).
Coastal Lowlands (1a) The
Coastal Lowlands ecoregion contains
beaches,
sand dunes and
spits, and low
marine terraces below elevation. Characteristic features include wet forests, shallow
freshwater lakes,
estuarine marshes, and low-gradient, meandering
tannic streams and
rivers. Residential, commercial, and recreational developments are expanding in the coastal corridor. Many
wetlands in the
floodplains of the region's streams have been drained and converted into
pastures for
dairy farms, and associated stream degradation has occurred. Mature forests in the region are dominated by a
canopy of Sitka spruce, western hemlock, and Douglas-fir, with
salal,
sword fern,
vine maple, and
Oregon grape in the
shrub layer. The
riparian zone supports
red alder, western redcedar, and
bigleaf maple with an
understory of
salmonberry;
California bay-laurel is common in the south. Estuaries and coastal wetlands may feature
Baltic rush,
Lyngby's sedge,
tufted hairgrass,
Pacific silverleaf, and
seaside arrowgrass with
shore pine,
sweet gale, and
Hooker's willow. Stabilized dunes support shore pine over salal,
rhododendron, and
evergreen blueberry, with
dune wildrye,
Chilean strawberry, and
dune bentgrass.
Soil textures range from
silty
clay loam to
sandy loam. The region covers in Oregon and in Washington, with the largest contiguous areas found near Grays Harbor, Willapa Bay, the mouth of the
Columbia River,
Tillamook Bay, and along the southern Oregon Coast. Public lands include the
Grays Harbor,
Willapa,
Nestucca Bay,
Siletz Bay, and
Bandon Marsh National Wildlife Refuges, the
Oregon Dunes National Recreation Area, and numerous state parks.
King Range / Mattole Basin (1j) In contrast to the
redwood forests to the north and south, the vegetation of the
King Range/Mattole Basin ecoregion includes a mixed
evergreen forest of
Douglas-fir,
tanoak, and
madrone, as well as areas of
grassland.
Prairies and
coastal scrub cover many of the
headlands. Although this is one of the wettest spots in California, the
King Range rises above the
coastal fog. In summer, warm, dry, offshore winds also help keep the fog away, making the King Range too dry to support the redwood forests that surround it on three sides. The King Range thrusts above the Pacific, making this area one of the more spectacular and remote stretches of coastline in the continental United States. In the northern part of the region, the
Bear and
Mattole Rivers drain a hilly-to-steep landscape of mixed evergreen forest, with a land cover that includes a relatively greater amount of
annual grasslands than in Ecoregions 1i to the north or 1k to the south. Timber production, livestock grazing, and recreation are primary land uses.
Coastal Franciscan Redwood Forest (1k) The main part of the
Coastal Franciscan Redwood Forest ecoregion extends through
Mendocino County from just south of the King Range to just south of the
Russian River in
Sonoma County. Unlike the conifer-dominated forests of Ecoregion 1i to the north, these central redwood forests typically are more a mixture of conifers and hardwoods. Vegetation includes a multi-story canopy of
redwood,
Douglas-fir,
tanoak,
bigleaf maple, evergreen shrubs, and various grasses. In the southern parts of the region, there are more
coast live oaks and grassland
savannas that are intermixed with denser areas of forest. The near-coastal part of the region that is influenced more by fog has more redwoods and similarities to Ecoregion 1i to the north. Soil temperature regimes are mostly
isomesic and mesic. Soil moisture regimes are predominantly
udic,
ustic, and
xeric. Runoff is rapid and many of the smaller streams are dry by the end of the summer. Natural lakes are absent.
Fort Bragg / Fort Ross Terraces (1l) The
Fort Bragg/Fort Ross Terraces ecoregion forms an elevated coastal plain that has less relief () than the adjacent mountains of Ecoregion 1k.
