Looking for Balance in the Carbon Cycle

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Certain types of wetlands are extraordinarily efficient at storing carbon through biological sequestration. The Great Dismal Swamp is an especially productive place to study how different approaches to managing the land could potentially increase carbon storage.

Looking for Balance in the Carbon Cycle

In 1763, young George Washington came to the Great Dismal Swamp intent on changing the local ecosystem. He organized the Dismal Swamp Company, with a group of shareholders, to drain, farm, and log portions of the huge swamp, which is located in southeastern Virginia and northeastern North Carolina. Much of this area, constituting over 176 square miles of forested wetlands, is now protected as the Great Dismal Swamp National Wildlife Refuge.

“Washington wouldn’t have used these terms,” said Chris Lowie, who manages the refuge for the U.S. Fish and Wildlife Service, “but, in effect, he was managing carbon in this area by draining the swamp and then using the carbon found in crops and timber to his commercial advantage. Today, we have different goals in managing carbon here. We want to understand how we can best help moderate the effects of climate change while working to restore the historical ecosystems of this remarkable landscape.”

Carbon Fundamentals

Biological carbon sequestration is part of the carbon cycle. Plants and microorganisms take in carbon dioxide from the atmosphere and store carbon in their stems and roots, and in water and soil.

Enhancing these natural carbon "sinks" can help offset increases in atmospheric carbon that come from widespread use of fossil fuels. Many countries have made public commitments to enhance carbon storage in forests and other natural systems.

The Hidden Talent of Wetlands

“Certain types of wetlands are extraordinarily efficient at storing carbon through biological sequestration,” said Dianna Hogan, a U.S. Geological Survey (USGS) ecologist. “This is one of the reasons that the wetlands of the Great Dismal Swamp are an especially productive place to study how different approaches to managing the land could potentially increase carbon storage. Simultaneously, we are considering how the same, or related, land management practices might promote certain vegetation communities that have existed here in the past.”

Hogan is the principal investigator for the Great Dismal Swamp project led by the USGS. The project is designed to analyze how the carbon cycle operates locally in this carbon-rich environment. The project also incorporates ecosystem service assessments to support U.S. Department of the Interior land management goals. The USGS conducts much broader assessments of carbon interactions with land at a national scale.

The Wetlands of the Great Dismal Swamp
Ground Water Well
Gary Speiran (USGS) and Fred Wurster (USFWS) install a ground water well to measure water table levels and carbon movement in the water.  Photograph credit: Nicole Cormier, USGS
Considering Carbon in Managing the Land

“Not so much Washington’s company, but the entrepreneurs that followed after Washington have definitely had an effect in ditching the swamp for drainage,” Lowie said. “The natural hydrology of the swamp has been severely altered by 150 miles of ditches that crisscross the landscape, creating an ecosystem generally adapted to drier conditions than in centuries past.”

“The research USGS is conducting will assist us in determining the carbon cost-benefit of different management actions for the refuge such as re-wetting the peat, selective timber harvesting, or conducting prescribed fire.”

“Carbon is basic in each of these examples,” Lowie said. “Peat soils excel at storing carbon. Timber stores carbon, too, but it has added considerations for historical ecosystem restoration. Of course, fire releases carbon directly into the atmosphere, yet it has a natural and important ecological role.”  

“The carbon data being collected with USGS guidance [are] correlated to water level, soil moisture, and existing vegetation in the swamp. Connections and insights like these are critical as we strive to re-wet the swamp to a more natural regime and restore historical vegetative communities, which, in turn, will affect the future carbon sequestration potential.”

“For us, carbon sequestration is not a stand-alone management goal, but it is a very important and helpful consideration—in part, because it gives us a clearer awareness of environmental interactions,” Lowie said.

“The long and varied expertise in the field of carbon cycle science that USGS provides has been key,” Lowie said. He concluded by saying, “When we have a better idea of how our actions affect carbon sequestration, we can more effectively incorporate this concept into our decisions and subsequently improve our habitat management.”

The multipartner Great Dismal Swamp Project includes the U.S. Geological Survey, the U.S. Fish and Wildlife Service, the Nature Conservancy, George Mason University, Southern Methodist University, Christopher Newport University, and Clemson University.

USGS Research in the Great Dismal Swamp
USGS study plots in the Great Dismal Swamp. 
Peat in the Great Dismal Swamp
A scientist holds peat, a type of soil that stores large amounts of carbon in the Great Dismal Swamp. Photograph credit: Dianna Hogan, USGS
For More Information

For more information, contact Virginia Burkett, USGS Associate Director for Climate and Land Use Change, at virginia_burkett@usgs.gov.   


Read more stories about USGS science in action.


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