King County has earned the highest level of green certification possible for the way it’s managing Island Center Forest, a 363-acre expanse that shelters the headwaters of Vashon’s largest salmon-bearing stream and provides miles of recreational trails.

The Forest Stewardship Council (FSC), the nation’s most demanding forest-certification program, has labeled the publicly owned landscape a sustainably managed forest. The certification means trees harvested from the forest can carry the FSC label, a voluntary, market-based system similar to organic certification for farmers or food processors.

The county worked closely with Friends of Island Center Forest, a community-based group, to prove to the FSC that the forest is being managed sustainably, county officials said.

“It’s a great honor to receive this certification,” Theresa Jennings, director of King County’s Department of Natural Resources and Parks, said in a news release. “Sound stewardship of county land is our top mission, and our partnership with the Friends of Island Center Forest helps ensure continued proper management of this tremendous land.”

Kristi McClelland, a King County forester, said the certification is important because it provides objective evidence that the county and its partners are using ecologically sound practices to manage the much-loved Vashon forest.

“To have any forest certified … helps demonstrate to a perhaps skeptical public that you really are open to having a third-party review your standards and methods and verify them,” she said.

Derek Churchill, an Islander who works with Vashon Forest Stewards and who wrote the management plan for Island Center Forest, agreed.

“This is an independent, outside body that comes in and looks at all aspects of the management,” he said. The certification, he added, “is several shades greener than the state forestry rules.”

Island Center Forest stretches from Cemetery Road to Bank Road and from the Westside Highway to 107th Ave. S.W. Once owned by the state Department of Natural Resources, which heavily logged it, the expanse of forest is now a popular recreation site laced by a maze of trails; cyclists, dog-walkers, horseback riders and even hunters often use the nine miles of trail that wend through the woods.

The expanse is also ecologically important. More than 70 bird species have been found in the forest, which also provides the headwaters to Judd Creek, Vashon’s largest watershed. Two ponds — Mukai and Meadowlake — shelter a number of amphibians.

According to the forest’s lengthy management plan, crafted in 2006 by the county and Friends of Island Center Forest, the landscape is to be managed with an eye toward its ecological restoration. Over the past three years, high school students and others have worked with Vashon Forest Stewards to replant native conifers, remove invasive species and build or repair trails.

At the same time, according to the management plan, commercial thinning and small-scale tree harvests are to be undertaken “to generate revenue and high-quality logs for local processing.”

David Warren, who heads Vashon Forest Stewards, said he was pleased by the certification. It required virtually no change to the management plan and won’t affect the kind of logging that’s slated to take place in the forest. But it will help in marketing the forest’s wood products, he said. The FSC label, he added, “is the guarantee that (the logging) was done right.”

While the county owns and manages six working forest sites totaling more than 3,200 acres, Island Center Forest is the first county land to achieve certification, McClelland said. The county plans to view the Vashon forest and its certification as a pilot project to see if the costs of certification — it requires a considerable amount of paperwork and other administrative effort — is worth the increased value of the wood products that come off of the land, she said.

“The presumption behind certification is that you’re going to have value added to your product,” she said. “We’ll need to see if this really changes the interface with a broader public and, if that’s the case, whether it offsets the costs.”