Chapter 18
Ecological Subregions of the United States

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Central Appalachian Broadleaf Forest - Coniferous Forest - Meadow

Four Sections have been delineated in this Province:
These Sections are located in the eastern conterminous States, including parts of Georgia, North and South Carolina, Virginia, West Virginia, Maryland, and Pennsylvania. The area of these Sections is about 68,100 mi2 (176,400 km2).

Section M221A--Northern Ridge and Valley

Geomorphology. This Section forms part of the Ridge and Valley geomorphic province. It is characterized by a series of parallel, southwest to northeast trending, narrow valleys and mountain ranges (high ridges) created by differential erosion of tightly folded, intensely faulted bedrock. The eastern boundary is the Great Valley low land; the western boundary is a steep, high ridge, the Allegheny Front. Drainage is structurally controlled, dominantly trellis with some dendritic patterns. Mass wasting, karst solution, and fluvial erosion, transport and deposition are the dominant geomorphic processes currently active. A notable but very minor landform is anthropogenic: lands that have been strip-mined exhibit hummocky or gouged topography. Elevation ranges from 300 to 4,000 ft (100 to 1,200 m). Local relief is 500 to 1,500 ft (150 to 450 m).

Lithology and Stratigraphy. A veneer of unconsonidated materials overlies most bedrock: residuum on flat and gently sloping uplands, colluvium on slopes, and alluvium in valley bottoms. Shale, siltstone, sandstone, chert, and carbonates form bedrock in the Section. Ordovician and Silurian units dominate the northern part of the Section, with some Devonian, Mississippian, and Pennsylvanian units (including coal) exposed in the larger synclines, and Cambrian limestone exposed in a few anticlines. The southern part is dominated by Devonian units with lesser amounts of Silurian and Ordovician rocks in some anticlines, and Mississippian and Pennsylvanian rocks in some synclines. Cambrian rocks show up along a few major thrust faults. Sandstone, chert, and some of the tougher carbonates hold up most of the upland portions of the Section. Weaker carbonates and shale underlie most valleys.

Soil Taxa. Soils are mostly Ultisols, Alfisols, and Inceptisols, with mesic temperature regimes and mostly udic moisture regime. They are derived from heavily-weathered shale, siltstone, sandstone residuum and colluvium, cherty limestone, and limestone residuum.

Potential Natural Vegetation. Because much of this area lies in the rain shadow of the Allegheny Mountains Section, vegetation reflects drier conditions. K\"uchler types are mapped as Appalachian oak forest, oak-hickory-pine forest, and some northern hardwoods forest. Braun classified much of the area as oak-chestnut. Before arrival of the blight that decimated the chestnut, this Section was a stronghold of the species. Oaks now dominate. As a broad generalization, red and white oaks occur on more productive, mesic sites. Eastern white pine can occur, with white oak on the lower portions of slopes. Scarlet and black oaks are more common on drier sites. On the driest sites, oaks are mixed with pitch, table mountain, or Virginia pines. The latter can also occur as pure stands.

Fauna. The black bear is the sole representative of large carnivores. Prior to European settlement, forests featured wolves and mountain lions, but they were hunted or trapped to local extinction. Woodland bison and eastern elk were the largest herbivores of this Section, but were eliminated by subsistence hunting. White-tailed deer are abundant and can have a major impact on understory flora. Smaller mammals include the gray and fox squirrels, deer mouse, meadow jumping mouse, weasels, and bats. The endangered Virginia big-eared and Indiana bats are associated with karst areas. Bird species are diverse and include a wide variety of both residents and neotropical migrants. Game birds include ruffed grouse and wild turkey. Bald eagles and peregrine falcons were never abundant historically. In recent years eagles have entered the area, and falcons have been reintroduced. Fish species include brook trout and sculpins at higher elevations, with the addition of smallmouth bass, rock bass, minnows, and darters at lower elevations. Amphibians and reptiles are abundant. Insect life is highly diverse. Some butterfly and moth species are still being identified. In recent years, gypsy moth has entered the area and become established.

