Scientists Weigh Benefits of Forest Burns

Aug 19, 2020

For decades, forest managers have set small fires– hoping to remove accumulated dead leaves and twigs that can increase the risk for bigger, more dangerous blazes in the future. 

Some people worry that these so-called controlled burns  promote climate change by releasing more carbon into the atmosphere. Scientists in Virginia are trying to figure out how much harm actually comes from low-level fires in our forests.

The Nature Conservancy's Blair Smyth surveys lush growth on the floor of a forest where controlled burns occurred.
Credit RadioIQ

On an ATV tour of Warm Springs Mountain in Bath County, the Nature Conservancy’s Blair Smyth shows me how much difference controlled burns make.

“If you look over here on our left, you see a lot of big trees, there’s a few dead ones interspersed there, but if you look underneath there’s this massive flush of young vegetation – loads of wildflowers, some grasses in there," he says.  "Game species like deer and bear and turkey love it, because look at all the food that’s out there for them, and places to hide.”

But to the right, an area that hasn’t been burned, large trees shade the forest floor, and fewer plants are growing there. 

Smyth maintains burning is a natural process, often started by lightning, that has been suppressed in modern times by people.

“Fire’s been present on this landscape for millennia.  Fire has shaped these mountains into what they are today.”

And today, blazes are an important tool when it comes to maintaining a healthy, diverse forest according to Nikole Simmons, restoration coordinator for the Nature Conservancy.

Nikole Simmons, restoration coordinator for the Nature Conservancy, says burning creates favorable conditions for new plants to grow.
Credit RadioIQ

“We burn to keep the forest floor clear of leaf litter so that when the acorns drop from the oak trees, they can regenerate with ease," she says. "We also burn to knock back some of the shrubs and bushes so that more light can hit the forest floor to encourage growth of grasses and wildflowers, blueberries and huckleberries, which provide a significant food source for a lot of different wildlife species.”

But is the upside of burning a fair trade for the pollution it causes – the addition of carbon to the atmosphere?  That’s one thing her group hopes to find out.

“We’re collecting a lot of data to find out what the effects of fire are, to add to the body of knowledge about what fire does in the Appalachians,” says Jean Lorber,  a land protection specialist at the Nature Conservancy.  Scientists are actually counting trees on Warm Springs Mountain to get a better idea of how much carbon is released by controlled burns. 

Jean Lorber, a land protection specialist for the Nature Conservancy, believes controlled burns may promote new plant growth that absorbs more carbon than was released by burning.
Credit RadioIQ

“It’s basically a forest inventory," Lorber explains.  "You measure a certain area of your woods. That’s your sample.  You extrapolate that to get an overall estimate of how much carbon is on a project. We have declining carbon from burned leaves and branches on one side.  We have increased carbon from new growth.  We have very, very slowly declining carbon from the big trees that we killed but that are still standing, and even  when they fall over, they decay very, very slow – for decades.”

It’s very possible, he says, that new growth after a fire sucks up even more carbon than what’s released during a burn.

“The carbon gain, then, is what happens after the burn.  How much increased growth do we see in the surviving trees, in the young growth? So there’s a small loss of carbon on the day of the burn and – we think – a long, slow increase in growth after the burn.”

The study will also allow the Nature Conservancy to more accurately assess the value of its forest preservation projects here in Virginia -- enabling the non-profit to sell carbon credits to environmentally conscious companies.   

“There are companies out there that need to buy some carbon credits to offset their carbon emissions , and that’s the voluntary market, where they’re not required to do it,” says  Allegheny Highlands Program Director Blair Smyth.

In California, he adds,  state law makes that mandatory for big polluters.

“So if companies in California do need carbon credits, they can buy carbon credits from people who have them to sell. That what the Nature Conservancy is doing,” Smyth says.

The conservancy hopes to finish its study and issue findings in about year.