Assessment-standard projection: Projection: Albers Equal Area Units: Meters Spheroid: GRS80 Datum: NAD83 First Standard Parallel: 27 degrees 30 minutes Second Standard Parallel: 37 degrees 30 minutes Central Meridian: -90 degrees 00 minutes Latitude of Origin: 25 degrees 00 minutes False Easting: 0.0 False Northing: 0.0
Appalachian Plateaus, New England lowlands, mid-Atlantic coastal plain, Piedmont Plateau, 104,500 mi2 (270,700 km2)
Land-surface form.--This province includes topography of diverse nature and origin. The northern part has been glaciated. West of the Appalachian Mountains are the Appalachian Plateaus. The sedimentary formations there are nearly horizontal, a typical plateau structure, but they are so elevated and dissected that the landforms are mostly hilly and mountainous. Altitudes range from about 1,000 ft (300 m) along their western edge to somewhat more that 3,000 ft (900 m) on the eastern edge. East of the mountains is the Piedmont Plateau and coastal plain, where altitudes range from sea level to about 1,000 ft (300 m). Climate.--The continental climatic regime here ensures a strong annual temperature cycle, with cold winters and warm summers. Average annual temperatures range from 40 to 60F (4 to 15C). There is year-round precipitation, averaging from 35 to 60 in (890 to 1,530 mm) per year. Precipitation is markedly greater in the summer months, when evapotranspiration is great and moisture demands are high. Only a small water deficit is incurred in summer, whereas a large surplus normally develops in spring.
Vegetation.--This province is characterized by a winter deciduous forest (sometimes called temperate deciduous forest) dominated by tall broadleaf trees that provide a dense, continuous canopy in summer and shed their leaves completely in winter. Lower layers of small trees and shrubs develop weakly. In spring, a luxuriant ground cover of herbs quickly develops, but is greatly reduced after trees reach full foliage and shade the ground. Forest vegetation is divided into three major associations: mixed mesophytic, Appalachian oak, and pine-oak.
Mixed mesophytic vegetation, the deciduous forest with the greatest diversity, occupies moist, well-drained sites in the Appalachian Plateaus. Widespread dominants include American beech, tuliptree (also called yellow-poplar), several basswoods, sugar maple, sweet buckeye, red oak, white oak, and eastern hemlock, in addition to 20-25 other species. The best indicators of this association are buckeye and basswood.
The Appalachian oak association occurs east of the mountains. The dominant species are white oak and northern red oak. Chestnut formerly was abundant, but a blight has destroyed most of this species.
Pine-oak forest--sometimes called "Pine Barrens"--occupies dry sandy soils that are frequently exposed to naturally occurring fires along the northern Coastal Plain. There is a thick shrub layer beneath the pines. Atlantic white-cedar swamps occur on mesic sites.
Soils.--The pedogenic process associated with deciduous forest is podzolization, moderated by warm wet winters. As a result, soils are characteristically Alfisols. Toward lower latitudes, the tendency to laterization becomes stronger and Ultisols are encountered. Inceptisols are found on the plateaus. In the deciduous forests, a thick layer of leaves covers the ground and humus is abundant.
Fauna.--Important mammals include the whitetail deer, black bear, bobcat, gray fox, raccoon, gray squirrel, fox squirrel, eastern chipmunk, white-footed mouse, pine vole, shorttail shrew, and cotton mouse.
Bird populations are large. The turkey, ruffed grouse, bobwhite, and mourning dove are game birds in various parts of the province. The most abundant breeding birds include the cardinal, tufted titmouse, wood thrush, summer tanager, red-eyed vireo, blue-gray gnatcatcher, and Carolina wren.
Characteristic reptiles include the box turtle, common garter snake, and timber rattlesnake.
