Chapter 25
Ecological Subregions of the United States

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Cascade Mixed Forest - Coniferous Forest - Alpine Meadow

Three Sections have been delineated in this Province:

These Sections are located in Washington and Oregon. The area of these Sections is about 53,400 mi2 (138,300 km2).

Section M242A--Oregon and Washington Coast Ranges

Geomorphology. These primarily highly dissected low mountains were shaped by debris slide and avalanche erosion processes on slopes of 40 to 120 percent. Incised valleys are distributed throughout the Section. The Olympic Mountains in the north are an anomalously high range, with very deeply incised, fault-controlled drainages which experienced episodes of glaciation. Coastal lowlands formed from active mountain erosion have slopes less than 30 percent and are formed into marine and riverine terraces. Dunes and bogs occur along the coast, with numerous headlands formed of more resistant rock. Elevation range from sea level to 1,800 ft (545 m) is dominant. Most mountain tops are below 4,000 ft (1,212 m). Olympic Mountains peaks extend to 8,000 ft (2,424 m). Local relief is 200 to 800 ft (60 to 242 m).

Lithology and Stratigraphy. Generally Eocene, Miocene, and late Oligocene marine sandstones, siltstones, and shales are interspersed with marine basalts. Northern portions are covered with till, outwash, and lacustrine sediments. Types range from metamorphosed Eocene and Oligocene sandstones to greenshists and graywackes form the Olympic Mountains. Coastal lowlands are formed of river-borne detritus from the low mountains and rest on complex deltaic sediments. Headlands formed from mostly basalt, but occasionally from conglomerates and sandstones.

Soil Taxa. On the low mountains that dominate this section, typical soils are moderately deep or deeper, and have dark, humus-rich topsoil and low base saturation. The upper horizons of these soils have low bulk density, and amorphous material is dominant in the clay-size fraction. Soil moisture regime is udic and soil temperature regime is mesic or frigid (Alic Hapludands and Andic Haplumbrepts). In the rain shadow east of the Olympic Mountains, the soil moisture regime is xeric (Dystric Xerochrepts and Typic Xerumbrepts). Soils on the high mountains are similar but colder, having a cryic soil temperature regime (Typic Haplocryands and Andic Cryochrepts). Some have a cemented layer that impedes water and roots (Typic and Alic Duricryands). Soils that are continuously moist, a perudic moisture regime (Alic Fulvicryands), occur in the high Olympic Mountains. In the coastal lowlands and hills, seasonal soil temperatures are moderated by fog and sea breezes, resulting in isomesic and isofrigid temperature regimes. Soils formed in sandy aeolian deposits have accumulations of iron, aluminum, and humus in subsoil horizons, and some have organic matter-rich surface horizons (Entic and Humic Haplorthods, and Andic Haplumbrepts). Poorly drained soils with an accumulation of organic matter near the surface occur on low marine terraces (Histic Haplaquepts, Typic Humaquepts, and Fluventic Humitropepts). On low hills in the fog belt are soils with humus-rich topsoil, low bulk density, and amorphous material in the clay-size fraction (Andic and Typic Humitropepts, and Alic Fulvudands).

Potential Natural Vegetation. K\"uchler vegetation types are spruce-cedar-hemlock forests in the coastal fog belt and lower mountain slopes. The dominant type, on upper slopes, is cedar-hemlock-Douglas-fir forests. The Olympic Mountains include an area of alpine meadows and barrens and western spruce-fir forests on cryic soils. More recent vegetation classification is more specific. Lower mountain slopes are dominated by Western Hemlock series. Coastal fog belt areas are dominated by Sitka Spruce and Western Hemlock series. Western Red Cedar series is abundant in the drainages and lower elevations where soil moisture is abundant. Pacific Silver Fir series is dominant on the cryic soils. Shore Pine series occurs on dunes.

