Chapter 33
Ecological Subregions of the United States

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Sierran Steppe - Mixed Forest - Coniferous Forest

Seven Sections have been delineated in this Province:The area of these Sections is about 68,300 mi2 (176,900 km2).

Section M261A--Klamath Mountains

Geomorphology. This is an uplifted and dissected peneplain on strong rocks; there are extensive monadnock ranges. Elevation ranges from 1,500 to 8,000 ft (456 to 2,432 m). This Section is in the Klamath Mountains geomorphic province.

Lithology and Stratigraphy. There are Paleozoic sedimentary and volcanic rocks, and Mesozoic ultramafic, granitic, sedimentary, and volcanic rocks.

Soil Taxa. Soils include Alfisols, Entisols, Inceptisols, and Ultisols, in combination with mesic and frigid soil temperature regimes and xeric and udic soil moisture regimes.

Potential Natural Vegetation. K\"uchler mapped vegetation as Klamath montane forest, mixed evergreen forest, Oregon oak forest and northern yellow pine forest. Predominant potential natural communities are Douglas-Fir, Ponderosa Pine, Mixed Conifer, Jeffrey Pine, White Fir and Red Fir series.

Fauna. Mammals include Roosevelt elk, black-tailed deer, black bear, mountain lion, coyote, bobcat, ringtail, marten, fisher, and river otter. Birds include eagles, hawks, owls, peregrine falcon, osprey, and ruffed grouse. Species of concern include marbled murrelet and northern spotted owl. Streams and rivers are used by anadromous fish.

Climate. Precipitation ranges from 40 to 120 in (1,020 to 3,050 mm). Temperature averages 45 to 55 oF (7 to 13 oC). The growing season lasts 60 to 250 days.

Surface Water Characteristics. Many rapid or moderately rapid flowing rivers and streams are in this Section. Most rivers flow westerly in deeply incised canyons with bedrock controlled channels. Some easterly flowing streams in deeply incised canyons flow inland to the Sacramento River. Some water is diverted from the westward flowing Trinity River system eastward to the Sacramento River. There are numerous lakes and meadows associated with glaciated areas above 5,000 feet.

Disturbance Regimes. At lower and mid elevations, historic occurrence of fire has changed from frequent, low intensity ground fires to infrequent, high intensity stand-replacing fires. At higher elevations, historic occurrence has changed from infrequent, low and moderate intensity ground fires to infrequent, low, moderate and high intensity surface or stand-replacing fires. The western part of the Section is seismically active with strong shaking and ground rupture. Wide fluctuations in precipitation and temperature for periods of years result in significant or catastrophic changes in biological communities.

Land Use. Composition and successional sequence of some communities have changed because of plant and animal species introduced between the mid 1800's and early 1900's. These introductions related to mining, grazing, forestry, and recreational activities.

Cultural Ecology. Humans have been utilizing the Klamath Mountains for about 8,000 years, and have been an integral part of the ecology for 2,000 to 3,000 years. The western portion of the Klamath Mountains lies in the northwest California culture area; the diversity of northwest California ethnographic cultures is the most complex in the United States, reflecting diverse prehistoric and historic uses, practices, and human adaptations. Early Euro-American influences and settlement came from mining booms concomitant with the Gold Rush. Contemporary attitudes and beliefs tend to be dominated by commodity oriented long-time resident values and a rural lifestyle. The economy is dominated by government employment, but the timber industry and recreation are also important.

Compiled by Pacific Southwest Region.

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Section M261B--Northern California Coast Ranges

Geomorphology. This area has parallel ranges, and folded, faulted, and metamorhosed strata; there are rounded crests of subequal height. Elevation ranges from 1,000 to 7,500 ft (304 to 2,280 m). This Section is in the Coast Ranges geomorphic province.

Lithology and Stratigraphy. There are late Mesozoic eugeosynclinal rocks of the Franciscan Formation, Mesozic ultramafic rocks, and Cenozoic volcanic rocks.

Soil Taxa. Soils include Alfisols, Entisols, Inceptisols, Mollisols and Ultisols in combination with mesic and thermic soil temperature regimes and xeric soil moisture regime.

Potential Natural Vegetation. K\"uchler mapped vegetation as Coast Ranges montane forest, mixed evergreen forest, chaparral, blue oak-foothill pine forest, and mixed hardwood forest. Predominant potential natural communities are Douglas-Fir, White Fir, Ponderosa Pine, Tanoak, Interior Live Oak, Coast Live Oak and Mixed Chaparral series.

