The Blue Mountains ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) in the Pacific Northwest, mainly in the state of Oregon, with small areas over the state border in Idaho and southeastern Washington. It is also contiguous with the World Wildlife Fund's Blue Mountain forests ecoregion.
Setting
This ecoregion extends from the Redmond area of Central Oregon, across a wide swath of the Columbia Plateau in Eastern Oregon, to Hells Canyon on the Snake River at the border of the three states. The ecoregion is named for the Blue Mountains and contains a complex of basins and mountain ranges that, at average 2100-2900m, are lower and more open than the neighboring Cascades and Northern Rocky Mountains but do include some steep landscape of which Hells Canyon at 1,660m is North America's deepest gorge. The mountains of the ecoregion include the Strawberry Range, Greenhorn, Elkhorn, Aldrich and Maury Mountains in the Blue Mountains, the gentler Ochoco Mountains to the west and the rugged Wallowa Mountains to the east. Rivers include the Grande Ronde, Powder Rivers and Malheur Rivers, all tributaries of the Snake and the John Day and Umatilla Rivers, tributaries of the Columbia.
Like the Cascades, but unlike the Northern Rockies, the Blue Mountains are mostly volcanic in origin. However, the core of the Blue Mountains and the highest ranges, the Wallowa and Elkhorn mountains, are composed of granitic intrusives, deep sea sediments, and metamorphosed rocks.
Flora
Habitats within the ecoregion include desert-like shrubland, bluebunch grasslands, pine forest and alpine highlands as well as riverbanks and wetlands. This area is home to some of North America's largest stands of old growth forest including ponderosa pine (Pinus ponderosa), Engelmann spruce(Picea engelmannii) and other spruces, western larch (Larix occidentalis) and grand fir (Abies grandis) and other firs (Abies spp.). Other important plants are sagebrush (Artemisia tridentata), juniper (Juniperus occidentalis), Douglas fir (Pseudotsuga menziesii), lodgepole pine (pinus contorta), shrubs, meadows, grasslands and alpine plants.
Fauna
Birds of the area include bald eagle, northern spotted owl, Lewis's woodpecker, Williamson's sapsucker, red-breasted nuthatch, golden-crowned kinglet and many migratory species, with the riverbanks important habitat for this birdlife. Mammals that move through the mountain grasslands include elk (including the largest herd in North America at Hells Canyon), bighorn sheep and mule deer. Native fish include Chinook Salmon, Steelhead, Redband Trout, Coho Salmon, Bull Trout, and Pacific Lamprey.
Threats and preservation
These habitats are vulnerable to logging, livestock grazing, river and fire control schemes and only about 10% of the original forest remains intact. The region includes significant landholdings by the United States Forest Service and the Bureau of Land Management. Much of the land is grazed by cattle, unlike the Cascades and Northern Rockies ecoregions. Large blocks of intact forest remaining include: Eagle Cap Wilderness in the Wallowa–Whitman National Forest, Hells Canyon National Recreation Area, the North Fork John Day Wilderness, Wenaha–Tucannon Wilderness of Umatilla National Forest, Strawberry Mountain Wilderness in Malheur National Forest and the northern part of Ochoco National Forest. These are all quite fragmented and logging of ponderosa pine in particular is an ongoing threat.
Level IV ecoregions
The Blue Mountains ecoregion has been subdivided into fourteen Level IV ecoregions, as described below. The EPA has not yet published an Ecoregions of Washington poster similar to the informational posters for Oregon and Idaho, and the Washington information presented here is not as complete as the information about the other two states.