Columbia Plateau (ecoregion)
According to the United States Environmental Protection Agency (EPA) classification, the Columbia Plateau ecoregion is a Level III ecoregion in the US states of Oregon and Washington as well as small areas in Idaho . The ecoregion stretches over large areas of the Columbia River basin from The Dalles (Oregon) via Lewiston (Idaho) to Okanogan (Washington) near the border between Canada and the United States . It comprises approximately 500 mi (800 km) of the course of the Columbia River and the lower reaches of its main tributaries such as the Snake River and Yakima River, as well as the associated drainage basins. It is named after the Columbia River Plateau , a flood basalt plateau formed by the Columbia Plateau basalt during the late Miocene and early Pliocene . The arid steppes of sage, shrubbery and grasslands of the region are flanked on all sides by moister, predominantly forested , mountainous ecoregions. Bedrock is basalt , which up to 2 mi (3.2 km) thick and partly by powerful loess - deposits covered. Where the rainfall is sufficient, the deep loess soils have been intensively cultivated for wheat cultivation. The water from the Columbia River is the subject of debate over resource use, including fishing , shipping , hydropower , recreation and irrigation . The Columbia Basin Project has dramatically changed much of the region by making agriculture possible in the first place.
The Columbia Plateau ecoregion (Level III) has been divided into at least 14 Level IV regions, which are described below. At the end of May 2018, the EPA had not yet published such an informative poster about the ecoregions in Washington as it has already done for Oregon and Idaho; therefore, the information on Washington is less detailed than that of the other two states.
Ecoregions level IV
Channeled Scablands (10a)
The Channeled Scablands ecoregion comprises the Coulees and Channeled Scablands of Washington, washed away by the cataclysmic Missoula floods . It stretches from Wenatchee to Spokane and includes publicly owned land in the Lake Roosevelt National Recreation Area and the Wenatchee National Forest .
Loess Islands (10b)
The Loess Islands ecoregion consists of large pockets of mighty loess deposits surrounded by the Channeled Scablands in east Washington . This includes publicly owned land in the Turnbull National Wildlife Refuge and Juniper Dunes Wilderness .
Umatilla Plateau (10c)
The Umatilla Plateau ecoregion , named after the Umatilla who originally lived in the area , is characterized by an almost flat to hilly, treeless plateau, the bedrock of which is basalt, overlaid by loess deposits. The height varies between 300 and 980 meters. Glacial features such as frost pattern soils are common. Areas with thick loess requirements are in dryland with winter wheat (if irrigated) or alfalfa and barley ordered. Grasslands dominate the more rugged areas where there are thin or no loess deposits. The mean annual rainfall is 230… 380 mm and increases with increasing altitude. In uncultivated areas, the moisture is generally sufficient to grassland with Pseudoroegneria spicata (Engl. "Blue bunch wheatgrass") Rispengräsern (Engl. "Sandberg bluegrass") and Idaho fescue to grow. The "sagebrush" (a collective term for several species of the genus Artemisia ), which also grows in such areas , is not represented here, but is more common in the Pleistocene Lake Basins (see below). Artemisia rigida ("Stiff sagebrush") can be found on very flat soils. The non-resident Dach-Trespe covers large areas. The ecoregion covers 9,614 km² in eastern Oregon including the Umatilla Indian Reservation and agricultural areas south of the Columbia River.
Okanogan Drift Hills (10d)
The Okanogan Drift Hills ecoregion is located in Douglas and Okanogan Counties, including part of the Colville Indian Reservation .
Pleistocene Lake Basins (10e)
The Pleistocene Lake Basins ecoregion is an almost flat to gently undulating lake plain that contained huge temporary Pleistocene lakes, the water of which came from the glacial lakes of Lake Missoula and Lake Columbia. In Oregon, the water from the east entrance of the Columbia River Gorge accumulated upstream to the Wallula Gap and formed the prehistoric Lake Condon . The height varies between 90 and 370 meters. Today this region is the driest and warmest part of the Columbia Plateau with average annual rainfall of 180… 250 millimeters. Major irrigation projects supply the region with water from the Columbia River, allowing large areas to be used for agriculture. Where available, the native vegetation consists of Stipa comata ("needle-and-thread"), Indian rice grass ( Oryzopsis hymenoides ; English "Indian ricegrass"), Pseudoroegneria spicata (English "bluebunch wheatgrass"), panicle grasses (eng. "Sandberg bluegrass") and mugwort . The foreign roof bricks covered large areas. As the largest sub-region of the Columbia Plateau, the Pleistocene Lake Basins cover 3,644 km² in eastern Oregon and larger areas in Washington that are among the lower elevations in the central Columbia Basin. It includes part of the Yakama Indian Reservation and publicly owned land in the National Wildlife Refuges Umatilla , Cold Springs , McNary and Columbia , the Hanford Site and the Hanford Reach National Monument .
