Saving the white oak

Biologists work to secure a keystone species’ future 

White oak trees—which provide the critical wood that ages Kentucky’s signature spirit—soar up to 100 feet tall, with a natural lifespan of centuries. These majestic trees play an outsize role in forest health and in industry, but when experts look to the future, they see warning signs. 

While there’s no shortage of white oaks in the near term, the trees are not regenerating quickly enough. According to the U.S. Forest Service, fewer than 1% of white oak seedlings live longer than five years. 

White oaks provide forest habitat, acorns that feed many wildlife species and hardwood for furniture, flooring and other construction needs. But perhaps most significantly for Kentucky, the state’s $9 billion bourbon industry depends on barrels made from white oak staves, which are responsible for up to 70% of the spirit’s flavor profile, according to University of Kentucky professor Jeffrey Stringer. 

Stringer, who chairs UK’s Department of Forestry and Natural Resources, says it typically takes 70 years for a tree to grow to cutting height. High demand for white oak, combined with the tree’s slow growth rate, raises concerns that forestry and industry experts are currently working to solve. 

As Alex Alvarez, formerly of Brown-Forman and now with Suntory Global Spirits, noted in a report by the White Oak Initiative, “We need to make sure we have oak to make barrels in the future and to keep the related ecosystem and supply infrastructure thriving.” 

The White Oak Initiative is an umbrella association of environmental, academic and governmental organizations that seeks to protect and develop the white oak species. One of its programs is the White Oak Genetics and Tree Improvement Initiative, housed in UK’s Department of Forestry and Natural Resources. 

The project began in 2019, when Stringer hired Laura DeWald as a tree improvement specialist, charged with creating a project to develop stronger and faster-growing white oak seedlings. 

A retired forestry professor from North Carolina, DeWald is a tree improvement expert who holds a doctorate in forestry and specializes in forest genetics. Under her leadership, the white oak project is breaking new ground. 

“Because white oak grows so slowly, there weren’t a lot of model tree improvement projects to go by,” DeWald says. 

The project’s goal is to find trees that produce superior offspring and use these trees to create seed orchards. Achieving that result will involve hundreds of volunteers and researchers, with production of these star seedlings for reforestation starting within the next 20 years. 

Laura DeWald speaks to guests during an event at the Kentucky Division of Forestry Morgan County Nursery. Photos: Steve Patton/ University of Kentucky 

Three-phase process

In the project’s first phase, volunteers collected acorns from beneath trees across the entire eastern United States, including from many Kentucky counties. The locations of these “mother trees” were carefully noted. Next, the acorns were planted at a nursery run by the Kentucky Division of Forestry. 

In the second phase, 1 1/2 years later, volunteers transplanted the seedlings into 23 test plots across the eastern U.S., including one at the Blue Grass Army Depot near Richmond, to assess them for superior performance. Seedlings planted in each of the different test plots were offspring only of mother trees considered adapted to the region of the test plot. 

“In 10 to 15 years we’ll make final decisions on which white oak mother trees produced superior offspring in the tests,” DeWald says. 

In the last phase of the project, the original mother trees that produced superior offspring in the test plots will be grafted to create seed orchards. Acorns from the seed orchards in Kentucky will be planted at the Kentucky Division of Forestry nursery to produce superior white oak seedlings for reforestation. 

DeWald points out the locations where white oak acorn collections originated. 

One more reason to develop strong white oaks: it could mitigate losses in the event of invasive insect damage. Invasive insects are not a problem right now, Stringer says, though scientists are keeping watch on the sponge moth. 

“White oak is pretty resilient,” he says. “It will hang in there, but a possible threat from an invasive insect could develop at any time, like the way the emerald ash borer damaged ash trees.” 

Stringer notes that farmers are an important part of white oak sustainability: “Fifty percent of our farms have viable woodlands. They provide over 25% of the wood harvested in the state.” 

While the supply of white oaks is adequate for industry needs now, research predicts challenges in the future. Given white oak’s slow growth rate, Stringer says foresters and industry stakeholders should plan ahead while taking immediate action. 

“Genetics plays just one part,” he says. “You can’t plant your way to sustainability. You have to manage forests well to have natural regeneration of trees.

Reforesting Appalachia

Another project affiliated with the White Oak Initiative is the Appalachian Regional Reforestation Initiative. It is operated by the Office of Surface Mining, Reclamation and Enforcement, part of the U.S. Department of the Interior. 

The ARRI program has been planting white oak and other tree seedlings on former mining land since 2004. Its two goals are to improve the air, water, and soil quality on barren mine sites and to provide jobs for unemployed veterans and coal miners.

Soil on former mining sites is so compacted that nothing desirable will grow there,Drouet explains, so workers use root rakes attached to bulldozers to yank out briars and other weeds. “Then we leave the brush to make habitats for deer, rabbits, turkey, and other wildlife,” he says.

“We’ve planted in eastern Kentucky the most, but this spring we planted 110 acres in western Kentucky, at a Kentucky National Guard training center in Muhlenberg County,” says Cliff Drouet, ARRI forester for Kentucky, eastern Ohio, southwest Virginia and eastern Tennessee.

“We plant 700 trees per acre, in 8-foot grids, so that was 77,000 trees,” Drouet explains. “We plant 250–300 White Oaks per acre. We mix them with red oak, black gum, American chestnut and wild plum for the wildlife and other species.”

Even within the state, Drouet says, he consults with local wildlife biologists and foresters for advice on what species will do best in each region. In western Kentucky, for example, he focuses on slightly different species than in eastern Kentucky.  

ARRI’s second planting this year was in Cumberland County, Tennessee, bordering Whitley County. The ARRI crew hand-planted 116,000 white oak and other tree seedlings onland now owned by The Nature Conservancy. 

ARRI plants tree seedlings from Kentucky Department of Forestry nurseries in the spring. Some sites are not inaccessible to the public, but Drouet tries to organize at least one planting each year that’s open to volunteers participating, usually tied to Earth Day or Arbor Day.