East-Central Drift and Lake-Bed Flats, Ozark Highlands, eastern interior uplands and basins, 270,000 mi2 (699,300 km2)
Land-surface form.--Most of the area is rolling, but some parts are nearly flat and in the Ozark Highlands the relief is moderate (up to 1,000 ft [300 m]). Low rolling hills, dissected plateaus, and basins are found in Tennessee and Kentucky. The northern parts of the province have been glaciated, but not the southern. Elevations range from 80 to 1,650 ft (24 to 500 m). Climate.--The climate has many characteristics in common with the oceanic broadleaf forest to the east, but precipitation decreases in quantity and effectiveness as one moves inland. Average annual temperatures range from 40F (4C) in the north to 65F (18C) in the south. Summers are hot, with frequent tornadoes. Precipitation varies from 20 in (510 mm) near the 95th meridian to 40 in (1,020 mm) in Ohio, and to 50 in (1,280 mm) in Tennessee. Most precipitation takes place during the growing season.
Vegetation.--Like its counterpart to the east, this province is dominated by broadleaf deciduous forest, but the smaller amounts of precipitation found here favor the drought-resistant oak-hickory association. Although other forests have oak and hickory, only this particular forest association has both species in abundance.
The oak-hickory forest is medium-tall to tall, becoming savannalike in its northern reaches from eastern Oklahoma to Minnesota, where it gradually turns into prairie.
From eastern Kansas to Indiana, it forms a mosaic pattern with prairie. Widespread dominants are white oak, red oak, black oak, bitternut hickory, and shagbark hickory. The understory is usually well developed, often with flowering dogwood. Other understory species include sassafras and hophornbeam. The shrub layer is distinct, with some evergreens. Many wildflower species occur. Wetter sites typically feature an abundance of American elm, tuliptree, and sweet gum.
Northern reaches of the oak-hickory forest contain increasing numbers of maple, beech, and basswood. The maple-basswood forest, dominated by sugar maple and American basswood, occurs from central Minnesota south through Wisconsin and northeastern Iowa. Glaciated areas of Ohio and Indiana feature a beech-maple forest defined by American beech and sugar maple. In these latter associations, oak and hickory occur on poor sites.
Soils.--As in the oceanic broadleaf forest, the soils change from Alfisols in the north to Ultisols in southerly latitudes. Toward the continental interior, calcification sets in as forest soils give way to the darker soils of the grasslands (Mollisols).
Fauna.--In the oak-hickory forest, acorns and hickory nuts provide abundant food for the ubiquitous gray squirrel. Fox squirrels are often found, as are eastern chipmunks.
Roving flocks of blue jays also feed on forest nuts. In summer, scarlet and/or summer tanagers, rose-breasted grosbeaks, and ovenbirds are common. The wild turkey is also found here. The cerulean warbler is common in the beech-maple forest, and occurs elsewhere as well.
Southeastern United States, 193,000 mi2 (499,900 km2)
Land-surface form.--This province comprises the Piedmont and the irregular Gulf Coastal Plains, where 50 to 80 percent of the area slopes gently toward the sea. Local relief is 100 to 600 ft (30 to 180 m) on the Gulf Coastal Plains, and 300 to 1,000 ft (90 to 300 m) on the Piedmont. The flat coastal plains have gentle slopes and local relief of less than 100 ft (30 m). Most of the numerous streams in the region are sluggish; marshes, lakes, and swamps are numerous. Climate.--The climate is roughly uniform throughout the region. Mild winters and hot, humid summers are the rule; the average annual temperature is 60 to 70F (15 to 21C). The growing season is long (200 to 300 days), but frost occurs nearly every winter. Precipitation, which averages from 40 to 60 in (1,020 to 1,530 mm) annually, is rather evenly distributed throughout the year, but peaks slightly in midsummer or early spring, when it falls mostly during thunderstorms. Precipitation exceeds evaporation, but summer droughts occur. Snow falls rarely and melts almost immediately.
Vegetation.--Climax vegetation is provided by medium-tall to tall forests of broadleaf deciduous and needleleaf evergreen trees. At least 50 percent of the stands are made up of loblolly pine, shortleaf pine, and other southern yellow pine species, singly or in combination. Common associates include oak, hickory, sweetgum, blackgum, red maple, and winged elm. The main grasses are bluestem, panicums, and longleaf uniola. Dogwood, viburnum, haw, blueberry, American beautyberry, youpon, and numerous woody vines are common. The West Gulf Coast is bordered along its shores by salt marshes characterized by the marsh grass Spartina.
