Chapter 45
Ecological Subregions of the United States

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Northern Rocky Mountain Forest-Steppe - Coniferous Forest - Alpine Meadow

Four Sections have been delineated in this Province:

These Sections are located in the northwestern conterminous States, Including parts of Washington, Idaho, and Montana The area of these Sections is about 38,100 mi2 (98,700 km2).

Section M333A--Okanogan Highlands

Geomorphology. This Section's features range from accretion of continetal shelf material forming the Okanagan Highlands, in response to the uplifting and movement of the oceanic shelf to the east, to the Rocky Mountain facies and volcanic influences from the rise of the Kettle Dome. Extreme metamorphism and deformation have occurred, as well as deposits of glacial till, outwash, and debris that cover most of the modern landscape. The area is inudated with glacial lakes, rivers, and streams, as well as mountains, and both narrow and broad valleys. Elevation ranges from 1,376 to 7,309 ft (444 to 2,358 m). Local relief ranges from 500 to 1,000 ft (161 to 322 m).

Lithology and Stratigraphy. Types include Precambrian metamorphics; Mesozoic intrusives and metamorphics; Tertiary intrusives, sedimentary rocks and extrusive volcanics; and Quaternary colluvium, alluvium, glacial debris, glacial outwash, and glacial till.

Soil Taxa. In the high mountains there are cold (cryic), usually moist (udic) soils under coniferous forest with volcanic ash and relatively low base saturation (Typic Vitricryands; Andic and Vitrandic Cryochrepts); soils with dark, organic matter-rich topsoil and medium base saturation (Vitrandic and Pachic Cryoborolls); and on high-mountain basin floors there are soils with a water table near the surface and organic topsoil (Histic Cryaquolls). On the medium elevation mountain slopes that dominate this Section there are cool (frigid), cobbly, and stony soils (Typic and Lithic Vitrixerands; Andic and Vitrandic Xerochrepts); that are formed by materials with variable amounts of volcanic ash and that are dry during late summer; there are also soils with dark, organic matter-rich topsoil (Vitrandic Haploxerolls).

On valley floors and foothills along major drainages are warm (mesic) soils that are usually dry during the summer (xeric). These include stratified, gravelly soils and cobbly, well drained soils with dark topsoil on terraces (Cummulic and Fluventic Haploxerolls) and poorly drained soils on flood plains (Fluvaquentic Haplaquolls). On footslopes above the valley floor there are soils formed in till and colluvium from the ice-scoured valley walls. Many of these soils have dark, organic matter-rich topsoil with variable depth to bedrock, topsoil thickness, and amount of volcanic ash (Typic, Pachic, Lithic, and Vitrandic Haploxerolls); also, soils without the dark topsoil (Typic Xerochrepts) are common.

Potential Natural Vegetation. Vegetation pattern in this Section is strongly influenced by the strong east-west precipitation gradient. Vegetation in the western third of the Section found west of the Kettle Mountains crest differs significantly from that in the eastern two-thirds. The Big Sagebrush series dominates the lowest elevations on mostly xeric soils. The Ponderosa Pine series occurs at slightly higher elevations, also on xeric soils. This series is replaced by the Douglas-Fir series at higher elevations. Soils with this series have a xeric moisture regime and mesic or frigid temperature regimes. The Subalpine Fir series occupies higher elevations to upper forest line on cryic soils.

Vegetation east of the Columbia River is characterized by the Douglas-Fir series at lowest elevations followed by the Grand Fir series, Western Hemlock and Western Red Cedar series, and the Subalpine Fir series with increasing elevation. The Douglas-Fir and Grand Fir series occur on xeric soils, with the Grand Fir series occupying slightly cooler and more mesic habitats. The Western Hemlock and Western Redcedar series occur on soils with udic regimes. The Subalpine Fir series occurs on cryic soils. The Whitebark Pine series and the Green Fescue series occur at the highest elevations throughout the Section above continuous forest line.

