Characteristics of the Savannah (by jiachun)

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Characteristics of the Savannah (by jiachun)

A community of plants that were adapted to the area and climate zone in which they lived (such as cacti in the deserts or oak forests in temperate climate and giant redwoods in California). These original plant communities are what is called "natural vegetation".

Tropical Grasslands: SavannahBy Alistar and Jia Chun

Location-Mainly between latitudes 5° and 15° north and south of the Equator.Climate-Rainfall ranges between 100 and 400 mm a year.a) When the rainfall is 100-200 mm, generally only grasses can survive the dry season.b) When the rainfall reaches 300 mm the soil retains enough water to sustain shrubs through the dry season as well.c) When the rainfall exceeds 300 mm, enough water is left to support solitary trees.d) When rainfall exceeds 400 mm, enough moisture remains during the dry season to allow trees to grow and form a canopy, which shades out the grasses.-In regions of higher rainfall (East Africa), savannah vegetation is maintained by periodic fires.Fires consume dry grass at the end of the wet season, burn back forest vegetation, check tree/shrub growth and stimulate new grass growth.-Temperatures remain high throughout the year, but there is a slightly cooler season when the sun in overhead the tropic in the opposite hemisphere.-Temperature may drop slightly at the start of the rainy season and the highest temperatures coincide with the summer rains.Vegetation Sub Zones-Savannah parkland; twisting, branching deciduous trees, e.g. baobobs, acacia, and eucalyptus, which grow fairly close to each other. Grasses grow beneath trees, adapted to seed and die back at the start of the dry season.-Savannah grassland; trees are less dense, and often draw water from an underlying aquifer through a long root system. Grasses tend to be tall and coarse in areas of higher precipitation, more sparse in areas with lessrecipitation.-Savannah scrub; vegetation tends to be a discontinuous layer of bushes, e.g. sagebrush and thorns and sparse, dried up tussocks of grass. This zone has experienced the worst effects of advancing desertification.Savannah trees;-Deciduous - lose their leaves to reduce transpiration because of the winter drought.-Xerophytic - drought resistant.-Sclerophyllous - Leaves are small, waxy and thorn like.-Roots are long and extended to reach deep underground.-Tend to grow to 6-12m in height and contain “Y” shaped branches.-Trunks are gnarled, and bark is thick to retain moisture.Example; The baobob tree has a trunk of up to 10m in diameter. Its root like branches hold only a minimum number of tiny leaves in order to restrict transpiration. Some are estimated to be thousands of years old. Their trunks are resistant to the local fires.Shrubs/Grasses;-Grasses grow in tufts and tend to have inward curving blades and silvery spikes.-After the onset of the summer rains, they grow very quickly to over 3m in height. Elephant grass grows to 5m.-They become yellow by sun drying.

Savannah[suh-van-uh]-Open grasslands, usually with scattered bushes or trees, characteristic of much of tropical Africa.

Characteristics ofthe Savannah