Soils.--Ultisols dominate throughout the region, with locally conspicuous Vertisols formed from marls or soft limestones. The Vertisols are clayey soils that form wide, deep cracks when dry. Inceptisols on floodplains of the major streams are among the better soils for crops.
Fauna.--Fauna vary with the age and stocking of timber stands, percent of deciduous trees, proximity to openings, and presence of bottom-land forest types. Whitetail deer and cottontail rabbits are widespread. When deciduous trees are present on uplands, the fox squirrel is common. Gray squirrels live along intersecting drainages. Raccoon and fox inhabit the whole region and are hunted in many areas. Among mammals frequently encountered in the western part of this province is the nine-banded armadillo.
The eastern wild turkey, bobwhite, and mourning dove are widespread. Of the 20-odd bird species present in mature forest, the most common are the pine warbler, cardinal, summer tanager, Carolina wren, ruby-throated hummingbird, blue jay, hooded warbler, eastern towhee, and tufted titmouse. The red-cockaded woodpecker is an endangered species.
Forest snakes include cottonmouth moccasin, copperhead, rough green snake, rat snake, coachwhip, and speckled kingsnake. Fench and glass lizards are also found, as is the slimy salamander.
Atlantic and Gulf Coastal Plains, Florida, 173,800 mi2 (450,100 km2)
Land-surface form.--This province comprises the flat and irregular Atlantic and Gulf Coastal Plains down to the sea. Well over 50 percent of the area is gently sloping. Local relief is less than 300 ft (90 m), although some areas are gently rolling. Most of the region's numerous streams are sluggish; marshes, swamps, and lakes are numerous. Climate.--The climate regime is equable, with a small to moderate annual temperature range. Average annual temperature is 60 to 70F (16 to 21C). Rainfall is abundant and well distributed throughout the year; precipitation ranges from 40 to 60 in (1,020 to 1,530 mm) per year.
Vegetation.--Temperate rainforest, also called temperate evergreen forest or laurel forest, is typical in this province. Temperate rainforest has fewer species of trees than its equatorial or tropical counterparts, and hence larger populations of individual species. Trees are not as tall here as in low-latitude rainforests; leaves are usually smaller and more leathery, and the leaf canopy less dense. Common species include evergreen oaks and members of the laurel and magnolia families. There is usually a well-developed lower stratum of vegetation that may variously include tree ferns, small palms, shrubs, and herbaceous plants. Lianas and epiphytes are abundant. At higher elevations, where fog and clouds persist, the trunks and branches of trees are often sheathed in moss. A striking example of epiphyte accumulation at lower elevations is the Spanish "moss" that festoons the Evangeline oak, baldcypress, and other trees of the eastern Gulf coast. Along the Atlantic coast, the extensive coastal marshes and interior swamps are dominated by gum and cypress. Most upland areas are covered by subclimax pine forest, which has an understory of grasses and sedges called savannas. Undrained shallow depressions in savannas form upland bogs or pocosins, in which evergreen shrubs predominate.
A word about the vegetation of the coastal Southeastern United States may prevent some misunderstanding. On forest maps of the United States and on numerous maps of world vegetation, this coastal zone is shown as having needleleaf evergreen or coniferous forest. It is true that sandy uplands have forests of loblolly and slash pine, and that baldcypress is a dominant tree in swamps; but such vegetation represents either xerophytic and hydrophytic forms in excessively dry or wet habitats, or second-growth forest following fire and deforestation. The climax vegetation of mesophytic habitats is the evergreen-oak and magnolia forest. Soils.--Soils are mainly Ultisols, Spodosols, and Entisols. Temperate rainforest grows on a wide variety of upland soils, but most tend to be wet, acidic, and low in major plant nutrients. The soils are derived mainly from coastal plain sediments ranging from heavy clay to gravel, with sandy materials predominant. Silty soils occur mainly on level expanses. Sands are prevalent in hilly areas, but they also cover broad flats in central Florida.
