by Carol Lea Spence

A squirrel with a hankering for adventure could travel from Maine to Mississippi in the canopy of chestnut trees and never touch the ground. Or so says one of the many legends surrounding the American chestnut tree. Perhaps it was true once, but it is no longer. Felled by the one-two punch of blight and root rot, the loss of the “redwood of the East” vividly illustrates how treasured parts of the natural world can be gone in a cosmic nanosecond.

A young American chestnut stands in the Berea Forest.

An American chestnut stands in the Berea Forest. Photo by Matt Barton

Once the dominant tree in the hardwood forests of the eastern United States, rising to 100 feet and numbering in the billions, the tale of the American chestnut's tragic, swift decline and the human fight to bring it back from ecological extinction is one of science, volunteerism, and determination.

To do something that has never been done before, to bring a species back from oblivion, is the result of research and teamwork by partners who want to restore the tree to its nearly mythic glory. In Kentucky, the University of Kentucky Department of Forestry and Natural Resources partners with the U.S. Department of Agriculture's Forest Service Southern Research Station and the Kentucky Division of Forestry under the umbrella of the Forest Health Research and Education Center. They, in turn, collaborate with the nonprofit organization, The American Chestnut Foundation. Even the Catholic Church is involved, spreading blessings and education about the importance of stewardship.

Burrs and chestnuts
Photo by Tom Barnes

The heart of the American chestnut's range is the Appalachian Mountains. In some areas, they composed 25 percent of the forest cover. On the ridgetops, they could be as much as 70 or 80 percent. Old timers reminisce about how the mountain peaks looked like they were covered in snow in June and July when the trees were in bloom. Known as the cradle-to-grave species, chestnuts were intrinsically wrapped into the area's culture. Cribs, homes, and coffins were built from its rot-resistant wood. It showed up in musical instruments. Its fruit fed both humans and wildlife and provided much-needed cash when locals would gather the nuts to sell during the Christmas season. Hogs, set out to roam free in the woods, would quite literally pig out on the sweet nuts, resulting in a sweeter meat come slaughter time.

Then the blight hit.

A Tale of Two Pathogens

The fungus Cryphonectria parasitica, introduced from Asia and first noticed in New York City in1904, swept through the range like wildfire. By the 1950s, the American chestnut was, for all intents and purposes, gone.

The fungus wraps itself around the trunk, cutting off the tree's circulatory system. Nutrients can't make it up, and carbohydrates can't make it down to the roots. The tree dies above the fungus line.

Chestnuts are prolific sprouters, so new sprouts will grow from the old root system. That may sound like good news, but the blight is still in the forest, waiting to pounce.

“We have stumps we think are 300 years old that are still pushing up these shoots, but they never make it to a mature tree,” said Christopher Barton, UK professor in Forestry and Natural Resources and president of Green Forests Work, a nonprofit organization that converts reclaimed mine sites into healthy forests.

The blight isn't the tree's only problem. Lying in the soil is another Asian fungus invader, Phytophthora cinnamomi, also known as ink stain disease. By inhibiting water uptake from the roots, this fungus kills the entire tree. There's no coming back from the dead if the Phytophthora root rot attacks.

“We have the blight, which started in the North and moved south, and at the same time there were issues going on with root rot in chestnuts in the South. It was weakening those trees, and when the blight hit, it was like a double whammy,” Barton said. “We don't know if it was a combination of the two that made it so devasting, but certainly in our restoration efforts, ink stain disease is just as much of an issue as the blight, because it's prevalent in all of our forests, especially here in Kentucky.”

Restoring a Forest Blessing

A song rose up from the group of people standing with Barton on the Paul Van Booven Wildlife Management Area in Powell County last summer. It was part of a blessing ceremony for four American chestnut seedlings led by Father John Rausch, a Catholic priest and environmental activist from Stanton.

“I'm just trying to help people open their eyes to the gift that this is,” he said.

This landscape, which once gave up its forest for the black energy below, seems like a hostile environment to plant a tree, so a blessing might be in order. Covered with stilted shrubs, grasses, and a few hopeful saplings, a lonely neglect seems to rise up from the old mining site. But the range of the Appalachian coalfield and the American chestnut overlap almost perfectly, and Barton has plans to restore the area with American chestnuts and other native species.

“The mine lands are actually a really good springboard for putting this species back in its natural range,” Barton said. “When you try to restore a species like this, you can't just go out to the forest and put some trees in the ground, because they're not going to have the right light conditions. These mine lands are sitting there usually in an open, grassland state.”

Graphic of a map with legend "The heart of the American chestnut's range corresponds with the Appalachian Mountain coalfields."
The heart of the American chestnut's range corresponds with the Appalachian Mountain coalfields.

