North of the Chehalis River Valley of Washington state, the ecoregion features a predominantly oceanic climate (KöppenCfb) with cool winters, mild summers, and plentiful rainfall throughout the year. South of the Chehalis River Valley and along the east coast of Vancouver Island, the ecoregion has a predominantly Mediterranean climate (KöppenCsb) with fresh, dry, sunny summers and cool winters with moderate precipitation and plentiful cloud cover. Small patches of oceanic climate can be found in the Willapa Hills of Washington state and the northern highlands of the Oregon Coast Range.[2]
The forests of the Central Pacific Coast are among the most productive in the world, characterized by large trees draped lush growths of mosses and lichens, and an abundance of ferns, herbs, and woody debris on the forest floor.[2]
Epiphytic species may include different mosses and lichens and epiphytic ferns such as Licorice fern can dominate areas with lots of shade, and wood.
On Vancouver Island, low-elevation coastal forest cover includes stands of western hemlock, Douglas-fir and amabilis fir. Western hemlock, Douglas fir and grand fir characterize most forests of eastern Vancouver Island.[3] Drier sites support stands of western hemlock and western red cedar. The driest areas in eastern Vancouver Island consist of mixed stands of Douglas fir and western hemlock with occasional Garry oak, Pacific dogwood and arbutus. The subalpine forests are composed of mountain hemlock, subalpine fir, amabilis fir and engelmann spruce, with some yellow cedar and western hemlock in high elevation areas in eastern Vancouver Island.[2]
While hemlock and fir dominate much of the ecoregion, the cool, wet conditions along the coast create a narrow band of forests distinguished by Sitka spruce. With its high tolerance of salt spray, in areas near the ocean Sitka spruce may form nearly pure forests or co-dominate with lodgepole pine. The Sitka spruce zone–in which hemlocks also occur in large numbers–may be only a few kilometers in width and generally occurs below 150 m (490 ft). Where mountains abut the coast, however, Sitka spruce forests may extend up to 600 m (2,000 ft).[2]
Riparian forests of this ecoregion are quite distinct from the Douglas-fir/hemlock forests. Broadleaf species such as black cottonwood and red alder replace the otherwise ubiquitous conifers along the many rivers and streams of the Pacific Northwest. Occasional grasslands, sand dune and strand communities, rush meadows and marshes, and western red cedar and alder swamps break up the conifer forests.[2]
Several relatively large blocks of more or less intact habitat remain, as do a number of smaller patches. Human activities have significantly altered nearly all habitats outside the parks.
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