Boundaries

This ecoregion extends along the Pacific Coast of Oregon and California to the northern shore of San Francisco Bay, including the western portion of the San Francisco peninsula south to Santa Cruz. In southern Oregon and Northern California, the ecoregion reaches further inland, encompassing the western drainages of the Klamath and Siskiyou Mountains.

Topography

This ecoregion has plentiful water resources because of its location on the slopes of four mountain ranges—the Cascades, the Coastal Ranges, the Klamath Mountains, and the Siskiyou Mountains.

Freshwater habitats

Characteristic freshwater habitats of the ecoregion include coastal headlands, tidal rivers, estuaries, floodplains, wetlands, streams and rivers. Along the Oregon coast rivers have cut steep dendritic drainages, with many of the large rivers terminating in sizeable estuaries (McNab & Avers 1994). These coastal estuaries contain high and low salt marshes, as well as freshwater marshes (Vander Shaaf et al. 2006). The northern California coast is characterized by relatively slow streams and rivers in alluvial channels that terminate primarily in brackish estuaries (McNab & Avers 1994).

Terrestrial habitats

Temperate coniferous forests make up a majority of the ecoregion, with dominant species including Douglas fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla) in the coastal mountains, and Sitka spruce (Picea sitchensis) in a narrow band along the coast (Vander Shaaf et al. 2006). Redwood (Sequoia sempervirens) forests are unique to the northern California coast, and are among the biggest, tallest, and oldest trees in the world. Broadleaf species such as black cottonwood (Populus trichocarpa) and red alder (Alnus rubra) replace the otherwise ubiquitous conifers along the many rivers and streams of the Pacific Northwest (Ricketts et al. 1999).

Description of endemic fishes

While this ecoregion contains no endemic mussel or crayfish species, roughly a quarter of its fish species are endemic, including the Umpqua squawfish (Ptychocheilus umpquae), the Klamath smallscale sucker (Catostomus rimiculus), the Klamath largescale sucker (C. snyderi), two sculpins (Cottus princes and C. tenuis), three lampreys (Lampetra folletti, L. minima and L. similis), two suckers (Chasmistes brevirostris and Deltistes luxatus), two chubs (Gila coerulea and (Oregonichthys kalawatseti), and Umpqua dace (Rhinichthys evermanni).

Justification for delineation

Ecoregion boundaries are taken from Abell et al. (2000) and are based on subregions defined by Maxwell et al. (1995).