Preserving Oregon’s Ash Trees


Department of Forestry is collecting ash seeds across Oregon

An unprecedented effort is underway by the Oregon Department of Forestry in conjunction with the USDA Forest Service’s Dorena Genetics Resource Center to preserve the genetic diversity of the Oregon ash tree before it’s lost to ash-killing insects.

“Emerald ash borer is an invasive insect from Asia that has been spreading across the U.S. since it was first detected in Michigan in 2002,” said ODF Forest Entomologist Christine Buhl, who appears in the video. “Millions of ash trees have been killed by this pest, which has reached as far west as Colorado. All species of North American ash trees are at risk, including Oregon’s lone ash species (Fraxinus latifolia).”

ODF Invasive Species Specialist Wyatt Williams has been managing the federal grant that has funded the work to save the Oregon ash tree.

Williams said infested areas in the eastern U.S. have seen 95 percent or more of their ash trees wiped out within 10 years. “Foresters in the rest of the country did not have time to gather up genetic material from their native ash trees before they were wiped out.

“We don’t know if or when emerald ash borer will arrive in Oregon. It could be 10 years from now or it could be tomorrow,” said Williams. “We are fortunate to have had more time to plan how to preserve the genetic diversity of our native ash tree before it disappears.”

Although of only minor commercial importance, mainly for firewood, Williams said Oregon ash is important to forest ecology. “Oregon ash is one of the few large trees in the state that grows well in flood plains of western and southern Oregon. Oregon ash can grow to 75’ and live up to 250 years. Shade from the trees keeps streams cool for fish and their roots slow erosion of streambanks.”

Williams says that birds, insects and small mammals eat the winged seeds, while deer and elk browse the foliage. The leaves are also food for the larvae of three types of swallowtail butterflies.

Because of that ecological importance, Williams said ODF and a few volunteers have worked since 2019 to gather seeds from everywhere in the state that Oregon ash grows. The seed is sent to Dorena Genetics Resource Center in Cottage Grove, as well as long-term seed banks in Fort Collins, Colorado and Ames, Iowa.

Richard Sniezko, PhD, is a USDA Forest Service research geneticist at Dorena. “One goal is to send seed to federal research stations in the east. They’ll be planted there to see if any might be resistant to emerald ash borer. If there are, then we can gather more seed from those populations and begin propagating those resistant trees for reforestation efforts in wetlands where Oregon ash dominates.”

Sniezko says the bulk of the seeds will be frozen for long-term storage. “If in the future we find a way to control emerald ash borer, we could then reintroduce Oregon ash with most of its genetic legacy intact. But even if the emerald ash borer settles in forever, the seeds we saved with their diverse traits could be crossbred with any resistant trees to avoid inbreeding and keep the tree’s gene pool healthy.”

Despite being widespread, Oregon ash has been little studied, according to Williams. “We know more about many trees in the Amazon than we do about Oregon ash,” said Williams. “It’s important not to lose the genetic base for the species before we even know much about it. This project is already helping us learn more, for example, what percent of seed is normally viable.”

Williams said one way people can help Oregon ash is by delaying the arrival of emerald ash borer to the West Coast. “The insect is usually spread by people moving firewood from infested areas to non-infested places. So buy firewood in the same area you intend to burn – don’t haul it long distances.”

Learn more about Oregon’s plan for emerald ash borer here:

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About Author

Jim Gersbach is a Public Affairs Specialist at Oregon Department of Forestry.

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