Fauna. Mammals include black-tailed deer, black bear, mountain lion, coyote, bobcat, and ringtail. Roosevelt elk, marten, and fisher occur in the northern part of the Section. Tule elk and mule deer occur in the southern part. Birds include eagles, hawks, owls, herons, and osprey. Species of concern include marbled murrelet and northern spotted owl in the northern part.

Climate. Precipitation ranges from 30 to 80 in (760 to 2,030 mm). Temperature averages 45 to 59 oF (7 to 15 oC). The growing season lasts 80 to 250 days.

Surface Water Characteristics. There are many rapid or moderately rapid rivers and streams in deeply incised canyons with weak bedrock channels; they flow westerly to the Pacific Ocean.

Disturbance Regimes. Historic occurrence of fire has changed from frequent, low, moderate, and high intensity surface fires to infrequent, high intensity ground or stand-replacing fires. This is a seismically active area with strong shaking and ground rupture. Wide fluctuations in precipitation and temperature for periods of years result in significant or catastrophic changes in biological communities.

Land Use. Composition and successional sequence of some communities have changed because of plant and animal species introduced between the mid 1800's and early 1900's. These introductions related to mining, grazing, forestry, and recreational activities.

Cultural Ecology. Humans have been utilizing the area for about 10,000 years; the Northern California Coast Ranges Section is the type location for the early, Borax Lake, Paleo-Indian component. Humans have been an integral part of Coast Range ecology for 2,000 to 3,000 years. The diversity of northwest California ethnographic cultures is the most complex in the United States, reflecting diverse prehistoric and historic uses, practices, and human adaptations. Contemporary attitudes and beliefs are dichotomized between emphasis on amenity for the newcomer and commodity for the long-time resident. All are overlain by a rural lifestyle. The economy is relatively diverse--government employment, the timber industry, recreation, and agriculture.

Compiled by Pacific Southwest Region.

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Section M261C--Northern California Interior Coast Ranges

Geomorphology. This area has parallel ranges and folded, faulted, and metamorhosed strata; there are rounded crests of subequal height. Elevation ranges from 200 to 2,500 ft (61 to 760 m). This Section is in the Coast Ranges geomorphic province.

Lithology and Stratigraphy. There are late Mesozoic shelf and slope sedimentary deposits.

Soil Taxa. Soils include Alfisols, Entisols, Inceptisols, Mollisols and Vertisols in combimation with thermic soil temperature regime and xeric soil moisture regime.

Potential Natural Vegetation. K\"uchler mapped vegetation as blue oak-foothill pine forest, chaparral and California prairie. Predominant potential natural communities are Blue Oak, Mixed Chaparral and Valley Needlegrass series.

Fauna. Mammals include mule deer, black-tailed deer, coyotes, ground squirrels, cottontails, jack rabbits, and kangaroo rats. Birds include turkey vulture, eagles, hawks, owls, quail, mourning dove, mockingbird, scrub jay, western meadowlark, finches, and sparrows.

Climate. Precipitation ranges from 20 to 40 in (510 to 1,020 mm). Temperature averages 55 to 64 oF (13 to 18 oC). The growing season lasts 120 to 270 days.

Surface Water Characteristics. Many rapid perennial or intermittent streams are in deeply incised canyons with weak bedrock channels; they flow easterly to the Sacramento River. Reservoirs for irrigation water and flood control are common.

Disturbance Regimes. Fires are low, moderate, and high intensity surface or stand-replacing fires.

Land Use. Composition and successional sequence of some communities has changed because of plant and animal species introduced between the mid 1800's and early 1900's. These changes related to grazing and agriculture.

Cultural Ecology. Humans have been utilizing the interior Coast Range foothills for 8,000 to 9,000 years, and have been an integral part of the ecology for 3,000 to 5,000 years. Historically, ranching and agriculture provided the primary Euro-American livelihood. Contemporary attitudes and beliefs are dichotomized between emphasis on values: amenity for the newcomer and commodity for the long-time resident. All are overlain by a rural lifestyle. Contemporary economic pursuits include government employment, agriculture, and recreation.

Compiled by Pacific Southwest Region.