Climate. Mean annual precipitation is generally 30 to 45 in (76 to 1,140 mm). In the transition to the Allegheny Plateau, rainfall may range as high as 60 in (1,520 mm). Approximately 20 percent of these totals falls as snow. At elevations above 3,500 ft (1,200 m) 30 percent falls as snow. Mean annual temperature is approximately 39 to 57 oF (4 to 14 oC). The growing season ranges from 120 to 180 days, with local variation.

Surface Water Characteristics. Streams are most active in the spring, reflecting relatively frequent rainfall and snowmelt. Many smaller streams dry up in the summer and are not recharged until October to November. This Section includes the headwaters of the Potomac and Greenbrier Rivers. Stream patterns are trellis shaped, reflecting the regular folding of the geomorphology. Streams are generally more alkaline and productive than in the Allegheny Mountains. Wetlands are scarce.

Disturbance Regimes. Fire was undoubtedly used extensively by Native Americans. Major historical disturbances include grazing from about 1780 onward and extensive logging from 1880 to 1920. Many logging operations were followed by fire. Since the 1930's, many fires have been suppressed through Federal and State agency efforts. Gypsy moth has affected forests in this Section, notably in Virginia.

Land Use. Farming, grazing, and hay production are common on river flood plains and on limestone areas in the Northern Ridge and Valley Section. On forested sites, timber production is an important industry. This Section receives light but extensive recreation pressure for fishing, hunting, camping, and hiking. Canoeing and rock climbing occur in certain areas. Settlements tend to be small and dispersed.

Cultural Ecology. This area has been used by Native Americans for at least 12,000 years. The first people, or Paleo-Indians, inhabited a boreal forest environment. They were highly mobile, sparsely distributed, lived in small family units, gathered plant foods, and were big game hunters. As the climate gradually became more temperate, an Archaic culture replaced the Paleo-Indian. People harvested a greater variety of plants and animals, and human populations increased. Archaic peoples moved seasonally within a well defined geographical area that offered a variety of resources. During the Woodland Period, permanent villages were established in fertile valleys, where agriculture was first attempted, while the uplands continued to be used for hunting and gathering. Fire may have been used to drive game, clear fields for agriculture, or open areas to improve hunting. From the start of European settlement, transportation was limited by the severity of the terrain. Because of crop failures on mountain farms, grazing came to dominate the area, and its influence continues. Farmers often created open grassy areas or sods by cutting the timber, removing the logs, and burning the slash. From 1880 to 1920, major logging and sawmilling denuded the landscape. Fires raged throughout the forest, laying soils open to erosion. Today, extractive industries prevail, along with an insular traditional mountain culture. Increasingly, however, a more recreation-oriented lifestyle has emerged to cater to the needs of urban dwellers from East Coast metropolitan areas.

Compiled by Eastern Region and Northeastern Area State and Private Forestry.

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Section M221B--Allegheny Mountains

Geomorphology. This Section comprises part of the Appalachian Plateaus geomorphic province. It is a maturely dissected plateau characterized by high, sharp ridges, low mountains, and narrow valleys. It has a prominent structural and topographic grain created by broad, northeast to southwest trending folds in the bedrock. Drainage is dendritic to trellis, but primarily the former. Mass wasting, karst solution, and fluvial erosion, transport and deposition are the primary geomorphic processes operating. Elevation ranges from 1,000 to 4,500 ft (300 to 1,400 m), with a few peaks higher, notably Spruce Knob (4,861 ft, 1,620 m), the highest point in West Virginia. Local relief generally ranges from 1,000 to 2,500 ft (300 to 600 m).

Lithology and Stratigraphy. Bedrock is overlain by residuum on the ridges and mountain tops, colluvium on the slopes, and alluvial materials in the valleys. Devonian shale and siltstone, Mississippian carbonates and sandstones, and Pennsylvanian shale, sandstone, and coal form bedrock in the Section. Sandstone and some of the tougher carbonates hold up most of the upland portions; weaker carbonates and shale underlie most valleys.

Soil Taxa. Soils are dominantly Ultisols, Inceptisols, and Alfisols, with mesic temperature regime and udic moisture regime. They are derived from heavily weathered shales, siltstones, sandstone residuum and colluvium, and limestone residuum. Spodosols with frigid temperature regime and aquic moisture regime occur in isolated pockets at the highest elevations.

