An oak savanna is a type of savanna, or lightly-forested grassland, found in central North America. The dominant tree is usually the black oak (Quercus velutina), although in some areas the burr oak or chinquapin oak predominate. The dominant grass species is typically the little bluestem. The oak savanna ecosystem is found in the Great Lakes region and the adjacent American Midwest.

History

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Before European settlement, the oak savanna ecosystem was sustained by a fire cycle. Fires, set by lightning or Native Americans, ensured that the savanna areas did not turn into forests. Only trees with a high tolerance for fire, principaly certain oak species, were able to survive. On sandy soils, black oak (Quercus velutina) predominated. On rich soils bur oak (Quercus macrocarpa) was the major tree in central North America. These savanna areas provided habitat for a many grazing animals, including bison, elk and deer.

European settlers cleared much of the savanna for agricultural use. In addition, they suppressed the fire cycle. Thus surviving pockets of savanna typically became less like savannas and more like forests or thickets. Many oak savanna plant and animal species became extinct or rare.

In the 1970s, conservationist began to try to restore and preserve these surviving pockets of savanna.

Current distribution

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Surviving pockets of oak savanna can be found throughout the historical range of this ecosystem. Many are protected and maintained by government bodies or non-profit organizations such as The Nature Conservancy. Examples include the Indiana Dunes National Lakeshore in Indiana, and in Ontario, Pinery Provincial Park on Lake Huron. A small section of Oregon White Oak savanna is also preserved at Mount Pisgah Arboretum in Eugene, Oregon.

Ecotope