and DCA) based on 125 plots of size 20 m × 20 m sampled from three districts across different functional land use units. By TWINSPAN, eight plant communities were identified: (i) Acacia drepanolobium-Pennisetum mezianum, (ii) Bidens hildebrandtii-Chrysopogon aucheri, (iii) Chrysopogon aucheri-Commiphora africana, (iv) Cenchrus ciliaris-Chrysopogon aucheri, (v) Acacia bussei-Pennisetum mezianum, (vi) Commiphora erythraea-Sansevieria ehrenbergii, (vii) Acacia melliphera-Setaria verticillata, and (viii) Heterpogon contortus-Hildebrandtia obcordata. Characteristic species at the different levels of TWINSPAN divisions were identified. The Chrysopogon aucheri-Commiphora africana community had the highest beta (3.37) and gamma (131) diversity, whereas the Heterpogon contortus-Hldebrandtia obcordata community had the smallest beta (0.35) and gamma (23) diversity. The frequency of plant communities was positively and strongly correlated with beta and gamma diversity.