Potential Natural Vegetation. K\"uchler mapped this Section as northeastern spruce-fir, northern hardwoods, mixed mesophytic, and oak-hickory-pine. Strongly influenced by elevation and aspect, the vegetation of the Allegheny Mountains can be placed in four broad groups: red spruce, northern hardwoods, mixed mesophytic, and oaks. Red spruce is characteristic above 3,500 ft (1,060 m) and includes stands of American beech and yellow birch. Beech is more common on northerly aspects, and yellow birch on southerly. The northern hardwood group features sugar maple occurring with beech and black cherry. The mixed mesophytic represents a transition to drier types and presents a wide variety of successional pathways. Characteristic species are red oak, basswood, white ash, and tulip poplar. The productive, diverse cove hardwoods are included in this group. Oak sites occur mostly on foothills, but are much less common in this Section than in the Northern Ridge and Valley Section.

Fauna. The black bear is the sole representative of large carnivores. Prior to European settlement, forests featured wolves, fishers, and mountain lions--but all were hunted or trapped to local extinction. Fishers have since been reintroduced with modest success. White-tailed deer are abundant and can impact understory flora. Woodland bison and eastern elk were found in this area as late as 1825 and 1887, respectively, but were then exterminated by subsistence hunting. Varying hare, red squirrel, and the endangered Virginia northern flying squirrel are associated with the red spruce vegetation zone (above 3,500 ft). Elsewhere gray and fox squirrels are more abundant. Throughout the Section, smaller mammals include the deer mouse, meadow jumping mouse, and various weasels, and bats. Bird species include a wide variety of both residents and neotropical migrants. Ruffed grouse and wild turkey are prominent game species. Fish species include brook trout and sculpins at higher elevations, with the addition of smallmouth bass, rock bass, minnows, and darters at lower elevations. The Cheat minnow is listed as a sensitive species, and some minnow and darter species in the New River basin are endemic. Amphibians and reptiles are abundant. The threatened Cheat Mountain salamander is found on high elevation red spruce and northern hardwood sites. Insect life is highly diverse. New butterfly and moth species are still being identified. Gypsy moth is now entering this Section.

Climate. Precipitation typically averages 45 to 60 in (1,140 to 1,520 mm) per year; about 20 percent of this is snow (30 percent at higher elevations). On average, this Section is notably moister than the Northern Ridge and Valley Section. Mean annual temperature is approximately 39 to 54 oF (4 to 12 oC). The growing season ranges from 140 to 160 days, with local variation.

Surface Water Characteristics. The drainage pattern is well established, dendritic to trellis, but primarily the former. This Section contains headwaters of the Cheat and Greenbrier Rivers, both of which eventually feed through other tributaries into the Ohio River. Streams are generally more acidic and less productive than in the Northern Ridge and Valley Section. Wetlands are scarce.

Disturbance Regimes. Erosional processes over eons have been the primary disturbance agents. In the pre-European settlement era, fire was not a significant element of change because of the relatively high precipitation. The current forest was largely shaped by logging and associated fires from about 1880 to 1920. In some areas, notably those in the red spruce zone above 3,500 ft (1,200 m) elevation, some areas burned so severely that soil was removed to the bedrock. These areas are now stunted forests with blueberry understories. Gypsy moth is now entering this Section. Its effect on this Section may be less than on the Northern Ridge and Valley Section, because oak, preferred by the moth, is less extensive here.
Land Use. Timber production of high-valued hardwoods is a major industry. Agricultural pastures and hay meadows are common on river and stream flood plains and on limestone soils. Recreation use is relatively light but extensive, and includes hunting, fishing, camping, and hiking. Tourism is a growing industry. Settlements are small and dispersed. Strip-mining for coal has been and continues to be an important activity in some parts of this Section.

