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West Cascade Range Crest, Oregon and Washington

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Pacific Northwest Research Station
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The Pacific Coast Old-Growth Forest

A Unique Ecosystem

Douglas-fir.The Pacific coast old-growth forest is a conifer forest, dominated by large, old trees. The coastal old-growth forests are in the region from southwest Oregon to southeast Alaska, from the Pacific Ocean to the crest of the Cascade Range. In this area, the most common type of old-growth ecosystem is forest dominated by Douglas-firs and western hemlocks, generally 350 to 750 years old. The youngest old-growth forests are 200 years old, and the oldest are about 1,000 years old.

  • In a narrow zone along the Pacific coast, old-growth forests are dominated by Sitka spruce and western hemlock, and at higher elevations in the Cascade Range, true fir and hemlock dominate the old-growth forests.

Among all the forests of the world, the Pacific coast old-growth forest is unique because of the size and old age of its trees, the accumulations of biomass (weight and density of living organisms), and the climate, with its wet, mild winters and dry, warm summers.

  • No other forest has an entire group of tree species that equals the trees in the Pacific coast old-growth forest for their size and long lives. Some of California's giant redwoods are bigger than the biggest Douglas-fir tree. But several species of big trees grow in the Pacific coast old-growth forest, not just one. In other forests, some junipers and bristlecone pines live longer.

Scientists have done a lot of research on old-growth forests in the last 30 years. Much of this work was done by Pacific Northwest Research Station scientists. Click on the other headings on this page to learn more about Pacific coast old-growth forests.


Pacific Northwest Old Growth Forest Poster

Old-growth poster.Synopsis: Lists some of the many plant and animal species that inhabit old-growth forests in the Pacific Northwest.

Description: This poster features a detailed illustration of an old-growth forest. Bordering this are smaller illustrations of some of the many species, along with their common and scientific names, associated with old-growth landscapes. Measures 24”x36.”

Order a copy of this poster






USDA Forest Service - Pacific Northwest Research Station
Last Modified: Monday, 16 December 2013 at 14:18:41 CST

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