Fauna.--This region provides habitat for a wide variety of animals. Except for a few isolated areas where black bear or the endangered Florida panther are found in small numbers, the whitetail deer is the only large indigenous mammal. Common small mammals include raccoons, opossums, flying squirrels, rabbits, and numerous species of ground-dwelling rodents.
Bobwhite and wild turkey are the principal game birds. Migratory nongame bird species are numerous, as are migratory waterfowl. Winter birds are are diverse and numerous. The red-cockaded woodpecker is an endangered species.
Of the numerous species of reptiles found in this province, the American alligator is the largest.
Land-surface form.--The province consists of flat to gently sloping broad floodplain and low terraces made up of alluvium and loess. From near sea level in the south, altitude increases gradually to about 660 ft (200 m) in the north. Most of the area is flat, with an average southward slope of less than 8 in/mi (127 mm/km). The only noticeable slopes are sharp terrace scarps and natural levees that rise sharply to several meters above adjacent bottom lands or stream channels. This is the land of oxbow lakes--the cutoff meanders. Swamps are significant in the extreme southern part of Louisiana. Climate.--The climate is similar to that found in adjoining parts of the Subtropical Division. Winters are warm, with temperatures ranging from 50 to 60F (10 to 16C), and summers are hot, with temperatures ranging from 70 to 80F (21 to 27C). Rain falls throughout the year, with a minumum in autumn. Temperature and precipitation decrease as one moves northward. At Natches, Mississippi, average temperatures for January and August are about 50F (10C) and 75F (24C), respectively. Average annual precipitation is 55 in (1,400 mm). Snowfall is negligible. Farther north, at Cairo, Illinois, average temperatures for January and August are about 41F (5C) and 77F (25C), respectively. Average annual precipitation is 43 in (1,100 mm).
Vegetation.--Before cultivation, this area was covered by bottom-land deciduous forest with an abundance of green and Carolina ash, elm, cottonwood, sugarberry, sweetgum, and water tupelo, as well as oak and baldcypress. Pecan is also present, associated with eastern sycamore, American elm, and roughleaf dogwood. Vines are prolific along water courses.
Soils.--The soils are a mosaic of Inceptisols (in alluvial bottom land), Alfisols (in areas of loess), and Mollisols (in areas with swampy vegetation).
Fauna.--Among the numerous bird species found here are the prothonotary warbler, white-eyed vireo, wood duck, yellow-billed cuckoo, Louisiana waterthrush, and all the species found in the Southeastern Mixed Forest.
Central lowlands, 218,200 mi2 (565,100 km2)
Land-surface form.--The Prairie Parkland (Temperate) Province covers an extensive area from Canada to Oklahoma, with alternating prairie and deciduous forest. The topography is mostly gently rolling plains, but steep bluffs border a number of valleys. Some areas are nearly flat; others have high rounded hills. Elevations range from 300 to 2,000 ft (90 to 600 m). The far northern portion of the province has been glaciated. Climate.--Summers are usually hot, and winters are cold, especially in the northern part of the province. Average annual temperatures may reach 40F (4C) in the north and 60F (16C) in the south. Winters are short and relatively mild in southerly areas. The frost-free season ranges from 120 days along the northern fringe to 235 days in the south. Average annual precipitation ranges from 20 to 40 in (510 to 1,020 mm), falling mainly during the growing season. Vegetation.--Vegetation in this province is forest-steppe, characterized by intermingled prairie, groves, and strips of deciduous trees. The alternation of forest and prairie in the western part of the province results chiefly from local soil conditions and slope exposure; trees are commonly found near streams and on northfacing slopes. The thin soils atop this area's limestone hills support very few trees. In the eastern part of the province, however, trees often cover the highest hills. The prairies seem to be areas that have not yet become forested, either because of frequent fires or because the last glaciation was too recent for final successional stages to have been reached.
Grasses are the dominant prairie vegetation. Most are moderately tall and usually grow in bunches. The most prevalent type of grassland is bluestem prairie, dominated by such plants as big bluestem, little bluestem, switchgrass, and Indian grass, along with many species of wildflowers and legumes. In many places where grazing and fire are controlled, deciduous forest is encroaching on the prairies. Due to generally favorable conditions of climate and soil, most of the area is cultivated, and little of the original vegetation remains.
