A serene, wooded area just north of Black Diamond is now closed to the public and will remain off-limits until perhaps late August.

King County Parks is thinning 75 acres of previously-logged land within Ravensdale Retreat Natural Area. The process aims to allow more sunlight to reach the forest floor, resulting in diverse undergrowth while helping the remaining trees to grow larger.

Work began July 22 with the expectation the thinning project will take five weeks to complete.

The area includes a trail system that is used regularly by walkers and those on horseback. Trails extend from Ravensdale Way and Ravensdale Park on the west side to Kent-Kangley Road on the east.

Members of Backcountry Horsemen and Friends of Rock Creek Valley are key partners at the site, helping to maintain the trails and to control invasive species.

This winter, when the weather is cool and wet, Parks will plant 800 seedlings in the newly-thinned area. The seedlings will diversify the age and species mix in the forest, helping the ecosystem be more resilient to threats.

In all, the Ravensdale Retreat Natural Area covers 145 acres in the Rock Creek Valley, approximately two miles north of Black Diamond and a mile east of Maple Valley.

Most of the site is upland, supporting a coniferous forest that was replanted following harvests during the 1980s, with small meadow patches. The area also supports a two-acre pond/wetland complex and Rock Creek flows through the site.