List of ecoregions in Oregon

The level III ecoregions in Oregon are the Coast Range (1), Willamette Valley (3), Cascades (4), Eastern Cascades Slopes and Foothills (9), Columbia Plateau (10), Blue Mountains (11), Snake River Plain (12), Klamath Mountains (78), and Northern Basin and Range (80). (Compare to map of Level IV ecoregions.)

This list of ecoregions in Oregon provides an overview of ecoregions in the U.S. state of Oregon designated by the U.S. Environmental Protection Agency (EPA) and the Commission for Environmental Cooperation (CEC). The Commission's 1997 report, Ecological Regions of North America, provides a spatial framework that may be used by government agencies, non-governmental organizations, and academic researchers as a basis for risk analysis, resource management, and environmental study of the continent's ecosystems.^[1] Ecoregions may be identified by similarities in geology, physiography, vegetation, climate, soils, land use, wildlife distributions, and hydrology.^[2]

The classification system has four levels. Levels I, III, and IV are shown on this list. Level I divides North America into 15 ecoregions; of these, 3 are present in Oregon. Level III subdivides the continent into 182 ecoregions; of these, 9 lay partly within Oregon's borders. Level IV is a further subdivision of Level III ecoregions. There are 65 Level IV ecoregions in Oregon,^[3] many of which continue into adjacent areas in the neighboring states of Washington, Idaho, Nevada, and California. The task of defining and mapping these ecoregions was carried out by the Oregon Ecoregion Project, a collaborative effort involving the EPA, the United States Geological Survey (USGS), the United States Forest Service (USFS), and other state and federal agencies. The new classification system they developed may differ from previous frameworks developed separately by the agencies.^[2]

Oregon is ecologically diverse. The west side of the state has a marine-influenced climate and receives plentiful precipitation three seasons of the year. In contrast, Eastern Oregon lies in the rain shadow of the Cascades and is much drier. The climatic gradient is evident in the state's landscapes: forested mountains, glaciated peaks, shrub- and grass-covered plains, agricultural valleys, beaches, desert playas, and wetlands.^[2]

Marine West Coast Forest

1 Coast Range

1a Coastal Lowlands
1b Coastal Uplands
1d Volcanics
1f Willapa Hills
1g Mid-Coastal Sedimentary
1h Southern Oregon Coastal Mountains
1i Redwood Zone

3 Willamette Valley

3a Portland/Vancouver Basin
3b Willamette River and Tributaries Gallery Forest
3c Prairie Terraces
3d Valley Foothills

Northwest Forested Mountains

4 Cascades

4a Western Cascades Lowlands and Valleys
4b Western Cascades Montane Highlands
4c Cascade Crest Montane Forest
4d Cascade Subalpine/Alpine
4e High Southern Cascades Montane Forest
4f Southern Cascades

9 Eastern Cascades Slopes and Foothills

9b Grand Fir Mixed Forest
9c Oak/Conifer Foothills
9d Ponderosa Pine/Bitterbrush Woodland
9e Pumice Plateau
9f Pumice Plateau Basins
9g Klamath/Goose Lake Basins
9h Fremont Pine/Fir Forest
9i Southern Cascades Slope
9j Klamath Juniper Woodland

11 Blue Mountains

11a John Day/Clarno Uplands
11b John Day/Clarno Highlands
11c Maritime-Influenced Zone
11d Melange
11e Wallowas/Seven Devils Mountains
11f Canyons and Dissected Highlands
11g Canyons and Dissected Uplands
11h Continental Zone Highlands
11i Continental Zone Foothills
11k Blue Mountain Basins
11l Mesic Forest Zone
11m Subalpine–Alpine Zone
11n Deschutes River Valley
11o Cold Basins

78 Klamath Mountains

78a Rogue/Illinois Valleys
78b Oak Savanna Foothills
78c Umpqua Interior Foothills
78d Serpentine Siskiyous
78e Inland Siskiyous
78f Coastal Siskiyous
78g Klamath River Ridges

North American Deserts

10 Columbia Plateau

10c Umatilla Plateau
10e Pleistocene Lake Basins
10g Yakima Folds
10i Deep Loess Foothills
10k Deschutes/John Day Canyons
10n Umatilla Dissected Uplands

12 Snake River Plain

12a Treasure Valley
12j Unwooded Alkaline Foothills

80 Northern Basin and Range

80a Dissected High Lava Plateau
80d Pluvial Lake Basins
80e High Desert Wetlands
80f Owyhee Uplands and Canyons
80g High Lava Plains
80j Semiarid Uplands
80k Partly Forested Mountains
80l Salt Shrub Valleys
80m Barren Playas

