Melissa Lucash and James Lamping stood in Alaska and saw a problem: vast tracts of old-growth forest stretching across the continent, yet no one really knew how much existed, where it all was, or how well it was actually protected. Now, after years of painstaking work, researchers at the University of Oregon have created the first comprehensive maps that reveal the true landscape of these ancient forests across Alaska and British Columbia—and the findings are unsettling.
Old-growth forests are among the planet's most vital ecosystems. They anchor biodiversity, lock away massive amounts of carbon, sustain Indigenous cultures, and generate economic value for communities. Yet in Alaska and British Columbia, these irreplaceable landscapes had never been reliably mapped. Different agencies applied different definitions, borders sliced through continuous forests, and global maps lacked the precision needed for real decision-making. The stakes are enormous: more than 40% of the region's mature and old-growth forests lack permanent legislative protection, and those unprotected forests happen to store the most carbon in the entire study area.
The study, recently published in the journal Ecosystems, was led by James Lamping, who began with forest inventory plots containing ground-truth data about tree species, vegetation, and forest structure. He then linked those measurements to satellite imagery, climate variables, and topographic data, creating a consistent framework that spans both Alaska and British Columbia without letting national borders distort the picture. The result is a set of detailed maps showing forest composition, carbon storage, and the percentage of mature or old-growth across the region.
The numbers reveal a troubling vulnerability. In Alaska alone, the researchers found 3,720 square kilometers of old-growth forests in Inventoried Roadless Areas—compared to just 1,560 square kilometers in national monuments and 730 square kilometers in national parks. Those Inventoried Roadless Areas sound protected. For more than 20 years, the 2001 Roadless Area Conservation Rule has prohibited road construction and timber harvests there. But here's the catch: these areas lack the permanent legislative protections that come with national park or wilderness designation. Instead, they're governed by federal administration—meaning that changes in political priorities can alter protections without Congress ever weighing in.
"One of the biggest takeaways from our research is that the highest amount of old-growth forests are in Inventoried Roadless Areas, which happen to be the most vulnerable to changes in the policies that govern these forests," said Melissa Lucash, the study's co-author and a geographer at the University of Oregon.
The researchers deliberately stopped short of prescribing policy solutions. Instead, they've provided something equally valuable: a precise, consistent picture of where old-growth forests exist, what they contain, and how they're currently classified. In the Pacific Northwest—Oregon, Washington, and Northern California—similar data has been used to inform the Northwest Forest Plan, which guides land use and management on federal lands. Alaska and British Columbia now have that same tool.
The mapping effort has laid bare a fundamental asymmetry: the forests most critical for carbon storage and biodiversity are also the ones most vulnerable to administrative whim. What happens next is up to the policymakers who will use these maps. But at least now they're looking at the full picture.