southwestern chain extending into Uganda is often called the Agoro Mountains. Watersheds The Kinyeti River and other streams that drain the northern slopes of the mountains feed the Badigeru Swamps, which are long and up to wide at high water, but generally only wide. Some of the water from the northern end of this swamp may filter eastward to the Veveno River, then via the Sobat River to the White Nile. Some of the water may filter westward to the Bahr el Jebel section of the White Nile. To the south and west the mountains are drained by the fast-flowing Aswa River / Ateppi system. To the northeast the mountains are drained by the Koss River, which flows between the Imatongs and the Dongotona Hills. Ecology Average annual rainfall in the Imatong range is about . Some of the mountain range's habitat is semi-protected within the Imatong Central Forest Reserve. Flora The plains and the lower parts of the mountains are covered by deciduous woodland, wooded grassland and bamboo thickets to the north and west. The areas to the east and southeast are in the rain shadow of the mountains, with dry subdesert grassland or deciduous or semi-evergreen bush. The mountains have rich diversity of flora, with hundreds of species that are found nowhere else in South Sudan. Their diversity is due to their position between the West African rain forest, the Ethiopian plateau and the East African mountains, coupled with their relative isolation for long periods during which new species could emerge. Vegetation in the lower areas includes woodlands of Albizia and Terminalia, and mixed Khaya lowland semi-evergreen forest up to . Above there is montane forest with Podocarpus, Croton, Macaranga and Albizia up to . The levels above do not seem to have ever been inhabited by humans, but have been visited by honey-gatherers and hunters, and the fires they have started have destroyed the forest on many hill tops. At the highest levels, the forest is replaced by Hagenia woodland, Erica (heather) thicket and areas of bamboo. Fauna According to a 1984 report, the mountains supported abundant wildlife, including healthy populations of colobus and blue monkey, bush-pig and a local sub-species of bushbuck. The south eastern Kipia and Lomwaga Uplands were least visited by hunters and had the largest populations of elephant, buffalo, duiker, hyaena and leopard. Mammals that normally inhabit a forest environment show greatest differentiation