References

^ "Ecological Regions of North America: Toward a Common Perspective" (PDF). Commission for Environmental Cooperation. 1997. Archived from the original (PDF) on 2004-01-04. Retrieved 2008-04-10.
^ ^a ^b ^c 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)" (PDF). Reston, Virginia: United States Geological Survey.
^ "Interactive Map of Oregon Level 4 Ecoregions". Retrieved 2010-11-17.

v t e Level III Ecoregions in Oregon
Marine West Coast Forest	1 Coast Range 3 Willamette Valley
Northwestern Forested Mountains	4 Cascades 9 Eastern Cascades Slopes and Foothills 11 Blue Mountains 78 Klamath Mountains
North American Deserts	10 Columbia Plateau 12 Snake River Plain 80 Northern Basin and Range
as defined by the United States Environmental Protection Agency [1]

v t e Level III Ecoregions in the United States
Marine West Coast Forest	1 Coast Range 2 Puget Lowland 3 Willamette Valley 111 Ahklun and Kilbuck Mountains 113 Alaska Peninsula Mountains 115 Cook Inlet 119 Pacific Coastal Mountains 120 Coastal Western Hemlock-Sitka Spruce Forests
Northwestern Forested Mountains	4 Cascades 5 Sierra Nevada 9 Eastern Cascades Slopes and Foothills 11 Blue Mountains 15 Northern Rockies 16 Idaho Batholith 17 Middle Rockies 19 Wasatch and Uinta Mountains 21 Southern Rockies 41 Canadian Rockies 77 North Cascades 78 Klamath Mountains 105 Interior Highlands 116 Alaska Range 117 Copper Plateau 118 Wrangell Mountains
Mediterranean California	6 Southern and Central California Chaparral and Oak Woodlands 7 Central California Valley 8 Southern California Mountains
North American Deserts	10 Columbia Plateau 12 Snake River Plain 13 Central Basin and Range 14 Mojave Basin and Range 18 Wyoming Basin 20 Colorado Plateaus 22 Arizona/New Mexico Plateau 24 Chihuahuan Deserts 80 Northern Basin and Range 81 Sonoran Basin and Range
Temperate Sierras	23 Arizona/New Mexico Mountains
Great Plains	25 Western High Plains 26 Southwestern Tablelands 27 Central Great Plains 28 Flint Hills 29 Central Oklahoma/Texas Plains (Cross Timbers) 30 Edwards Plateau 31 Southern Texas Plains 34 Western Gulf Coastal Plain 40 Central Irregular Plains 42 Northwestern Glaciated Plains 43 Northwestern Great Plains 44 Nebraska Sand Hills 45 Piedmont 46 Northern Glaciated Plains 47 Western Corn Belt Plains 48 Lake Agassiz Plain
Eastern Temperate Forest	32 Texas Blackland Prairies 33 East Central Texas Plains 35 South Central Plains 36 Ouachita Mountains 37 Arkansas Valley 38 Boston Mountains 39 Ozark Highlands 51 North Central Hardwood Forests 52 Driftless Area 53 Southeastern Wisconsin Till Plains 54 Central Corn Belt Plains 55 Eastern Corn Belt Plains 56 Southern Michigan/Northern Indiana Drift Plains 57 Huron/Erie Lake Plains 59 Northeastern Coastal Zone 60 Northern Appalachian Plateau and Uplands 61 Erie Drift Plain 63 Middle Atlantic Coastal Plain 64 Northern Piedmont 65 Southeastern Plains 66 Blue Ridge 67 Ridge and Valley 68 Southwestern Appalachians 69 Central Appalachians 70 Western Allegheny Plateau 71 Interior Plateau 72 Interior River Valleys and Hills 73 Mississippi Alluvial Plain 74 Mississippi Valley Loess Plains 75 Southern Coastal Plain 82 Laurentian Plains and Hills 83 Eastern Great Lakes and Hudson Lowlands 84 Atlantic Coastal Pine Barrens
Northern Forests	49 Northern Minnesota Wetlands 50 Northern Lakes and Forests 58 Northeastern Highlands 62 North Central Appalachians
Tropical Wet Forests	76 Southern Florida Coastal Plain
Southern Semi-Arid Highlands	79 Madrean Archipelago
Taiga	101 Arctic Coastal Plain 102 Arctic Foothills 103 Brooks Range 104 Interior Forested Lowlands and Uplands 106 Interior Bottomlands 107 Yukon Flats 108 Ogilvie Mountains
Tundra	109 Subarctic Coastal Plains 110 Seward Peninsula 112 Bristol Bay-Nushagak Lowlands 114 Aleutian Islands
as defined by the United States Environmental Protection Agency [2]