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), and lodgepole pine (pinus contorta).
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. Wolves were extirpated in the early 20th century but several wolf packs have recolonized the ecoregion. 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.
John Day/Clarno Uplands (11a) The John Day/Clarno Uplands ecoregion forms a ring of semi-arid foothills and low mountains surrounding the western perimeter of the Blue Mountains. Elevation varies from 1,200 to 5,500 feet (366 to 1,676 m). Highly dissected hills, palisades, and colorful ash beds flank the valleys of the John Day and Crooked rivers. Scattered buttes occur. The region has a continental climate moderated somewhat by marine influence. Grasslands support Bluebunch wheatgrass, Idaho fescue, basin wildrye, Wyoming big sagebrush, and Thurber needlegrass.
Higher elevations feature western juniper in transition to the ponderosa pine forests of the neighboring John Day/Clarno Highlands. Juniper woodlands have expanded markedly into the sagebrush-grassland during the twentieth century due to a combination of climatic factors, fire suppression, and grazing pressure. Riparian areas support white alder, mockorange, western chokecherry, clematis, willows, black cottonwood, and water birch. The largest of the Blue Mountains subregions, the John Day/Clarno Uplands covers in Oregon, including all three units of the John Day Fossil Beds National Monument and portions of the Warm Springs Indian Reservation and the Crooked River National Grassland.
John Day/Clarno Highlands (11b) The John Day/Clarno Highlands ecoregion is characterized by moderately to highly dissected hills and low mountains that are uniformly covered by Western ponderosa pine forest with a grass and shrub understory. Elevation varies from 3,000 to 6,200 feet (914 to 1,990 m). The region includes broad streams fed more by springs than by snow melt. The continental climate is tempered by a marine influence; it is not as dry, nor are temperature extremes as great, as in the Continental Zone Highlands. Historically, frequent low intensity wildfires reduced fuel loading in forests of widely spaced old-growth ponderosa pine. Today, after years of fire suppression and high grade logging, land managers attempt to emulate historical fire regimes to reverse the trend toward dense thickets of young growth that carry hot, stand-replacing fires.
Potential vegetation is mostly open ponderosa pine, with some Douglas-fir, western juniper, mountain-mahogany, snowberry, mountain big sagebrush, elk sedge, Idaho fescue, and bluebunch wheatgrass. Riparian areas support grand fir, mountain alder, red-twig dogwood, ninebark, Wood's rose, Rocky Mountain maple, and willows. The region covers in Oregon, including parts of the Ochoco, Malheur, and Umatilla national forests and lower elevations in the Mill Creek, Bridge Creek, Black Canyon and North Fork John Day wilderness areas.
Maritime-Influenced Zone (11c)
The Maritime-Influenced Zone ecoregion is the portion of the Blue Mountains ecoregion that directly intercepts marine weather systems moving east through the Columbia River Gorge. It is characterized by a dissected, gently-sloping to hilly volcanic plateau and mountain valleys. Elevation varies from 3,000 to 6,000 feet (914 to 1,829 m). Loess and ash soils over a substrate of basalt retain sufficient moisture to support forest cover at lower elevations than elsewhere in the Blue Mountains. A dense and diverse shrub layer grows beneath the relatively open canopy of ponderosa pine and Douglas-fir, which may delay tree regeneration after logging.
Vegetation is dominated by Western ponderosa pine forests, with some Douglas-fir and grand fir. The understory and riparian shrub cover feature snowberry, spiraea, ninebark, serviceberry, and red-twig dogwood. The herbaceous ground cover features heartleaf arnica, pinegrass, elk sedge, Idaho fescue, Sandberg's bluegrass, and bluebunch wheatgrass. The region covers in Oregon, as well as small areas across the border in Washington, and includes public land within the Umatilla National Forest.
Melange (11d) The Melange ecoregion is characterized by dissected mid-elevation mountains with the complex geology typical of mélange formations. Elevation varies from 3,500 to 7,500 feet (1,067 to 2,286 m). The mountains are mostly blanketed in Tertiary basalt but have a core of mixed metamorphic, metavolcanic, metasedimentary, and sedimentary rocks. Soils are droughty and high in magnesium, creating a poor medium for plant growth; reforestation problems limit logging. Placer mining for gold altered the structure of many stream channels and left extensive tailings piles in riparian areas. Lithology affects soil, vegetation, and the quantity and quality of surface water, which vary across the region. Forests are dominated by Douglas-fir, ponderosa pine, and lodgepole pine, with subalpine fir, western larch, and grand fir; elsewhere, juniper steppe woodlands, shrublands, and grasslands are found. Understory plants include mountain-mahogany, snowberry, serviceberry, grouse huckleberry, snowberry, prince's pine, sidebells pyrola, twinflower, pinegrass, elk sedge, heartleaf arnica, Idaho fescue, and bluebunch wheatgrass.
Riparian areas support mountain alder, red-twig dogwood, prickly currant, black currant, Columbia monk's hood, and bluebells. The region covers in Oregon and in Idaho, including parts of the Malheur, Umatilla, and Payette national forests and lower elevations in the Strawberry Mountain, Monument Rock, and North Fork John Day Wildernesses.
Wallowas/Seven Devils Mountains (11e) The Wallowas/Seven Devils Mountains ecoregion consists of deeply dissected mountains in the Wallowas and Seven Devil ranges. It occupies the mid-elevation zone between the Subalpine-Alpine Zone and the Continental Zone Foothills, at an elevation of 3,000 to 9,200 feet (914 to 2,804 m). Perennial streams following fault lines have eroded deep canyons. The character of the region's xeric forest varies between moister maritime-influenced and drier continental areas, particularly in the diversity and extent of the shrub understory. The region is dominated by Western ponderosa pine, lodgepole pine, Douglas-fir, and grand fir, with western larch, ninebark, snowberry, Rocky Mountain maple, serviceberry, mountain big sagebrush, low sagebrush, big huckleberry, grouse huckleberry, twinflower, prince's pine, elk sedge, and pinegrass. Higher elevations support subalpine fir. The region covers in Oregon and in Idaho, containing parts of the Wallowa-Whitman, Nez Perce, and Payette national forests.
Canyons and Dissected Highlands (11f) The Canyons and Dissected Highlands ecoregion is characterized by steeply sloping, upper river canyons and dissected plateaus in the rain shadow of the mountains. It includes the southern Seven Devils Mountains and pieces of the uplifted Columbia Plateau, where the basalt has been eroded to a series of knife-edge ridges flanked by deep canyons. The region occupies the elevational zone above the unforested Canyons and Dissected Uplands, at an elevation of 4,000 to 6,400 feet (1,219 to 1,951 m). The steep terrain limits human activities. The region is drier than the marine-influenced Mesic Forest Zone that exists at similar elevations to the west. Moisture retaining loess and ash soils support Douglas-fir, larch, and grand fir on relatively level benches and Douglas-fir in unstable colluvial soils on steep canyon slopes. Western ponderosa pine forest is also present, with ninebark, snowberry, oceanspray, heartleaf arnica, elk sedge, Idaho fescue, bluebunch wheatgrass, and bluegrass. Riparian areas support mountain alder, stinking and prickly currant, thimbleberry, and Columbia monk's hood. The region covers in Oregon, in Idaho, and smaller areas in Washington, including parts of the Wallowa-Whitman, Nez Perce, and Payette National Forests, the Wenaha–Tucannon Wilderness, and the Hells Canyon National Recreation Area.
Canyons and Dissected Uplands (11g)