Chapter 44
Ecological Subregions of the United States

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Middle Rocky Mountain Steppe - Coniferous Forest - Alpine Meadow

Seven Sections have been delineated in this Province:

These Sections are located in the northwestern conterminous States, including parts of Oregon, Washington, Idaho, and Montana. The area of these Sections is about 81,800 mi2 (211,900 km2).

Section M332A--Idaho Batholith

Geomorpholgy. These are mountains with alpine ridges and cirques at higher elevations. Large U-shaped valleys with broad bottoms indicate that the area has been strongly glaciated. Mature surfaces are dissected with major drainages deeply incised, resulting in steep breaklands. Elevation ranges from 3,000 to 10,000 ft (900 to 3,000 m). Local relief ranges from 3,000 to 5,000 ft (900 to 1,500 m). This Section is within the Northern Rocky Mountains physiographic province.

Lithology and Stratigraphy. Lower Tertiary and Mesozoic granite forms the Idaho Batholith. Areas of Tertiary and Quaternary sediments and basalts have also been identified.

Soil Taxa. There are Frigid and cryic Ochrepts and Boralfs, with some Udands and Cryands occurring on areas where significant volcanic ash has accumulated. Soils are generally shallow to moderately deep, with loamy to sandy textures. Volcanic ash accumulations in some soils causes them to be very productive.

Potential Natural Vegetation. K\"uchler mapped vegetation as grand fir--Douglas-fir forest, western spruce--fir forest, and western ponderosa forest.

Fauna. Birds are typical of the northern Rocky Mountains, including such species as Steller's jay, olive-sided flycatcher, and western wood-pewee. Specialists include flammulated and boreal owl, Lewis' woodpecker, Townsend's solitaire, and Nashville and yellow-rumped warblers. Several species nearing the edge of their ranges are mountain quail, spruce grouse, chestnut-backed chickadee, red-eyed vireo, Townsend's warbler, and American redstart. Typical herbivores and carnivores include white-tailed deer, mule deer, elk, mountain goat, moose, black bear, bobcat, and cougar. Common smaller herbivores include the snowshoe hare and the northern flying squirrel. Rare species associated with this Section includes grizzly bear, gray wolf, lynx, fisher, and wolverine. Herpetofauna typical of this Section are the spotted frog, wood frog, Pacific treefrog, western toad, long-toed salamander, and the Pacific giant salamander.

Climate. Precipitation ranges from 20 to 80 in (510 to 2,030 mm). Most occurs during fall, winter, and spring as snow. Storms are cyclonic from the Pacific Ocean. Climate is maritime-influenced, cool temperate with dry summers. Mean air temperature ranges from 35 to 46 oF (2 to 7 oC), but may be as low as 24 oF (-4 oC) in the high mountains. The growing season lasts 45 to 100 days.

Surface Water Characteristics. Many perennial streams and lakes occur. Lakes include Payette Lake, Cascade Reservoir, Warm Lake, and Redfish Lake. Breaklands have very steep, straight tributaries with a high sediment delivery efficiency. Older surfaces have much gentler, complex dendritic and structurally-controlled drainage patterns with much lower sediment delivery efficiencies. Major rivers include the Salmon and Payette.

Disturbance Regimes. Fire, insects, and disease are the dominant natural sources of disturbance. Fires have been frequent, low intensity, and patchy, and occasionally high intensity and continuous. Mass wasting is also an important source of disturbance in some areas.

Land Use. Timber harvest is the dominant land use, with some grazing also occurring. Mining and recreational uses are also important.

Cultural Ecology. Reserved.

Compiled by Northern Region.

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Section M332B--Bitterroot Valley

Geomorphology. This area includes high, glaciated mountains with alpine ridges and cirques at higher elevations and glacial and lacustrine basins at lower elevations. Steep slopes, sharp crests, and narrow valleys are characteristic. Elevation ranges from 2,500 to 6,000 ft (763 to 1,830 m) in basin areas; the range is 3,000 to 8,000 ft (915 to 2,440 m) in mountains, with some alpine areas up to 10,000 ft (3,050 m). This Section is within the Northern Rocky Mountains physiographic province.

