As Level IV mapping is not yet complete in California, information is only included for the sections in
Washington and
Oregon.).
Yakima Plateau and Slopes (9a) The high,
unglaciated Yakima Plateau and Slopes ecoregion is characterized by
plateaus, buttes, and
canyons, with medium to high gradient permanent and intermittent
streams and
rivers on a surface of
basalt. Natural
springs occur, especially in the south. Elevation varies from . The dry continental climate supports open
woodlands dominated by ponderosa pine and
bitterbrush, with some
Douglas-fir and
Oregon white oak. Fire is an integral part of the
ecosystem. The region covers in Washington, mainly on land belonging to the
Yakama Nation.
Grand Fir Mixed Forest (9b) The
Grand Fir Mixed Forest ecoregion is characterized by high, glaciated plateaus,
mountains, and canyons containing high gradient streams and rivers. Scattered
lakes occur in glacial rock basins. Elevation varies from . The frigid
soils and snowy, continental climate support a mix of
grand fir and Douglas-fir, with some ponderosa pine and
western larch. Plants in the
understory include
vine maple,
hazel,
snowberry, and
oceanspray. The region covers in Washington and in Oregon, on the eastern slopes of
Mount Rainier,
Mount Adams, and
Mount Hood, and on
Black Butte. It contains land belonging to the Yakama Nation and public land within the
Wenatchee,
Gifford Pinchot,
Deschutes, and
Mount Hood National Forests (including the
Badger Creek Wilderness).
Oak/Conifer Foothills (9c) The
Oak/Conifer Foothills ecoregion is lower and drier than the Grand Fir Mixed Forest and more
diverse than other parts of the Eastern Cascades. It consists of foothills, low mountains, plateaus, and valleys from .
Marine weather enters the region via the
Columbia River Gorge, moderating the otherwise continental climate. As a result, soil, climate, and vegetation share characteristics of both
eastern and
western Oregon. The region is characterized by Oregon white oak woodlands and ponderosa pine forests in the east and Douglas-fir and
western hemlock forests in the west. Some
grasslands also occur. Understory plants include
Idaho fescue,
bluebunch wheatgrass,
antelope bitterbrush,
Oregon grape, hazel, and snowberry. Common land uses include
forestry,
recreation,
grazing, rural residential development,
orchards, and, in the valleys, grain and hay
farming. The land is mostly privately owned. The region covers in Washington and in Oregon along the
Columbia River corridor, including the lower reaches of the
White Salmon and
Klickitat River drainages.
Ponderosa Pine/Bitterbrush Woodland (9d) The
Ponderosa Pine/Bitterbrush Woodland ecoregion has a terrain dominated by high, undulating volcanic plateaus and canyons, with permanent, medium gradient streams. Elevation varies from . Stream flow is consistent year-round, due to the volcanic
hydrogeology. The well-drained, frigid soils are derived from
Mazama Ash, which was produced by the catastrophic eruption of
Mount Mazama about 6,845 years ago, and support nearly homogenous stands of ponderosa pine. Historically, frequent fires burned undergrowth, creating open groves of pines. Lodgepole pine is largely absent here. Understory vegetation varies with elevation; at lower elevations, antelope bitterbrush is important winter browse for
deer. At higher elevations,
greenleaf manzanita and snowberry are found.
Riparian areas support
mountain alder,
stream dogwood,
willows, and
sedges. The region covers in Oregon, east of
Mount Jefferson,
Three Fingered Jack, and the
Three Sisters, in the
Deschutes National Forest and on the
Warm Springs Indian Reservation.
Pumice Plateau (9e) The
Pumice Plateau ecoregion is a high volcanic plateau, characteristically covered by thick deposits of Mount Mazama ash and
pumice. Elevation varies from . Residual soils are very deep, highly permeable, and subject to
drought, with intermittent, low to medium gradient streams and spring-fed
creeks and
marshes. Freezing temperatures are possible any time of year. Ponderosa pine forests are common on slopes, with
white fir at higher elevations. Colder
depressions and flats, where pumice deposits are thickest, are dominated by lodgepole pine, with an understory of antelope bitterbrush and Idaho fescue. Riparian areas support mountain alder, stream dogwood, willows, and
quaking aspen. The Pumice Plateau is the largest of the Eastern Cascades subregions, covering in Oregon between
Bend and
Klamath Falls. It contains extensive areas within the
Deschutes and
Fremont-Winema National Forests (including the
Gearhart Mountain Wilderness) and the lower elevations of the
Newberry National Volcanic Monument.
