 |
|
|
Coastal Retreat In Face Of Rising Sea Levels Found To Be Influenced By WildfiresNORFOLK, Va. -- The retreat of coastlines due to rising sea levels maybe accelerated by wildfires, a Duke University researcher hasdiscovered. In the absence of such fires, forests can slow theencroachment, he found. At such fire scenes, though, finger-likepatches of marshlands can extend into former forest by as much asseveral hundred yards. The result is a "punctuated" near-shorelinelandscape, the scientist said. Such punctuated advance of the sea is insharp contrast to the widespread belief that coastal change would begradual due to sea-level rise. The researcher's findings about the impact of wildfires raisequestions about whether fire suppression or controlled periodic burningare the best strategies in areas being gradually inundated by risingseas resulting from global warming, said Benjamin Poulter. He is aresearch scientist at Duke's Nicholas School of the Environment andEarth Sciences as well as a visiting lecturer at the University ofNorth Carolina at Chapel Hill. Poulter will describe his findings during a 5:45 p.m. talk onThursday, Oct. 20, 2005, during an Estuarine Research Federationconference at the Marriott Waterside Hotel and Convention Center inNorfolk, Va. His research was mostly funded by NASA. In analyses for his doctoral degree, Poulter mapped how plantlife is responding to one of the world's highest rates of sea-levelrise -- about 30 to 40 centimeters per century -- along the westernshoreline of two interconnected North Carolina estuaries, the Pamlicoand Albemarle Sounds. As a starting point, Poulter took advantage of newhigher-resolution digitized data that he said enable the firstsensitive analysis of elevations lower than 1 meter above sea level.Ocean heights are predicted to rise by 1 meter by the year 2100. Overlaying those maps with aerial photographs made in the years 1932,1969 and 1998, Poulter could then assess visually how far marshlandshad penetrated into forested areas at various points within thiscritical inundation zone over a 66-year period. "From looking at these photographs we found that there are someareas that haven't changed at all," Poulter said in an interview."There were other areas where there have been gradual changes of justseveral meters. But there were also areas where large expanses offorest have been converted into marsh." Scientists initially hypothesized that since the sea level isrising gradually all changes would also be gradual. But the photographsshowed that, in places, "the forest is retreating in large patches," hesaid. "Those retreats have been about 200 meters over 70 years." Visiting some of those sites of large retreat, Poulter noticeddead trees with fire scars amid the invading marsh grasses. That ledhim to consult U.S. Fish and Wildlife Service fire history records forthe area, which since 1970 have identified "ignition points" where eachwildfire originated. When he digitally superimposed those ignition points on thedigitized landscape he found a correlation. "It appeared that the morefrequent the fires were the more likely the forest was to retreat inthis patchy way," he said. At a site where a forest of loblolly and pond pines had beenburned in May 2004, he found only marsh grasses growing and no signs ofregenerating pine seedlings. He hypothesized that, in the absence oftrees to release water vapor into the air, the water table had movedupward. Attempting to explain the lack of forest regeneration, Poulterinitially hypothesized that when marsh grass species migrate infollowing a fire, plant competition and the higher water table preventthe pines from returning. But after further experiments showed that pine seedlings wereable to grow prolifically under the marsh plants at high water tables,Poulter developed a new hypothesis. He suggests that after a fire both marsh grass and pineseedling can coexist and proliferate in burned areas. Then, if landmanagers prevent new wildfires for longer than 10 to 15 years, theforest may re-establish itself. "In some of those areas where fire hasbeen suppressed, you do see forests moving back out into the marsh," hesaid. On the other hand, if a new fire occurs over a shorterinterval, "you would have to start the process over," he said. And thepine seedlings could lose out in the second round of competition. "I think this is a great example of how there is some kind ofbuilt-in tolerance to environmental change that gets disrupted when adisturbance such as fire passes through the system," he said. "The changes that you end up having are unpredictable, punctuated changes rather than gradual change." According to Poulter, land managers are rethinking their oldextended fire suppression policies in his study area, a pristine regionof protected land especially rich in plant and animal species. Plans call for restoring the environment to more natural andfrequent cycles of periodic burning and regeneration. "But undercertain situations there is the potential to increase the rates offorest retreat in this region," he said. Poulter noted that both marsh grasses and pine forests actuallydepend on fire for periodic renewal. "These are such highlyfire-dependent systems that fire suppression as a strategy to reducemarsh invasion does not make much sense," he said. "The reintroduction of controlled burning to minimize marshplant invasion of forests should be done under optimal weatherconditions and during the appropriate season of the year," he said. Can't find it? Try searching ScienceDaily or the entire web with: |
Science Video News
Hawaii's Kilauea volcano is once again putting on a show. > watch video
A local zoo showcases baby leopards, the first to be born in a South Korean zoo. > watch video
A new report finds that in the Northern Hemisphere, average global surface temperatures climbed... > watch video
Related News Topics> more ...
