The Cascadia Bioregion is also referred to as the Pacific Northwest Bioregion and encompasses all of Washington, and portions of Oregon, Idaho, California, Nevada, Wyoming, Montana, Alaska, Yukon, and British Columbia.

This is the land of old-growth forest superlatives. The enormous, ancient trees that live here are among the tallest, widest, oldest, and most massive in the world with individual lifespans reaching 500 to 2,000 years. Cascadia’s forests have more than twice the volume of biomass per unit of area as the world’s tropical rainforests and support huge varieties of mosses lichens, ferns, and shrubs in addition to countless mammals, birds, and insects.

This guide focuses on the specific forested regions within Cascadia with the largest and oldest trees - western Washington (particularly the Olympic Peninsula), southwest British Columbia and Vancouver Island, California’s redwood forests, and western Oregon. For the most part, the following reports highlights the five giant tree species of the region: coastal redwood, western red cedar, Douglas fir, Sikta spruce, and western hemlock. The redwoods that grow at Cascadia’s southern end receive enough precipitation to shatter height, girth, and volume records. Similarly, western red cedars can grow to absolutely gigantic proportions, particularly in the wet climates of the Olympic Peninsula and Vancouver Island. Sitka spruces are generally found near coastal regions and are sometimes completely enveloped by moss, giving them an incredible primordial look. The great Douglas fir tree may not be as large as the others but it can grow to towering heights that rival the redwoods. This fir’s prominence in Pacific Northwest folklore has made it the symbol of the unofficial flag of the Cascadia bioregion.



Situated squarely in the heart of the Cascadian giant tree forest, Washington houses some of the largest and widest trees in the region. The Olympic Peninsula and specifically, Olympic National Park, is perhaps the region’s most biodiverse and productive forest. The Park is home to four major temperate rainforest valleys, the Hoh, Queets, Quinault, and Bogchiel - which together make up a massive wilderness area of huge western red cedar, Sitka spruce, Douglas fir, bigleaf maple, and western hemlock trees. These are some of the rainiest and most lush places in all of North America.

To the east, Douglas Firs and western red cedars grow at the foothills of Washington’s Cascade Range. As opposed to the near-constant rain that feeds the trees in the Olympic Peninsula and Washington coast, these trees are nourished by the ample snowpack that falls throughout the winter. The valleys of North Cascades National Park up into Lower Mainland Canada feature some beautiful overnight backpacking trails into prime virgin ancient old-growth forest.

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British Columbia

British Columbia’s giant tree forests can be divided into two main regions: Vancouver Island and Lower Mainland. Together with the Olympic Peninsula, Vancouver Island is the epicenter of Cascadia’s old-growth forests. It receives enough rain to produce wonderfully lush, green landscapes and prevent widespread fire outbreaks, permitting fire-sensitive trees like Sitka spruces to grow for centuries. The island has been the site of many conservation battles due to its logging past but several protected areas, including Carmanah Walbran Provincial Park, Avatar Grove, Pacific Rim National Park Reserve, Cathedral Grove, and Meares Island provide beautiful glimpses into the beauty that once covered the entire island.

Lower Mainland encompasses greater Vancouver and several wilderness areas to the east. Its largest trees typically grow at the foothills of the mountains that extend south into Washington’s Cascade Range. Several trails in Chilliwack Lake Provincial Park and Skagit Valley Provincial Park allow backpackers access into British Columbia’s best forest hikes.

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Redwood trees grow at the very southern end of Cascadia’s geographic extent in a small section of far northern California. Though the natural range of coast redwoods is vast, extending from the Oregon border to parks just south of San Francisco, Cascadia’s redwoods are by far the largest and tallest. These redwoods receive far more rainfall and morning fog than other redwood parks further south, allowing the trees to reach maximum height and circumference.

The redwoods here are strictly protected in a complex of parks together named Redwood National and State Parks. Spanning both Del Norte County and Humboldt County, these parks include Redwood National Park and three California state parks : Jedediah Smith Redwoods, Del Norte Coast Redwoods, and Prairie Creek Redwoods. Humboldt Redwoods State Park , a nearby sister park just beyond Cascadia’s southern border, also shares a similar climates and supersized trees as the parks found in Cascadia proper.

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Oregon’s old-growth landscape is divided similarly to Washington’s with Sitka spruces near the coast, Douglas firs dominating the Cascade Range foothills, and western red cedars sprinkled throughout. It is thought that before extensive logging, Oregon’s coast may have held some of Cascadia’s largest and tallest trees. Today, only a few scattered pockets of protected areas can take hikers back to what Oregon’s forests 150 years ago but those pockets are absolutely beautiful.

Travelers to the state’s northern coast may encounter notable specimens like the Cape Meares Giant and the toppled Klootchy Creek Sitka Spruce as well as ancient forests near Cannon Beach. Further south, Oregon is home to some of the tallest living Douglas firs today, including the Doerner Fir, the tallest non-redwood tree on the planet at 327 feet and 3 inches tall.

Inland, several federally protected wilderness areas, including Willamette National Forest and Umpqua National Forest offer hikers access to remote valleys and hikes with amazingly beautiful old-growth scenery.

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