Lithology and Stratigraphy. Lower Tertiary, Mesozoic, and Precambrian granite and metasedimentary rock occur.

Soil Taxa. There are frigid and cryic Ochrepts, Boralfs, and Orthents, with significant areas of rockland and talus. Soils in basins are Borolls, Ochrepts, and Fluvents. Xeric intergrades probably occur. These soils are generally shallow to moderately deep, with loamy or sandy textures containing large amounts of rock fragments. Some soils at higher elevations are moderately influenced by volcanic ash accumulations.

Potential Natural Vegetation. K\"uchler classified vegetation as Douglas-fir forest and western ponderosa forest (80 percent) and foothills prairie (20 percent), mostly in the lower valleys. The upper timberline occurs at about 8,800 ft (2,667 m). Common tree species include western larch, Douglas-fir, subalpine fir, and ponderosa pine. Grassland species are mainly bluebunch wheatgrass, Idaho fescue, and rough fescue.

Fauna. Birds are typical of the northern Rocky Mountains, including species such as black-capped chickadee, Steller's jay, and western tanager. The slightly drier and more open areas also provide habitat for dryland species such as sage grouse, black-billed magpies, and horned larks. Other species of note are the harlequin duck, flammulated owl, Lewis' woodpecker, black-backed woodpecker, American dipper, and Nashville warbler. Species near the edge of their range are pileated woodpecker, chestnut-sided chickadee, and Townsend's warbler. Typical herbivores and carnivores include white-tailed deer, mule deer, elk, moose, black bear, bobcat, and cougar. Smaller common herbivores include the snowshoe hare and the northern flying squirrel. Rare species include the grizzly bear, gray wolf, lynx, wolverine, and northern bog lemming. Herpetofauna typical of this Section are the spotted frog and long-toed salamander.

Climate. Precipitation ranges from 14 to over 80 in (360 to 2,030 mm). Most of the precipitation in fall, winter, and spring is snow. Climate is cool temperate with some maritime influence. Summers are relatively dry. Temperature averages 36 to 46 oF (2 to 8 oC). The growing season lasts 45 to 130 days.

Surface Water Characteristics. Many perennial streams with dendritic and structurally controlled patterns occur. Many third order drainages are deeply incised into narrow, V-shaped canyons as they leave the mountains. Major rivers include the Bitterroot and the Clark's Fork.

Disturbance Regimes. Fire, insects, and disease are the dominant natural sources of disturbance. Fires were generally low intensity, frequent ground fires prior to fire suppression efforts. Fuel accumulations have now set the stage for large, high-intensity fires.


Land Use. Land use is mostly timber harvest with some livestock grazing. Mining and recreational uses are also important.

Cultural Ecology. Reserved.

Compiled by Northern Region.

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Section M332C--Rocky Mountain Front

Geomorphology. There are glaciated mountains with limestone scarps and ridges interspersed with glacial and lacustrine intermontane basins. Alpine ridges and cirques occur at higher elevations. Elevation ranges from 5,500 to 8,500 ft (1,678 to 2,593 m). This Section is within the Northern Rocky Mountains physiographic province.

Lithology and Stratigraphy. Precambrian and Paleozoic limestone and marine clastic rocks occur.

Soil Taxa. Soils include frigid and cryic Ochrepts, Boralfs, Orthents, and Borolls. Fluvents occur in the basin areas. These soils are generally shallow to moderately deep with loamy to sandy textures.

Potential Natural Vegetation. Douglas-fir forest and western spruce-fir forest (15 percent), occur mostly between 4,500 to 8,000 ft (1,360 to 2,425 m). Extensive aspen groves also occur. Limber pine is also present. Foothills prairie (85 percent) occurs on lower elevation foothills. Common grasses include wheatgrasses, fescues, and needlegrass.

