GRASSLAND: THREE MAJOR TYPES OF GRASSLANS
Grasslands occur mostly in the interiors of continents in areas that are too moist for deserts to form and too dry for forests to grow. Grasslands persist because of a combination of seasonal drought, grazing by large herbivores, and occasional fires—all of which keep shrubs and trees from growing in large numbers. The three main types of grassland—tropical, temperate, and cold (arctic tundra)—result from combinations of low average precipitation and varying average temperatures. 1. TROPICAL GRASSLAND: One type of tropical grassland, called a savanna, contains widely scattered clumps of trees such as acacia, which are covered with thorns that keep some herbivores away. This biome usually has warm temperatures year-round and alternating dry and wet seasons. Tropical savannas in East Africa are home to grazing (mostly grass-eating) and browsing (twig- and leafnibbling) hoofed animals, including wildebeests, gazelles, zebras, giraffes, and antelopes, as well as their predators such as