Fauna. Birds of this Section are generally typical of the forested portions of the Rocky Mountains. These include rufous hummingbird, Steller's and gray jays, common raven, varied thrush, mountain bluebird, solitary vireo, Townsend's warbler, western tanager, and red crossbill. Birds which reach or nearly reach their southern, eastern, or western geographical extent in this Section are spotted owls (replaced by barred owls in the eastern portion of this Section), hawk owl, boreal chickadee, red-eyed vireo, American redstart, and white-winged crossbill. The Section's abundant water systems provide for a very high population of waterfowl, osprey, and bald eagle. Other threatened, endangered, or rare species include harlequin duck and upland sandpiper (in the lowlands). The woodland caribou reach the southern portion of their range within this mapping Section. Typical herbivores and carnivores include white-tailed deer, mule deer, bighorn sheep, elk, moose, black bear, bobcat, and cougar. Smaller common herbivores include the snowshoe hare and northern flying squirrel. Rare mammals associated with this Section include grizzly bear, woodland caribou, gray wolf, lynx, fisher, wolverine, and northern bog lemming. Herpetofauna typical of this Section are the spotted frog, wood frog, Pacific treefrog, western toad, and long-toed salamander and possibly the Pacific giant salamander.
Climate. Precipitation occurs mostly as snow. Thirty to 80 in (760 to 2,030 mm) occur per year. Rain on snow is common. June and July are very wet months. August through November is dry. Humidity is low year round. The climate is maritime-influenced. Adequate soil moisture is generally present during the growing season on all but the most severe sites. Annual average temperatures range from a minimum of 30 to 58 oF (- 1 to 14 oC), with a mean temperature of 44 oF (7 oC). Warmest months are late July through August. The growing season generally last 45 to 120 days, but as long as 140 days in some lower valleys.

Surface Water Characteristics. There is a high frequency of rapidly flowing rivers and streams during June. Rivers follow faults in the crust over the Kettle Dome to the west. The Pend Orielle and the Columbia Rivers both run from the north to the south, with tributaries entering from the northeast and northwest predominantly. Most creeks flow through glacial outwash and debris material within narrow valleys. There are many glacial lakes and wet meadows associated with the last retreat of the glaciers in northeastern Washington.

Disturbance Regime. Historic fire events have changed a large portion of the forest. Changes are periodic and range from high intensity, high severity, continuous fires to low severity, infrequent fires. Composition and successional sequences of some communities has changed because of harvesting practices and the introduction of animal species into the valleys. Wide fluctuations in precipitation and temperatures for periods of years result in significant changes in biological communities. Insects and diseases are frequent disturbance features.

Land Use. The Section is mostly rural. Forestry, livestock grazing, mining, and localized agriculture are principal uses. Communities are mostly small. Summer residences are common at lakes and large river systems. Outdoor recreation in all seasons is rapidly increasing.

Cultural Ecology. Humans have occupied the Okanogan Highlands Section for at least 12,000 years. For the last 5,000 years, groups spent much of the year in river-oriented pithouse villages of 30 to 300 people. Hunting, salmon fishing, and root and berry collecting were the primary economic activities. They were also the backdrop for much of the social organization and spiritual beliefs. Hunting and fishing were important not only for the sustenance they provided, but for where, when, and how they were carried out. Burning (both intentional and otherwise) to improve plant growth for berry crops and big game forage was common; however, hunting pressure prior to Euro-American settlement may have contributed to the extinction of the Columbia Basin bison population (never a large population at any time in prehistory). Large pithouse villages with between 30 and 200 pit depressions have created small-scale localized ecological effects. Euro-American settlement and exploitation of the area began in the mid 1800's and intensified between 1875 and 1925. Historic activities--including lumbering (especially in the Okanogan Highlands), railroad construction, dam building, grazing, wheat ranching, and irrigated farming--have all created ecological effects on plant and animal species and other resources that far exceed most of those from prehistoric times.

Compiled by Pacific Northwest Region and Northern Region.

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Section M333B--Flathead Valley

Geomorphology. There are glaciated mountains, glacial moraines, large glacial troughs, and glacial and lacustrine basins. Elevation ranges from 2,000 to 7,000 ft (610 to 2,135 m). This Section is within the Northern Rocky Mountains physiographic province.

