In the spring of 2008, volunteers planted 1,000 acorns in eastern Washington's Swauk Valley to try and restore a native oak woodland. Volunteers and researchers recently returned to the site to find out how those little oaks were doing.

An Experiment in Restoration

What does it take to restore a native oak woodland on the dry side of the Cascade Mountains? It turns out that oak restoration research has been done in the Puget Sound area and in the Willamette Valley of Oregon.

But oak woodlands on the east side of the mountains are much drier and support different wildlife. The Conservancy wanted to test methods explored on the wetter west side to see if they could help restore dry eastside oak woodlands, too.

Enter the University of Washington. The Conservancy, under the guidance of ecologist Jim Evans, combined its restoration experience and the power of its volunteer program with scientific expertise in ecology and experimental design. 

UW graduate student Laura Blume and forest ecologist John Bakker designed the restoration to ensure that the project produces information that will help anyone interested in restoring dry oak woodlands.

The researchers designed an experiment to test four different factors:

• Square, plastic weed barriers around the base of some seedlings to discourage other plants from crowding them.
• Tall, blue plastic shelter tubes to shelter some seedlings and prevent browsing by deer and other critters.
• Age of seedlings when planted, to see of 1-year-old oaks or 3-year-old oaks would fare better.
• Irrigation, meaning some seedlings would get extra water while others would get only what fell from the sky.

Some oak seedlings would get more than one of these treatments, while others would have to go it alone.

Getting Started, and Early Results

The owners of the Swauk Valley Ranch have been great supporters of and partners in restoration. The area around their property boasts the northernmost oak woodlands on the east side of the Cascades.

One field in particular—cleared many years ago for farming, and since abandoned—seemed a great site for this oak restoration experiment. The old farm field was cleared of non-native grasses and prepared for the new little oaks.

Then in March of 2008, after the experiment was designed, volunteers helped the researchers plant 1,000 oak seedlings according to the experimental design. Click here to read our pre-planting feature from Fall 2007.

Since the planting, researchers and volunteers have returned to check on the seedlings and see which ones are surviving. Early, unofficial results: More than 40 percent of the seedlings did not survive the first year. Those with plastic weed barriers fared better, and those that were irrigated fared well. The blue tube shelters didn't seem to make a meaningful difference. 

What's Next?

Conservancy and UW researchers will continue to visit the site with volunteers to monitor the success or failure of certain treatments and see how the young oaks are doing. Hopefully in time there will be a new, open oak woodland once again in the old field.

Beyond this one place, the Conservancy hopes that what it learns will help others restore valuable oak woodlands. Such restoration can help to knit together the pieces that remain. The researchers plan to publish a scientific paper about the role and effects of early planning conditions on dry oak woodland restoration in the coming year.

This work will hopefully inspire renewed interest in restoring Oregon white oak habitat throughout the Cascades for the wildlife values that it provides. As ecologist Evans says, "the objective of a project like this is never to get trees to survive for three to five years, but to get them to survive for 200 years."

Oak Woodlands For Wildlife

Oak woodlands are extremely rich in wildlife. Washington is known as the Evergreen State for its vast forests of straight-trunked conifers. But it turns out that stands of gnarled old oak trees provide even more food and shelter for critters.

As Nature Conservancy ecologist Jim Evans describes in a short oak restoration video, the acorns that oak trees produce are an essential source of food for wildlife, from insects to rodents to birds to elk. The cavities found in oak trees are very popular shelter. Research has shown that oak trees, when present, are used more than nearby conifers by many bird species.

Washington is home to only one native species of oak tree, the Oregon white oak. This species is the state's most drought-tolerant tree and can live to be more than 400 years old. They are native to both sides of the Cascade Mountains. They are found, for example, along the Columbia Gorge, at the Ridgefield National Wildlife Refuge, on the South Puget Sound Prairies, in the San Juan Islands, in Klickitat County and in the Tieton River Canyon.

Indigenous people have traditionally enjoyed a rich relationship with oak trees. Tribes who had acorns traded these prized foods with tribes who did not. More recently, settlers cleared many oak woodlands and turned them farm fields.

Watch our oak project video!

Check out our initial story - with photos - from Fall 2007.

Nature picture credits: All photos and video © Jeff Compton/TNC.