Fauna. The Roosevelt elk and blacktail deer, large herbivores, were not common in coastal Douglas-fir forests prior to settlement and forest harvest. Both species are now common and widespread. Black bear, a common species, represents the large predator and coyotes represent the opportunistic small predator. Cougar and bobcat are now common predators, but, like the elk and deer, were not common prior to forest harvest. Spotted owl and murrelet were common species associated with late seral coastal forest plant associations. Both species are Federally listed due to limited opportunity to find habitat within late seral stage forest types. Nutria and opossum, non-native species, are commonly associated with rivers, lakes, and estuaries. Townsends mole is a widespread and abundant inhabitant of lowland flood plains and meadows. The saltwater-freshwater interface zone supports a variety of shore birds, waterfowl, mollusks, and anadromous fishes. The silver spot butterfly, a Federally listed species, is found only in this area and is very limited in distribution. Mountain beaver occurs only in this area as a unique species. Large mammals, including the whale, sea lion, and seal, are common components of adjoining marine waters. Other important inhabitants are more than 7,000 species of arthropods, a variety of amphibians and reptiles, and slugs.

Climate. Precipitation averages 60 to 240 in (1,520 to 6,100 mm) as rain during November to April. Summers are relatively dry. The rain shadow of the Olympic Mountains is about 30 in (760 mm). Average annual temperature is 32 to 53 oF (0 to 12 oC). The growing season lasts 30 to 250 days, but in most areas is more than 140 days.

Surface Water Characteristics. The streams and rivers are a high density of deeply incised, steep gradient, dendritic drainages. Many larger rivers become low-gradient systems prior to entering the tidal influence zone. Relatively small (less than 10 acres) freshwater lakes are disbursed throughout the Section. The Coastal terraces and dune areas are occupied by some lakes that are several hundred acres. Numerous bays and estuaries occur along the coast at the mouth of larger rivers.

Disturbance Regimes. Winter storms of 25 to 100 year magnitude produce windthrow and landslides. Stand replacement fires occurred at irregular intervals of 90 to 250 years. They may have been more frequent on upper slopes and ridges and near the coast.

Land Use. Dominant land use is intensive forestry. Sport fishing and hunting are common. Gathering of special forest products, such as mushrooms, ferns, shrubs, lichens, and mosses, is increasing. Coastal areas are dominated by small communities and tourism.

Cultural Ecology. The rugged Pacific coastline and Coast Range environments of Oregon and Washington have undergone many changes as a result of human settlement and use. The earliest campsites of Native American peoples were apparently covered by rising sea levels as the last Ice Age ended some 12,000 years ago. By 8,000 years ago, archaeological sites discovered near the coastline show that these early peoples hunted terrestrial mammals, gathered roots and berries, and exploited the anadromous fish runs. Technological innovations and population growth increasingly drew American Indians to the ocean headlands, bays, and estuaries as rich and reliable sources of food and favorable places for fishing stations and semi-permanent village sites. By 5,000 years ago, these popular fishing stations and villages created extensive midden deposits along the Pacific coastline and altered local topographic settings and vegetation; today many coastal communities are located atop ancient shell middens and villages. The Euro-American settlement of the Oregon Coast Range from the mid-1800's to late 1800's caused numerous, accidentally set fires that cumulatively burned millions of acres of Coast Range forest. Coast Range homesteaders also cleared the forest and introduced new plant and tree species, thus creating environmental "patches" or niches that are important today for big game forage, wildlife diversity, and recreation. Beginning in the 1940's, industrial logging, road construction, valley bottom farming, commercial fishing, and recreational developments along the Pacific coastline and in the Coast Range have all left significant imprints on the natural environment of this region.

Compiled by Pacific Northwest Region.