Lithology and Stratigraphy. Types include predominantly Precambrian metasedimentary rocks of the Belt supergroup, with glacial deposits and valley fill.

Soil Taxa. Soils include frigid and cryic Ochrepts, Boralfs, Orthents, Udands, and Cryands in the mountains, with Borolls, Ochrepts, Xerolls, Psamments, and Fluvents in the basins and valleys. These soils are generally moderately deep to deep with loamy to sandy textures. Most of the soils have been strongly influenced by volcanic ash deposits, which make them very productive.

Potential Natural Vegetation. K\"uchler mapped vegetation as Douglas-fir forest and western ponderosa forest. Principal tree species include Douglas-fir, ponderosa pine, hemlock, cedar, and grand fir.

Fauna. Birds are typical moist northern Rocky Mountain species, including Vaux's swift, calliope hummingbird, pileated woodpecker, gray jay, red-eyed vireo, and Townsend's warbler. Other species of note are common and Barrow's goldeneyes, harlequin duck, osprey, boreal owl, barred owl, Cordilleran flycatcher, American dipper, and varied and Swainson's thrush. Species nearing the edge of their range are the boreal and chestnut-backed chickadees, and northern water thrush. The endangerd bald eagle is a relatively common breeder in this Section. Typical herbivores and carnivores include white-tailed deer, mule deer, elk, moose, black bear, bobcat, and cougar. The woodland caribou were historically present within this Section but are now absent. Smaller common herbivores include the snowshoe hare and northern flying squirrel. Rare mammals include the grizzly bear, gray wolf, lynx, fisher, wolverine, northern bog lemming, and the Coeur d' Alene salamander. 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 over 2,540 mm); most of the precipitation in fall, winter, and spring is snow; summers tend to be dry. Climate is cool temperate with some maritime influence. Temperature averages 36 to 45 oF (2 to 7 oC). While maritime influences are present and winters are relatively mild, outbreaks of arctic air occur frequently in winter. The growing season ranges from 45 to 120 days.

Surface Water Characteristics. Several major rivers, including the Yaak and Kootenai, and many perennial streams with dendritic drainage patterns dominate the area. There are many lakes, including Lake Koocanusa and Flathead Lake, as well as bogs, and wetlands.

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

Land Use. Timber harvest, wildlife habitat, and recreation are important land uses. Livestock grazing and farming occur in some valley areas.

Cultural Ecology. Reserved.

Compiled by Northern Region.

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Section M333C--Northern Rockies

Geomorphology. There are steep glaciated overthrust mountains with sharp alpine ridges and cirques at higher elevations. Some areas of glacial deposition also occur. Elevation generally ranges from 3,000 to 9,500 ft (915 to 2,898 m). Some alpine areas range from 8,000 to 10,000 ft (2,440 to 3,050 m). This Section is within the Northern Rocky Mountains physiographic province.

Lithology and Stratigraphy. Precambrian metasedimentary and Upper Tertiary soft sedimentary rocks occur; glacial deposits are also present.

Soil Taxa. Soils include frigid and cryic Ochrepts, Boralfs, and Orthents. These soils are generally shallow to moderately deep, with loamy to sandy textures containing rock fragments. Some soils at higher elevations have been moderately influenced by volcanic ash deposits.

Potential Natural Vegetation. K\"uchler mapped potential vegetation as Douglas-fir forest. The alpine treeline occurs at about 8,000 ft (2,420 m). Foothills prairie with wheatgrasses, fescues, and needlegrass occurs in the drier valleys. Principal tree species include Douglas-fir, hemlock, cedar, and grand fir.

Fauna. Birds are very similar to those in Section M333B, but with more high altitude species such as white-tailed ptarmigan, boreal owl, and American pipit. Birds of special note are the common loon, common and Barrow's goldeneyes, harlequin duck, varied thrush, Swainson's thrush, Townsend's warbler, and pine siskin. Species nearing the edge of their range include chestnut-backed and boreal chickadees and northern water thrush. 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 mammals include the grizzly bear, gray wolf, lynx, fisher, wolverine, and northern bog lemming. Herpetofauna typical of this Section are the spotted frog, Pacific treefrog, western toad, long-toed salamander, and possibly the Pacific giant salamander.

