sentence: People keep many animals for food.
sentences_before: More land has become barren. This is called deforestation. Because people farm intensively in order to grow more crops, the soil becomes dry and infertile. In the long run, no crops can be grown. We called this overcultivation.
sentences_after: However, the grass cannot support so many grazing animals. We called this overgrazing. Finally the desert spreads towards the surrounding areas.
concept_name: People
headings: Sahel
categories: Geography of Africa Biomes