Selective thinning at King County’s Black Diamond Open Space

Crowded former timber plantation forestland now managed by King County Parks for recreational use and fish and wildlife habitat is about to get some much-needed work to improve forest health.

The following is a press release from King County.

To build a healthier forest, King County Parks has developed a plan to selectively thin overcrowded Douglas fir trees growing on former industrial timberlands now managed as Henry’s Ridge Open Space and Ravensdale Retreat Natural Area, both north of Black Diamond.

The forest thinning will be done by Anderson Logging Company and is expected to last about six weeks beginning in mid- to late August. To protect public safety, trails will be closed in this portion of the open space during the work.

In its current condition, the forest is overcrowded with the same types of trees, making the landscape susceptible to widespread disease including root rot. This dense former plantation provides little desirable wildlife habitat.

Thinning trees allows more sunlight to reach the forest floor and means standing trees can grow broader, resulting in a healthier forest that is more resilient to disease, pests and wildfire.

Trails affected by the tree thinning operation will be rebuilt once the work has been completed. All revenue generated from the sale of the logs will fund ongoing management of this and other King County-owned forestlands.

This winter, a number of tree species will be planted in several of the newly opened areas to improve the diversity of the forest. Example species include western red cedar, western white pine and western hemlock.

Improving forest health is an essential component of Executive Dow Constantine’s One Million Trees campaign, which seeks to improve rural and urban communities through tree plantings and sound forest stewardship.

More information about the tree-thinning work is available by contacting Kelly Heintz, project manager,