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Westlake Oak Woodland: Protecting a Vanishing Habitat

The Westlake neighborhood, which was created in the 1980s, is graced with mature oak trees in private yards and green spaces. Many of the homes in the neighborhood back up to the wooded open space, which was left undeveloped when the houses were built in order to provide privacy and proximity to nature.

The green space is designated for wildlife habitat, and it is owned and managed by the Westlake Homeowners Association (HOA).

Until recently, the management consisted only of regular arborist inspections of trees on the edges of the property to cut branches or sometimes whole trees that were in poor health and in danger of falling on houses.


Want to get involved?

To be added to the Friends of the Westlake Oak Woodlands email list,  email Tom at and express your interest! And, check out the Oswego Lake Watershed Council Event Page to see all scheduled events and sign up. We hope to see you at our next volunteer event!

In 2017, the HOA board recognized that the woodland dominated by mature Oregon white oaks is a remnant of a vanishing habitat type and that it was becoming overrun by invasive species. Before white settlement, Native American tribes often set fires to make oak woodlands more conducive to hunting and gathering acorns and camas roots. The fires also had the effect of preventing other species, especially Douglas fir, from outcompeting the oaks. When settlers arrived, the burning ended and most oak woodlands were either cleared for farmland or overtaken by Doug firs, whose shade kills mature oaks and prevents oak seedlings from growing. Statewide, the remaining oak woodlands are less than 5 percent of their range 200 years ago.

The HOA board commissioned a study of the 17-acre woodland, which determined that its continued health is threatened by invasive plants including ivy, hawthorn, blackberry, holly, and cherry, as well as competition from native ashes, maples, and Doug firs. The board contacted the Oswego Lake Watershed Council (OLWC), which applied to the city of Lake Oswego for grants to restore the land. Two City grants were awarded, one to remove invasive species and the other to thin native trees that compete with the oaks. That work began in Fall 2018 and will continue for three more years. Clackamas Soil and Water Conservation District also funds OLWC for a wide variety of activities, including community outreach & education, and provides technical guidance on this project. The HOA also contributed funds toward the work and has committed to maintaining the woodland once it is restored.
Thus far, the hawthorn and holly trees have been removed, and ivy that is climbing trees has been cut at the base so it will die above. Ivy and blackberries are being sprayed or removed by hand. An inventory of the trees is being compiled, and an arborist will determine which of the ash, maple, and Doug fir trees need to be cut. Trees that fall in the woodland are left to decompose, becoming nurse trees and nourishing the soil. When trees have been cut because they are hazards, the bottom 20 feet or so is usually left standing to become dead snags that provide shelter and food for wildlife. Likewise, some of the non-native trees will be girdled and left standing to provide places for birds and squirrels to nest. As the snags decay, woodpeckers mine the wood for insects. The restoration work will be coordinated with fire authorities to ensure that the downed wood does not present an unacceptable fire hazard, and chipping may be used to reduce flammability.

In order to expand community involvement in this project, a group called Friends of the Westlake Oak Woodlands has been formed. The members meet with Oswego Lake Watershed Council on the third Saturday of each month to clear ivy around native plants so the natives are not harmed when the ivy is sprayed. Volunteers also have cut the ivy around the base of the trees and will help with planting of native shrubs as the project proceeds. Neighborhood residents are encouraged to join the group to share the satisfaction of restoring the woodland.

When the project is complete, the woodland will be ecologically healthier with a diversity of native understory plants that provide habitat and food throughout the year for birds. The woodlands are home to a pair of red-tailed hawks as well as many white-breasted nuthatches, which are associated with oak woodlands. At night, owls can be heard in the neighborhood, and occasionally a deer is sighted. The woodland allows Westlake residents to enjoy living with nature and to help preserve an important habitat in Oregon.