Fauna. Birds are typical of the drier, open areas of the northern Rocky Mountains, including such species as common raven, black-capped chickadee, hermit thrush, Cassin's finch, and dark-eyed junco. Other birds include the harlequin duck, blue grouse, spruce grouse, gray jay, black-billed magpie, Clark's nutcracker, American dipper, Townsend's solitaire, American pipit, yellow-rumped warbler, fox sparrow, western tanager, and pine siskin. Several species meet the edge of their range at the intersection of Rocky Mountain and plain, including Vaux's swift. Typical herbivores and carnivores include white-tailed deer, mule deer, elk, moose, black bear, bobcat, and cougar. Smaller common herbivores include the snowshoe hare and the northern flying squirrel. Rare species include the grizzly bear and gray wolf. Herpetofauna typical of this Section are the spotted frog, wood frog, Pacific treefrog, western toad, and long-toed salamander.

Climate. Precipitation ranges from 18 to over 100 in (460 to 2,540 mm), with forests receiving an average of 30 to 40 in (760 to 1,020 mm). Maximum precipitation occurs from spring through early summer; winter precipitation is snow. Severe chinook winds and dramatic fluctuations of winter temperatures are common. Climate is cold continental. Temperature averages 36 to 45 oF (2 to 7 oC). The growing season averages 45 to 90 days.

Surface Water Characteristics. There is generally a dendritic drainage pattern with some structural control. Major water bodies include St. Mary's lake and Gibson reservoir. Smaller lakes occur in high elevation cirque basins. Major rivers include the Sun and the Middle Fork of the Flathead.

Disturbance Regimes. Fire, insects, and disease are the principal natural sources of disturbance. Strong chinook winds that cause windthrow are also a source of disturbance.

Land Use. Livestock grazing is important, along with some timber harvest. Recreation, watershed, and wildlife habitat are other important land uses.

Cultural Ecology. Reserved.

Compiled by Northern Region.

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Section M332D--Belt Mountains

Geomorphology. This Section comprises high mountains, gravel-capped benches, and intermontane valleys bordered by terraces and fans. Plains and rolling hills surround the isolated mountain ranges. Elevation ranges from 4,000 to 8,500 ft (1,220 to 2,593 m) in the mountains; elevation ranges from 2,500 to 5,000 ft (763 to 1,525 m) on the plains. Most of this Section is within the Northern Rocky Mountains physiographic province, but the eastern part extends onto the Missouri Plateau within the Great Plains physiographic province.

Lithology and Stratigraphy. There are Paleozoic and Precambrian metamorphic and Cretaceous soft sedimentary rocks.

Soil Taxa. Frigid and cryic Ochrepts, Boralfs, and Borolls occur in the mountains. These soils are shallow to moderately deep with loamy to sandy textures. Frigid Orthents, Borolls, and Fluvents occur on the plains. These soils are generally moderately deep to deep with loamy to clayey textures.

Potential Natural Vegetation. K\"uchler classified vegetation as foothills prairie (75 percent) and Douglas-fir forest--eastern ponderosa forest (25 percent). Forests are associated with prominent mountain ranges and the Missouri River breaks, and cover all but the highest peaks. Typical prairie species include wheatgrasses, fescues, grama, and needlegrass. Common tree species are Douglas-fir, ponderosa pine, limber pine, and subalpine fir.

Fauna. Birds are typical of short-grass prairie or the drier portions of the Rocky Mountains. Species of note are ferruginous and Swainson's hawks, golden eagle, prairie falcon, sage grouse, Lewis' woodpecker, western kingbird, horned lark, yellow-rumped warbler, and lazuli bunting. Several birds near the extent of their range in this Section, including both eastern and western screech-owls, calliope hummingbird, red-headed woodpecker, mountain chickadee, Sprague's pipit, ovenbird, and McCown's longspur. Typical herbivores and carnivores include white-tailed deer, mule deer, elk, moose, black bear, bobcat, and cougar. Smaller common herbivores include the snowshoe hare and northern flying squirrel. Rare species include the northern bog lemming. Herpetofauna typical of this Section are the spotted frog, Pacific treefrog, western toad, and long-toed salamander.

