Ecoregions of Oregon

North America has been divided into “level I” ecological regions by scientists. These fifteen broad regions highlight major ecological areas of the continent.1

Viewing the ecological patchwork at this broad scale provides a context for seeing global or intercontinental patterns. Level I ecological regions are: Arctic Cordillera, Tundra, Taiga, Hudson Plains, Northern Forests, Northwestern Forested Mountains, Marine West Coast Forests, Eastern Temperate Forests, Great Plains, North American Deserts, Mediterranean California, Southern Semi-Arid Highlands, Temperate Sierras, Tropical Dry Forests and Tropical Wet Forests.2 My fair state of Oregon (outlined in red on the map) is home of three of these Level I regions:

Level I Ecoregions of North America

The level I ecoregions have been broken down into 50 level II ecological regions to provide a more detailed description of the large ecological areas nested within the level I regions. For example, the Tropical Wet Forests of level I is the region covering coastal portions of the United States and Mexico (including Oregon), and is composed of six level II regions. Again, I’ve outlined the state of Oregon in red. Level II ecological regions are useful for national and subcontinental overviews of ecological patterns. Three level I regions (Hudson Plains, Marine West Coast Forest, and Mediterranean California) have no subdivisions at level II. The Temperate Sierras, Tropical Dry Forests, and Tropical Wet Forests level I regions, on the other hand, each have six level II subdivisions.3

Level II Ecoregions of North America

Level III ecoregions are providing yet more detailed descriptions of nested ecological areas. I’ve shown a map of the Level III ecoregions of the contingent United States instead of Level III North American Ecoregions to show more detail of Oregon. If you look closely, you’ll see that there are nine Level III Ecoregions, providing more detail of the three Level II Ecoregions of the state.

And now we reach the most detailed level created by the US Environmental Protection Agency: Level IV Ecoregions. Again, you can find a detailed map and descriptions for all of North America, but since The Wilds Project will only concentrate on those in Oregon, I’m showing only a map of the state’s Ecoregions. My goal is to visit as many of these Level IV Ecoregions as I can within Oregon’s Wilderness Areas.

Level IV Ecoregions of Oregon

As I visit the Level IV Ecoregions, I will create pages dedicated to each and link to them below. Here’s the full list:

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
  1. USEPA Western Ecology Division – Ecoregions of North America –
  2. USEPA Western Ecology Division – Ecoregions of North America –
  3. USEPA Western Ecology Division – Ecoregions of North America –