Racing to save white ash trees from extinction in the NC mountains

On a recent June day, Matt Drury , the Appalachian Trail Conservancy’s associate director of science and stewardship, tapped a nail securing a round metal tag etched with the number 213 into a white ash tree along the Tennessee-North Carolina border on a ridge separating the Pisgah and Cherokee National Forests.

It’s one of more than 800 ash trees that the Appalachian Trail Conservancy , ATC, is protecting from the emerald ash borer, an invasive beetle from Asia. Each of the protected trees in North Carolina, Tennessee and Georgia receives number and is marked on a map with its GPS coordinates.

Since its discovery in the U.S. in 2002, the emerald ash borer has devastated millions of white ash trees and other ash species throughout North America, making Drury’s work critical for the future of ash trees in the Southern Appalachians .

“Rarely do I see one that isn’t impacted by the (emerald ash borer),” Drury said. “This is incredibly urgent since it kills trees so quickly. We want to be in a position to keep white ash alive on the landscape.”

The clusters of ash trees that remain in the North Carolina mountains are the result of rapid action by Drury and MountainTrue biologist Josh Kelly . The pair began discussing a plan in 2016 to safeguard mature ash trees along the Appalachian National Scenic Trail in hopes they’ll reseed future generations.

Their effort treats select trees with an insecticide to increase their chances of survival.

The pest arrived in Michigan in the late 1990, likely hitching a ride on wood-packing material transported by cargo ships.

The metallic green beetle, roughly the size of a paperclip, harmlessly nibbles on ash leaves. Its larvae, however, burrow in the bark of its canopy and feed voraciously on its interior, strangling the tree from the top down by disrupting its ability to transport water and nutrients.  It can take between 2 and 5 years for a tree to die from an infestation, but the emerald ash borer can be difficult to detect in its early stages since damage is initially hidden behind the bark.

“Experts knew it was happening, but didn’t have the capacity to intervene because it happened so quickly,” Drury said.

Drury, who studied forestry at Warren Wilson College in Asheville, discovered impacted ash trees in the French Broad River valley in 2016. Around the same time, Kelly observed damaged or dead ash along Interstate 40 in the Pigeon River Gorge in Haywood County.

The pair soon detected the emerald ash borers in ash stands at elevations above 3,500 along the Appalachian National Scenic Trail, an indication the pest had settled in North Carolina several years earlier.

Since then, in less than a decade most white ash in North Carolina’s mountains are dead or withering. Among the casualties is a towering ash tree next to the Appalachian National Scenic Trail in Madison County near Match Patch Road, its gray trunk entirely devoid of bark.

The tree’s bare mast extends to a breach in the forest’s leafy summer canopy, revealing a patch of blue sky in the opening. Soon, the tree will likely collapse to the forest floor, nudged by wind or snapped due to its compromised structure.

The sunlight peeking through gaps in the canopy, Drury said, threatens the forest’s biodiversity, potentially unleashing a cascade of ecological changes.

“These higher elevations of ash stands have a really unique suite of plant and animal species that depend on them,” he said. “The species composition and the understory totally changes when an ash tree dies.”

Many of the native herbaceous plants, such as grasses, ferns, wildflowers and other ground cover, can’t survive in full light conditions and are replaced by non-native invasive species, including Oriental bittersweet, which thrives in sunlight and can rapidly colonize the forest floor, beating out other native plants.

Despite the presence of dozens of dead or dying ash trees scattered along this section of the trail are several dozen that appear to be thriving in a mature forest of red oak, buckeye, basswood and hickory.

One of them was tagged number 213 moments before. Drury selected the tree in 2018 because of its size and its relative health, having incurred minimal damage from the borer to its crown and branches.

After capturing the tree’s GPS coordinates, Drury, wearing hiking bikes, long pants and shirt to shield his skin from stinging nettles and swarms of gnats, scribbles the diameter of the tree’s trunk on a clipboard and calculates the appropriate dose of the insecticide.

Kelly kneels at the base of the tree boring eight small holes with a cordless drill, then inserting a small black plug in each. The ATC’s nonnative invasive species coordinator Emily Powell follows Kelly shooting a dark blue fluid, the insecticide, into each hole with a pneumatic pump. The tree does the rest, transporting the chemicals upward, protecting it from the EAB’s larvae for roughly three years.

