User:Northwesterner1/ecoregion12
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The Snake River Plain ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) in the U.S. states of Idaho and Oregon. It follows the Snake River across Idaho, stretching roughly 400 miles (640 km) from the Wyoming border to Eastern Oregon. The plains and low hills of the ecoregion are part of the xeric intermontane west. It is considerably lower and less rugged than surrounding ecoregions. Many of the alluvial valleys bordering the Snake River are used for agriculture. Where irrigation water and soil depth are sufficient, sugar beets, potatoes, alfalfa, small grains, and vegetables are grown. Elsewhere, livestock grazing is widespread. Cattle feedlots and dairy operations are found locally.
Potential natural vegetation is mostly sagebrush steppe but barren lava fields and saltbush–greasewood also occur. Streams generally have lower gradients, are warmer, and have finer grained substrates than do streams in the montane ecoregions. Streams typically have higher primary productivity than streams with a forest canopy overstory. Natural stream fish assemblages in the region are typically a mix of mesothermal minnows and suckers, but some stenothermal salmonids and sculpins are also present. The region has many large springs along the Snake River that support endemic fish and mollusc species. Shoshone Falls is a major zoogeographic barrier, and different species occur above and below it.[1][2]
The Snake River Plain ecoregion has been subdivided into ten Level IV ecoregions, as described below.
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[edit] Level IV ecoregions
[edit] Treasure Valley (12a)
The Treasure Valley ecoregion (named for the Treasure Valley) is an unglaciated rolling valley containing many canals and incised rivers. Elevation varies from 2,000 to 2,800 feet (640 to 853 m). The valley is underlain by Quaternary alluvium, loess, lacustrine, and alluvial fan deposits. Soils have an aridic moisture regime, and they originally supported sagebrush-grassland before the valley was converted to agriculture. Canals and diversions in this portion of the Snake River Plain supply water to pastureland and cropland as well as municipalities. Surface water quality has been significantly affected by channel alteration, dams, irrigation diversions, irrigation return flow, and agricultural pollution. Crops include wheat, sugar beets, alfalfa, potatoes, and onions. Population density is greater than in neighboring, rangeland-dominated ecoregions. Crop diversity is greater, temperatures are warmer, and the mean frost-free season is longer than in the Upper Snake River Plain and the Magic Valley. Vegetation outside of agricultural areas is characterized by Wyoming big sagebrush, basin big sagebrush, bluebunch wheatgrass, bluegrass, basin wildrye, Thurber's needlegrass, rabbitbrush, and cheatgrass. In saline areas, shadscale, greasewood, and saltgrass occur. The region covers 1,302 square miles (3,372 km²) in Idaho and 499 square miles (1,292 km²) in Oregon, where the Payette, Boise, Weiser, Malheur and Owyhee rivers converge into the Snake. It includes lowland areas from Boise to Vale and contains the Deer Flat National Wildlife Refuge.[2][1]
[edit] Lava Fields (12b)
The Lava Fields ecoregion contains basalt flows, cinder cones, and spatter cones rising from irregular plains, at an elevation of 3,800 to 5,500 feet (1,158 to 1,676 m). Exposed basalt or very shallow loessial soils over volcanics are characteristic. Surface water availability is extremely limited, and the region is either barren or sparsely covered by hardy shrubs and grasses, including basin sagebrush, mountain sagebrush, Wyoming big sagebrush, rabbitbrush, bluegrass, bluebunch wheatgrass, bottlebrush squirreltail, Thurber needlegrass, and Indian ricegrass. Livestock carrying capacity is low. The region covers 1,122 square miles (2,906 km²) in Idaho in pockets of the eastern Snake River Plain, including Craters of the Moon National Monument and parts of the Idaho National Engineering Laboratory.[2]
[edit] Camas Prairie (12c)
The Camas Prairie ecoregion is a cold, wet valley containing nearly level to rolling terraces, bottomlands, basalt plains, and, on the periphery, alluvial fans. Elevation varies from 4,700 to 5,100 feet (1,443 to 1,554 m). It is flanked by the semi-arid foothills of the Snake River Plain and the Idaho Batholith, which trap mountain runoff on the prairie. Resultant wet soils and flooding occur and are local and seasonal problems. Frigid mollisols are common and are colder than the soils of the lower Treasure Valley. Wet bottomlands support rushes, sedges, meadow grasses, and willows. Alluvial fans and terraces are covered by bluebunch wheatgrass, Idaho fescue, bluegrass, basin big sagebrush, and mountain sagebrush. Lava plains support alkali sagebrush, bluegrass, squirreltail, and Idaho fescue. The region covers 530 square miles (1,373 km²) in Idaho along the Camas River and is used for used for small grain and alfalfa farming, pasture, range, and wildlife habitat.[2]
[edit] Dissected Plateaus and Teton Basin (12d)
The Dissected Plateaus and Teton Basin ecoregion is characterized by dissected plateaus, alluvial fans, low terraces, bottomlands, outwash plains, and nearly flat, poorly-drained basins. Elevation varies from 4,700 to 6,300 feet (1,443 to 1,920 m). Mollisols developed in thick loess deposits or alluvium and are subject to wind erosion. Loess is far more extensive than in the Upper Snake River Plain subregion. Sprinkler-irrigated land supports potatoes, alfalfa, and pasture; however, surface irrigation is far less common than in the Upper Snake River Plain subregion, which is lower, flatter, and adjacent to the Snake River. Non-irrigated land grows small grains. Potential natural vegetation is sagebrush steppe, with mountain big sagebrush, threetip sagebrush, bluebunch wheatgrass, bluegrass, Idaho fescue, and cheatgrass. Wet meadows occur in the poorly-drained, relatively cold Teton Basin. The region covers 1,059 square miles (2,743 km²) in Idaho in the farthest eastern reaches of the Snake River Plain, approaching the Teton Mountains. It includes portions of the Caribou-Targhee National Forest.[2]
[edit] Gallery
[edit] Flora
 Western chokecherry leaves and berries |
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[edit] Fauna
 Pinyon Jay, found in juniper-pinyon woodlands |
 Yellowstone cutthroat trout in the Snake River system |
 Sage grouse in shrub-steppe habitat |
[edit] Landscapes
.jpg/120px-Summer_Lake_(Oregon).jpg) Salt deposits at Summer Lake |
 The cracked playa surface of the Alvord Desert |
 Cheatgrass covers the fault scarp of Abert Rim. |
[edit] See also
- Ecoregions defined by the EPA and the Commission for Environmental Cooperation:
- List of ecoregions in North America (CEC)
- List of ecoregions in the United States (EPA)
- List of ecoregions in Oregon
- The conservation group World Wildlife Fund maintains an alternate classification system:
- List of ecoregions (WWF)
- List of ecoregions in the United States (WWF)
[edit] References
- ^ a b Thorson, T.D.; Bryce, S.A.; Lammers, D.A. & et al. (2003), Ecoregions of Oregon (color poster with map, descriptive text, summary tables, and photographs), Reston, Virginia: United States Geological Survey, <ftp://ftp.epa.gov/wed/ecoregions/or/or_front.pdf> (and the Reverse side)
- ^ a b c d e McGrath, C.L.; Woods, A.J.; Omernik, J.M. & et al. (2002), Ecoregions of Idaho (color poster with map, descriptive text, summary tables, and photographs), Reston, Virginia: United States Geological Survey, <ftp://ftp.epa.gov/wed/ecoregions/id/id_front.pdf> (and the Reverse side)
