Monday, November 16, 2009

Inferring Ancient Fires in Southeastern Appalachians

A U.S. Forest Service-funded research project that took advantage of a modern-day controlled burn provides a glimpse at how Native Americans might have used flame to manage forests of the Appalachian mountains before European settlers re-rearranged the landscape.

At a Nov. 13 University Program in Ecology seminar at Duke, Norm Christensen, former Dean of the Nicholas School of the Environment, described how he and former masters degree student Kurt Fesenmeyer used charcoal from that burn as a reference layer to look for more ancient signs of fire.

They did so by probing underlying soil layers of the 3,000 foot-high section of Western North Carolina's Nantahala National Forest. They then estimated the ages of tiny flecks of older charcoal they found there with an expensive carbon dating method called accelerator mass spectrometry.

Before expending their $70,000 research budget, the researchers "found fire everywhere," Christensen said. There was evidence for blazes as far back as 8,550 B.C., though most dates fell between 1,200 and 400 years ago.

Fires appeared to be of lower intensity during a period roughly coinciding with the Woodland Culture which ended about 800 A.D. Those Native Americans kept their own populations relatively low while carefully managing the landscape for game, he said. Fire intensities increased after that, coinciding with the Mississippian Culture -- an era of mound-building and higher populations that ended around 1500.

Christensen, who is a fire expert, said European settlers who moved in noticed that Appalachian woodlands seemed especially open and grassy then, a contrast to today's denser conditions. Many of the pines thought to have once dominated higher elevations have also been replaced by broad-leaved species like oaks and chestnut with rhododendron growing underneath.

All of that could be signs that former fire management that has been supplanted by modern day fire control. In fact, today's Southeastern forests "are generally moist" and "not particularly flammable," he said.