Climate. Precipitation ranges from 16 to over 100 in (410 to over 2,540 mm); most of the precipitation in fall, winter, and spring is snow. Climate is cool temperate with minor maritime influence; summers are dry. Temperature averages 36 to 46 oF (2 to 8 oC); arctic air intrusions occur during winter. The growing season ranges from 45 to 120 days.

Surface Water Characteristics. Abundant perennial streams occur, including the North and Middle Forks of the Flathead River. These drainages are moderately to deeply incised. Many lakes occur in glaciated terrain and at higher elevations, including Whitefish Lake and Lake McDonald.

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

Land Use. Land use is dominated by wildlife habitat and recreation. Some timber harvest also occurs.

Cultural Ecology. Reserved.

Compiled by Northern Region.

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Section M333D--Bitterroot Mountains

Geomorphology. This area comprises steep dissected mountains, some with sharp crests and narrow valleys. Elevation ranges from 1,200 to 7,000 ft (366 to 2,135 m). This Section is within the Northern Rocky Mountains physiographic province.

Lithology and Stratigraphy. Predominant rocks are Precambrian metasedimentary of the Belt supergroup.

Soil Taxa. There are frigid and cryic Ochrepts and Boralfs, with some Udands and Cryands on areas where significant amounts of volcanic ash have been deposited. In general, many of the soils have been strongly influenced by deposits of volcanic ash which have made them productive. These soils are generally shallow to moderately deep with loamy to sandy textures.

Potential Natural Vegetation. K\"uchler classified potential vegetation as cedar-hemlock-pine forest, Douglas-fir forest, and western ponderosa forest. Common species include western redcedar, western hemlock, western white pine, Douglas-fir, and ponderosa pine. Other important tree species include grand fir and mountain hemlock.

Fauna. Birds are typical of the northern Rocky Mountains, such as Steller's jay and pine siskin. Dabbling ducks, common goldeneye, and harlequin ducks also occur. Other species are flammulated owl, boreal owl in the higher elevations, Lewis' woodpecker, American dipper, pygmy nuthatch, Townsend's solitaire, and yellow-rumped, Nashville, and Townsend's warblers. White-headed woodpeckers reach the edge of their range in this Section. Typical herbivores and carnivores include white-tailed deer, mule deer, elk, moose, black bear, marten, bobcat, and cougar. The woodland caribou historically reached the southern extent of its range within this Section, but is now absent. Smaller common herbivores include the snowshoe hare and the northern flying squirrel. Rare mammals include the gray wolf, fisher, wolverine, northern bog lemming, and Coeur d' Alene salamander. Typical Herpetofauna are the spotted frog, Pacific treefrog, western toad, long-toed salamander, and possibly the Pacific giant salamander.

Climate. Precipitation averages 40 to 80 in (1,020 to 2,030 mm); most precipitation in fall, winter, and spring is snow; summers are relatively dry. Temperature averages 36 to 45 oF (2 to 7 oC). Climate is maritime-influenced, cool, moist temperate with relatively mild winters and dry summers. The growing season ranges from 45 to 100 days.

Surface Water Characteristics. Perennial streams are generally fairly steep and deeply incised, exhibiting much structural control. Major rivers include the Clark Fork and the North Fork of the Clearwater.

Disturbance Regimes. Fire, insects, and disease are the principal natural sources of disturbance. Mass wasting also occurs in some areas. Fires were mostly large, low frequency, high intensity, stand-replacing fires, except for the eastern quarter of the Section, which had mostly low intensity, frequent ground fires. Fire suppression efforts have altered the fire regime to a large extent.

Land Use. Timber harvest, wildlife habitat, and recreation are dominant land uses. Some grazing and mining also occur.

Cultural Ecology. Reserved.

Compiled by Northern Region.

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