Floristic Composition and Diversity of Vascular Plants inRemnant Patches of Arsi-Bale Massif of Oromia RegionalState, Ethiopia

Abstract

This research was done in Arsi-Bale Massif remnant vegetation of southeast Ethiopia to investigate vascular plant diversity and endemism in forest patch, riverine, and grazing land-use types. A total of 126 quadrats, each with 900 m2 (30 m × 30 m), were selected systematically along the altitudinal gradient. Shannon Weiner Diversity index and R Package 3.2 were applied to analyze species composition and diversity, whereas the similarity ratio among land use and other related vegetation was determined using Sorensen’s index. From the study, 382 vascular plant species under 223 genera and 92 families were identified. The growth forms revealed that there were 118 woody (26 trees, 10 lianas, and 82 shrubs) and 239 herbaceous species of plant. Of these, 216, 165, and 154 species are shared by riverine, forest patch, and grazing land-use types, respectively. Asteraceae with 68 species was the most dominant family in the present study, followed by Poaceae, Lamiaceae, and Cyperaceae with 30, 21, and 13 species, respectively. Forty-four endemic species were documented in this study. According to the IUCN Red List, 22 species were not evaluated; 10 species were least concerned; 1 species was endangered; and 1 species was vulnerable, while 4 species have been categorized as not threatened. The highest similarity was observed between grazing and riverine land-use types; this may be due to the presence of many adjacent plots in both land use, associated mechanisms of adaptation, and requirements for species occurrence. Moreover, the floristic composition similarity of the study area in comparison with other vegetation types of Ethiopia shows variation (Ss = 0.223–0.526), maybe due to climatic variation, ecological distance, and disturbances. Generally, the total diversity and evenness of the studied remnant vegetation were 2.917 and 0.948, respectively. This lower diversity value clearly indicates that there are many human-induced factors deteriorating the plant species of the studied vegetation. Therefore, the concerned body of the government should work with local farmers to conserve the remaining plant species including many endemic species by developing appropriate conservation and management plans.