City to conduct controlled burn in Asheville watershed

On first impression, wildfires have a devastating impact on plant life: Leaves disintegrate, bark chars and trees crumble into ash. Some plants, however, plan ahead.

Josh Kelly, an ecologist with MountainTrue, says young oaks tend to thrive in locations where other trees suffer. “Oaks invest a lot of energy into their roots,” he says. When a fire sweeps through their habitat, seedlings can rise from the ashes even if the above-ground portion of the tree has been obliterated, something that ecologists call “top kill.”

The city of Asheville is taking a page from the oaks in anticipating wildfires to come. Later this month, the North Carolina Forest Service will help the city carry out a series of controlled burns on at least 95 acres around the North Fork and Bee Tree Reservoirs, thereby reducing the risk of more severe fires in a watershed that serves more than 125,000 area residents.

“We’ve got a lot of fuel that has accumulated through the years,” says city Watershed Manager Lee Hensley, “and with all the fire suppression that’s been going on through the years, these fuels have been allowed to build up.”

Buncombe County Ranger Dillon Michael, who will be overseeing the operation on behalf of the N.C. Forest Service, says controlled burns help counteract the buildup of plant matter that powers more intense blazes. “This is considered a hazard reduction burn,” Michael says, “and the objective of it is to remove a portion of the woody debris that’s collected on the forest floor.”

Spark of prevention

The city’s decision comes in response to a 2014 study by Forest Stewards, a nonprofit affiliated with Western Carolina University that conducts forest assessments for landowners. The study says that prescribed burns on the watershed can promote forest health and limit the risk of wildfires.

“Low-intensity fires can thin out an overcrowded forest, resulting in less severe disease and insect outbreaks,” the study says. “Controlled burns can also reduce leaf litter and woody fuels that could increase chances of wildfires and wildfire intensities.”

Over the course of his five-year career, Michael says, no catastrophic fire has yet taken place in the Asheville watershed. But even minor blazes can cause problems for firefighters when they flare up deep in the roughly 20,000 acres of forest surrounding the city’s reservoirs.   

“We have had smaller fires in there caused by lightning strikes,” Michael explains. “They can be so remote and hard to access that it does end up consuming a fair amount of resources to suppress them.”

Michael and other N.C. Forest Service personnel will conduct the controlled burns with funding from the U.S. Forest Service’s Community Protection Plan, which offers grants to states to prevent and limit the risk of wildfires in communities that are within a 10-mile radius of a national forest. The Pisgah National Forest surrounds Asheville’s watershed to the east, north and west.

However, Michael was unable to confirm exactly how much money has been set aside for the burn. “We’ll know more once we’re finished and we add up the cost,” he says.

Safety first

The prescribed burns in the Asheville watershed will produce low-intensity flames that are just hot enough to consume the top layer of leaves and plants, Michael says. He adds that crews will try to preserve the layer of organic matter underneath the leaf litter — also known as the duff — to help mitigate any erosion that could occur as a result of the burning.

Kelly, however, emphasizes that fires pose a less severe erosion risk in Southern Appalachia than in other ecosystems thanks to the region’s established forests. “Even if the top layer of duff is burnt, there’s just a mat of roots underneath the ground holding everything together,” he says.

Organizers plan on conducting the burns in a series of “units,” using barriers like creeks and the network of roads that crisscross the forest as firebreaks to limit the spread of the flames.

In places without readily accessible barriers, crews can produce makeshift firebreaks by clearing a line of woody debris off the forest floor. “It’s basically a buffer clear of anything that could burn,” Michael says.

Workers can also control the movement of the fire by carefully choosing its starting location. “When fire runs uphill uncontrolled, it tends to get a lot hotter and move a lot faster,” Michael says. Fire traveling downhill, in comparison, tends to burn slower and with less intensity.

Keep the fire burning

Michael hopes to see the project expand into a long-term partnership with the city — the 2014 Forest Stewards study calls for further burns in the southern reach of the watershed, which is adjacent to housing. “We would like to see more acreage burned throughout several years of us working together on this project,” he says.

MountainTrue’s Kelly agrees that a sustained approach to burning is necessary to keep the risks of large fires at bay. The moist environment of Southern Appalachia generates fuel more quickly than arid Arizona or Colorado, he says, and the wildfire reduction benefits of controlled fires last only three to five years before returning to pre-burn levels.

“What people need to realize is that, because it’s a short-term solution, it’s going to need to be a repeated action,” Kelly explains. “It’s not something you can do once and say you’re done.”

Even though wildfires are more prevalent in the West, Kelly continues, Asheville should avoid becoming complacent about the threat. He points to the 2016 blazes that devastated portions of the Great Smoky Mountains, causing millions of dollars in property damage and killing 14 people, as a “wake-up call” for fire prevention through controlled burning.

“What happens when people put fires out is they burn at the worst times in the worst possible conditions,” Kelly says. “Whereas if people can use fire as a management tool that kinds of mimics the natural ecology, then when those fires do happen … they’re theoretically not as severe.”