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Section M261D--Southern Cascades

Geomorphology. These volcanic mountains are variously eroded; there is no distinct range. Elevation ranges from 1,500 to 14,000 ft (456 to 5,256 m). This Section is in the Cascade Range geomorphic province.
Lithology and Stratigraphy. These are Cenozoic volcanic rocks.

Soil Taxa. Soils include Alfisols, Andisols, Inceptisols, and Ultisols, in combination with mesic and frigid soil temperature regimes and xeric and udic soil moisture regimes.

Potential Natural Vegetation. K\"uchler mapped vegetation as Sierran montane forest, sagebrush steppe, yellow pine-shrub forest and northern yellow pine forest. Predominant potential natural communities are White Fir, Ponderosa Pine, Mixed Conifer, Red Fir, Lodgepole Pine and Oregon Oak series.

Fauna. Mammals include black-tail and mule deer, mountain lion, coyote, bobcat, yellow-bellied marmot, marten, fisher, Sierra Nevada red fox, wolverine, and porcupine. Birds include eagles, hawks, owls, woodpeckers, falcons, osprey, quail, northern goshawk, and blue grouse. Species of concern include the California and northern spotted owl.

Climate. Precipitation ranges from 20 to 80 in (510 to 2,030 mm). Temperature averages 42 to 58 oF (5.5 to 14 oC). The growing season lasts 30 to 200 days.

Surface Water Characteristics. There are many slow and moderately rapid rivers and streams. Rivers flow in alluvial or weak bedrock channels westerly to the Klamath and Sacramento Rivers, and easterly to basins in the Modoc Plateau Section.

Disturbance Regimes. At lower and mid-elevations, historic occurrence of fire has changed from frequent, low intensity, surface fires to infrequent, high intensity, stand-replacing fires. At higher elevations, historic occurrence has changed from infrequent, low and moderate intensity surface fires to infrequent, low, moderate, and high intensity surface or stand-replacing fires. Wide fluctuations in precipitation and temperature for periods of years result in significant or catastrophic changes in biological communities. This Section contains locations with eruptive activity (lava flows and ash fall) within the past 200 years. Land Use. Composition and successional sequence of some communities has changed because of plant and animal species introduced between the mid 1800's and early 1900's. These introductions related to mining, grazing, forestry and recreational activities. Expanding foothill communities are scattered throughout the Section.

Cultural Ecology. Humans have been utilizing the Cascades for about 8,000 years, and have been an integral part of its ecology for 2,000 to 3,000 years. The 14,000 ft volcano of Mt. Shasta dominates much of the landscape. It is a traditional cultural property of vital significance to five Native American groups, and of symbolic importance to Euro-Americans as well. The timber industry played an important role historically; railroad logging systems spread throughout timbered areas. Contemporary attitudes and beliefs tend to be dominated by commodity oriented long-time resident values and a rural lifestyle. The economy is dominated by government employment, but the timber industry, recreation, and ranching are also important.

Compiled by Pacific Southwest Region.

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Section M261E--Sierra Nevada

Geomorphology. This block mountain range tilts west and has accordant crests. Elevation ranges from 1,000 to 14,495 ft (300 to 4,407 m). Local relief ranges from 500 to 2,000 ft (150 to 600 m). It is in the Sierra Nevada Range geomorphic province.

Lithology and Stratigraphy. There are Mesozoic granitic and ultramafic rocks, Paleozoic and Mesozoic strongly metamorphosed sedimentary and volcanic rocks, and Cenozoic volcanic rocks.

Soil Taxa. Soils include Alfisols, Andisols, Entisols, Inceptisols, Mollisols, and Ultisols, in combination with mesic, frigid, and cryic soil temperature regimes, and xeric, udic, and aquic soil moisture regimes.

Potential Natural Vegetation. K\"uchler mapped vegetation as Sierran montane forest, upper montane-subalpine forest, alpine communities and barren, and northern Jeffrey pine forest. Predominant potential natural communities are Ponderosa Pine, Ponderosa Pine-Mixed Conifer, Douglas Fir-Mixed Conifer, White Fir-Mixed Conifer, Red Fir, Lodgepole Pine, Jeffrey Pine, Big Sagebrush, Canyon Live Oak, White Alder, Mountain Alder, Huckleberry Oak, Carex and Aspen series.

