Plant and animal life
There are two main vegetation zones that correspond to the climatic regions of the Sudan and the Sahel. In the Sudanic zone, localized forest corridors are found along the Guinean border and in the river valleys; the rest of the area is covered with savanna. The trees include the néré, or twoball nitta tree (Parkia biglobosa), the karite (Butyrospermum parkii), the cailcedra (Senegal khaya; Khaya senegalensis), and the kapioka. The incidence of trees decreases to the north as the Sudanic zone merges with the Sahel. The Sahel is characterized by steppe vegetation, notably such drought-resistant trees as the baobab, doum palm, and palmyra. These trees also disappear to the north, where short, thorny plants such as the mimosa, acacia, and cram-cram (Cenchrus biflorus, a member of the grass family) grow; all vegetation is absent in the far-north region of the Sahara. Beginning in the latter half of the 20th century, deforestation, overgrazing, and repeated episodes of drought served to greatly speed the rate of naturally occurring desertification, resulting in the encroachment of the desert on the Sahel.
The animal life of the Sudan and of the Sahel is rich and varied. Large herbivorous mammals include gazelles, antelopes, giraffes, and elephants. The main carnivores are lions, panthers, and hyenas. Crocodiles and hippopotamuses inhabit the rivers, and there are a wide variety of monkeys, snakes, and birds (including the ostrich). Boucle du Baoulé National Park along the Baoulé River in the west and the Ansongo-Ménaka Animal Reserve and Douentza (Gourma) Elephant Reserve in the east are major wildlife sanctuaries.