Dissected Loess Uplands (10f)
The Dissected Loess Uplands ecoregion consists of isolated hills and flat remnants of plateau cut through by Lower Snake Canyon and Clearwater Canyon. The height varies between 460 and 1,100 meters. Pure grasslands dominate the lower areas with Pseudoroegneria spicata ("bluebunch wheatgrass"), Idaho fescue and bluegrass (English "Sandberg bluegrass"). Mountain bushes (English "mountain brush") grow on the northern slopes and in the higher, more humid locations; it is mostly snowberries and coniferous roses . Livestock - Pastures and crops have reshaped much of the natural vegetation. Nevertheless, the Dissected Loess Uplands are less suitable for agriculture than the neighboring regions, as the soils are much flatter. The Dissected Loess Uplands cover 580 km² in western Idaho and larger areas in southeast Washington south of the Snake River between Dayton and Lewiston including part of the Nez Perce Indian Reservation .
Yakima Folds (10g)
The Yakima Folds ecoregion , named after the Yakama people who originally settled the area, consists of unforested anticlinal ridges , which are composed of layers of basalt several thousand meters thick. The height varies between 300 and 1,070 meters. Loess covers the southern slopes and enables dry cultivation with wheat. The steep, rocky northern slopes are mostly used as pastures. The average annual rainfall is 250… 300 mm. Mugwort and tussock societies dominate the vegetation in the near-natural areas with stipa comata (“needle-and-thread”), bluegrass (sandberg bluegrass) and sagebrush including its subspecies Artemisia tridentata wyomingensis . The introduced roof bristle covers large areas. The region covers 282 km² in Oregon and much larger areas in Washington, which extend from the Horse Heaven Hills in the south to the Kittitas Valley in the north, also includes parts of the Yakama Indian Reservation, the Hanford Reach National Monument, the Wenas Wildlife Area and the Yakima Research Station .
Palouse Hills (10h)
The Palouse Hills ecoregion contains the western foothills of the northern Rocky Mountains that are not influenced by the Ice Age and are known as Palouse ; they are named for the Palouse River that flows through them and the Palouse people who originally lived in the area. The height ranges from 760 to 910 meters. Continuously water-bearing mountain streams and temporary streams on loess soil have their source in the region. The soils are rich in organic matter and very productive; they enable intensive wheat cultivation, but are highly subject to erosion . Dry streams can be worked on. Fescue-wheatgrass, fescue-snowberry and fescue- hawthorn societies occur in the region, as well as yellow-pine savannahs and open yellow-pine- Douglas fir forests. The region covers 1,173 km² along the Idaho borders, including portions of the St. Joe National Forest and the Coeur d'Alene Indian Reservation , as well as larger areas in Whitman and Spokane Counties, Washington.
Deep Loess Foothills (10i)
The ecoregion of the Deep Loess Foothills encompasses the lower elevations of the northwest slopes on the eastern Blue Mountains with their continuous water-bearing streams that are fed by the snowmelt in the surrounding high mountains. The heights range between 460 and 910 meters. The moisture supply is sufficient to allow grasslands with Idaho fescue, bluegrass (English "Sandberg bluegrass") and Pseudoroegneria spicata (English "bluebunch wheatgrass") to grow, but the region is not irrigated by crops of winter wheat, barley, alfalfa and green peas dominate the highly productive loess-rich soils. The region covers 378 km² in Oregon and an adjacent area in Washington in a narrow band from Pendleton to Dayton, including part of the Umatilla Indian Reservation.
Nez Perce Prairie (10y)
The Nez Perce Prairie ecoregion is a loess-covered plateau named after the Nez Percé people who originally inhabited this area and whose reservation is now there. It is higher up, climatically cooler, less hilly and has flatter floors than the Palouse Hills. The altitude fluctuates between 600 and 1,250 meters, with Härtlingen up to 5,700 ft (approx. 1,700 m) high . Idaho fescue and Pseudoroegneria spicata (English "bluebunch wheatgrass") are native; Yellow pines and Douglas firs grow on the northern slopes. The fields are not cultivated intensively and produce wheat, barley, peas and hay. The source areas of many continuous water-bearing streams are influenced by agricultural use. The inputs have a negative effect on the water quality of the downstream canyon sections. The region covers 1,878 square kilometers in Idaho, the Nez Perce Indian Reservation and surrounding areas.
