Zoology

Central Pacific coastal forests

May 22, 2013, 12:59 am
Content Cover Image

Olympic National Forest, Washington, USA Photograph by John Morrison

The Central Pacific Coastal Forests stretch from southern Oregon to the northern tip of Vancouver Island. Major habitats of this diverse region include sea stacks, sandy beaches, rocky coastal cliffs, coastal headlands, tidepools, mudflats, salt marshes, estuaries, streams, and rivers of various sizes, grass balds, and many forest types.

Climate

Influenced by cool moist air from the ocean, the Central Pacific Coastal Forests experience frequent clouds and fog, with most precipitation occurring in the winter. Generally, precipitation is greater in the western half of the ecoregion. Annual rainfall ranges from 2,000-4,080 millimeters (mm), with higher coastal mountain areas receiving the bulk of this precipitation. Mean annual temperature is around 13°C. Vancouver Island experiences a mean annual temperature of 8.5°C, averaging 13.5°C in the summer, and 3.5°C in the winter. The climate on the island is marked by warm summers and mild winters, being one of the mildest areas in Canada. Rainfall varies between 1,500-3,500 mm per year. Precipitation in the eastern side of the island ranges from 800-2,500 mm per year. Climate in this ecoregion is a combination of alpine, subalpine, and maritime south Pacific Cordilleran. The Columbia River is the river of largest volume that flows through this ecoregion.

Ecosystem

The forests of the Central Pacific Coast are among the most productive in the world, characterized by large trees, substantial woody debris, luxuriant growths of mosses and lichens on trees, and abundant ferns and herbs on the forest floor. The major forest complex consists of Douglas-fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla), encompassing seral forests dominated by Douglas-fir and massive old-growth forests of fir, hemlock, western red cedar (Thuja plicata), and other species. These forests occur from sea level up to elevations of 700-1,000 meters (m) in the Coast Range and Olympic Mountains. This forest type occupies a wide range of environments with variable composition and structure and includes such other species as grand fir (Abies grandis), Sitka spruce (Picea sitchensis), and western white pine (Pinus monticola).

On Vancouver Island, low-elevation coastal forest cover includes stands of western hemlock, Douglas-fir and amabilis fir (A. amabilis). Western hemlock, Douglas-fir and grand fir characterize most forests of eastern Vancouver Island. Drier sites support stands of western hemlock and western red cedar. The driest areas in eastern Vancouver Island are comprised of mixed stands of Douglas-fir and western hemlock with occasional Garry oak (Quercus garryana), Pacific dogwood (Cornus nuttallii) and arbutus (Arbutus menziesii). The subalpine forests are composed of mountain hemlock (T. mertensiana) and amabilis fir, with some yellow cedar (Chamaecyparis nootkatensis) and western hemlock in high elevation areas in eastern Vancouver Island. Coastal areas of British Columbia are best characterized as hydroriparian forest ecosystems, such that the hydrologic cycle is the most important ecological process influencing forest dynamics. High winds, sea salt spray and fog strongly influence forest dynamics. Fires are not as important as in other areas.

Although Douglas-fir is the most abundant species at lower elevations in the region, western hemlock is the major climax species. Douglas-fir typically dominates young forest because of its relatively large and hardy seedlings and rapid growth rate. Western hemlock and several other species of fir are more tolerant of shade, however, and in mature forest Douglas-fir cannot regenerate.

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 (Pinus contorta). The Sitka spruce zone–in which hemlocks also occur in large numbers–may be only a few kilometers (km) in width and generally occurs below 150 meters. Where mountains abut the coast, however, Sitka spruce forests may extend up to 600 m. The alluvial rainforests of the western Olympic Peninsula are outstanding examples of the spruce-hemlock forest.

Riparian forests of this ecoregion are quite distinct from the Douglas-fir/hemlock forests. 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. Occasional grasslands, sand dune, and strand communities, rush meadows and marshes, and western red cedar and alder swamps, these last often formed by beaver activity, break up the conifer forests.

Biological Distinctiveness

The Central Pacific coastal forests are among the richest temperate coniferous forests in North America for amphibians and birds. Gray’s Harbor in Washington, for example, is a critical migratory stopover site for shorebirds. Rare and endangered species found in this ecoregion include California Condor (Gymnogyps californianus), Hoary Elfin Butterfly (Incisalia polios obscurus), Seashore Plantain (Plantago macrocarpa), and possibly the Pacific Fisher (Martes pennanti). Other characteristic wildlife include Elk (Cervus elaphus), Black-tailed Deer (Odocoileus hemionus), Coyote (Canis latrans), Black Bear (Ursus americanus), Mink (Mustela vison), Raccoon (Procyon lotor), Grouse (Dendragapus spp.), seabirds, shorebirds and waterfowl.

Conservation Status

Habitat Loss

Human activity, particularly clearcut logging, plantation forestry, road building, agriculture, and development have heavily altered the Central Pacific Coastal Forests. Only about four percent of the region remains as intact habitat. Some ecosystem types, such as the coastal temperate rain forests in Oregon, have been virtually destroyed.

