Name: In the longleaf ecosystem: more fire, more carbon stored?
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How much carbon does a frequently burned longleaf pine ecosystem store?

Longleaf pine habitats are managed with prescribed fire, which releases carbon into the atmosphere. But might this ecosystem actually store carbon? We travel to the Jones Center at Ichauway in south Georgia, where researchers are studying this question. One answer might lie in partially charred plant matter, called black carbon, which persists in the soil over time.This video was produced in collaboration with NOVA and is made possible in part by the Corporation for Public Broadcasting, a private corporation funded by the American people.

Longleaf pine habitats are managed with prescribed fire, which releases carbon into the atmosphere. But might this ecosystem actually store carbon? We travel to the Jones Center at Ichauway in south Georgia, where researchers are studying this question. One answer might lie in partially charred plant matter, called black carbon, which persists in the soil over time.

In the longleaf ecosystem: more fire, more carbon stored?

How much carbon does a frequently burned longleaf pine ecosystem store?

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Rob Diaz de Villegas: The forest is on fire. But what looks like destruction is actually helping the plants and animals that live here. Josh Puhlick: Open canopy, lower tree stocking. Those characteristics are really good for a lot of our plant and animal biodiversity here. Ryan Means: Fire reduces competition. The bloomers pop up and they all start competing with one another to set seed because you've got open ground everywhere after a fire. Rob Diaz de Villegas: Good for plants and animals, but could regular fire do much more and actually help this ecosystem take carbon dioxide from the atmosphere? Josh Puhlick: Right now we're on a prescribed burn. We typically burn about 12000 to 13000 acres of our longleaf pine forests every year. Rob Diaz de Villegas: Josh Puhlick is a scientist at the Jones Center, a 29,000 acre research facility and preserve in south Georgia, composed mostly of longleaf pine forests. Today, the Jones Center crew is intentionally burning part of their preserve. Josh Puhlick: A lot of people will think that these fires are massive fires, but with a prescribed fire, it's really reducing a lot of the understory component. So not a very intense fire. Rob Diaz de Villegas: Fire thins out the underbrush while leaving fire resistant longleaf pines unharmed. This eliminates what could become fuel for a more intense wildfire while making space for native wildlife that has evolved in this landscape. Ryan Means is with the Coastal Plains Institute. Ryan Means: Historically, before Europeans arrived and altered the natural fire regime of the longleaf pine ecosystem, fires were ignited by lightning. And that's been the case climatically for thousands, if not tens of thousands and even millions of years here. Rob Diaz de Villegas: But fire does have an environmental drawback. Josh Puhlick: During prescribed fires here we are emitting carbon to the atmosphere. Rob Diaz de Villegas: All that plant material that is burning is composed of carbon, mostly stored as carbohydrates in the plants' bodies. When it burns, much of it turns into carbon dioxide. So how is it that burning can be beneficial to the environment? To understand just shows as part of the lonely forest that hasn't been managed with fire. Josh Puhlick: Right here in this position, we can't see over 100 hundred feet into the woods here. It's very hard for us to see visually through this stand. Rob Diaz de Villegas: You might think the more densely packed vegetation means more carbon is stored here. That's true, but it also means there's more fuel. Josh Puhlick: So you have a lot of buildup of what we call ladder fuels. So if a fire was to occur in here, a wildfire, then fire could move up through that mid-canopy position and then carry on into the crowns of those overstory longleaf pine. So you may have a high intensity crown fire which would release a lot of carbon and probably result in a lot of mortality of overstory pine. Rob Diaz de Villegas: Florida is the lightning capital of the USs, so the plants and animals that thrive here are adapted to fire. Regular burning in this ecosystem helps prevent catastrophic wildfires, which can burn even the big fire-resistant trees, the ones that store the most carbon. So this smaller fire helps keep that carbon in the trees and out of the air. But still, with regular burning of the underbrush, could the system be burning away more carbon than it stores? Josh Puhlick: During prescribed fires here we are emitting carbon into the atmosphere, but usually what we have is this regrowth of plant species and then a lot of flushing of new foliage from these longleaf pine. Rob Diaz de Villegas: Plants in the forest grow by capturing carbon through photosynthesis. New growth between zero and 60 days after burn is considered to be growth that the burn promoted. But is the carbon captured by the growth more than the fire emitted? To figure this out, researchers take all the living and dead organic material within one square meter, weigh it and figure out the carbon concentration. This gives them an idea of the average content of an area. Josh Puhlick: In about 30 to 60 days, the net carbon uptake of this system is similar to pre fire levels, a very resilient system. It recovers really well after prescribed fire. Rob Diaz de Villegas: And for as much carbon as is stored above ground. There may be more below. Josh Puhlick: In a lot of forest ecosystems you can have as much as half of the total ecosystem carbon in the forest soil. Rob Diaz de Villegas: Carbon in soil comes from decomposing plant material, but fire burns plant matter. Partnering with Tall Timbers Research Station, Ping Hsieh has been studying soil in long leaf plots where fire has been excluded and those which are frequently burned. Ping Hsieh: The soil organic matter level in the burn plot actually is higher than the unburned plot. Rob Diaz de Villegas: One reason might be black carbon. Ping Hsieh: For months and even years after a burn, you can see the freshly charred pine needles and twigs and pine bark and such, and rub it around your fingers and and see the black carbon there. Rob Diaz de Villegas: This partially combusted material makes its way into the soil where it can stay for a while. Research conducted by one of Dr. Hsieh's students finds that dead plant material might store carbon longer if it's burned. Ping Hsieh: On average, if you harvest plant material like my student did and the bury into the soil- 3 to 4 years, all this material will go back to the atmosphere. And if you turn that raw material into black carbon, the main resins time will increase at least 100 times. Rob Diaz de Villegas: To be clear, there are some drawbacks with burning. For example, it can send smoke into inhabited areas where it can affect people with respiratory ailments. But smoke can have a much greater health impact in uncontrolled wildfires. While the Jones Center is still in the process of researching carbon in the longleaf pine ecosystem, what it has learned so far is that with regular burning to promote healthy growth, the system is at worst carbon neutral and can even possibly help draw CO2 from the atmosphere. And so for a longleaf pine forest in the American Southeast, regular fire creates the best carbon scenario.

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In the longleaf ecosystem: more fire, more carbon stored?

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Support Provided By

Explore More

Can We Cool the Planet?

Chasing Carbon Zero

Weathering the Future