Many people in central Africa farm to produce the food they eat. The Masai tribe of the Kenyan Serengeti practise nomadic farming, a traditional method of farming allows vegetation to recover from animal grazing whenever the farmers move on to another area.
However, in the past 40 - 50 years the Masai's way of life and farming have been disrupted as a result of commercial pressures and government policies. The ecosystem has also started to suffer.
These interventions forced the nomadic Masai farmers onto marginal land. Their traditional pastoral migration patterns have been disrupted and they have been compelled to use smaller areas of land for their cattle. Overgrazing has been the inevitable result.
The Serengeti's increasing population has resulted in a growth in demand for meat, which has led to a rapid increase in meat poaching. Poachers are now killing around 150,000 wildebeest a year - and a dramatic fall in the wildebeest population will cause a knock-on effect throughout the ecosystem.