The upland forest in this province is dominated by oak and hickory, forming part of the oak-hickory forest described above for the Eastern Broadleaf Forest (Continental) Province. On floodplains and moist hillsides, the deciduous forest is richer. In the western part of the province, it includes eastern cottonwood, black willow, and American elm.
Soils.--Mollisols dominate throughout the province. Alfisols are found in the Mississippi Valley.
Fauna.--In addition to prairie animals that do not need woody vegetation, many forest animals are found in this province. They inhabit the wooded valleys that extend westward across the region.
Few forms are peculiar to the region, but certain mammals are indicative of its riverine forests, including mink and river otter. On the prairies, thirteen-lined ground squirrels and blacktail prairie dogs are commonly seen.
Birds of the riverine forests include the belted kingfisher, bank swallow, spotted sandpiper, and green-backed heron. Upland birds include the horned lark, eastern meadowlark, and mourning dove.
West Gulf Coastal Plain, central lowlands, 80,100 mi2 (207,500 km2)
Land-surface form.--This province is a region of gently rolling to flat plains, many of them part of the Gulf Coastal Plain. Over 50 percent of the area is gently sloping. Elevations range from sea level to 1,300 ft (400 m), with a local relief of less than 300 ft (90 m). Most of the Coastal Plain streams and rivers are sluggish; there are numerous wetland areas along the coast.
Climate.--The climate is similar to that of the temperate prairies described above, except that winters are warmer and there is more precipitation, mostly in the form of rain instead of snow. Winters are warm (50 to 60F [10 to 16C]) and summers are hot (70 to 80F [21 to 27C]). Average annual precipitation ranges from 35 in (890 mm) in the north to 55 in (1,410 mm) in the south along the coast. Rain falls throughout the year, brought by on-shore winds in summer and by depressions in winter. Hurricanes are frequent in autumn. On the coast, the climate is almost without frost.
Vegetation.--This region consists of prairies and savannas. Like the temperate prairies to the north, it is part of the grassland-forest transition area of the central United States. Due to aridity and probably also to fires and grazing, this area is dominated by various short and medium-to-tall grasses, along with a few hardy tree species. Trees are typically evergreen and are widely spaced and short of stature, rarely more than 25 ft (8 m) tall. Post oak and blackjack oak dominate the cross timbers region of Oklahoma and Texas. Hickories are common only in stands near the forest region. Soil is a key factor in local distribution. Fine, heavy soils generally support grassland vegetation, and coarse, lighter soils are covered with stands of savanna.
Bluestem is the principal grass throughout the region. The Gulf Coast of Texas has an extensive border of marshes stretching inland 5 to 10 mi (8 to 16 km), sometimes farther.
Soils.--Mollisols, Alfisols, and Vertisols are the dominant soils. Dry Alfisols are found on the savannas, with Mollisols and Vertisols on the prairies.
Fauna.--Whitetail deer are abundant, as is the nine-banded armadillo. The red wolf is classified as an endangered species.
The scissor-tailed flycatcher, eastern meadowlark, lark sparrow, and eastern and western kingbirds are indicator species of the region.
Southern Florida, Florida Keys, 7,800 mi2 (20,200 km2)
Land-surface form.--The Everglades occupy an extensive, almost flat marl and limestone shelf generally covered with a few feet of muck and a little sand. Elevation ranges from sea level to 25 ft (7.6 m). The low, level coastal plain contains large areas of swamps and marshes, with low beach ridges and dunes rising several feet above them. Poorly defined broad streams, canals, and ditches drain into the ocean. In the interior, hammocks rise a few feet above the general area.
Climate.--Average annual temperatures in this tropical climate range from 70 to 75F (21 to 24C), with minimums from October to February. The area is frost-free practically all year. An average of 50 to 65 in (1,280 to 1,660 mm) of rain falls per year, mostly between late spring and the middle of autumn.