Climate. Precipitation ranges from 10 to 40 in (250 to 1,020 mm), with maximum precipitation occurring in spring and early fall; winter precipitation is snow. Climate is cold continental. Temperature averages 36 to 45 oF (2 to 7 oC). Temperature extremes are common throughout the winter months; strong winds are common throughout the year. The growing season ranges from 45 to 140 days.

Surface Water Characteristics. Perennial streams have a dominantly dendritic drainage pattern and are fairly widely spaced. Some drainages are deeply incised as they leave the mountains. Holter and Canyon Ferry lakes are in this Section. Smaller lakes occur at higher elevations. Major rivers include the Missouri and the Smith.

Disturbance Regimes. Fire, insects, and disease are the principal natural sources of disturbance.

Land Use. Land uses are dominantly livestock grazing, timber harvest, watershed, wildlife habitat, and recreation.

Cultural Ecology. Reserved.

Compiled by Northern Region.

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Section M332E--Beaverhead Mountains

Geomorphology. This area encompasses complex and high, steep mountains with sharp alpine ridges and cirques at higher elevations, glacial and fluvial valleys, and alluvial terraces and flood plains. Elevation ranges from 2,500 to 6,500 ft (763 to 1,983 m) in valleys; elevation ranges from 4,000 to 10,000 ft (1,220 to 3,050 m) in the mountains. This Section is within the Northern Rocky Mountains physiographic province.

Lithology and Stratigraphy. Composition is complex, including Precambrian granitic, Paleozoic metamorphic, and Tertiary sedimentary and volcanic rocks.

Soil Taxa. Soils include frigid and cryic Ochrepts, Boralfs, and Borolls, with some Fluvents and Aquepts in alluvial valleys. Mountain soils are generally shallow to moderately deep and have loamy to sandy textures with rock fragments. Valley soils are moderately deep to deep and have loamy to clayey textures.

Potential Natural Vegetation. Vegetation consists of sagebrush steppe with small areas of alpine vegetation (75 percent) above 9,500 ft (2,880 m), and Douglas-fir forest (25 percent) the latter spans an elevation range of only about 1,000 to 1,500 ft (300 to 450). Typical steppe species include big sagebrush, fescues, wheatgrasses, and needlegrass. Douglas-fir, limber pine, and lodgepole pine are common tree species.

Fauna. Birds are similar to those in M332B, with a larger number of species typical of the Great Plains. Species of note are trumpeter swan, Barrow's goldeneye, Swainson's hawk, golden eagle, sage grouse, sandhill crane, American dipper, Townsend's solitaire, and Brewer's sparrow. Birds nearing the edge of their range are spruce grouse, black-throated hummingbird, pileated woodpecker, eastern kingbird, red-eyed vireo, and northern water thrush. Typical herbivores and carnivores include white-tailed deer, mule deer, pronghorn, elk, moose, black bear, bobcat, and cougar. Smaller common herbivores include the snowshoe hare and northern flying squirrel. Rare species include the gray wolf, lynx, wolverine, pygmy rabbit, Great Basin pocket mouse, and the northern bog lemming. Herpetofauna typical of this Section are the spotted frog, wood frog, Pacific treefrog, boreal toad, western toad, and long-toed salamander.

Climate. Precipitation ranges from 10 to 50 in (250 to 1,270 mm). Most fall, winter, and spring precipitation is snow. Winters are cold, and growing season conditions are dry. Soil moisture is not sufficient for tree growth on some south and west aspects below timberline; hence, grasslands often extend from the valley floors to the mountain tops. Climate is cold dry continental. Temperature averages 36 to 46 oF (2 to 8 oC). The growing season ranges from 45 to 100 days.

