Maintaining Forest Health on Cougar Mountain
Written by Svetoslav Semov, attendee of our Forest Stewardship hike with Senior Forester Paul Fischer
Cougar Mountain's forests have changed significantly since the early 1800s when they primarily consisted of coniferous tree species like Douglas fir, hemlock, and western red cedar. The landscape transformed with Seattle's rise as a logging city and the burgeoning demand for coal driven by industrialization.
Today, areas around De Leo Wall and Wilderness Peak still feature a high density of conifers. However, red alder dominates large portions of Cougar Mountain, particularly in the northwest and middle regions, as it's the first species to spring up in disturbed areas.
Red Alder near Cave Hole/Quarry Trail, Fall 2022 (photo courtesy of Svet S.)
Diverse forests, both in composition and structure, are more resilient to climate change and crucial for maintaining biodiversity — both pressing concerns given current environmental trends.
To gain a comprehensive understanding of Cougar Mountain's forest health, King County Park’s Forest Stewardship Program has employed lidar technology. Lidar creates 3D images of tree and vegetation structures, enabling unprecedented scale in forest health studies. Prior methods involved small-scale field studies whose results researchers would extrapolate to larger areas. Lidar now enables a new breed of studies designed to understand the impact of various forest restoration treatments by looking at difference-in-differences comparisons between treated and control areas.
King County Parks' Forest Stewardship Program aims to enhance forest health and resilience to climate change. They have conducted gap treatments on Cougar Mountain, a restoration treatment involving the removal of red alders and the planting of conifers. To date, the program has completed projects on seven sites, covering 11 acres.
Managing 29,000 acres of public forest lands—about 3.5% of all forest land in King County—the Forest Stewardship Program is considering scaling up its treatments. Cougar Mountain Regional Wildland Park accounts for roughly 3,000 acres or 10% of the program’s area.
Senior forester Paul Fischer shows Board President Anne Newcomb a tree (photo courtesy of Kelly J.)
Cougar Mountain's story is part of a larger narrative of Pacific Northwest forest transformation over centuries. Once, old-growth conifer forests covered two-thirds of the Pacific Northwest; now, an estimated 72% has been lost. Yet there is hope for positive change.
The efforts of King County Parks’ Forest Stewardship could help restore Cougar Mountain’s original species composition over the coming centuries. This ambitious goal can benefit from community participation. IATC is exploring a partnership with King County to offer volunteer opportunities. Planting conifers successfully is a multi-year effort, complicated by Washington’s wet climate, which intensifies competition from neighboring vegetation. These young conifers need our regular help to grow and thrive. Keep an eye out for ways to get involved.