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Healthy Forests

From the top of towering Douglas-firs down to the leafy ferns in the understory, forests are an iconic symbol of our home here in King County. These forestlands are important for our everyday lives improving air and water quality, and providing places for us to hike, bike, ride a horse, or just sit and enjoy the view.

Over 29,000 acres of King County’s public forest lands are managed by King County Parks – Your Big Backyard. Of this acreage, roughly 3,800 acres are designated as working forests. These working forests provide many social and economic benefits for communities, including jobs and wood products, and provide sites for forestry education. King County Parks also owns conservation easements on 145,000 acres of public and private forest lands.


2019 Project Dashboard

During 2018 King County Parks will be implementing several forest stewardship projects at designed working forests locations. These forested lands once belonged to logging companies, meaning that the properties were logged 20, 30, 50 or more years ago and then not maintained for their ecological benefits. Now, it is up to King County to restore these forests and make sure they are healthy and resilient.

Some trails will be closed during operations and then opened again when the project has been completed. Trail closures and operation notices will be posted here.

Overview: King County Parks is planning to thin the forest on 75 acres at Ravensdale Retreat Natural Area starting as early as mid-July, followed by a planting of 800 trees this winter. Thinning the park this summer will allow sunlight to reach the new conifers and give them an opportunity to thrive in a multi-generational forest. For safety’s sake, the natural area will be closed to public access for up to five weeks while this work is in progress.

Questions? Contact Kelly Heintz, Natural Resource Land Planner. (206) 477-6478.


Overview: King County Parks is planning to selectively remove trees from a 10-acre portion of the 440-acre Island Center Forest, a working forest certified by Forest Stewardship Council® (license code FSC-C008225). Stay tuned for more details as plans are evolving. 

This work will build on previous projects in 2008 and 2014 to improve the health of portions of the forest that are crowded and overstocked with tall, skinny Douglas fir. Starting in January 2020, King County Parks will plant 2,000 conifers in Island Center Forest. 


Questions?  Contact David Kimmett, Natural Resource Land Planner (206) 477-4573


Overview: King County Parks is planning a selective thinning project on 70 acres of Sugarloaf Mountain Forest. This particular thinning project is a “drop-and-leave,” where thinned trees will be cut down and left on the ground as habitat features like downed logs or constructed into brush piles. Downed logs provide cavities and food for insects and are sources of nutrients from which other trees can grow. Brush piles serve as shelter for small mammals such as rabbits, chipmunks and foxes as well as a variety of birds, reptiles and amphibians. Thinning the dense alder forest also opens the tree canopy so sunlight will reach the 20,000 seedlings that will be planted in January 2020. Over time, this work will encourage a more diverse conifer-dominated forest.

Currently, there is no legal public access to Sugarloaf Mountain Forest although King County Parks has long-term plans to secure public access. 


Questions? Contact Daphne Payne, Natural Resource Land Planner, (206) 477-3391

Overview: Last winter, Parks planned to thin 136 acres at Taylor Mountain Forest prior to a spring planting of 50,000 trees. Due to wet soil conditions, the project was halted with 30 acres to go. This July, Parks plans to finish the thinning project on those last 30 acres. This work is expected to last up to three weeks. There will be some trail closures during this work. Taylor Mountain Forest is a working forest certified by Forest Stewardship Council® (license code FSC-C008225).


Taylor Mountain Forest Stewardship Project Trail Closure Map

Trails are expected to be closed for up to four weeks beginning the week of July 22, 2019.


Questions?  Contact Kelly Heintz, Natural Resource Land Planner or (206) 477-6478

During Operations - Exact operations will vary but often during forest thinning heavy machinery such as a feller-buncher will be used to cut logs which are then taken to a gathering area called a landing. Only designated paths will be used to transport logs from where they are cut to the landing, as this will reduce the impacts to the forest floor. Once the logs are transported to the landing they are cut to lengths mills will accept.

After Operation
s – Once the machinery leaves a diversity of tree species will be planted, and any damage to trails will be repaired. After operations have stopped the forest and ground may appear rough, with soil disturbances and open areas. While areas may look rough they will quickly begin growing with vegetation. In the years after the operations the forest’s vegetation and trees will grow quickly providing a diversity of habitat for wildlife.

Types of Stewardship Actions

Many county forests are the product of past management actions that were not necessarily designed to create natural old forest structure. In order to help return forests to a more natural condition, King County Parks uses a variety of forest stewardship practices that mimic natural events. By implementing these practices, King County Parks ensures diversity of not only trees, but the animals that call the forest home.

Developing Stewardship Plans: King County is developing and implementing stewardship plans for our forests. These plans describe how the forests will be managed and the appropriate recreational activities for each site. 

Ensuring Forest Health:
In some cases, King County will conduct forest management activities that mimic natural events like fires and wind storms. These actions, such as thinning, vary the density and spacing of trees and promote diverse species and ages.

To increase the diversity of tree species in a forest, a variable thinning practice may be implemented. Using this method, foresters select the type of trees that need to be cut and removed to: 

  • Allow remaining trees to grow 
  • Make space to plant different species

After trees are removed, the area is replanted with a diverse array of tree species that results in a forest that has a mix of young and old trees. 

There are two main types of variable forest management: 

1. Variable Density - 
In a variable density thinning, the trees are removed in a mixed manner, leaving large and small trees and retaining under-represented species to maintain biodiversity. 

2. Variable Retention - 
This practice mimics tree mortality that results from natural disturbances such as wind storms or fires much like old growth forests. In a variable retention harvest, trees are removed in patterns that create small to large gaps (up to 5 acres in King County forests) and intentionally leave groups and scattered standing live and dead trees. 

Many of King County Parks’ forests were logged heavily and then neglected, allowing for red alder trees to dominate the landscape. Red alder is a pioneer tree species that quickly adapts to disturbed sites following fires, windstorms and large cut over areas known as clearcuts. To increase biodiversity and improve habitat, a red alder forest management practice can be implemented.

Using the variable retention technique, foresters create gaps in the canopy by removing most red alder in some areas, while retaining some alder and most or all conifers elsewhere. A variety of conifers such as Douglas-fir, western red cedar, grand fir, Sitka spruce and western white pine are planted in the open spaces that are created following tree removal. 

Red alder conversions provide the following benefits:

  • Improved habitat - By planting a variety of native conifer species while retaining red alder patches, the forest will eventually develop multiple canopy layers and more variable spaces that provide diverse wildlife habitat.
  • More resistant forests - With more native conifers, forests become more bio-diverse. Research shows a more diverse forest is more resistant to disturbances such as insect attacks and disease, and is also better able to recover from such events. Diverse forests with a variety of tree species and ages are also more resilient to site conditions impacted by changes in climate.

A common tree disease in King County known as root rot is a fungus that destroys the roots of Douglas-fir, true firs, and western hemlock. The rot typically spreads via root contact in a circular direction, infecting the roots of surrounding healthy trees.

To prevent the disease from spreading, affected trees can be cut down around the center of the rot. The area is then replanted with trees (often western redcedar, white pine or broadleaf trees) that are not affected. In some cases, the affected trees are cut and left on the ground to return valuable nutrients to the soil.