Cultural Ecology. This area has been used by Native Americans for at least 12,000 years. The first people, or Paleo-Indians, inhabited a boreal forest environment. They were highly mobile, sparsely distributed, lived in small family units, gathered plant foods, and were big game hunters. As the climate gradually became more temperate, an Archaic culture replaced the Paleo-Indian. People harvested a greater variety of plants and animals, and human populations increased. Archaic peoples moved seasonally within a well defined geographical area that offered a variety of resources. During the Woodland Period permanent villages were established in fertile valleys, where agriculture was first attempted, while the uplands continued to be used for hunting and gathering. Fire may have been used to drive game, clear fields for agriculture, or open areas to improve hunting. From the start of European settlement, transportation was limited by the severity of the terrain. Because of crop failures on mountain farms, grazing came to dominate the area, and its influence continues. Farmers often created open grassy areas or sods by cutting the timber, removing the logs, and burning the slash. From 1880 to 1920, major logging and sawmilling denuded the landscape. Fires raged throughout the forest, laying soils open to erosion. Today extractive industries prevail, along with an insular traditional mountain culture. Increasingly, however, a more recreation-oriented lifestyle has emerged to cater to the needs of urban dwellers from East Coast metropolitan areas.

Compiled by Eastern Region and Northeastern Area State and Private Forestry.

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Section M221C--Northern Cumberland Mountains

Geomorphology. This section is in the Appalachian Plateaus geomorphic province. Synclinal structure resulting from folding, faulting, and uplift, followed by differential erosion, has resulted in long monoclinal mountains and dissected uplands. Landforms are mainly low mountains where less than 20 percent of the area is gently sloping. Drainage is dendritic to trellis; mass wasting, karst solution, and fluvial erosion, transport and deposition are the primary geomorphic processes operating. Elevation ranges from 2,000 to 2,600 ft (600 to 800 m). Local relief ranges from 100 to 300 ft (30 to 90 m).

Lithology and Stratigraphy. Bedrock is overlain by a veneer of residuum on the ridges and mountain tops, colluvium on the slopes, and alluvial materials in the valleys. Pennsylvanian sandstone caps most uplands, including the linear mountains. Pennsylvanian shale and coal, and Mississippian sandstone, shale, and limestone form bedrock on the slopes and underlie most valleys.

Soil Taxa. Soils are mainly Ochrepts, Udults, and Aquults. On plateaus and upper slopes, Dystrochrepts, Hapludults, and Fragiudults have formed in material weathered from sandstone, siltstone, and shale on nearly level surfaces. Ochraquults are along foot slopes in weathered shale. Dystrochrepts have formed in alluvium. Soils have a mesic temperature regime, an udic or aquic moisture regime, and mixed mineralogy.

Potential Natural Vegetation. K\"uchler classified vegetation as mixed mesophytic forest, Appalachian oak forest, and northern hardwoods. The predominant vegetation form is cold-deciduous broad-leaved forest with a mixture of evergreen needle-leaved trees. Existing forest types consist of oak-hickory. The component consists of white, black, scarlet, and blackjack oaks; common hickories include mockernut and pignut.

Fauna. The white-tailed deer occurs throughout much of this Section. The oak forest and the openings and farms within it provide food and cover for a varied fauna. The black bear is present in many areas. The wolf is no longer common, but the red fox and gray fox are widespread, as is the bobcat. Several species of squirrels are in the forest, and a number of smaller rodents inhabit the forest floor. The turkey, ruffed grouse, bobwhite, and mourning dove are game birds in various parts of this Section. Songbirds include the ovenbird, red-eyed vireo, hermit thrush, scarlet tanager, blue jay, black-capped chickadee, wood pewee, magnolia warbler, cardinal, tufted titmouse, wood thrush, summer tanager, blue-gray gnatcatcher, hooded warbler, and Carolina wren. The herpetofauna include the box turtle, common garter snake, and timber rattlesnake.

Climate. Precipitation averages 40 to 47 in (1,020 to 1,200 mm); snow averages about 35 in (900 mm). Mean annual temperature averages 45 to 50 oF (7 to 10 oC). The growing season lasts 140 to 160 days.

Surface Water Characteristics. There is a moderate density of small to medium intermittent and perennial streams and associated rivers, most with low to moderate rates of flow. A dendritic drainage pattern has developed with influence from the underlying bedrock.

Disturbance Regimes. Fire has probably been the principal historical source of disturbance. Climatic influences include occasional summer droughts and ice storms.

