Efforts begin to put water back into Great Dismal Swamp peat bogs
Efforts begin to put water back into Great Dismal Swamp peat bogs
12 March 2012
published by www.washingtonpost.com
USA — Now that the long-burning wildfire in Virginias Great Dismal Swamp has been extinguished, managers of the refuge are going to try to get more water into the peat bogs to make catastrophic fires less likely and possibly revive the prized Atlantic white cedar that loggers who drained the swamps in the first place were after.
Refuge manager Chris Lowie said grants totaling $117,000 will purchase four water-control structures this summer, to be installed before the end of December to partially complete the task of raising the water table. Certainly we have the need for more than four, he said.
Water-control structures are culverts large cement pipes underneath levees. Removable boards seal the culverts off at different heights, allowing water levels to be raised as high as the structures themselves. Water is then directed across the peat bogs to basically mimic seasonal flooding, according to Sara Ward, U.S. Fish and Wildlife Service ecologist. Its fairly low-tech.
Peat bogs trap carbon, which is a major argument for restoring them, said Brian van Eerden, Southern Rivers Program director with nonprofit conservation organization the Nature Conservancy. Even though they only occupy 3 percent of the worlds land area, [peat bogs] such as the Dismal Swamp and areas in northeast North Carolina . . . contain the equivalent to twice the carbon stock of all the forest biomass worldwide, he said.
And when they catch fire, clouds of carbon-rich smoke spread over communities. As well as razing vegetation, the wildfires burn underground, feeding on the peat, and make them much harder to douse. Only burning fossil fuels and deforestation cause more CO2 emissions than peat wildfires, experts say.
Restoring the North Carolina peat bogs has been the focus of efforts starting in the early 1990s and continuing piecemeal over about 15 years as funding became available. By altering the flow of water to mimic seasonal flooding, more than 20,000 acres of peat bog at Pocosin Lakes in northeast North Carolina have been restored, Ward said. The results were not instantaneous but the pattern has been apparent for about two full seasons, she said.
An additional 100,000 acres of peat bogs in Fish and Wildlife Service-controlled refuge lands in the Albemarle watershed, in southeast Virginia and northeast North Carolina, are still in need of restoration, van Eerden said.
According to Fish and Wildlife Service research, the project to raise the water table in Pocosin Lakes will offset the average annual CO2 footprint of 11,000 Americans, or 82,000 tons, every year, through avoidance of wildfires and erosion.
One source of inspiration for restoring dried-up peat bogs can be found in Russia, where Germany is funding an initiative of Netherlands-based Wetlands International, a nonprofit, to rehydrate almost 90,000 acres. Experts say it is the worlds largest peat restoration project and could prevent the release of up to a million tons of CO2 due to fire by 2015.
Wildfires in drained peat bogs near Moscow in 2010 accounted for 80 to 90 percent of the citys smog, according to Wetlands International.
The Lateral West Fire in the Great Dismal Swamp National Wildlife Refuge in southeastern Virginia and northeastern North Carolina charred 6,574 acres before it was declared out last November.
It burned for 111 days, sporadically blanketing the nearby Hampton Roads region in acrid smoke that reportedly drifted as far as Annapolis.
Lowie said the wildfire and another in 2008 that burned about 5,700 acres cost about $12 million each to fight. The Nature Conservancy puts the total bill for these wildfires and others since 2008 in North Carolinas Alligator and Pocosin Lakes national wildlife refuges at more than $50 million.
An Environmental Protection Agency analysis on the health impacts of a 2011 Pocosin Lakes wildfire concluded that the increase in visits to emergency departments for asthma, chronic obstructive pulmonary disease, pneumonia, acute bronchitis and heart failure was striking and persuasive.
Van Eerden said data on health impacts of the Lateral West Fire are unavailable, but that anecdotally a significant spike in people seeking treatment for asthma and other respiratory conditions occurred.
Ward said wildfires also impact tourism and decrease elevation in areas where you can least afford to lose it.
These are fire-dependent ecosystems, so we certainly arent talking about preventing fire on the landscape, but basically trying to allow the hydrology regime to come back in a way that fire can occur without catastrophic consequences, she said.
Loggers after the prized Atlantic white cedar dug ditches and canals to drain refuge swamps in the late 18th and 19th centuries. Today, Atlantic white cedar refers to both a species of tree and a type of ecosystem, one that is classified as globally threatened.
Rob Atkinson, director of the Christopher Newport University Center for Wetland Conservation, said that the Great Dismal Swamp cedar stands, which were the ecosystems largest in the United States, have been declining for 100 years and may be lost after 2011s deep-burning fire incinerated remnant seeds.
By its high productivity and slow decomposition, cedar swamps can sequester more carbon than perhaps any other native forest type, he said.
Although Atkinson says he and his research team hope to work with Virginia and North Carolina refuge authorities to restore cedar where it once grew, Lowie said he is fairly certain that the Great Dismal Swamp burn scar is not cedar habitat anymore.
As far as Atlantic white cedar specifically . . . we dont have intentions of planting cedar in the areas that have been burnt twice in the last four years, Lowie said.
The future in terms of replanting will depend on the results of topography contour mapping using optical remote-sensing technology, which Lowie says will be compared with data obtained via the same method after the 2008 fire to learn how much peat has been lost.
That will help us make better decisions about what we think will actually regrow in the area and what will survive, he said.
The Fish and Wildlife Service reports that mature Atlantic white cedar bogs, which have naturally acidic waters and are cooler than surrounding hardwood swamps or pinelands, support breeding-bird densities as high as 425 to 554 pairs per 100 acres.
Fish and Wildlife Service biologist John Stanton, who heads the South Atlantic Migratory Bird Coordination Office, said the fragmentation of stands combined with the non-existence of records from the 1800s make it hard to assess the impact on animals of dewatered peat bogs and the subsequent loss of Atlantic white cedar.
Device helps restore bogs
The key to restoring a drained peat bog is to make it wet again. One simple but effective tool is a flashboard riser, which allows water levels to be adjusted manually to mimic seasonal flooding
Sources: Ecologist Sara Ward of the U.S. Fish and Wildlife Service, North Carolina Department of Environment and Natural