Quaternary and
Tertiary sandstones and
mudstones form the terraces, and some areas are deeply
dissected, forming ravines that expose
Cretaceous sedimentary rocks. Elevations range from sea level to about . Soil moisture regimes are
udic and some
aquic, and soil temperatures are
isomesic. Monthly and annual temperature variations are minimal and summer fog is common. Vegetation includes coastal grasslands and shrubs, stunted
beach pine,
Bishop pine, or
pygmy cypress, along with areas of some
grand fir and
western hemlock. Terrace soils typically are unsuitable for
redwoods, although they do occur in ravines and on some bluffs.
Point Reyes / Farallon Islands (1m) The
Point Reyes/Farallon Islands ecoregion includes the
Point Reyes Peninsula,
Bodega Head and the sand spit at the north end of
Bodega Bay, and the offshore
Farallon Islands. The maritime climate is temperate and humid, with frequent fog. There are
granitic rocks along with
Pliocene and
Miocene sandstone and
mudstone, and
Quaternary sands. Soil temperature regimes are mostly
isomesic, with some mesic. Soil moisture regimes are mostly
ustic. Common vegetation includes
Douglas-fir,
tanoak,
Bishop pine,
coast live oak,
Pacific reedgrass, and
coyote brush. A few
redwoods occur. Most of the streams are small, and dry by the end of the summer. The Farallon Islands, about 20 miles southwest of Point Reyes, are a group of small granitic islands providing important habitat for
seabirds,
seals, and
sea lions. A small outlier of the region occurs in the south in
Marin County that includes the coniferous and hardwood forests of
Mount Tamalpais and
Bolinas Ridge. This small area of redwoods and other forest types ranges in elevation from sea level to more than . It has more relief and coniferous forest than the
Marin Hills ecoregion (6o). Various types of coniferous and hardwood forests occur, composed mostly of
Douglas-fir,
redwoods,
tanoak,
madrone,
California bay, and
coast live oak. Mount Tamalpais and Bolinas Ridge force moisture out of the air as it cools and ascends the steep western mountain faces. These western parts are heavily forested with redwoods and Douglas-fir. A few areas of drier exposures or shallow soils contain grasslands,
coastal scrub, or
chaparral.
Santa Cruz Mountains (1n) The
Santa Cruz Mountains ecoregion covers the western and southwestern parts of
the range where vegetation includes
redwood,
Douglas-fir,
tanoak,
coast live oak, and
California bay, along with some
chaparral and
coastal scrub species. The shrub layer under forest canopy generally is sparse. Species of limited range in this area include the
Santa Cruz cypress and
Shreve oak. Forests of this region are ecologically and genetically distinct from those of the redwood ecoregions (1i, 1k) farther north. Clear-cut logging was typical from the late 1800s to about the 1960s. Most logging now uses smaller selective cuts. Climate varies from the west to the east, as the high mountain ridges reduce the penetration of maritime air. Winters are cool and wet. On the western side, summers are cool, and fog or low overcast is typical. Soil temperature regimes are mostly
mesic and isomesic, with some
thermic. Soil moisture regimes are mostly
ustic and
xeric. Streams on the northeastern side of the mountains generally are dry during the summer, but streams on the seaward side generally are perennial.
San Mateo Coastal Hills (1o) The
San Mateo Coastal Hills ecoregion has lower relief and elevations than Ecoregion 1n, with more coastal scrub vegetation and a few small areas of cropland rather than the denser forest and woodland of the Santa Cruz Mountains ecoregion (1n).
Marine terraces,
coastal benches, and small valleys are the primary landforms. Elevations range from sea level to about .
Pliocene sandstone and
siltstone are the main rock types compared to the mix of geology in Ecoregion 1n that includes older sedimentary and some igneous rocks.
Mollisol soil type is typical, with mostly
thermic to isomesic temperature regimes. Soil moisture regimes are mostly
xeric and
ustic. Summer fog is common and winters are cool and moist. ==Gallery==