Oak Savanna
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An oak savanna is a type of
savanna A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to ...
—or lightly forested
grassland A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...
—where
oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...
s (''Quercus ''spp.) are the dominant trees. The terms "oakery" or "
woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the ''plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (see ...
s" are also used commonly, though the former is more prevalent when referencing the Mediterranean area. These savannas were maintained historically through
wildfire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire ...
s set by lightning, humans, grazing, low
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
, and/or poor soil. Although there are pockets of oak savanna almost anywhere in North America where oaks are present, there are three major oak savanna areas: 1)
California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
, British Columbia, Washington and Oregon in the west; 2)
Southwestern United States The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural region of the United States that generally includes Arizona, New Mexico, and adjacent portions of California, Colorado, Ne ...
and northern
Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
; and 3) the prairie/forest border of the
Midwestern United States The Midwestern United States, also referred to as the Midwest or the American Midwest, is one of four census regions of the United States Census Bureau (also known as "Region 2"). It occupies the northern central part of the United States. I ...
. There are also small areas of oak savannas in other parts of the world. (See also
Eastern savannas of the United States The eastern woodlands of the United States covered large portions of the southeast side of the continent until the early 20th century. These were in a fire ecology of open grassland and forests with low ground cover of herbs and grasses. The fre ...
for information on pine savannas of the U.S. South.)


Midwestern oak savannas

The oak savannas of the Midwestern United States form a transition zone between the arid
Great Plains The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, an ...
to the west and the moist broadleaf and mixed forests to the east. Oak savannas are found in a wide belt from northern
Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...
and southern
Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...
, down through
Iowa Iowa () is a state in the Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wisconsin to the northeast, Illinois to the ...
,
Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...
, northern and central
Missouri Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...
, eastern
Kansas Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the ...
, and central
Oklahoma Oklahoma (; Choctaw language, Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a U.S. state, state in the South Central United States, South Central region of the United States, bordered by Texas on the south and west, Kansas on the nor ...
to north-central
Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...
, with isolated pockets further east around the
Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...
including Ontario. The
bur oak ''Quercus macrocarpa'', the bur oak or burr oak, is a species of oak tree native to eastern North America. It is in the white oak section, ''Quercus'' sect. ''Quercus'', and is also called mossycup oak, mossycup white oak, blue oak, or scrub o ...
''(Quercus macrocarpa)'' is the dominant species in northern oak savannas, although black oak ''(Quercus velutina)'', white oak ''(Quercus alba)'', and Hill's oak ''(Quercus ellipsoidalis)''are sometimes present. The dominant
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
in the south is usually the
black oak Black Oak may refer to: Places in the United States * Black Oak, Arkansas * Black Oak, Daviess County, Indiana * Black Oak, Lake County, Indiana, a neighborhood of Gary, Indiana * Black Oak, Missouri Other * Black Oak Arkansas Black Oak Ar ...
(''Quercus velutina''), although the
chinquapin oak ''Quercus muehlenbergii'', the chinquapin (or chinkapin) oak, is a deciduous species of tree in the white oak group (''Quercus'' sect. ''Quercus''). The species was often called ''Quercus acuminata'' in older literature. ''Quercus muehlenbergii ...
''(Quercus muhlenbergii)'', post oak (''Quercus stellata''), and black-jack oak (''Quercus marilandica'') are also common. The flora of the
herbaceous layer Stratification in the field of ecology refers to the vertical layering of a habitat; the arrangement of vegetation in layers. It classifies the layers (sing. ''stratum'', pl. ''strata'') of vegetation largely according to the different heights to w ...
generally consists of species associated with tallgrass prairies, both grasses and flowering plants, although some woodland species may be present. There are also a few species that are unique to oak savannas. Oak savannas, because of their mixture of grassland, woodland, and unique savanna species, typically have a higher plant diversity than grasslands and woodlands combined.


