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5.4.5: Savannas

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    34096

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    Learning Objective

    Recognize distinguishing characteristics of savannas & plant adaptations of the biome.

    Savannas are rolling grasslands scattered with shrubs and isolated trees. Not enough rain falls on a savanna to support forests. Savannas are also known as tropical grasslands. They are found in a wide band on either side of the equator on the edges of tropical rainforests. One can find savannas in Africa, South America, and northern Australia. Savannas are hot, tropical areas with temperatures averaging from 24oC –29oC (75oF –84oF) and an annual rainfall of 51–127 cm (20–50 in). Savannas have both a wet season and an extensive dry season with frequent fires. As a result, scattered in the grasses and forbs (herbaceous flowering plants) that dominate the savanna, there are relatively few trees (Figure \(\PageIndex{1}\)) . 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 dotted with pine trees.
    Figure \(\PageIndex{1}\): Although savannas are dominated by grasses, small woodlands, such as this one in Mount Archer National Park in Queensland, Australia, may dot the landscape. (credit: "Ethel Aardvark"/Wikimedia Commons)

    Adaptations

    In the dry season, plants have adapted to the lack of water in Savannas. For example, trees and larger shrubs have deep roots so they can access underground water during the direst time of the year. Some trees, like the Baobob tree in Madagascar, store water in their trunk (up to 120,000 liters or 32,000 US gallons) to endure harsh drought conditions. Some trees may lose their leaves (deciduous) and grow them back during the rainy season, when water is available. In general, many savanna plants have small leaves to reduce water loss. Grasses are dormant during the drought, with their growth season mainly during the wet season.

    Attributions

    Curated and authored by Kammy Algiers using Terrestrial Biomes from Biology 2e by OpenStax (CC-BY). Access for free at openstax.org

    This page titled 5.4.5: Savannas is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Kammy Algiers (ASCCC Open Educational Resources Initiative) .