Legacy Forest?
and why are they so important?
What Are
Legacy Forests are structurally complex, mature, natural forests on the verge of becoming old growth, often containing rare old-growth remnants. These forests store more carbon per acre than any other forest type, almost twice as much as tropical rainforests.
Many were logged prior to 1945 before the widespread industrial practices of clearcutting, herbicide use, and conversion of ancient-biodiverse-native-forests into monocrop tree farms.
Legacy Forests are critical for biodiversity, water quality, watershed health, and salmon habitat. They store and sequester vast amounts of carbon, mitigate flood and drought, purify water, provide habitat for at-risk species, and are highly resistant to wildfire, windthrow, and disease.
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To classify as a Legacy Forest, these forests generally have the following characteristics:​
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Pre-1945 origin
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Un-planted, naturally regenerated
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Structurally complex (different stages of life cycle)
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Genetically & biologically diverse
With so little natural forest remaining, Legacy Forests are biological legacies that also hold important spiritual and cultural value.
If protected, Legacy Forests will soon become the Old Growth of our Future!
Where Are Legacy Forests?
Legacy forests are located throughout Western Washington. Some examples of legacy forests in WA include parts of Capitol State Forest and the Elwha Watershed, as well as many other forests in these lowland areas.
These forests are home to a wide variety of plant and animal species, and they play an important role in protecting the region's climate, water supply, and air quality. Importantly, many of the unprotected legacy forests reside within critical watersheds.
Protecting and conserving these forests is crucial for maintaining the health and well-being of both the ecosystem and the communities that depend on them.
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The Many Reasons WHY Legacy Forests are so Important
Salmon Recovery
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Old-growth and mature forests are vital for salmon survival. Their intact canopies and soils regulate stream temperature and flow, maintaining the cool, clean water salmon require. Clearcutting and plantation forestry disrupt these systems—warming streams, increasing sediment, and altering hydrology.
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Without deep root systems, clearcut soils erode easily. Compaction from plantation machinery further accelerates sediment runoff. The resulting erosion and sedimentation smother salmon redds (nests), reduce oxygen to eggs, and fill rearing pools, degrading critical habitat and food sources.
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Protecting older forests is critical to effective salmon recovery and long-term watershed resilience.
Biodiversity
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Legacy forests preserve the ancient genetic diversity unique to this bioregion—diversity that underpins ecosystem stability and resilience. Most primary forests have already been converted to industrial monocultures dominated by Douglas fir, eliminating structural and species diversity.
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Industrial logging further erodes biodiversity through clearcutting and the use of herbicides that suppress all vegetation except commercial species. This simplification of ecosystems reduces habitat complexity, disrupts ecological interactions, and weakens natural resilience to climate stress.
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With regional biodiversity already critically diminished, conserving remaining legacy forests is essential to maintaining ecological integrity and life-supporting processes across the biosphere.
Carbon Storage and Sequestration
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Washington’s state forests contain 77,000 acres of older, carbon-dense forest—some of the planet’s most effective natural climate tools. These mature conifer forests store nearly twice as much carbon per acre as tropical rainforests.
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Claims that young plantations are better for the climate confuse carbon sequestration rate with total carbon stored. While younger trees sequester carbon faster, older trees store more volume due to their larger mass—like choosing 50% of $5 versus 20% of $100.
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Industrial plantations are managed on 30–40-year rotations, yet Douglas fir live 500–1,000 years. Harvesting at 30–40 years removes them centuries before peak carbon storage.
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Studies show that after clearcutting, a forest stand is a net carbon emitter for 10–20 years.
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Timber industry analyses often ignore carbon released from soil, decaying leftover wood, and emissions from harvesting, road-building, transport machinery, and cargo ships—sources that together produce over five times more carbon than all wildfires combined.
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Science unequivocally shows intact, older forests are far superior for long-term carbon storage, fire resilience, and watershed stability.