Vegetation.--About one-fifth of the area is covered by tropical moist hardwood forest. Cypress forests are most extensive, but mangrove is widespread along the eastern and southern coasts. Much of the area is open marsh covered by phreatophytic grasses, reeds, sedges, and other aquatic herbaceous plants. Several areas covered by dense grasses are classified as medium-tall grasslands, with sawgrass and three-awns as major plants. Within these grasslands there are mesic habitats called "hammocks" that rise above the surrounding, usually wetter areas. These hammocks contain groves of low to medium-tall broadleaf evergreen trees and shrubs. Mahogany, redbay, and several palmettos are common. One also finds strangler fig and abundant epiphytes.
Soils.--Histosols are the principal soils. In slightly less wet parts of the southern Everglades, Inceptisols occupy extensive areas.
Fauna.--The Everglades have a wide variety of influent species from adjacent areas of palmetto prairie, cypress swamp, magnolia forest, and mangrove. Slight changes in water level create substantial changes in habitat and fauna.
Among the many mammals found are whitetail deer, Florida panther, black bear, raccoon, bobcat, opossum, skunk, various bats, marsh and swamp rabbits, cotton rat, and fox squirrel. Manatees inhabit estuaries and interlacing channels. Numerous species of birds live in this province. Before the water level in much of the Everglades was lowered by drainage, the area was home to large numbers of herons, egrets, limpkins, mottled ducks, Florida Everglade kites (snail kites), and other birds. The Florida Everglade kite is now classified as endangered. Characteristic lizards are the Caroline anole and the brown red-tailed skink. The rough green snake, key rat snake, and southern Florida coral snake are found here. The endangered American alligator is a year-round resident.
Land-surface form.--This province is composed of subdued low mountains of crystalline rocks and open low mountains with valleys underlain by folded strong and weak strata. Some dissected plateaus with mountainous topography are also present. The relief is high (up to 3,000 ft [900 m]). Elevations range from 300 to 6,000 ft (90 to 1,800 m), and are higher to the south, reaching 6,684 ft (2,037 m) at Mount Mitchell, North Carolina.
Climate.--The climate is temperate, with distinct summer and winter, and all areas are subject to frost. Average annual temperatures range from below 50F (10C) in the north to about 64F (18C) at the south end of the highlands. The average length of the frost-free period is about 100 days in the northern mountains, and about 220 days in the low southern parts of the Appalachian Highlands. Average annual precipitation varies from 35 in (890 mm) in the valleys to up to 80 in (2,040 mm) on the highest peaks--the highest in the Eastern United States. Precipitation is fairly well distributed throughout the year (see Appendix 2, climate diagram for Boone, North Carolina). Snowfall is more than 24 in (610 mm) in Pennsylvania, increasing southward along the mountains to about 30 in (770 mm) in the Great Smoky Mountains. Southeast- and southfacing slopes are notably warmer and drier than northwest- and northfacing slopes, because they face the sun and are on the lee side of the ridges. One result is that forest fires are more frequent on southfacing slopes.
Vegetation.--Vertical zonation prevails, with the lower limits of each forest belt rising in elevation toward the south. The valleys of the southern Appalachian Mountains support a mixed oak-pine forest that resembles its counterpart on the coastal plains (described below for the Southeastern Mixed Forest Province). Above this zone lies the Appalachian oak forest, dominated by a dozen species each in the white oak and black oak groups. Chestnut was once abundant, but a blight has eliminated it as a canopy tree. Above this zone lies the northeastern hardwood forest, composed of birch, beech, maple, elm, red oak, and basswood, with an admixture of hemlock and white pine. Spruce-fir forest and meadows are found on the highest peaks of the Allegheny and Great Smoky Mountains. Mixed mesophytic forest extends into narrow valleys (coves) of the southern Appalachians, where oak vegetation predominates.
The pattern of vegetation is complicated by topography and substrate. For example, the forests of the Great Smoky Mountains range from open oak and southern pine stands on drier, warmer slopes at low elevations to northern coniferous forests of spruce and fir on cold, moist slopes higher up. But southern pine stands reach up along exposed ridges, and hemlock forest extends down into protected ravines where moisture and local temperature conditions resemble those found at higher elevations.
