Plant species composition and diversity in wetlands under forest, agriculture and urban land uses.

We investigated the full range of vegetation diversity in six wetlands under different land uses of Ethiopia. In total, 122 vascular plant species that belong to 86 genera and 37 families were identified. The family Poaceae and Asteraceae contributed the highest number of species. The beta and Shannon diversity ranged from 3.7 to 10.7 and 1.5–3.4 and differed significantly across wetlands. When considering the land uses, the agricultural and urban wetlands could even be more diverse than the forested wetlands and therefore, were not significantly different. The ranges of plant species diversity among the impaired wetlands were observed to be related to disturbance and competitive exclusion processes, and environmental heterogeneity. As observed, disturbances due to drainage, overgrazing, cultivation and pollution reduced the plant diversity through removing sensitive species, and increase species diversity through creating diverse habitats suitable for invader species. The dominant (or characteristic) species of each wetland showed that the urban and agricultural wetlands were highly degraded when compared to forested wetlands. The principal component analysis revealed highest similarity between Boye and Merewa wetlands can be explained from their extensive environmental heterogeneity. Moreover, these impaired wetlands were invaded by upland weeds by outcompeting socioeconomically and ecologically important native species. Thus, data of species and their environmental stresses in wetlands of Ethiopia could be used to prioritize and develop management strategies for east African wetlands.