Watershed Health & Hydrologic Maturity
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In Western Washington, most original Douglas-fir forests have been clear-cut and replaced with uniform monoculture plantations—biologically closer to a cornfield than a forest. Pristine mature and old-growth stands now cover only a fraction of their former extent.
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Older, diverse forests are hydrologically mature. Acting as a giant sponge, the hydrological system of older forests efficiently stores large volumes of water to mitigate flood and drought.
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In peak summer drought, water can continue to seep from older forests’ sponge-like soils, downed logs, and epiphytes, providing late summer streamflows critical to salmon survival and watershed health. In winter, these structurally complex forests absorb large volumes of heavy rainfall, significantly reducing flood risk.
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In contrast, plantations retain far less water, increasing wildfire risk and degrading water supply. Plantation soils are compacted, hydrologically degraded, and unable to absorb heavy rains, significantly increasing surface runoff, flood hazards, and landslide risks as seen in heavy logged rural areas of BC and Washington during severe rain events.
Legacy Forest -
Dense Plantation -
Wildfire Resilience
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Older, structurally complex forests—also called legacy forests—are highly resilient to wildfire due to their stable ecosystems, species diversity, and hydrological capacity. These forests act as giant sponges, retaining water even during drought, and feature large trees with thick, insulated bark, which reduces fire severity.
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In contrast, young, densely planted monocultures burn hotter and faster.
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Maintaining intact older forests preserves ecological functions and helps protect communities from wildfire. Fire mitigation efforts should focus on poorly managed, overstocked plantations rather than mature, structurally complex forests.
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The timber industry is using fear of fire to justify backcountry logging, but such logging is ineffective at protecting communities. Creating defensible space near homes, home hardening, and emergency preparedness are far more effective strategies for safeguarding homes from wildfires.
Microclimate & Evapotranspiration Efficiency
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Older forests create their microclimate through evapotranspiration and the shade provided by their canopy. Even in the height of summer, forest interiors remain cool, whereas clearcuts lack shade and functional plant life. The resulting dry, noxious weeds and slash debris in clearcuts also create a significant fire hazard compared to the lush, moist conditions of older forests.
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Forested canopies retain moisture and reduce temperatures dramatically. On a hot summer day, areas in contiguous older forests can be 20–40°F cooler than nearby exposed areas, such as clearcuts and parking lots.
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Young plantations have inefficient evapotranspiration rates due to rapid growth and high leaf area index—they are up to six times less efficient with water than older forests. This inefficiency can exacerbate drought, create drier conditions, and increase fire susceptibility, highlighting the ecological value of mature, structurally complex forests.
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Industrial clearcut logging and plantations reduce summer low-flows by 50%, yet forest practice rules regulate only water quality and peak flows, not minimum summer flows, which is catastrophic to the health of salmon and watersheds.
Structural Complexity
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A common misconception is that older trees are of little ecological value because they are nearing the end of their life. In reality, these forests rely on standing and downed deadwood to sustain their ecosystems. Downed logs and decaying wood contribute to habitat complexity, nutrient cycling, carbon storage, and water retention. The accumulation of organic material on the forest floor enhances soil moisture, which contributes to the fire resilience of mature, structurally complex forests.
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By contrast, most contemporary industrial plantations lack these features, resulting in simplified ecosystems with reduced biodiversity, lower water retention, and increased fire susceptibility.
Windbreaks & Disease Resilience
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Fires spread faster under high wind conditions, but older, intact forests act as natural windbreaks, reducing wind velocity and slowing fire propagation. Clear-cut logging removes canopy cover, leaving dry debris and flammable grasses exposed, which allows fires to spread farther and faster. Clearcuts also increase the risk of blowdown to remaining large old-growth trees, as intact forests normally buffer these trees from severe wind events.
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Older forests are additionally more resilient to disease due to their high genetic and species diversity. In contrast, monoculture plantations are far more susceptible to disease outbreaks because of their uniform genetic composition.