Surface Water Characteristics. Drainage patterns are complex, reflecting the complex geology. Intermittent drainages are common, indicating the somewhat arid nature of the area. Lakes occur in glaciated areas at higher elevations. Major rivers include the Lemhi, Beaverhead, and Ruby.

Disturbance Regimes. Fire, insects, and disease are the principal natural sources of disturbance.

Land Use. Livestock grazing is the dominant land use. Limited timber harvesting, mining, wildlife habitat, and recreation are also important land uses.

Cultural Ecology. Reserved.

Compiled by Northern Region.

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Section M332F--Challis Volcanic

Geomorphology. This Section occurs within the Middle Rocky Mountain physiographic province. The Challis Volcanics Section is in central Idaho. Mountain ranges include White Cloud Peaks, Pioneer Mountains, Smokey Mountains, Boulder Mountains, White Knob Mountains, and portions of the Salmon River Range. Areas of glaciation occur in this Section. Most of the mountain ranges have residual weathering. Elevation ranges from 4,000 to 11,800 ft (1,200 to 3,600 m).

Lithology and Stratigraphy. Challis volcanic rocks, mostly Tertiary, dominate. Some areas of granite and Precambran rock are in the western portion of the Section. Challis volcanics consist of latite-andesite flows, basalts, tuffs, and rhyolites. Precambrian rocks consist mainly of quartzite.

Soil Taxa. Alfisols, Mollisols, Inceptisols, and Entisols occur in combination with frigid and cryic soil temperature regimes, along with xeric, udic, and aquic soil moisture regimes.

Potential Natural Vegetation. K\"uchler vegetation types include a mixture of western spruce-fir forest and sagebrush steppe. Douglas-fir forest occurs also in this Section. The Soil Conservation Service identifies the potential natural vegetation as mixed conifer forest. Also included are areas of Lodgepole Pine series. Whitebark Pine and Subalpine Fir series also occur at the highest elevations. Areas of Big Sagebrush series are on southerly exposure and at lower elevation.

Fauna. Characteristic mammals include mule deer, elk, bighorn sheep, mountain goat, pronghorn, and moose. Bison, once present, are now extirpated. Feral or wild horses arrived in the area in the late 1700's. Predators include bobcat, wolverine, marten, coyote, red fox, black bear, and mountain lion. The gray wolf and grizzly bear have been extirpated from the area; however, the gray wolf may be re-colonizing from northern populations. Grouse (sage, blue, ruffed, and spruce), northern goshawk, northern flicker, dark-eyed junco, mountain chickadee, and black-billed magpie are representative avian species. Concentrations of wintering bald eagles use the large riverine habitats. Peregrine falcon historically nested within the Section. Herpetofauna is represented by the spotted frog, western toad, sagebrush lizard, western rattlesnake, gopher snake, and the western garter snake. Chinook salmon and steelhead and bull trout were once common, but are now greatly reduced in number and distribution.

Climate. Precipitation ranges from 10 to 45 in (250 to 1,200 mm) annually, with an average of 22 in. Most occurs during fall, winter, and spring. High mountain barriers to the west reduce precipitation due to a rain shadow effect. Climate is influenced by prevailing winds from the west and the general north-south orientation of the mountain ranges. Summers are dry with low humidity. Precipitation during the frost-free period is 30 to 40 percent of the evaporation potential. The mean annual air temperature is 34 to 50 oF (3 to 10 oC), but may be as low as 24 oF (-4 oF) in the high mountains. The growing season ranges from 70 to 120 days.

Surface Water Characteristics. This Section is primarily drained by the Wood River, Big Lost River, and the Salmon River. Many perennial streams exist.

Disturbance Regimes. Common high intensity forest fires occur during summer thunderstorms. Erosion by water is occurring.

Land Use. Forest related industries and livestock production are important in this Section. Approximately 50 percent of the land is forested and used for timber production and livestock grazing. Mining is also an important use that produces gold and silver. Recreation remains very important.

Cultural Ecology. Reserved.

Compiled by Intermountain Region.