Soils.--Ultisols are found on ridge crests, in areas of gentle topography, and in intermountain basins. Soils on steeper landforms are Inceptisols.
Fauna.--The southern limit of distribution of many northern forest mammals coincides with the boundaries of this province. Species distribution maps show fingers of distribution for many species running southward along the crest of the Appalachians. But many species are being confined to scattered areas at higher elevations as forests are cleared or lost due to spruce-fir die-off. The black bear, widely distributed in other parts of North America, occurs quite commonly in the Appalachians and surrounding areas. The eastern cougar, once an important predator, is now thought to be extinct. Whitetail deer are very common.
At upper elevations in extensions of boreal forest, red-breasted nuthatches, black-throated green warblers, golden-crowned warblers, golden-crowned kinglets, and northern juncos forage in red spruce and Fraser fir trees. In the hardwood forests, there are crow-sized pileated woodpeckers, downy, hairy, and red-bellied woodpeckers, common flickers, and wild turkeys. The understory, especially in areas with rhododendrons and azaleas, hosts worm-eating warblers, and the brilliant hooded warbler is found in lush undergrowth. Louisiana waterthrush patrol the streamsides. The mixed mesophytic forest in coves supports a large variety of nesting birds, including the wood thrush, ovenbird, summer tanager, rose-breasted grosbeak, and all the other species already named. The passenger pigeon, once abundant, is now extinct.
Unique to the region is its great variety of salamanders: 27 species inhabit the southern Appalachians--more than any other part of North America.
Ozark Highlands, 6,400 mi2 (16,600 km2)
Land-surface form.--This is an area of low dissected mountains composed of sandstone and shale, with altitudes up to 2,000 ft (600 m) and a relief of 1,500 ft (460 m). Valleys are narrow, with steep sides and gradients.
Climate.--The climate is hot continental, with cold winters and hot summers. Rainfall occurs throughout the year, with drier periods in summer and autumn. In Mountain Home, Arkansas (on the outskirts of this province), the average annual temperature is 59F (15C) and the average annual precipitation is 41 in (1,050 mm).
Vegetation.--This region supports oak-hickory forest. The primary overstory species are red oak, white oak, and hickory. Shortleaf pine and eastern redcedar are important on disturbed sites, shallow soils, and south- and westfacing slopes.
Soils.--The major soils are warm, moist Ultisols.
Fauna.--No bird or mammal species is uniquely abundant in this province and not in neighboring ones. Bird and mammal communities are similar to those in the Eastern Broadleaf Forest (Continental) Province. Several endemic salamanders, however, are found here.
Land-surface form.--The fold mountains here were eroded from sedimentary rock formations compressed into great folds; the upturned edges of the resistant formations form the mountain ridges. The linear ridges reach maximum altitudes of about 2,600 ft (790 m), about 1,500 ft (460 m) above the adjoining valleys. The folds and the mountains trend east-west.
Climate.--The climate is similar to that found in adjoining parts of the Subtropical Division. Winters are warm and summers hot. Rain falls throughout the year, but summers are relatively dry. On the outskirts of this province, in Fort Smith, Arkansas, the average annual temperature is 63F (17C). Average annual precipitation is 41 in (1,050 mm).
Vegetation.--The area supports oak-hickory-pine forests. The primary overstory species are southern red oak, black oak, white oak, and hickories. Pine constitutes as much as 40 percent of the cover (shortleaf pine in the uplands, with loblolly pine on lower lying alluvial soils). The dry sandstone ridges of the Ouachita Mountains are covered on their southern slopes by a mixture of shortleaf pine, oak, and hickory, and on their northern slopes by hardwood forests made up mainly of oak and hickory. Hardwoods populate the rich bottom lands of the valleys, and pines predominate on poorer lands.
Soils.--The major soils are Ultisols. They are stony and nonstony, with medium textures.
Fauna.--Bird and mammal species are similar to those found in the surrounding Southeastern Mixed Forest. One amphibian, the Ouachita dusky salamander, is found exclusively in this province's rocky, gravelly streams.
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