Cold Wet Pumice Plateau Basins (9f) The
Cold Wet Pumice Plateau Basins ecoregion includes
Sycan Marsh,
Klamath Marsh, and
La Pine Basin, which are surrounded by the Pumice Plateau but have distinct vegetation and
topography. At an elevation of , they function as cold air catch-basins during the winter, which results in lower minimum temperatures. Soils in the
basins have
water tables at or near the surface for significant periods of the year, in contrast to the soils of the Pumice Plateau. The La Pine Basin is underlain by thick
lacustrine deposits that exhibit high
groundwater levels during the spring
snowmelt. It supports lodgepole pine stands, as well as wet, forested
wetlands of lodgepole pine, willow, and aspen. Scattered ponderosa pine shrub forest is found on the driest soils. The Sycan and Klamath marshes support wetland
meadow vegetation, including
tules and
tufted hairgrass. Marshes, lakes,
reservoirs, wetland forests, and medium and low gradient rivers provide important habitat for
migratory waterfowl. The region covers in Oregon, a mixture of private and public lands, including the Deschutes and Fremont-Winema National Forests and the
Klamath Marsh National Wildlife Refuge.
Klamath/Goose Lake Warm Wet Basins (9g) The
Klamath/Goose Lake Warm Wet Basins ecoregion (named for
Upper Klamath and
Goose lakes) is drier than elsewhere in the eastern Cascades, yet it contains
floodplains,
terraces, and a
pluvial lake basin. Elevation varies from . A variety of
wildrye,
bluegrass, and
wheatgrass species once covered the basins, but most of the
wet meadows and wetlands have been drained for rural
residential development,
pasture, and cropland, including
alfalfa,
potatoes, and small grains. Potential vegetation includes
bluebunch wheatgrass, Idaho fescue, antelope bitterbrush,
big sagebrush, and
low sagebrush on the steppes, with tules,
cattails, and sedges in the wetlands. Several marshland wildlife refuges within the
Klamath Basin National Wildlife Refuges Complex are key to preserving regional
biodiversity, particularly at-risk bird and fish species. The region covers in
Klamath and
Lake counties, Oregon. Contiguous areas in California have not been mapped yet.
Fremont Pine/Fir Forest (9h) The
Fremont Pine/Fir Forest ecoregion contains steeply to moderately sloping mountains and high plateaus that rarely exceed
timberline. Elevation varies from . Residual soils are common in the region, in contrast to the Pumice Plateau, where soils have been deeply buried by pumice and ash. Reservoirs, a few glacial rock-basin lakes, many springs, and high gradient intermittent and ephemeral streams occur. The continental climate and diverse terrain support a range of vegetation types. Ponderosa pine and
western juniper woodlands are common at lower elevations. White fir,
sugar pine,
whitebark pine, lodgepole pine, and
California incense-cedar are found on north slopes and at higher elevations. Understory plants include snowberry,
heartleaf arnica,
Wheeler bluegrass, antelope bitterbrush, and
longstolon sedge. The region covers in Oregon, mainly on public land within the Fremont-Winema National Forest. Contiguous areas in California have not been mapped yet.
Southern Cascades Slope (9i) The
Southern Cascades Slope ecoregion is a transitional zone between the
Cascades ecoregion and the drier Eastern Cascade Slopes and Foothills, characterized by moderately sloping mountains with medium to high gradient streams. Elevation varies from . It is higher than other subregions in the Eastern Cascades and typically receives greater precipitation. Forests of ponderosa pine blanket the mountainous landscape; white fir, Shasta red fir, Douglas-fir, and incense cedar grow at higher elevations. Understory plants include Idaho fescue, antelope bitterbrush,
Ross' sedge,
western fescue, snowberry, and
golden chinkapin. The region covers in Oregon, south of
Aspen Butte in the
Klamath River watershed, including
Bear Valley National Wildlife Refuge. Contiguous areas in California have not been mapped yet.
Klamath Juniper Woodland (9j) The
Klamath Juniper Woodland ecoregion is composed of undulating hills, benches, and
escarpments covered with a mosaic of
rangeland and woodland, at an elevation of . Mean annual precipitation ranges from per year. Western juniper grows on shallow, rocky soils with an understory of low sagebrush, Wyoming big sagebrush, bitterbrush, and bunchgrasses. Several species found in the
shrub-steppe grasslands are uncommon in eastern Oregon, such as
woolly wyethia,
Klamath plum, and
birchleaf mountain-mahogany. The diverse shrublands provide important wildlife habitat. Reservoirs dot the landscape and are important to lowland
irrigation. The region covers in Oregon, south of Klamath Falls in the
Lost River watershed, a mixture of public and private land. Contiguous areas in California have not been mapped yet. ==Gallery==