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Section M242B--Western Cascades

Geomorphology. This is an uplifted sequence of extrusive volcanics and volcanoclastic rocks, interspersed with intrusives, that have been dissected by large order riverine systems. Two predominant landforms of the western slope are ancient slide complexes with deep weathering zones on relatively gentle terrain, and a steeply dissected debris slide terrain associated with thin soils and resistant rock units. Alpine glaciation has left till and outwash deposits at the higher elevations. The high Cascades to the east of the Section are active volcanoes with evidence of recent, and in some cases, remnant glaciation. The northern part of the Section contains more metasediments than the southerly portion and abounds with classical U-shaped valleys and cirques. Elevation ranges from near sea level at the Columbia River to greater than 14,000 feet (4,516 m) in the peaks of the Cascade Mountains. Most of the Section is between 2,000 and 7,000 feet (645 and 2,258 m). Local relief is more than 1,000 feet (322 m) in most of the Section.

Lithology and Stratigraphy. Types include mostly a mixture of Miocene-Pliocene extrusive rocks, dacite to basalt, with intrusive granites, and diorites interspersed. These are sandwiched in with numerous pyroclastic deposits of tuffs and breccias. In a number of locations, hydrothermal alteration has played a significant role in secondary mineralization of breccias. The high Cascades are 85 percent basalt, with dacites secondary. Active mountain building has taken place from early Pliocene to the present. In the northern third of the Section, above the Olympic-Wallowa lineament, gneisses, schists, metasediments, and metavolvanics and lacustrine deposits occur.

Soil taxa. Soils on the west slope of this Section have organic matter-rich topsoil with low base saturation. Included soils have low bulk density and contain amorphous material (Typic and Alic Hapludands, and Andic Haplumbrepts); contain volcanic ash (Typic and Humic Udivitrands); or have iron, aluminum, and humus accumulation in subsoils (Typic Haplorthods). These soils have a udic moisture regime, and most have a frigid soil temperature regime. At lower elevations, warmer soils with a mesic temperature regime have organic matter-rich topsoil with low base saturation (Typic Haplumbrepts), and soils in well-weathered parent material have clay-enriched subsoils (Typic Haplohumults). In the High Cascades and North Cascades are cold, stony soils with a cryic temperature regime. Included are soils with generally greater amounts of organic matter, but otherwise very similar to frigid soils on the West Slope (Andic and Typic Humicryods, Typic and Vitric Haplocryands, Typic Fulvicryands, and Andic Cryumbrepts).

Potential Natural Vegetation. According to K\"uchler, the dominant vegetation is silver fir--Douglas--fir forest. The next most abundant is fir-hemlock forest. At the highest elevations, there are dispersed areas of alpine meadow and barrens. In the northernmost portion, there is western spruce-fir forest. Western Hemlock series dominates the frigid and udic regimes. Western red cedar is common in drainages. Cryic regimes are dominated by Pacific Silver Fir, Mountain Hemlock and Subalpine Fir series. Parkland of forbs, grasses, shrubs, lichens, mosses, and krummholz are interspersed at the high elevations above timberline.

Fauna. Large herbivores and carnivores include Roosevelt elk, blacktailed deer, and black bear. Mountain goats inhabit high elevations in the central and northern part of the Section. Smaller members are beaver, otter, raccoon, fisher, marten, skunk, coyote, couger, squirrel, rabbit, and numerous rodents. A variety of birds such as blue and ruffed grouse, band-tailed pigeon, mountain quail, owls, hawks, and songbirds are common. The pileated woodpecker and other cavity nesters are common. The wetlands are home to many waterfowl, including Canada geese, ducks, herons, and various song birds. The bald and golden eagle and the peregrin falcon are somewhat rare; osprey are common along riparian areas. Anadromous fish such as coho, chinook, chum, and pink salmon and steelhead and sea-run cutthroat trout inhabit the streams and rivers. Rainbow and bull trout are in warm water lakes and streams. Shad and smelt are uniques species that occur in some major river systems, but numbers are diminished. Other important inhabitants are more than 7,000 species of arthropods, a variety of amphibians and reptiles, and slugs.

Climate. Precipitation ranges from 50 to 150 in (1,300 to 3,600 mm), mostly as rain and snow during October to June. Summers are relatively dry. Average annual air temperature is 30 to 52 oF (-1 to 11 oC). The growing season ranges from less than 30 days to 240 days.

