ABSTRACT
The landscape of east Africa, which includes Ethiopia, parts of the Horn of Africa, Sudan, Kenya, Uganda, Rwanda, Burundi and Tanzania, has changed dramatically over the last 14-10 million years from a relatively flat, homogenous region covered with mixed tropical forest, to a varied and heterogeneous environment, with mountains over 4,000 m high (Maslin et al., 2014). Volcanic activities which occurred between 14 and 8 Ma during the Miocene resulted in the formation of the Great Rift Valley, greatly altering the relief, hydrology and climate of the landscape. The change in physiography led to the rise of a variety of vegetation types, ranging from forests, savannas, grasslands and deserts. The region sits on an area of 6.2 × 106 sq km, 75 per cent of which is covered by grasslands with varying altitudes (Fig. 13.1), soil types, climates and woody vegetation. They comprise expansive semi-arid to arid grasslands, wooded grasslands, savanna, bushlands and woodlands as well as the extensive highlands, including the high elevation mountain regions (FAO, 2005). Productivity of these grasslands is variable and rainfall is the main determining factor. Generally, the regional rainfall pattern decreases northwards, away from the equator, except in the highlands; hence most grasslands in northern Kenya, most parts of Ethiopia and Sudan and the Horn of Africa are drier compared to the southern parts of Kenya, Uganda, Rwanda, Burundi and Tanzania. Some of the most expansive pure grasslands in the region are found in central and southern parts of former Sudan, extending into some parts of Ethiopia, western Kenya and northern and western Tanzania. At higher rainfall availability, grasslands are likely to be converted into farmlands. Most grasslands here have evolved with grazing by wildlife and livestock as part of their environment. They, however, suffer from a history of economic and political marginalization, demographic, socio-political and ecological challenges.
