What changes in the Sahel are affecting the nomadic people?

Im doing this in geography for my coursework and basically the nomadic people are the ones changing the Sahel by doing a process called slash and burn. Slash and burn is when the tribe uses the land and all its resources and then just moves on to a new peice of land. The land before is left baron and dry, this is the process of desertification. hope i could help lol :) Hannah,14