Surface Water Characteristics. Stream densities commonly are one and one-half to two miles of perennial streams per square mile. Intermittent streams are equally common. Many major rivers occur from the northern end to the southern range of the Section. Water quality is exceptionally high. Many of the stream systems from glacial areas are naturally milky and turbid during the spring snowmelt. Numerous natural lakes resulting from glacial processes and ancient landslides occur throughout the Cascades. Man-made reservoirs are common at the lower elevations. Localized wetlands are scattered throughout the Section.

Disturbance Regimes. Fire periodicity is extremely variable from decades to centuries for major stand replacement occurrences. Snowpacks of tens of feet may be accompanied by rain-on-snow events at the low to mid elevations and may result in frequent floods and erosional processes. Insects and diseases, especially root rots, are common. Windthrow is common in localized areas. Periodic volcanic eruptions alter the physical terrain, biota, and aquatic features.

Land Use. Most of the Section is in national forest and other Federal and State public land. It is managed under principles of ecosystem management for uses ranging from intensive forestry to wilderness. Much of the area is in municipal supply watersheds. There are two national parks and several designated scenic and recreation areas, and a national volcanic monument. Lowest elevations frequently are in industrial forest management and small areas of nonindustrial private forestry. The river valleys usually have small, rural communities and dispersed settlements. They also are grazed by livestock, produce hay and other crops, and are major travel corridors for tourists and commerce.

Cultural Ecology. Human occupation of the Cascade Mixed Forest Province began at least 8,000 years ago, possibly as a response to drier conditions and expanding game populations. Prior to about 5,000 years ago, small, highly mobile hunting and gathering groups used the area, moving their camps to obtain seasonally available montane resources. With the subsequent development of more permanent settlements and increasing human populations, the focus of upland use was to acquire and process specific berries, roots, and game animals as supplements to lowland staples. Settlements consisted of small plankhouse or pithouse clusters along the upper reaches of major rivers draining the Cascades, with each cluster being populated by two or three family groups. East-west interactions between groups on both sides of the Cascades was facilitated by travel routes along ridges and through mountain passes. Deer were a principal economic resource, and productive habitat was maintained through intentional burning, a practice which also improved the productivity of huckleberries and certain root crops. Fishing for salmon was also important, and was generally conducted using traps and weirs or netting at falls and rapids. Euro-American settlement began in the mid-1800's, increasing substantially about 1880. Historic settlements initially involved farming or ranching in the valley bottoms, with the economic focus eventually shifting to timber resources. Mining activity, though localized in mineralized areas, commenced in the early 1860's with discovery of gold in the Swauk and Liberty districts. Placer operations resulted in substantial soil and vegetation disturbance, as well as significant water source diversions. From the 1880's through the 1930's, industrialized mining occurred: gold in the Monte Cristo vicinity; coal from present day Black Diamond through the Cascades to Roslyn; copper from Holden Mine in the Railroad Creek drainage tributary to Lake Chelan; and tungsten on the east flank of the North Cascades. These operation involved removal of vegetative cover for mine timbers, extensive land modification, and deposit of overburden, spoils, and tailings, including toxic materials used in processing. Timber harvest, grazing, mineral extraction, and the construction of dams resulted in ecological effects far greater than those produced by the prehistoric cultures of the region.

Compiled by Pacific Northwest Region.

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Section M242C--Eastern Cascades

Geomorphology. Glaciation of high volcanic peaks has resulted in a relatively steep eastern slope for the Section. High energy streams and flows of debris and mud are common. Glacial forms have not stabilized. Classical U-shaped valleys and cirques abound in the northern part of the Section. To the south, glaciation was less severe and gradually diminishes towards the southern limit of the Section. Individual volcanic peaks rise above the surrounding incised topography. Many are still active, primarily south of the Olympic-Wallowa lineament. Statistically, an eruption occurs about every 25 years. Small recent volcanic vents are common on the flanks of larger volcanoes. Large areas of fresh lava flows abound in the east of this Section. Volcanic ash from earlier eruptions originally blanketed the east slope. This ash has been concentrated in a southern pumice plateau, blanketing all but the higher hills and ridges. Elevation ranges from near sea level at the Columbia River to more than 10,000 ft (3,300 m) in the high mountain peaks. Most of the Section is between 3,000 and 7,000 ft (968 and 2,258 m). Local relief varies from about 200 ft in the plateau regions to more than 2,000 ft in the deeply dissected mountains.