Remaining Blocks of Intact Habitat

Several relatively large blocks of more or less intact habitat remain, as do a number of smaller patches. Important blocks include:

  • Strathcona Provincial Park - southwestern British Columbia - 2,193 square kilometers (km2)
  • Olympic National Park - northwestern Washington - 1,200 km2 (assuming that roughly half the park is forested) N.B.: Forests at the upper elevations of the park are Cascadian in nature and fall within the North Cascades Forest Ecoregion.
  • Brooks Peninsula Provincial Park - southwestern British Columbia - 380 km2
  • Tahsish watershed - southwestern British Columbia

Degree of Fragmentation

Although heavily altered, most of the ecoregion remains forested. More than half of the remaining fragments have some degree of interaction with other intact habitat blocks.

Degree of Protection

caption Blue grouse. (Photograph by Barry Thornton)

 

The only protected habitats in this ecoregion are in national and provincial parks. Several of those protected areas, however, are relatively large and contain undisturbed forests. Human activities have significantly altered nearly all habitats outside the parks.

  • Olympic National Park - northwestern Washington
  • Strathcona Provincial Park - southwestern British Columbia - 2193.04 km2
  • Pacific Rim National Park - southwestern British Columbia - 499.6 km2
  • Checleset Bay Ecological Reserve - southwestern British Columbia - 346.5 km2
  • Brooks Peninsula Provincial Recreation Park - southwestern British Columbia - 287.8 km2
  • Pacific Rim-West Coast Trail National Park - southwestern British Columbia - 263.3 km2
  • Megin Watershed Provincial Park - southwestern British Columbia - 213 km2
  • Brooks-Nasparti Provincial Park - southwestern British Columbia - 212.98 km2
  • Cape Scott Provincial Park - southwestern British Columbia - 150.7 km2
  • Pacific Rim - Broken Islands Group National Park - southwestern British Columbia - 106.5 km2
  • Tahshish - Kwois Provincial Park - southwestern British Columbia - 106.27 km2

Types and Severity of Threats

So little intact habitat remains outside national and provincial parks that conversion of the Central Pacific Coastal Forests has ceased to be an important issue for conservationists. Degradation from pollution, grazing, burning, introduced species, road building, and excessive recreational impacts is causing significant mortality in some native plant communities.

Suite of Priority Activities to Enhance Biodiversity Conservation

  • Establish protected areas where ecological gaps remain in the protected areas system, for example, in Clayoquot Sound.
  • Extend Olympic National Park to connect coastal and upland sections.

The following areas in the Oregon Coast Range are high priorities for protection and restoration. All require consolidation, road closures, and revegetation. These areas contain substantial old-growth and other late-successional forests, are of high value to fisheries and aquatic biodiversity, support numerous spotted owl (Strix occidentalis) nesting sites, and form important natural linkages in a network of significant sites:

caption Spotted owl. (Photograph by WWF)
  • Cummins Creek/Rock Creek - 427 km2
  • Drift Creek - 229 km2
  • Mount Hebo/Nestucca River - 506 km2
  • Mary’s Peak/Grass Mountain - 141 km2
  • Elliott State Forest - 364 km2

These five areas are among 31 proposed high priority reserves that together cover 5065 km2, or over 23 percent of the Oregon Coast Range Bioregion. The high priority reserves by themselves are too small to conserve viable populations of wide ranging species or to maintain natural disturbance regimes. The high priority areas must be linked and insulated by reserves under slightly less strict protection and by multiple-use buffer zones. Together, these three classes of reserves would form a continuous network through the Coast Range.

  • More protected areas are required that represent the middle and lower elevation coastal rain forest communities.
  • Proper enforcement of the British Columbia Forest Practices Code is required. Further damage to remaining salmon (Oncorhynchus spp.) habitat must be avoided and other riparian habitats restored.

Conservation Partners

  • Canadian Parks and Wilderness Society, British Columbia Chapter
  • Clayoquot Biosphere Project
  • Friends of Ecological Reserves
  • Friends of Strathcona Park
  • Friends of the Stikine
  • Islands Trust
  • The Nature Conservancy, British Columbia
  • Nature Trust of British Columbia
  • Northwest Wildlife Preservation Society
  • Sierra Club, Western Canada
  • Victoria Natural History Society
  • Western Canada Wilderness Committee
  • World Wildlife Fund Canada

Relationship to Other Classification Schemes

Bailey combines the Central Pacific Coastal Forests and the Cascades into a single province. We follow Omernik by distinguishing the regions on the basis of climate, elevation, and dominant communities. We have further divided the area by delineating two ecoregions within the Cascades: British Columbia Mainland Coastal Forests, which run from central Washington to northern British Columbia; and the Central and Southern Cascades Forests which run from Washington almost to the Oregon/California border. Although the mountains of the Olympic Peninsula fall entirely within the coastal ecoregion, like Omernik we include the higher elevation forests with the North Cascades ecoregion. Conservation strategies for the coastal and montane forests would be unwieldy if managed as a single large unit stretching nearly from California to the Yukon Territory.

The Canadian portion of the Central Pacific Coastal Forests rests on Vancouver Island (TEC 193 and 194). In addition to Southern and Northern Pacific Coast vegetation (2 and 3), Vancouver Island also has Coastal Subalpine forests (3).

Disclaimer: This article contains certain information that was originally published by the World Wildlife Fund. Topic editors and authors for the Encyclopedia of Earth have edited its content and added new information. The use of information from the World Wildlife Fund should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.

 

Glossary

Citation

Fund, W. (2013). Central Pacific coastal forests. Retrieved from http://www.eoearth.org/view/article/151023

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