Biology » Ecology and the Biosphere » Terrestrial Biomes

Savannas

Savannas

Savannas are grasslands with scattered trees, and they are located in Africa, South America, and northern Australia (see the figure below). Savannas are hot, tropical areas with temperatures averaging from 24 °C to 29 °C (75 °F to 84 °F) and an annual rainfall of 10–40 cm (3.9–15.7 in).

 This world map shows the eight major biomes, polar ice, and mountains. Tropical forests, deserts and savannas are found primarily in South America, Africa, and Australia. Tropical forests also dominate Southeast Asia. Deserts dominate the Middle East and are found in the southwestern United States. Temperate forests dominate the eastern United States, Europe, and Eastern Asia. Temperate grasslands dominate the midwestern United States and parts of Asia, and are also found in South America. The boreal forest is found in northern Canada, Europe, and Asia, and tundra exists to the north of the boreal forest. Mountainous regions run the length of North and South America, and are found in northern India, Africa, and parts of Europe. Polar ice covers Greenland and Antarctica, which the latter is not shown on the map.

Each of the world’s major biomes is distinguished by characteristic temperatures and amounts of precipitation. Polar ice and mountains are also shown.

Savannas have an extensive dry season; for this reason, forest trees do not grow as well as they do in the tropical wet forest (or other forest biomes). As a result, within the grasses and forbs (herbaceous flowering plants) that dominate the savanna, there are relatively few trees (see the figure below). Since fire is an important source of disturbance in this biome, plants have evolved well-developed root systems that allow them to quickly re-sprout after a fire.

 A grassy slope plain is dotted with small trees.

Savannas, like this one in Taita Hills Wildlife Sanctuary in Kenya, are dominated by grasses. (credit: Christopher T. Cooper)

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