By Matthew Ward
CHESAPEAKE, Va (Reuters) - The legacy of George Washington's centuries-old logging venture in the Great Dismal Swamp is contributing to the possible demise of a valuable ecosystem as a barely contained fire burns on the Virginia-North Carolina border, experts say.
As of late Sunday the brush fire had burned 6,156 acres and was probably ignited by a lightning strike on or around August 4, officials said.
Feeding largely on carbon-rich peat, the fire is sending smoke as far as Annapolis, Maryland -- four hours by car -- and causing respiratory health concerns among the nearby Hampton Roads population of 1.5 million.
Officials said the fire is being battled by 385 firefighters and is 10 percent contained, as it burns within the Great Dismal Swamp Wildlife Refuge in Virginia and North Carolina's Dismal Swamp State Park.
In the firing line, according to Christopher Newport University's Center for Wetland Conservation director Rob Atkinson, is Atlantic white cedar.
Also known as juniper, cedar or Chamaecyparis thyoides, the threatened ecosystem's largest U.S. stands were in the Great Dismal Swamp, where they have been in decline for 100 years, Atkinson said.
He and his team of research students began replanting cedars and studying the results after the refuge's last pure stand, 3,000 acres, was decimated by Hurricane Isabel in 2003 and burned out during another fire in 2008.
"We had nearly completed the second year measurements when the fire precluded our access and then burned our study plots," Atkinson said.
Atlantic White Cedar occurs from Maine to Mississippi. With a high carbon content, it reduces greenhouse gasses "probably more than any other ecosystem in North America," Atkinson said.
The fire is causing the elevation of the swamp to drop as it consumes the peat as fuel.
Refuge manager Chris Lowie said the ground beneath the fire was dropping by "four to six feet, depending on the depth of the peat."
"We're losing elevation out there," he said. "It takes 900 years to accumulate one inch of peat. What was a mature forest is now going to be greenbriers and grape vine and ... scrub brush."
Atkinson began studying the swamp in 1995. He said fire has always been a feature, but that in modern times the water level has been further from the surface: cedar seeds that were earlier protected from fire within the moist peat are now destroyed.
Experts say the water level dropped after a system of canals and ditches were developed in the late 18th and early 19th centuries to drain the swamp for logging. George Washington was the project's main, and most famous, proponent.
"Atlantic White Cedar is both a species and a type of swamp," Atkinson said.
"It's a species that will persist in the refuge, perhaps indefinitely, but the habitat type or swamp type that cedar creates is what we're in danger of losing."
He said his team should be able to gauge the extent of the swamp's de-elevation using study plots.
"We will have a good estimate of how much peat was lost, as well as what the water level was like, in each of those 25 plots," he said.
According to Lowie, the 2008 fire consumed 4,844 acres but did not burn as hot or deep as this time around. "We're thinking (this fire) may have a more devastating effect. The plant community is going to change," he said.
Atkinson said that only a replanting effort will re-establish the cedars.
"Unless they replant, which I certainly hope they will, the seed bank (within the peat) will not be adequate to replace even a small fraction of the normal cedar swamp."
"As a society, I think we can understand the loss of the species; we have an Endangered Species Act designed to prevent that. But it's hard for people to imagine what it means to lose a whole type of habitat," he said.
(Editing by Jerry Norton)