Fauna. Mammals include black-tail and mule deer, black bear, mountain lion, coyote, bobcat, red and gray fox, ringtail, weasels, skunks, badger, mountain sheep, yellow-bellied marmot, marten, fisher, wolverine, and porcupine. Grizzly bear, native to the western slope, became extinct in 1924. Birds include eagles, hawks, owls, woodpeckers, falcons, osprey, stellar jay, herons, quail, kingfisher, goshawk and blue grouse. Species of concern include the California spotted owl. Introduced species include turkey and beaver.

Climate. Precipitation ranges from 20 to 80 in (500 to 2,030 mm) during fall, winter, and spring. It occurs mostly as snow above 6,000 ft. Rain on snow is common. Summers are dry with low humidity. Temperature averages 42 to 60 oF (5.5 to 15.5 oC). The growing season lasts 20 to 230 days.

Surface Water Characteristics. There are many rapidly flowing rivers and streams. Rivers flow west from the crest in deeply incised canyons with bedrock controlled channels to the Great Valley Section and Pacific Ocean. Rivers flow east from the crest in mostly bedrock controlled channels terminating in basins in the Mojave Desert, Mono or northwestern Basin and Range Sections. Numerous lakes and wet meadows are associated with glaciated areas above 5,000 feet.

Disturbance Regimes. At lower and mid-elevations, historic occurrence of fire has changed from frequent, low intensity ground fires to infrequent, high intensity stand-replacing fires. At higher elevations, historic occurrence has changed from infrequent, low and moderate intensity ground fires to infrequent, low, moderate, and high intensity surface or stand-replacing fires. Seismically active areas occur along the eastern boundary with strong shaking and ground rupture. Wide fluctuations in precipitation and temperature for periods of years result in significant or catastrophic changes in biological communities. Snow avalanches are common at higher elevations.

Land Use. Composition and successional sequence of some communities have changed because of plant and animal species introduced between the mid 1800's and early 1900's. These introductions related to mining, grazing, forestry, and recreational activities. Expanding urban uses occur, scattered throughout the foothills and some high elevation areas. Water diversions for hydroelectric power, agriculture, and municipal and domestic use are common within and between river systems.

Cultural Ecology. Humans have been utilizing the Sierra for about 10,000 years, and have been an integral part of its ecology for 3,000 to 5,000 years. This is particularly apparent through documented use of fire to facilitate gathering and to generate species preferred for foodstuffs, basketry materials, and other needs. Extensive procurement and processing of lithic, acorn, pine nut, basketry fiber, and other resources resulted in innumerable areas of lithic quarry, bedrock mortar, pinyon, Jeffrey pine, sugar pine, oak grove, and other resource alteration. Contemporary attitudes and beliefs are dichotomized between emphasis on values: amenity for the newcomer and commodity for the long-time resident. Human environment is characterized by a rural lifestyle of open space and outdoor leisure activity. Recreation is the primary economic emphasis, trailed by government employment, lumbering, mining, and grazing. The Sierra is experiencing rapid retiree and commuter resident growth, and large transient recreation populations that provide constant resource pressures.

Compiled by Pacific Southwest Region.

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Section M261F--Sierra Nevada Foothills

Geomorphology. This block mountain range tilts west and has accordant crests. Elevation ranges from 500 to 3,500 ft (152 to 1,064 m). It is in the Sierra Nevada Range geomorphic province.

Lithology and Stratigraphy. These are Mesozoic sedimentary, granitic, volcanic and ultramafic rocks.

Soil Taxa. Soils include Alfisols, Entisols, Inceptisols, and Mollisols, in combination with thermic soil temperature regime and xeric soil moisture regime.

Potential Natural Vegetation. K\"uchler mapped vegetation as blue oak-foothill pine forest, and chaparral. Predominant potential natural communities are Blue Oak, Interior Live Oak, Valley Needlegrass and Mixed Chaparral series.

Fauna. Former inhabitants include grizzly bear and pronghorn antelope. Mammals include black-tailed and mule deer, coyote, ground squirrel, cottontail, jack rabbit, and kangaroo rat. Common birds include turkey vulture, falcons, eagles, hawks, owl, quail, mourning dove, mockingbird, scrub jay, herons, ravens, western meadowlark, fin, and sparrows. Introduced species include turkeys and chukars.

Climate. Precipitation ranges from 20 to 40 in (510 to 1,020 mm). Temperature averages 55 to 64 oF (13 to 18 oC). The growing season lasts 200 to 320 days.