Following their discovery of the emerald ash borer in 2016, Drury and Kelly consulted with scientists studying the pest and collaborated with the Pisgah and Nantahala National Forests to expedite an environmental analysis in order to approve the treatment.

Approval from Cherokee National Forest in Tennessee and the Chattahoochee National Forest in Georgia soon followed. In all they’ve treated and monitored 875 ash trees along the trail corridor. Drury and Kelly selected trees to apply the insecticide that were among the tallest and ones minimally impacted by the borer since trees that are too far compromised have a lower chance of survival even with treatment.

They focused on several sections of the trail near Max Patch, a popular mountain bald in Madison County, including a 2.5 mile section of trail between Max Patch Road and Brown Gap. White ash trees are typically thinly scattered throughout Southern Appalachian forests, however, the relatively high elevation and its rich soil type has a higher concentration of ash.

“The Appalachian Trail is pretty unique since it ties together so many different pieces of public land,” Kelly said. “By using the (trail) as an organizing principle for treatment there’s a connected network of ash sites that should preserve a lot of the genetic diversity in the Southern Appalachians since we’re working across the whole north and south transect of the Blue Ridge Mountains.”

They also selected trees within sight of the iconic footpath, aligning with the ATC’s mission to protect the trail user experience and conserve the biodiversity of the surrounding ecosystem.

“What’s the value of a National Scenic Trail that traverses a compromised landscape?” Drury said. “You can have 2,200 miles of tread anywhere, but if it goes through a biologically compromised area then the trail experience is diminished.”

Dead trunks and branches pose a hazard to hikers and require maintenance when they fall across the trail.

Along with injecting tree 213, Drury and his team of three re-treated over 30 ash trees in a single field day. This summer, Drury has budgeted 10 to 12 field days to treat roughly 400 surviving trees. Since 2017, 98% of the treated trees survived, while the majority of untreated trees are dead or dying.

But adding more trees to their treatment plan isn’t feasible. “We’re kind of over the hump as far as destruction,” Drury said. “Rarely do I see an ash tree that isn’t impacted.”

Despite their success so far, the long-term outcomes are uncertain. Factors such as a changing climate, other nonnative invasive species, and human activities could influence the results.

“When you have multiple interacting problems and when you combine multiple stresses, the loss of ash trees becomes a bigger problem,” Kelly said. “The more diverse our ecosystems, the more they can withstand since there are multiple pieces that can react to different stresses. We’re losing pieces, unfortunately, and we’re trying to keep as many as we can.”

In addition to its ecological duties, ash trees are also culturally significant. White ash is famously used in producing baseball bats, tool handles, furniture and Fender Stratocaster electric guitars.

There’s hope that once the borer has exhausted its food source, the threat will dissipate. The team plans to continue treating the trees, potentially through the mid-2030s, depending on funding. Treating a single tree has a price tag of roughly $150 for the insecticide alone.

Recently, the ATC received a grant from the National Park Service’s America the Beautiful program, which will support treatments for the next three years. The Biden administration created the program to accelerate land, water and wildlife conservation.

“Once that tapers off, we’ll need to figure it out again. We’re rubbing nickels together and hustling to find future funding,” said Drury, who also mentioned that proceeds from North Carolina’s Appalachian Trail License Plate Grant Program have been used to support the treatments.

On the ridge near tree 213, Kelly examined a jagged gray stump he identified as the remains of an American chestnut that perished decades ago. Once a dominant species, the blight that wiped out the American chestnut was thorough and the species is functionally extinct since it can no longer reproduce.

This initiative, along with several other efforts in the Appalachians, has managed to treat and protect over 1,000 ash trees in the Southern Appalachians, including patches in the Great Smoky Mountains National Park and several dozen treated by the ATC under Drury’s supervision in New England.

Though this represents only a tiny percentage of the scores of white ash trees killed in the Southern Appalachians, Drury hopes their effort will be enough to avoid the fate of the chestnut.

“When we started this we knew we could have a potential extinction event,” Drury said. “I have faith that our work is protecting lots of other species and ecological functions and keeping ash alive on the landscape.”