History

Before European settlement, the oak savanna, a characteristic
fire ecology Fire ecology is a scientific discipline concerned with natural processes involving fire in an ecosystem and the ecological effects, the interactions between fire and the abiotic and biotic components of an ecosystem, and the role as an ecosystem p ...
, was extensive and was often a dominant part of the ecosystem. Fires set by lightning, ensured that the savanna areas did not turn into
forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...
s. Savannas normally were found next to large prairies near rolling hills and this combination of habitat was perfect for deer, bison, elk, and other grazing animals. Only trees with a high tolerance for fire, principally certain oak species, were able to survive. On sandy soils, black oak (''
Quercus velutina ''Quercus velutina'', the black oak, is a species of oak in the red oak group (''Quercus'' sect. ''Lobatae''), native and widespread in eastern and central North America. It is sometimes called the eastern black oak. ''Quercus velutina'' was pre ...
'') predominated. On rich soils bur oak ''(
Quercus macrocarpa ''Quercus macrocarpa'', the bur oak or burr oak, is a species of oak tree native to eastern North America. It is in the white oak section, ''Quercus'' sect. ''Quercus'', and is also called mossycup oak, mossycup white oak, blue oak, or scrub oa ...
)'' was the major tree in Midwestern North America. These savanna areas provided habitat for many animals, including
American bison The American bison (''Bison bison'') is a species of bison native to North America. Sometimes colloquially referred to as American buffalo or simply buffalo (a different clade of bovine), it is one of two extant species of bison, alongside the ...
,
elk The elk (''Cervus canadensis''), also known as the wapiti, is one of the largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. The common ...
, and
white-tailed deer The white-tailed deer (''Odocoileus virginianus''), also known as the whitetail or Virginia deer, is a medium-sized deer native to North America, Central America, and South America as far south as Peru and Bolivia. It has also been introduced t ...
. The most fire-tolerant of the oak species is the bur oak (''
Quercus macrocarpa ''Quercus macrocarpa'', the bur oak or burr oak, is a species of oak tree native to eastern North America. It is in the white oak section, ''Quercus'' sect. ''Quercus'', and is also called mossycup oak, mossycup white oak, blue oak, or scrub oa ...
''), which is especially common in hill-country savannas in the Midwest. 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.


Restoration

With the rise in interest in
environmental conservation *Environmental protection *Nature conservation Nature conservation is the moral philosophy and conservation movement focused on protecting species from extinction, maintaining and restoring habitats, enhancing ecosystem services, and protec ...
, restoration and preservation of surviving areas of oak savanna began. Low intensity, spring prescribed burns have been used since 1964 at the
Cedar Creek Ecosystem Science Reserve The Cedar Creek Ecosystem Science Reserve is an ecological research site located primarily in East Bethel, Minnesota in the counties of Anoka and Isanti on the northern edge of the Minneapolis-Saint Paul metropolitan area. Name Originally t ...
in Minnesota in an attempt to restore the area to an oak savanna. Burned areas are now more savanna like (having greater grass and forb and lower shrub and lower tree representation) than unburned areas but still have higher overstory densities than apparently existed in presettlement times. Restoration work began in the 1970s in Illinois, followed by work in Wisconsin, Indiana, Iowa, Missouri, and Minnesota. The Bald Hill Natural Area in
Corvallis, Oregon Corvallis ( ) is a city and the county seat of Benton County in central western Oregon, United States. It is the principal city of the Corvallis, Oregon Metropolitan Statistical Area, which encompasses all of Benton County. As of the 2020 United ...
was established in the 1990s in part to protect oak savanna remnants. At one point in time the oak savanna was the most common type of vegetation found in the midwest, but it is now endangered with many ecologists every year working on replacing the oak savannahs that have been destroyed in the past.