Lithology and Stratigraphy. The Section is composed of pre-Pliocene to recent andesite and basalt flows, forming composite cones and intracanyon flows. These rest on extensive deposits of Pliocene to lower Pliestocene basalt and andesitic varicolored tuff, tuff breccia, and agglomerate. Deposits of volcanic ash, pumice, and cinders are common and may be hundreds of m thick. Locally, there are intrusive granitics, gneisses, schists, metavolcanics, and metasediments. The stratigraphy is variable even in the local sense.

Soil Taxa. This Section includes a narrow area of the High Cascades described in the Western Cascades Section (M242B). Soils in the High Cascades of this Section are the same as those in the High Cascades of the Western Cascades Section, except in southern Washington. That area includes soils with a thick volcanic ash mantle (Typic Vitricryands) and soils with thick, dark, base-rich topsoil (Pachic Cryoborolls). Due to the rain shadow, soils on the east slope are usually dry for a significant time during the summer. These soils have a xeric moisture regime. Many of these soils are influenced by volcanic ash, some have low bulk density, some have organic matter-rich topsoil, and some have subsoils with accumulated clay (Typic and Humic Vitrixerands; Dystric, Typic and Vitrandic Xerochrepts; Typic and Vitrandic Xerumbrepts; Ultic and Vitrandic Haploxeralfs and Palexeralfs; and Ultic Haploxerolls). In the southern part of this Section, soils have formed in volcanic ash and pumice from Mount Mazama on a plateau with relatively low relief, compared to the rest of this Section. Due to thermal properties of the tephra and dry climate, cold soils with a cryic temperature regime are common. The cold, cryic soils (Xeric Vitricryands) occur in depressions; the cool, frigid soils (Humic and Lithic Vitrixerands) occur on upland positions in the landscape.

Potential Natural Vegetation. According to K\"uchler, the dominant vegetation is silver fir--Douglas--fir forest. The next most abundant is fir-hemlock forest. At the highest elevations, there are dispersed areas of alpine meadow and barrens. In the northernmost portion, there is western spruce-fir forest. Vegetation series is highly variable and diverse in the Eastern Cascades Section. Ponderosa Pine and Lodgepole Pine series dominate the lower elevations. In the pumice plateau of Oregon they are largely on cryic and xeric soils. Ponderosa Pine series also is in the mesic and frigid and xeric regimes. In the northern part of the Section, Lodgepole Pine series is mostly in cryic regimes. Douglas-fir series occupies frigid and xeric regimes. The higher elevations are dominated by White Fir, Grand Fir, Pacific Silver Fir, and Subalpine Fir series. Local areas of White Bark Pine, and Engelmann Spruce series occur. Quaking aspen occurs adjacent to and in some wet areas. Grass and sedge meadows (dry to wet) are scattered.
Fauna. Large herbivores and carnivores include elk, blacktailed and mule deer, and black bear. Mountain goats inhabit high elevations in the central and northern part of the Section, but are absent from the southern portion of their range. Small mammals are beaver, otter, raccoon, marten, skunk, coyote, couger, squirrel, rabbit, and numerous rodents. Fisher, once common in this Section, are now rare or extirpated from much of their former ranges. A variety of birds such as blue and ruffed grouse, band-tailed pigeons, mountain quail, owls, hawks, and songbirds are common. Pileated woodpeckers and other cavity nesters are common. The wetlands are home to many waterfowl such as Canada geese, ducks, herons, and various song birds. The bald and golden eagle inhabit a small portion of their historic ranges and are very limited in distribution. The peregrine falcon, once common, is now represented by a few pairs introduced by "hacking" potential sites. Anadromous fish such as coho, chinook, chum, and pink salmon and steelhead and sea-run cutthroat trout inhabit the streams and rivers, their distribution and numbers are significantly reduced. Rainbow trout are the common cold water inhabitant. Bull trout are found, but their occurrence is significantly restricted from historic ranges. Kokanee, an introduced species, is found in some lakes and streams, primarily in the north portion of this Section. Other important inhabitants are more than 7,000 species of arthropods, and a variety of amphibians and reptiles.