Related Science Stories> more ...
Related Encyclopedia Articles> more ...
Related Book ReviewsNew Technology Helps Fire Managers Anticipate Smoke Problems (September 19, 2003) -- Smoke from planned fires and wildfires affects air quality and visibility. Firefighters, forest managers, farmers, motorists, and people with respiratory problems all need accurate and timely ... > full story Sea Level Rise Behind Tree Deaths On Florida's West Coast, UF Researchers Report (October 15, 1999) -- In a landmark study recently published in the journal Ecology, a team of University of Florida and U.S. Geological Survey researchers concluded the cabbage palms and many other coastal trees are ... > full story Mathematical Rule Said To Be Widely And Wrongly Used To Forecast Future Beach Erosion (March 22, 2004) -- A decades-old mathematical model is being inappropriately used in at least 26 nations to make potentially costly predictions about how shorelines will retreat in response to rising sea levels, two ... > full story Antarctic Ice Shelf Retreats Happened Before (February 28, 2005) -- The retreat of Antarctic ice shelves is not new according to research published this week (24 Feb) in the journal Geology by scientists from Universities of Durham, Edinburgh and British Antarctic ... > full story
Plan Fires Timed To La Nina Or El Nino Years, University Of Arizona Tree-Ring Lab Director Urges (October 5, 2000) -- Fire history expert Thomas Swetnam, director of the University of Arizona Laboratory of Tree-Ring Research, hopes this summer's experience will encourage forest managers to consider the climate ... > full story
Exploring Link Between Climate Change And Air Quality (October 16, 2003) -- The National Center for Atmospheric Research (NCAR) and other institutions are launching a far-reaching project this month to help the government keep polluted areas in compliance with Clean Air Act ... > full story Are Wildland Fires Fueling The Greenhouse? (December 27, 2002) -- Wildland fires are taking tons of carbon out of storage and feeding it into the atmosphere as carbon dioxide, a primary greenhouse gas. Drought makes things worse, stunting tree growth and turning ... > full story Wildfire -- A wildfire, also known as a forest fire, vegetation fire, grass fire, brush fire, or bushfire (in Australasia), is an uncontrolled fire often occurring in wildland areas, but which can also consume ... > full article Erosion -- Erosion is the displacement of solids (soil, mud, rock, and other particles) by the agents of wind, water, ice, movement in response to gravity, or living organisms. Erosion is an important natural ... > full article Coastal erosion -- Coastal erosion is common phrase referring to the loss of subaerial landmass into a sea or lake due to natural processes such as waves, winds and tides, or even due to human interference. Large ... > full article Engineering geology -- Engineering Geology is the application of the science of geology to the understanding of geologic phenomena and the engineering solution of geologic hazards and other geologic problems for ... > full article Estuary -- An estuary is a semi-enclosed coastal body of water which has a free connection with the open sea and within which sea water mixes with fresh ... > full article Deforestation -- Deforestation is the conversion of forested areas to non-forested. Generally this removal or destruction of significant areas of forest cover has resulted in a degraded environment with reduced ... > full article Effects of global warming -- The predicted effects of global warming are many and various, both for the environment and for human life. There is some speculation that global warming could, via a shutdown or slowdown of the ... > full article Ice sheet -- An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² (19,305 mile²). The only current ice sheets are Antarctic and ... > full article National Weather Service -- The National Weather Service (NWS) is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration (NOAA) of the United States government. It is tasked with ... > full article Extinction -- In biology and ecology, extinction is the ceasing of existence of a species or group of taxa. The moment of extinction is generally considered to be the death of the last individual of that species. ... > full article
|