Current distribution

Presettlement there was approximately 50,000,000 acres of oak savanna in Midwestern United States, all of it being exclusively in a wide strip stretching from southwestern Michigan to eastern Nebraska and from southern Manitoba to central Texas. After Europeans arrived, fire suppression and settlement diminished the oak savannas to a fraction of their former expanse, which currently exist in many fragmented pockets throughout its native range. Many sites are protected and maintained by government bodies or
non-profit A nonprofit organization (NPO) or non-profit organisation, also known as a non-business entity, not-for-profit organization, or nonprofit institution, is a legal entity organized and operated for a collective, public or social benefit, in co ...
organizations such as
The Nature Conservancy The Nature Conservancy (TNC) is a global environmental organization headquartered in Arlington, Virginia. it works via affiliates or branches in 79 countries and territories, as well as across every state in the US. Founded in 1951, The Natu ...
, the Wisconsin and Minnesota Departments of Natural Resources, and the Iowa Natural Heritage Foundation. In the midwest, about only 30,000 acres total of oak savanna still exist. The savannas that remain are fairly small at about 100 acres and this rarity has caused them to be categorized as “globally imperilled”. It is estimated that about only less than 0.02% of the original savannas remain due to human interaction and many organizations and conservations are prioritizing restoring and recreating these ecosystems in the midwest. Examples of remnant oak savanna include: * Neal Smith Wildlife Refuge near
Prairie City, Iowa Prairie City is a city in Jasper County, Iowa, Jasper County, Iowa, United States. The population was 1,700 at the time of the 2020 United States Census, 2020 census. It is twenty-two miles east of Des Moines, Iowa, Des Moines. History Prairie Ci ...
. *
Indiana Dunes National Park Indiana Dunes National Park is a United States national park located in northwestern Indiana managed by the National Park Service. It was authorized by Congress in 1966 as the Indiana Dunes National Lakeshore and was redesignated as the nation ...
in
Indiana Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th s ...
. * Hobart Nature District in
Hobart Hobart ( ; Nuennonne/Palawa kani: ''nipaluna'') is the capital and most populous city of the Australian island state of Tasmania. Home to almost half of all Tasmanians, it is the least-populated Australian state capital city, and second-small ...
,
Indiana Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th s ...
. * Numerous State Natural Areas in Wisconsin. * Lake County Forest Preserve District in Illinois. *
Waterfall Glen Forest Preserve Waterfall Glen is a forest preserve in Downers Grove Township, DuPage County, Illinois, between the towns of Darien and Lemont, covering . It contains several waterfalls on Sawmill Creek as it empties into the Des Plaines River. Rocky Glen Fall ...
near
Darien, Illinois Darien is a city in DuPage County, Illinois, United States. Per the 2020 census, the population was 22,011. A southwestern suburb of Chicago, Darien was named after the town of Darien, Connecticut. Darien is just north of I-55 and Historic U.S. ...
. *
Cook County Forest Preserve District The Forest Preserve District of Cook County is a governmental commission in Cook County, Illinois, that owns and manages a network of open spaces, containing forest, prairie, wetland, streams, and lakes, that are mostly set aside as natural areas ...
and Iroquois County State Wildlife Area in Illinois. *
Oak Openings Preserve Metropark Oak Openings Preserve Metropark is a nature preserve located in Swanton Township, Ohio, owned and operated by Metroparks Toledo. Most of the park is an oak savanna ecosystem, characterized by alternating wetland and vegetated dunes. The park hos ...
in
Ohio Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...
. *
Pinery Provincial Park Pinery Provincial Park is a provincial park located on Lake Huron near Grand Bend, Ontario. It occupies an area of 25.32 square kilometres (6,330 acres). It is a natural environment-class Provincial Park created to help preserve oak savannah and ...
on
Lake Huron Lake Huron ( ) is one of the five Great Lakes of North America. Hydrology, Hydrologically, it comprises the easterly portion of Lake Michigan–Huron, having the same surface elevation as Lake Michigan, to which it is connected by the , Strait ...
in
Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...
, Canada. Examples of restored oak savanna sites: * Indiana's Conrad Savanna Nature Preserve in north Newton County.The Nature Conservancy
/ref> * Oak savanna restoration project site on
Winchell Trail Winchell Trail is a round trip, pedestrian-only trail in Minneapolis, Minnesota, United States, that runs along the west side of the Mississippi River between Franklin Avenue South and East 44th Street. Popular with bird watchers and naturalist ...
in
Minneapolis, Minnesota Minneapolis () is the largest city in Minnesota, United States, and the county seat of Hennepin County. The city is abundant in water, with thirteen lakes, wetlands, the Mississippi River, creeks and waterfalls. Minneapolis has its origins ...
* Wisconsin's Pleasant Valley Conservancy State Natural Area. * Minnesota's Belwin Conservancy.


See also

*
California oak woodland California oak woodland is a plant community found throughout the California chaparral and woodlands ecoregion of California in the United States and northwestern Baja California in Mexico. Oak woodland is widespread at lower elevations in coasta ...
*
Dehesa A ''dehesa'' () is a multifunctional, agrosylvopastoral system (a type of agroforestry) and cultural landscape of southern and central Spain and southern Portugal; in Portugal, it is known as a ''montado''. Its name comes from the Latin 'defens ...


References


External links

* *
Oak Savannas: Characteristics, Restoration, and Long-Term Management



Oak Savannah
Documentary produced by
Oregon Field Guide ''Oregon Field Guide'' is a weekly television program produced by Oregon Public Broadcasting focusing on recreation, the outdoors, and environmental issues in the state of Oregon. The show has become part of the Oregon zeitgeist. Steve Amen is th ...
{{DEFAULTSORT:Oak Savanna California chaparral and woodlands Grasslands Plant communities of California Plant communities of the Western United States Savanna Temperate grasslands, savannas, and shrublands