The Wabi Shebelle is the main river in central Somali Region. Rising between the Arsi and Bale mountains, it curves round the Bale massif and flows south-east to Somalia. This site, i.e. the lower section of the Wabi Shebelle, starts at Imi. It then continues for more than 300 km through Gode, Kelafo and Mustahil, dropping gradually to c.250 m near the Somalia border. In this area, the Wabi Shebelle and its main seasonal tributary from the east, the Fafen, cut through a series of wide, flat shelves of sedimentary rock. These are often overlain, as in the Gode valley, by deep, alluvial soils. The highest areas, at around 1,000 m, are east of the Fafen river. Between Imi and Kugno, Tamarix spp. and Terminalia brevipes grow together. Below this, and towards Kelafo, the river flows through a flat plain where the riverbanks and adjacent land are subject to seasonal inundation. Such areas are often covered in a tangled growth of small bushes and herbs that include wild relatives of cotton. At Kelafo, the river cuts through and runs parallel to a low limestone ridge with Acacia–Commiphora –Boswellia bushland on it. In the Mustahil area, the river forms flood-plains: these are covered with tall herbaceous vegetation comprising various salt-tolerant species, e.g. Schoenoplectus maritimus and other sedges, Limonium spp., shrubby Indigofera spp., climbers, and various grasses. Grasses dominate the areas around the flood-plains. Away from the river basin, the vegetation is mostly Acacia–Commiphora–Boswellia bushland. This association contains some interesting succulents, not least several endemic species of Jatropha and Euphorbia.
See Box and Tables 2 and 3 for key species. Within this area Eupodotis humilis is not uncommon, and Streptopelia reichenowi is locally fairly common. Sylvietta philippae is considered rare, and is only known from Warder. The site supports a number of Somali–Masai biome species that are little known or relatively uncommon elsewhere in Ethiopia. In addition to the three species mentioned above, biome species include Merops revoilii, Pseudalaemon fremantlii, Eremopterix signata, Neotis heuglinii, Oenanthe phillipsi, Nectarinia hunteri, N. nectarinioides, Ploceus bojeri, Passer castanopterus, P. gongonensis and Speculipastor bicolor. Spizocorys personata, Mirafra collaris and Tmetothylacus tenellus have also been recorded. Other species of interest include Charadrius mongolus, Rhinoptilus chalcopterus and Turdoides squamulatus. There is also an as-yet-unidentified greenbul living in the riverine thickets, and if Laniarius liberatus were to be found in Ethiopia then this would be the most likely site.
Non-bird biodiversity: What little is known of the vegetation in this area is sufficient to show that there are many species restricted to these arid areas which are either very poorly known, or new to science. Examples include Boswellia ogadensis, first collected from Kelafo, and not known from any other locality, and Acacia pseudonigrescens, known only from between Kelafo and Mustahil. Several species of Jatropha and Euphorbia are endemic to this part of Somali Region in Ethiopia, or also to neighbouring areas of Somalia.
Pressure/threats to key biodiversity
Away from the river, very little is known about the flora or fauna of this area. It is quite possible that vegetation through much of the area has come under increasingly severe pressure as a result of population increases, particularly from refugees, as well as from agricultural development schemes. The most important plant in the area is Cordeauxia edulis, a small tree (up to 2.5 m) that can grow on almost pure sand with less than 200 mm of rain a year. It has a highly nutritious fruit that is much prized by the local people. Once ripe, the nuts are collected and boiled or roasted to preserve them. Nothing has been done to determine the status of this plant, or indeed ensure its conservation. There is much to be done to document the wildlife, and determine conservation priorities in this area.