Ancient Trees Bear Witness

by Melissa Roy-Hart

Standing beside a grand old oak tree amidst rolling prairie, Ed Alverson can sense the history of Oregon’s Willamette Valley. He can reach out and touch it, too.

The Oregon white oak is a witness tree, one of two that Alverson, a Conservancy stewardship ecologist based in Eugene, recently identified. He was exploring two new land acquisitions supported by habitat mitigation grants from the Bonneville Power Administration.

A 152-acre conservation easement at Baskett Butte, adjacent to the Baskett Slough National Wildlife Refuge west of Salem — in combination with a 10-acre purchase at Willow Creek Preserve in West Eugene — will enable the Conservancy to further protect and restore key Willamette Valley oak and prairie habitats, one of Earth’s most imperiled ecosystems.

Witness trees were used as landmarks for government surveys in the mid 1850s, when the fertile valley was officially mapped out for homesteaders. Witness trees were blazed for identification purposes. Alverson found the scars somewhat healed over, but otherwise unchanged.

The Valley is a Different Story

Due to population growth, agriculture and development, the Willamette Valley has undergone dramatic changes in the past 160 years.

“The entire Willamette Valley was once dominated by prairie and oak savanna, but today less than 2% of those habitats remain,” Alverson said. “To me, these trees symbolize why this new acquisition is important since, unlike the rest of the valley, it’s still relatively intact. The family has taken great care over the years to keep the native oaks healthy.”

Both newly acquired properties provide and connect critical habitat for several endangered species including the Fender’s blue butterfly — found only in the Willamette Valley — and its host plant, the threatened Kincaid’s lupine. The hope, Alverson said, is that butterflies will use the habitat corridors to mix populations and diversify the species.

The Nature Conservancy is working with the U.S. Fish and Wildlife Service to manage the Baskett Butte acquisition in sync with strategies at the wildlife refuge. Restoration activities at both new sites will include invasive species management, thinning of encroaching trees and plantings of native vegetation including the lupine and other butterfly-friendly species.
“It will take time and a sustained effort to restore the native prairie and oak woodlands,” Alverson said. “But I believe we’ll get there. I hope these oak trees, if not me, are here to witness that.”

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