Land Use. Natural vegetation has been cleared for agriculture on most of the area. Strip mining for coal has disturbed about 5 percent of the area.

Cultural Ecology. Reserved.

Compiled by Southern Region.

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Section M221D--Blue Ridge Mountains

Geomorphology. This Section is in the Blue Ridge geomorphic province. The Section was formed by tectonic faulting and uplift of resistant, crystalline bedrock into a relatively narrow band of highly metamorphosed, somewhat parallel mountain ranges. The northern part of this Section (north of Roanoke Gap in Virginia) is characterized by a single, broad (5 to 10 mi, 8 to 16 km) ridge that extends into southern Pennsylvania. The southern half of the Section is broader, higher, more mountainous, and displays little or no structural grain. Though high (46 peaks are over 6,000 ft (1,820 m) in elevation), the mountains are rounded and generally lack prominent angularity. Drainage is structurally controlled, dominantly trellis in the north; dendritic patterns dominate the southern half. Landforms on about 80 percent of the Section are low mountains. The remainder of the Section is open, low mountains. Elevation ranges from 1,000 to over 6,000 ft (300 to 1,800 m). Local relief ranges from 500 to 1,000 ft (150 to 300 m). Mt. Mitchell, the highest point in eastern North America (6,684 ft, 2,025 m), occurs here.

Lithology and Stratigraphy. Bedrock is overlain by a veneer of residuum on the ridges and mountain tops, colluvium on the slopes, and alluvial materials in the valleys. Although structural grain is not evident in the south half, the whole Section is bounded on the eastern and western margins by southwest to northeast trending thrust faults, between more faults and tight folds. Bedrock is composed primarily of Proterozoic metasediments (quartzite, schist, and gneiss) and meta-igneous rocks (granite, rhyolite, basalt, and gabbro). Smaller areas underlain by Paleozoic granite occur along the eastern edge of the Section, with lower Cambrian sandstone, shale and dolomite, and broad zones of intensely sheared and altered rock. The Lower Cambrian rocks occur intermittently along the western edge as well.

Soil Taxa. Soils are dominated by Ochrepts and Udults. Dystrochrepts are on steep slopes of lower elevation mountains. Hapludults are on the low foothills, and Haplumbrepts have formed on foot slopes and in valleys. Haplumbrepts are also common at higher elevations, while Hapludults are dominant in broad valleys. Rhodudults have formed over rocks with a high content of mafic minerals. Soils are generally moderately deep and medium textured. Boulders and bedrock outcrops are common on upper slopes, but are not extensive. These soils have a mesic temperature regime, a udic moisture regime, and mixed mineralogy. Similar soils with a frigid temperature regime are typically present at elevations above 4,800 feet. Soils receive adequate moisture for growth of vegetation throughout the year.

Potential Natural Vegetation. K\"uchler classified vegetation in this Section as Appalachian oak forest, southeastern spruce-fir forest, and northern hardwoods. The predominant vegetation form is montane cold-deciduous broad-leaved forest dominated by the genus {\it Quercus}. The oak forest type consists of black, white, and chestnut oaks that dominate dry mountain slopes; pitch pine is often a component along ridge tops. Mesophytic species such as yellow-poplar, red maple, northern red oak, and sweet birch dominate the valleys and moist slopes. Smaller areas of cold-deciduous broad-leaved forest with evergreen needle-leaved trees are present in the intermontane basins, with the hardwood-pine cover type of scarlet, white, blackjack, and post oaks and shortleaf and Virginia pines. Table Mountain pine, a fire-dependent species with serotinous cones, occurs on xeric ridge tops where fire was historically more common. Eastern white pine dominates small areas of coarse-textured soils and parts of the Blue Ridge escarpment joining the Southern Appalachian Piedmont Section. Mesic sites at higher elevations (4,500 ft, 1,360 m) are occupied by northern hardwoods (e.g., sugar maple, basswood, and buckeye); drier sites are dominated by northern red oak. The broad-leaved forest changes to evergreen needle-leaved forest with conical crowns (e.g., red spruce, Fraser fir) above altitudes of about 5,000 to 6,000 ft (1,800 m).

