The Ouadi Rimé–Ouadi Achim Faunal Reserve, one of the largest protected areas in Africa, is situated in the centre of the country and covers three major habitat-types, Sahelian wooded grassland, sub-desert grassland, and desert. The wooded grassland includes areas of fixed dunes separated by wadis and depressions. The vegetation of this habitat is characterized by annual grasses interspersed with trees such as Acacia senegal, Balanites aegyptiaca, Combretum glutinosum and Boscia senegalensis. Sub-desert grassland covers some two-thirds of the reserve. Characteristic grasses include Aristida mutabilis, Chloris prieurii and Cenchrus biflorus, while the herbs Limeum viscosum, Indigofera hochstetteri and Blepharis linariifolia are also common. Trees, particularly Acacia tortilis, are concentrated in dune depressions. In the desert there is little permanent vegetation, but the hardy plant Cornulaca monacantha occurs in clumps on sandy soils. Topographically, the reserve is relatively featureless and, apart from one small area of volcanic outcroppings, there is little rocky country. The Goz Kerky is a long, largely continuous dune cordon which runs north–south through the reserve.The site is bordered to the east by a series of 1,500 m high massifs, from which arise the series of parallel wadis which dissect the reserve. With their associated flood-plains, temporary pools and inundation zones, these wadis greatly enhance the topographical and biological diversity of the reserve. Rainfall is restricted to July–September. There is considerable variation in mean annual rainfall, both between the north and the south of the reserve and between years at any one place. Thus, representative figures for the Sahelian wooded grassland are (e.g. at Abeché) mean annual rainfall 413 mm (range 105–980 mm), for sub-desert grassland (e.g. Arada) 205 mm (range 43–570 mm), and for desert (e.g. at Faya) 14 mm (range 0–73 mm).
See Box and Table 2 for key species. A total of 267 bird species have so far been recorded for the site. In addition to those mentioned below, the site also holds three species of the Sudan–Guinea Savanna biome; see Table 2. Thousands of migrant Palearctic waterbirds are reported to visit the wadis during the short rainy season.
Non-bird biodiversity: Threatened mammals include Gazella dama (EN, few), Gazella dorcas (VU) and Gazella rufifrons (VU). In addition, Acinonyx jubatus (VU) and Addax nasomaculatus (VU) used to occur but probably no longer do so, while Oryx dammah (EW) has certainly been extirpated.
BirdLife International (2019) Important Bird Areas factsheet: Ouadi Rimé - Ouadi Achim. Downloaded from http://www.birdlife.org on 26/08/2019.