Climate. Precipitation ranges from 20 to 120 in (500 to 3,040 mm), occurring mostly as rain and snow in fall, winter, and spring. Temperature ranges from 30 to 52 oF (-1 to 11 oC). The growing season lasts 30 to 220 days.

Surface Water Characteristics. Stream densities are variable. In the pumice region of Oregon, streams are few. In the northern part of the Section, densities may be as high as one and one-half to two miles of perennial streams per square mile. Water quality is exceptionally high. Numerous man-made reservoirs occur at the lower elevations. Many streams are flashy, and differences between peak and low flows are large. Localized wetlands are scattered.

Disturbance Regimes. Fire periodicity is extremely variable. In the ponedrosa pine-lodgepole pine mix at the lower elevations, fires commonly occurred in 10 to 15 year intervals prior to fire suppression in the last several decades. Fire also is common at the higher elevations. Insect epidemics are common in dense, overstocked stands. Root rots are common.

Land Use. Most of the Section is in national forest and other Federal and State public land. It is managed under principles of ecosystem management for uses ranging from intensive forestry to wilderness. Much of the area is in municipal supply watersheds. There are portions of two national parks and several designated scenic and recreation areas. Lowest elevations frequently are in industrial forest management. Two large Native American reservations are partly in and adjacent to this Section. The river valleys usually have small, rural communities and dispersed settlements. They also are grazed by livestock, produce hay and other crops, and are major travel corridors for tourists and commerce. Cultural Ecology. Human occupation of the Cascade Mixed Forest Province began at least 8,000 years ago, possibly as a response to drier conditions and expanding game populations. Prior to about 5,000 years ago, small, highly mobile hunting and gathering groups used the area, moving their camps to obtain seasonally available montane resources. With the subsequent development of more permanent settlements and increasing human populations, the focus of upland use was to acquire and process specific berries, roots, and game animals as supplements to lowland staples. Settlements consisted of small plankhouse or pithouse clusters along the upper reaches of major rivers draining the Cascades, with each cluster being populated by two or three family groups. East-west interactions between groups on both sides of the Cascades was facilitated by travel routes along ridges and through mountain passes. Deer were a principal economic resource, and productive habitat was maintained through intentional burning, a practice which also improved the productivity of huckleberries and certain root crops. Fishing for salmon was also important, and was generally conducted using traps and weirs or netting at falls and rapids. Euro-American settlement began in the mid-1800's, increasing substantially about 1880. Historic settlements initially involved farming or ranching in the valley bottoms, with the economic focus eventually shifting to timber resources. Mining activity, though localized in mineralized areas, commenced in the early 1860's with discovery of gold in the Swauk and Liberty districts. Placer operations resulted in substantial soil and vegetation disturbance, as well as significant water source diversions. From the 1880's through the 1930's, industrialized mining occurred: gold in the Monte Cristo vicinity; coal from present day Black Diamond through the Cascades to Roslyn; copper from Holden Mine in the Railroad Creek drainage tributary to Lake Chelan; and tungsten on the east flank of the North Cascades. These operations involved removal of vegetative cover for mine timbers, extensive land modification, and deposit of overburden, spoils, and tailings, including toxic materials used in processing. Timber harvest, grazing, mineral extraction, and the construction of dams resulted in ecological effects far greater than those produced by the prehistoric cultures of the region.

Compiled by Pacific Northwest Region.

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