Surface Water Characteristics. There are many rapidly flowing rivers and streams. Rivers flow westerly in deeply incised canyons with bedrock controlled channels to the Great Valley Section and Pacific Ocean. Reservoirs for municipal water supply, irrigation, and flood control are common.

Disturbance Regimes. Fires are low, moderate, and high intensity surface or stand-replacing fires.

Land Use. Composition and successional sequence of some communities have changed because of plant and animal species introduced between the mid 1800's and early 1900's. These introductions related to mining, grazing, and agriculture. Rapidly expanding foothill urban areas are scattered throughout the Section. Large and small water impoundments are common.

Cultural Ecology. Humans have been utilizing the Section for about 10,000 years, and have been an integral part of its ecology for 3,000 to 5,000 years. Sierran foothills contain some of the densest year-round prehistoric habitation locations in California, particularly along riparian areas, where intensive occupation, resource procurement and processing practices, and vegetation manipulation often altered the environment. Contemporary attitudes tend to be dichotomized between values: amenity for the newcomer and commodity for the long-time resident. Human environment is characterized by a rural lifestyle of open space and outdoor leisure activity. Recreation is the primary economic emphasis, trailed by government employment. The foothills, in particular, are experiencing rapid retiree and commuter resident growth.

Compiled by Pacific Southwest Region.

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Section M261G--Modoc Plateau

Geomorphology. This area comprises northwesterly trending fault-block mountains and ridges, with intervening basin-like grabens commonly interspersed with lake bed deposits, shield volcanoes, cinder cones, or lava flows. Elevation ranges from 3,000 to 9.900 ft (912 to 3,010 m). This in in the Modoc Plateau geomorphic province (part of the Basin and Range Province flooded with volcanics related to those of the Cascade Range Province).

Lithology and Stratigraphy. There are Cenozoic volcanic and nonmarine sedimentary rocks and alluvial deposits.

Soil Taxa. Soils include Alfisols, Andisols, Aridisols, Entisols, Inceptisols, Mollisols, and Vertisols, in combination with mesic and frigid soil temperature regimes and xeric and aridic soil moisture regimes.

Potential Natural Vegetation. K\"uchler mapped vegetation as yellow pine-shrub forest, juniper-shrub savannah, sierran montane forest, sagebrush steppe, upper montane-alpine forests, and northern Jeffrey pine forest. Predominant potential natural communities are Ponderosa Pine, Mixed Conifer, Western Juniper, White Fir, Big Sagebrush, Low Sagebrush and Carex series.

Fauna. Mammals include mule deer, pronghorn, black bear, mountain lion, coyote, bobcat, yellow-bellied marmot, wolverine, jack rabbit, and porcupine. Birds include eagles, hawks, owls, woodpeckers, falcons, osprey, quail, and sage grouse. The Section contains wetlands that are important resting, feeding, and nesting areas for migrating waterfowl. Species of concern include the California and spotted owl (western part). Species no longer occurring in the Section include mountain sheep and sharp-tailed grouse.

Climate. Precipitation ranges from 12 to 30 in (300 to 760 mm). Temperature averages 45 to 52 oF (7 to 11 oC). The growing season lasts 70 to 140 days.

Surface Water Characteristics. There are few slow flowing rivers and few slow to moderately rapid flowing streams, although most streams do not flow throughout the summer. Rivers and streams flow in alluvial and bedrock controlled channels to the Sacramento and Klamath Rivers, or to basins within the Modoc Plateau or the northwestern Basin and Range Section. Numerous small to very large lakes and reservoirs occur throughout the Section.

Disturbance Regimes. Historic occurrence of fire has changed from frequent, low intensity ground fires to infrequent, high intensity stand-replacing fires.

Land Use. Composition and successional sequence of some communities have changed because of plant and animal species introduced between the mid 1800's and early 1900's. The introduced species related to grazing, forestry, and agriculture.

Cultural Ecology. Humans have been utilizing the plateau for about 10,000 years, and have been an integral part of its ecology for 3,000 to 5,000 years. Extensive prehistoric procurement and processing of obsidian resources have left vast areas of the plateau pockmarked and littered with lithic debitage. Euro-American influx into the area in the mid-1800's, along the Oregon and California Trails, ushered in agricultural pursuits. Contemporary attitudes and beliefs tend to be dominated by commodity oriented long-time resident values and a rural lifestyle. The economy is dominated by government employment, but ranching and lumbering continue to be important.

Compiled by Pacific Southwest Region.

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