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Section M332G--Blue Mountains

Geomorphology. This is a moderately dissected wide, uplifted plateau dominated by landslide and fluvial erosion processes in the western portion. Mesas and buttes are common. Moderately dissected mountains dominated by glacial and fluvial erosion processes are in the eastern half. From the low-lying Ochoco Mountains in the southwest, individual ranges, separated by north-south trending valleys, rise to ice-sculpted peaks and deep canyons in the Wallowa Range. Wide, low elevation valleys between ranges are alluvium-filled fault troughs. Elevation ranges from 1,000 to 10,000 ft (300 to 3,300 m). Most of the mountainous part of the Section is between 4,000 and 7,500 ft (1,212 and 2,273 m), and the valleys are less than 4,000 ft (3,030 m). Local relief is 2,000 ft (606 m) or more in the mountains and 100 to 500 ft (30 to 150 m) on the broad valley floors.

Lithology and Stratigraphy. Five Paleozoic accreted terrains, composed of metamorphic and volcanic island arc sequences, are recognized. These and Late Mesozoic plutons cover the central to eastern portion. Portions have a thin veneer of glacial debris. The western area is composed of Eocene, Miocene, and Oligocene tuffs, siltstones, sandstones with basalts, andesites, and rhyolites. Some areas are overlain by up to 1,000 ft (330 m) of multi-flow Miocene basalts.

Soil Taxa. Most soils in this Section are influenced by a mantle of volcanic ash from Mount Mazama. The ash mantle is relatively undisturbed in places, on gentle north slopes under forest canopy. On southerly exposures, the ash has been mostly removed by erosion. Commonly the ash is re-deposited and mixed with loess, colluvium, and alluvium from other sources. In the high mountains are cold, usually moist soils with relatively high amounts of volcanic ash and low base saturation. Some have dark, organic matter-rich surface layers (Humic Vitricryands; Vitrandic, Typic, and Lithic Cryumbrepts); others have clay-enriched subsoils (Alfic Vitricryands; Andic or Vitrandic Cryoboralfs); and in wet meadows are soils with a high water table and an organic surface layer (Histic Cryaquepts). At lower elevations, are cool, usually moist soils with a thick ash mantle (Typic Udivitrands) and clay-enriched subsoil (Alfic Udivitrands; Andic and Vitrandic Eutroboralfs).

On lower mountain slopes, soils are dry in late summer and base saturation is greater than in the high mountains. Some soils have relatively high amounts of volcanic ash (Typic Vitrixerands) with an organic matter-rich surface layer (Humic Vitrixerands) or with a clay-enriched subsoil (Alfic Vitrixerands). Other soils have medium amounts of ash (Vitrandic Haploxeralfs and Xerochrepts) and an organic matter-rich surface layer (Vitrandic Argixerolls and Haploxerolls). Soils with little volcanic ash have organic matter-rich surface layers, with or without clay-enriched subsoil (Typic, Lithic, Ultic, and Pachic Argixerolls and Haploxerolls). On valley floors, soils under a grass-shrub vegetation are dry for most of the summer and have organic matter-rich topsoil with high base saturation (Typic, Lithic, and Pachic Argixerolls and Haploxerolls).

Potential Natural Vegetation. The K\"uchler vegetation types are dominantly grand fir--Douglas-fir forests, followed by western ponderosa forests. High elevation forests are western spruce-fir. Great basin sagebrush and juniper steppe woodland are interspersed on relatively dry, mesic regime sites. Wheatgrass-bluegrass occurs on mesic-xeric soils in canyons and south slopes. Alpine meadows and barrens occupy the highest elevations. Grand fir and Lodgepole Pine are the dominant series and are at mid elevations on the moderately deep and deep volcanic ash soils with frigid temperature regimes and udic to xeric moisture regimes. Some lodgepole pine is on cryic soils. Ponderosa Pine series dominates at mid to low elevations on mesic and frigid xeric soils. Douglas-Fir series is intermediate between the Lodgepole Pine and Ponderosa Pine series. Subalpine Fir series dominates at the highest elevations on cryic soils. Western Juniper series occurs at low elevations on mesic and xeric soils. Shrub series of Snowberry, Mountain Mahogany, Bitterbrush, Common Snowberry, and Low Sage are interspersed. Grasslands are at the highest and lowest elevations. High elevation, cryic soils are dominated by green and Idaho fescues, and sedges. At mid and low elevations, Idaho fescue and bluebunch wheatgrass, occur with lesser amounts of Sandbergs bluegrass and prairie junegrass. Wet meadows are dominated by sedges and tufted hairgrass.

