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.


Olympic Peninsula

Situated squarely in the heart of the Cascadian giant tree forest, the Olympic Peninsula contains some of the largest and widest trees in the region. The most heavily forested section of the Peninsula is the interior, comprised of Olympic National Park and Olympic National Forest. As one of the rainiest and cloudiest places in North America, this, along with Vancouver Island, is perhaps Cascadia’s most biodiverse and productive forest.

The Peninsula is home to four major temperate rainforest valleys, the Hoh, Queets, Quinault, and Bogchiel. Together they make up a massive wilderness filled with huge western red cedar, Sitka spruce, Douglas fir, bigleaf maple, and western hemlock trees. These valleys collect nearly 12 feet of rain annually in some places, which prevents fires from destroying the diverse environment and accelerates the growth of the trees.

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Vancouver Island

Outside of the Olympic Peninsula, no other region in Cascadia is more renowned for magnificent ancient forests and giant trees than Vancouver Island. Its frequently foggy and overcast climate, coupled with a very long wet season (between approximately September through May), spurs the growth of monumental trees here. The cedars, spruces, and hemlocks cultivated in its dark, nourishing forests are among the largest anywhere and have long been a source of inspiration and fascination for big tree hunters.

Though these forests have also been the site of intense confrontations between conservationists and loggers, beautiful sections of old-growth remain on the Island — including Carmanah Walbran Provincial Park, Avatar Grove, Pacific Rim National Park Reserve, Cathedral Grove, and Meares Island — transporting intrepid explorers to stunning, almost primordial environments.

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Washington Cascades

The Cascade Range runs like a spine through the middle of Washington State and traps precipitation of weather systems originating from the coast. As opposed to the near-constant rain that feeds the trees in the Olympic Peninsula and the coast, trees in the Washington Cascades are nourished by the ample snowpack that falls throughout the winter. Giant Douglas Firs and western red cedars dominate the the valleys and hillsides throughout the mountainous region.

In the north, several beautiful overnight backpacking trails into prime virgin ancient old-growth forest exist in and around North Cascades National Park and up into Lower Mainland, Canada. These hikes are situated in deep valleys that cut far below the rocky, vertical peaks.

Further south, the valleys and flat lands around Mount Rainier and Mount St. Helens, two of Cascadia’s tallest mountains, receive enough precipitation to produce stellar Cascadian old-growth forests. Both parks are home to a number of beautiful trails that lead through giant Douglas fir, hemlocks, and cedars. Due to their federally protected status, these ancient forests are generally protected from the extensive logging and deforestation that occurred beyond their borders. The result is miles of undisturbed giant trees, rain-soaked moss, rich plant-life, and abundant wildlife.

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British Columbia

British Columbia’s Lower Mainland encompasses greater Vancouver and several wilderness areas to the east. It’s largest trees typically grow at the foothills of the mountains that extend south into Washington’s Cascade Range. Like Vancouver Island to the west, Lower Mainland receives enough rain to produce wonderfully lush, green landscapes yet the trees here also draw nourishment from the slow melting snowpack that accumulates consistently through the fall and winter.

One can encounter giant trees in either the parks around the Vancouver metro area (Lynn Headwaters Provincial Park, Hollyburn Ridge, etc.) or the wilderness areas further east, including in Chilliwack Lake Provincial Park and Skagit Valley Provincial Park, which allow backpackers access to British Columbia’s ancient, old-growth forests.

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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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