Fauna. Many species of small mammals and birds with northern or boreal affinities reach their southernmost range in eastern North America in the Blue Ridge Section. These include the New England cottontail rabbit, northern water shrew, rock vole, northern flying squirrel, blackburnian warbler, and saw-whet owl. This Section supports the largest diversity of salamanders in North America. At least 12 species of the genus {\it Plethodon} and six species of the genus {\it Desmognathus} are endemic to the Blue Ridge Section. Most endemic species are found in the central and southern subsections, where topographic relief is greater, peaks are more isolated, and higher rainfall occurs. Disjunct and isolated populations of the green salamander and bog turtle are found in the southernmost subsection.

Climate. Average precipitation is 40 to 50 in (1,020 to 1,270 mm) but ranges up to 60 in (1,500 mm) on the highest peaks. Only 35 to 40 in (900 to 1,020 mm) fall in the Asheville Basin, an area surrounded by higher mountains. Along parts of the southern Blue Ridge escarpment bordering the Southern Appalachian Piedmont Section, rainfall averages over 80 in (2,000 mm); the highest in the eastern U.S. Precipitation is about equally distributed throughout the year and relatively little occurs as snow. Mean annual temperature is 50 to 62 oF (10 to 16 oC) and ranges from 38 oF (3 oC) in January to 76 oF (24 oC) in July. The growing season lasts 150 to 220 days, but varies according to elevation and the influence of local topography.

Surface Water Characteristics. There is a high density of small to medium size perennial streams and associated rivers; those in intermountain basins have moderate rates of flow. Some streams on mountainous areas in zones of high rainfall are characterized by high rates of flow and velocity. A dendritic drainage pattern has developed on deeply dissected surfaces, with some control from the underlying bedrock. Isolated areas in some locations are wet all year as a result of seeps. The largest rivers are the French Broad and Little Tennessee.

Disturbance Regimes. Fire, wind, ice, and precipitation are the principal causes of natural disturbance. It is believed that native Americans used fire for many purposes, especially at low elevations in intermountain basins, where drier conditions prevail. Fire caused by lightning is more prevalent in some areas, especially in the vicinity of Grandfather Mountain. Tornadoes are uncommon, but more prevalent are localized "micro-bursts" of intense winds, which cause small patches of trees to be up-rooted, especially on mountain slopes. Winter ice storms are not uncommon at mid-to-high elevations and cause extensive damage to tree crowns. Occasional events of prolonged, intense precipitation cause localized scouring and erosion of drainage channels, followed by siltation, sedimentation, and flooding downstream. An introduced pathogen, the chestnut blight, caused considerable disturbance to composition of most forest stands from 1920 to 1940 by top-killing all American chestnut trees. Gypsy moth has not affected forests in the central and southern subsections, but has the potential to cause a major impact on forest vegetation because of the dominance by oaks.

Land Use. Natural vegetation has been cleared for agriculture and urban development on about 35 percent of the area, mostly in broad valleys between major mountain ranges.

Cultural Ecology. Cherokee Indians have inhabited this Section for thousands of years and, it is thought, extensively used fire for agricultural and hunting purposes. European settlement began in the late 1700's and consisted of subsistence agriculture and hunting throughout the intermountain basins and larger coves. By 1840, the Cherokee Indians had been displaced by settlers. Many of the Eastern Cherokee Indians occupy a reservation in western North Carolina. Population growth in the Section has been relatively slow, limited somewhat by unfavorable terrain for large commercial development. However, a favorable climate and scenic views have caused tourism to be a major part of the economy since the early 1900's; more recently the retirement community has increased rapidly. Some permanent and seasonal residents advocate reduced forest and resource management on National Forests, which occupy much of the mountain slopes in some areas. Hunting, hiking, and trail biking are major forest recreational uses. Two national parks were authorized in 1926, the Great Smoky Mountains (517,014 ac, 1,277,024 ha) in western North Carolina and Shenandoah (193,000 ac, 476,000 ha) in northern Virginia. The Parks are connected by the 469 mi (750 km) long Blue Ridge Parkway, which follows the highest ridge lines. Limited high-quality water supplies, waste disposal, and air pollution have caused concern about the pace of future development.

Compiled by Southeastern Forest Experiment Station.

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