Knowing that the soil's fungus and bacteria were hauled away with mine debris or buried under tons of rock, Barton figured planting chestnuts on the mines would allow the trees to get established and grow resilient before the root rot fungus eventually re-invades these sites.

So far, Barton, fellow chestnut enthusiast Michael French, countless volunteers up and down the region, and The American Chestnut Foundation have planted more than 50,000 American chestnuts on old mine sites in Appalachia. Because there are so many of these big mine lands across the region, they're creating islands of seed the team hopes will eventually spread out to repopulate the entire range.

“We started what we called Operation Springboard through the Appalachian Regional Reforestation Initiative,” said French, director of operations of Green Forests Work.

CAFE alumnus Patrick Angel, from ARRI in the Office of Surface Mining Reclamation and Enforcement, stands with a 7-year-old American chestnut.

CAFE alumnus Patrick Angel, from ARRI in the Office of Surface Mining Reclamation and
Enforcement, stands with a 7-year-old American chestnut. Photo provided by Michael French.

ARRI is an initiative of the Office of Surface Mining Reclamation and Enforcement. Its mission is to find solutions to growing trees on compacted mine sites. ARRI works with environmental groups, state regulatory agencies, and researchers at a number of universities including UK. They came up with the Forestry Reclamation Approach, which is basically a list of five steps for leaving the mine sites hospitable for reforestation. But there are still between 500,000 and 1 million acres on older reclaimed mine lands.

There, trees fight a losing battle with the severe soil compaction that used to be the standard reclamation practice. That's why Green Forests Work was created in 2009. Green Forests Work is a nonprofit that closely works with UK—in fact, it is housed within the Department of Forestry and Natural Resources. To date, they have supported tree planting initiatives in 10 states, contracting with herbicide applicators to take care of the invasive species on the sites and bringing in large bulldozers to break up the soil compaction by cross-ripping the ground. And while these sites are planted with a variety of tree species, Operation Springboard made sure blight-resistant American chestnuts were part of the mix.

Back from the Dead

The U.S. Department of Agriculture began a breeding program in the 1930s, crossing American chestnuts with their more blight-resistant Chinese cousins. From those half-American, half-Chinese offspring, they got a half-level of disease resistance. But crossing that generation with another Chinese chestnut to get better disease resistance, they ended up with more of the Chinese form, a smaller, crooked tree that was not timber worthy.

Father John Rausch, in green, blesses American chestnut seedlings before they are planted.

Father John Rausch, in green, blesses American chestnut seedlings before they are planted. Photo by Matt Barton

The American Chestnut Foundation realized the USDA had the right idea with those early crosses, but they hadn’t gone far enough. Charles Burnham, one of the organization's founders and a geneticist at the University of Minnesota, suggested the backcross method, which is what the foundation uses today. By backcrossing an American-Chinese chestnut hybrid with an American chestnut generation after generation, they eventually arrive at a tree that is 15/16 American chestnut. Among that group, those that show strong blight resistance are planted in the wild.

“There's still a lot of American chestnut out there, but they're basically sprouts, and most of the time, they get blighted and die back before they can produce seed,” explained Dana Nelson, research geneticist and director of the Forest Health Research and Education Center, based in the College of Agriculture, Food and Environment.

“Occasionally they do, though, and that has provided the American Chestnut Foundation with trees they can use for breeding.”

a Chestnut Burr

American chestnut burr.  Photo provided by Christopher Barton.

TreeSnap gives those who are out in the forest a way to collect tree data that researchers can access. It promises to be a big improvement in how organizations currently collect data.

Rex Mann, a retired U.S. Forest Service forester and member of the American Chestnut Foundation, said TreeSnap is “one of the greatest tools that's come along.”

“We are going to be working with landowners and doing two things,” he said. “Number one, actually digging up some of these sprouts (they've found). We've had good luck in moving a bunch of those sprouts; we got them to flower and pollinated them and included them in our breeding program. The other thing is opening up the canopy above some of the sprouts that are out there and getting them to flower in the wild, then collecting the nuts and planting them in conservation orchards we're going to be establishing all over the state.”

Microscopic Answers
to a Macroscopic Problem

Though much of the work to restore the American chestnut to its range rests with good, old-fashioned hybridization efforts, a map of the chestnut genome and genetic markers have proven invaluable tools to breeders. The Forest Health Research and Education Center, working with the University of Tennessee and Penn State University, has sequenced the Chinese chestnut genome, looking for the specific resistance genes.

“We have markers for those genes, so those markers can help in the breeding program,” Nelson said. “The genes also are of interest to scientists who do genetic engineering.”

The center is working closely with labs at the University of Georgia and the State University of New York on genetic engineering efforts.

“It's the science that drives us,” Mann said. “We're really looking to folks like the University of Kentucky and the Forest Health folks to help us find out some of the answers to bring the American chestnut back.”