King County’s extensive forest lands, totaling more than 800,000 acres countywide, and urban tree canopy provide a wide range of economic, ecological, and cultural benefits. These forests and urban tree canopy regulate water quantity and quality, improve air quality, improve mental health, support recreational opportunities, and cool urban heat islands. County forests also provide renewable timber resources and have the capacity to sequester and store carbon, an ecosystem service critical to reducing climate change. For additional SCAP forest actions related to carbon sequestration, see the Forests and Agriculture Focus Area in the Reducing GHG Emissions section.
Retaining and expanding tree canopy and ensuring equitable access to green space has become increasingly important and challenging as development intensifies in the King County region. Equally important is ensuring that forests and urban tree canopy can remain healthy in the face of stressors like disease, drought, heat stress, and invasive species. Forest health treatments such as selective thinning, replanting to include a diversity of species, and removal of invasive species may be needed to restore forest health. Actions needed to help grow a more robust and healthier urban tree canopy include routine tree maintenance (e.g., pruning and trimming), proper siting and site conditions for planting, invasive weeds control, and adequate watering for new trees.
What's at stake
King County Parks has approximately 27,000 acres of forests that provide many regional benefits but also pose a significant management challenge given growing environmental stressors from climate change, drought, urban development, and increased fire risk. Prior to County ownership, most of the forests now managed by King County regenerated from clearcut harvests, leading to excessively dense or sparse stands, low species diversity, and/or minimal understory vegetation. These site conditions, if left unaddressed, leave County forests susceptible to insects, diseases, and extreme weather such as heat, drought, and windstorms.
Urban tree canopies are also facing increasingly challenging conditions. Between 1992 and 2016, forest cover in cities in King County declined from 23 percent to 18 percent (a loss of more than 10,000 acres) and from 37 percent to 29 percent in urban unincorporated areas (a loss of approximately 2,000 acres) as the area of developed land increased.26 High mortality rates among newly planted trees in urban environments are common due to hotter summer temperatures, poor planting conditions, and challenges with proper tree care as young trees are getting established. Established trees are also seeing increased stress and damage from heat, drought, insects, and disease.
A better outcome
King County envisions forests and green spaces that are protected, widespread, equitably distributed, healthy, and connected in ways that sustain habitat, clean air, cool waters and air temperatures, and natural streamflow. The county’s urban tree canopy is thriving and inequities in tree cover and green space, especially in urban heat islands and low-canopy neighborhoods, are eliminated. Investments in pursuit of this outcome are paired with strategies and policies to prevent displacing low-income residents.
What we've done to get here
- Developed the King County 30-Year Forest Plan (2021), a shared countywide vision for rural and urban forest cover and forest health. Includes priorities, goals, and strategies related to climate change and urban tree canopy.
- Committed to preparing 1,000 acres of forest (about 500,000 trees) to be more resilient in a changing climate with warmer, drier summers.
- Increased the amount of funding available for land conservation through a voter-approved reset to the Conservation Futures Tax levy (2022).
- Created the Urban Forestry Forum (2022) and hired an Urban Forestry Program Manager (2023) to foster collaboration on countywide urban forestry objectives.
- Incorporated forest resilience and urban tree canopy priorities into countywide strategies on wildfire risk reduction (2022) and extreme heat (2024).
26 King County Department of Natural Resources & Parks, “King County 30-Year Forest Plan,” 2021.