Deschutes / John Day Canyons (10k)
The Deschutes / John Day Canyons ecoregion consists of very steep to rugged canyons on the Deschutes River and the John Day River . Carved deeply into the basalt, these canyons are a patchy and sparsely populated area of the Umatilla Plateau. The canyons are up to 2,000 ft (600 m) deep and offer drier conditions than prevail on the plateau. Sparse tussocks, sagebrush and bristles grow in the stony, colluvial soils . The bank vegetation is in the narrow areas on a band of white alder on the bank and some pipe bushes (English "mock orange"), tongue- leaved clematis ( Clematis ligusticifolia ; English "western clematis") and Virginian bird cherries (English "chokecherry") limited; wider floodplain and gravel banks are dominated by introduced species, so there are growing reed canary grass (Engl. "reed canarygrass"), sweet clover ( "sweet clover" Engl.) and carding (English "teasel".). Migratory king salmon and steelhead trout can be found in the rivers . The region covers 1,746 km² in Oregon on the lower reaches of the Deschutes and John Day Rivers and their tributaries.
Lower Snake and Clearwater Canyons (10l)
The Lower Snake and Clearwater Canyons ecoregion consists of deep canyons cut into the basalts of the Columbia Plateau by the Snake and Clearwater River. The canyons are up to 1,400 ft (approx. 430 m) deep and create drier conditions than in the surrounding regions; the mean annual rainfall is 300… 640 mm. Outside the cities and roads, the canyons offer good habitat conditions for bighorn sheep and wild boar ; The vegetation contains Pseudoroegneria spicata (English "bluebunch wheatgrass"), Idaho fescue, bluegrass (English "bluegrass") and sagebrush. The region covers 207 km² in Idaho and little larger areas in Washington on the lower reaches of the Snake and Clearwater Rivers and their tributaries.
Okanogan Valley (10m)
The Okanogan Valley ecoregion lies on the lower reaches of the Okanogan and Methow Rivers and their tributaries in northeast Washington; this includes land cultivated by the Okanogan National Forest . The extension of this ecoregion northward into Canada includes the Okanagan Valley of British Columbia .
Umatilla Dissected Uplands (10n)
The Umatilla Dissected Uplands ecoregion consists of separate, hilly plateaus with a terraced appearance where the arid grasslands of the Columbia Plateau meet the wooded ecoregion of the Blue Mountains. The slopes are moderately to very steep. The height varies from 490 to 1,340 meters. The hills and plateaus are covered with Idaho fescue, bluegrass (English "Sandberg bluegrass") and Pseudoroegneria spicata (English "bluebunch wheatgrass"). Near the Blue Mountains there are Douglas firs and yellow pines on some northern slopes, as well as snowberries, riding grasses ( Calamagrostis spec. ) And bladder sparrows ( Physocarpus spec .; English "ninebark"). The region is mostly used as pasture land, as the deep, cultivable loess deposits that cover the agriculturally used Umatilla Plateau are missing. Scablands (dt. About "wasteland"), composed of grass hills surrounded by rock polygons, are relics of the cold ages in the Pleistocene. The region covers 1,924 km² in eastern Oregon, in a narrow band along the northern boundary of the Umatilla National Forest , mostly outside its borders.
Individual evidence
- ↑ a b c d e f g h Thorson, TD, Bryce, SA, Lammers, DA, et al .: Ecoregions of Oregon . Retrieved May 29, 2018.
- ↑ a b c d e McGrath, CL, Woods, AJ, Omernik, JM, et al .: Ecoregions of Idaho . Retrieved May 29, 2018.
- ↑ US Environmental Protection Agency: Level III and IV Ecoregions of Washington . Retrieved May 29, 2018.
- ↑ a b c d e f g h i j U.S. Environmental Protection Agency: Draft: Level III and IV Ecoregions of the Northwestern United States . Retrieved May 29, 2018.
Coordinates: 47 ° 0 ′ 0 ″ N , 119 ° 0 ′ 0 ″ W.