USA — Pacific Northwest

What is here

The Pacific Northwest temperate rainforest, broadly defined, runs roughly 3,500 kilometres along the Pacific coast of North America. The dominant species change as you move north — coast redwood (Sequoia sempervirens) in northern California, Douglas-fir / western hemlock / Sitka spruce / western redcedar from Oregon up through southeast Alaska — but the structural pattern is consistent: long-lived conifers, very high biomass per hectare, frequent precipitation, deep duff and coarse-woody-debris layers, multi-layered canopy with emergent giants.

The biomass per hectare in old-growth Pacific Northwest forest is among the highest of any forest type measured anywhere in the world. The largest individual stems — coast redwoods, Sitka spruces, Douglas-firs — are among the largest individual living things on Earth.

The places worth knowing

Redwood National and State Parks (California). The remaining 5% of the original old-growth coast-redwood range, mostly protected since the 1968 establishment of Redwood National Park and the 1994 cooperative-management arrangement that combined it with three California state parks. Maintained jointly by the National Park Service and California State Parks. Save The Redwoods League, founded in 1918, has been the consistent private-philanthropy actor restoring and connecting the remaining patches^[5].

Olympic National Park (Washington). The Hoh, Quinault, and Queets river valleys on the western flank of the Olympic Peninsula carry some of the most famous temperate-rainforest old growth on Earth — mossy, massive, wet, and largely intact. Olympic itself was established as a national park in 1938 and substantially expanded in 1953 to bring most of the western valleys under federal protection^[2].

Mount Hood, Willamette, and Gifford Pinchot National Forests (Oregon and Washington). The bulk of the old-growth Douglas-fir / western hemlock cathedral forest of the western Cascades. These are working national forests — subject to harvest under federal law — but the Northwest Forest Plan substantially constrained harvest of mature and old-growth stands on federal land in the spotted-owl range from 1994 onward^[4]. Most of what survives in the Cascades survives because of that plan.

H. J. Andrews Experimental Forest (Oregon). The 6,400-hectare research forest in the Willamette National Forest where Jerry Franklin and his colleagues did the foundational structural studies that produced the modern definition of old growth (covered in that primer). Still active as a Long-Term Ecological Research site^[3].

Tongass National Forest (Alaska). The largest national forest in the U.S. system at 6.8 million hectares, encompassing most of the temperate-rainforest archipelago of southeast Alaska. The Tongass holds the bulk of the country’s remaining unfragmented old-growth temperate rainforest^[1]. Harvest of old growth on the Tongass has been the subject of repeated policy reversals over twenty years: the 2001 Roadless Rule restricted road-building (and therefore practical harvest) in most of the forest; an exemption for the Tongass was finalised in 2020 and reversed in 2023; the political fight over how much of the Tongass to keep roadless is ongoing.

The fight for the last 5%

The numbers cited most often, by both scientists and conservation groups, put the remaining old-growth fraction across the original Pacific Northwest temperate-rainforest range at roughly 5% — a back-of-envelope figure for “how much is left” that is broadly consistent with the structural-stage data the U.S. Forest Service publishes on its mature-and-old-growth inventory^[7]. Most of that remaining 5% is on federal public land. Most of it is in a few specific places: the Tongass, the western Olympic, the upper-elevation Cascades, the Klamath ranges, the inner redwood belt.

The proximate threat in 2026 is policy: the federal protections that currently keep harvest off most of this land are statutory, regulatory, and partly executive. Each is reversible by administration change. The Mature and Old-Growth Inventory commissioned under Executive Order 14072 in 2022 produced its first national results in 2024 and is the technical basis for any future durable protection rule^[7]; the actual rulemaking that would protect mature and old-growth stands on federal land has been repeatedly drafted and delayed, and at the time of writing remains incomplete.

Who works on this and how to join

Save The Redwoods League — private-philanthropy and land-acquisition arm focused on coast redwoods specifically. Has restored, reconnected, and re-protected substantial fragmented redwood land over a century^[5].

Audubon Alaska — Tongass programme. Long-running advocacy on the Roadless Rule and Tongass-specific old-growth protection^[8].

USDA Forest Service comment periods. Most federal forest-management actions — rulemakings, project-specific timber sales, environmental impact statements — have public comment periods on regulations.gov. This is the most direct, most under-used channel for any U.S. citizen who wants to weigh in on Pacific Northwest old-growth decisions. The map’s headline action for U.S. visitors links to the active comment processes when one is open.

Local land trusts. Coast-redwood, Olympic, and Cascade ranges all have active local land trusts working on small-scale acquisition and stewardship. iNaturalist’s “projects” feature lets you find the active citizen-science survey closest to you on most of these landscapes; volunteering on a single survey day is a structurally meaningful contribution because most of the long-term monitoring is volunteer-collected.

The longer view

The Pacific Northwest is the place where modern old-growth ecology was invented. Franklin, Maser, Cromack, Spies, and Harmon walked these forests with tape measures and notebooks in the 1970s and 1980s, climbed the canopies on rope rigs they had to invent, weighed and measured the down logs, and produced the structural definitions the rest of the world’s old-growth science has used ever since^[3][4]. The Pacific Northwest is also the place where the cost of being wrong about old growth was demonstrated most concretely — the hundred-year industrial harvest of the early 20th century took most of the original old-growth volume, and the forest function that came back is meaningfully different from the forest function that was lost.

The remaining 5% is, in a real sense, the reference forest. It is the calibration sample for every other temperate-rainforest old-growth assessment on Earth. Its role in science alone — before any of the carbon, biodiversity, or watershed arguments — is enough to justify its protection. Whether that protection becomes durable in this generation is a political question, and political questions are answered by people showing up.