Fauna. The principal mammals are Rocky Mountain elk, mule deer, black bear, cougar, bobcat, and coyote. Elk and deer populations have fluctuated widely since settlement due to changes in vegetative cover. Several fur bearers are common, including beaver, pine marten, raccoon, and fisher; they occur in a variety of habitats. A wide variety of birds occupy various habitats. Hawks, golden eagle, chukar, owls, and a variety of song birds inhabit cliffs and talus slopes. A variety of cavity nesters, including pileated woodpecker, other woodpeckers, nuthatches, chickadees, bluebirds, and others, are dispersed throughout the Section. Anadromous fish include chinook and coho salmon and steelhead, but are at diminished levels and are on threatened or endangered lists. Resident fish include rainbow, bull trout, and brook trout. A variety of amphibians and reptiles are common.

Climate. Precipitation averages 9 to 18 in (230 to 460 mm) in the valleys and 17 to 100 in (430 to 2,540 mm) in the mountains. Temperature ranges from 28 to 52 oF (-2 to 11 oC). The growing season ranges from less than 30 to 130 days.

Surface Water Characteristics. Stream density varies from 1.5 to 2 mi/mi2 (3.9 to 5.2 km/km2) wetter areas, to no perennial streams in drier areas. Numerous springs are scattered throughout the Section. Some alpine lakes are clustered in high elevation glacial areas. Reservoirs are on several streams. The Snake River canyon is a major feature near the eastern edge of the Section.

Disturbance Regimes. Fire was a major factor in disturbance until the early the advent of fire control in the early 20th century. Periodicities ranged from as few as 10 to 15 years. to as infrequent as several decades on the cooler and wetter sites. A variety of insects, including beetles, tussock moth, spruce budworm, and others, are endemic; periodic epidemics appeared and declined until recently. Epidemic occurrences have had significant effects in the recent decade. A variety of diseases also have had some local effects. Periodic floods and ice jams are important in some watersheds.

Cultural Ecology. Humans have occupied the Blue Mountains and high lava plains for at least 12,000 years. This region exhibited prehistoric lifestyles that were transitional between Great Basin cultural patterns to the south and Columbia Plateau cultural patterns to the north. Root digging, seed and berry gathering, hunting, and fishing were the primary economic activities, and their relative importance shifted with changing climatic conditions. Peoples tended to live in groups comprising a couple of families during much of the year to utilize resources that were scattered over the landscape and ripened at different times. Several such groups would come together seasonally at camps on rivers, streams, or large upland meadows to exploit concentrated resources and utilize stored resources. Burning was practiced to improve the production of berries, big game forage, and to drive game. Extensive deposits of obsidian and basalt were intensively used, and these materials were re-distributed widely. Euro-American settlement and exploitation of the area began in the mid 1800's and intensified during the 1860's with the discovery of gold. Locally heavy alteration to the landscape and hydrology occurred due to hydraulic mining and attendant ditch building and use, later followed by hardrock mining and dredging. Mineral extraction and activities related to improved transportation systems and agriculture led to relatively large settled human populations. Logging, logging railroad construction, cattle and sheep grazing, and fire suppression have also played a significant role in alteration of the environment. Historic uses of the land created ecological effects on plant and animal species and other resources that far exceed those from prehistoric times.

Compiled by Pacific Northwest Region.

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