September 8, 2011
Tree Rings Provide Information About Past Forest Fires
A researcher from Texas A&M University had published research showing how tree rings can provide clues to events such as forest fires, some of which might date back hundreds of years.
"Lafon analyzed the tree rings of several pine species and found clear evidence of 'scarring,' a disfiguring of the wood that is the unmistakable sign of a previous fire," the Texas A&M press release said. "More examinations showed that trees in the area had sustained numerous fires over the past centuries."
While many of the trees had experienced multiple fires, which were likely caused either humans or lightning strikes, one of them had survived "at least 14 fires," the professor said.
"By piecing together the fire-scar record from numerous trees, he and his students and collaborators learned that fires occurred frequently, about once every 2-10 years," the university media advisory noted, adding that some of the scars found on the trees date back "to the mid-1600s."
Lafon's research has been published in the journals Applied Vegetation Science and Physical Geography.
"We know that Indians often set fires to clear areas, and from records we have learned that the early settlers of the area also set fires so they could clear lands for grazing and planting crops," he said. "Eventually, by the late 1800s and early 1900s, there was a tremendous amount of logging because America needed a lot of timber at that time. Devastating fires accompanied the logging, and those fires motivated the fire protection campaign of the 20th century."
"The point is, there have always been fires in forests. Sometimes fires are a good thing because they are nature's way of starting over and producing new growth, and sometimes they are destructive," Lafon added, noting that the amount of fires decreased dramatically after the 1930s, likely due to an increase in public awareness campaigns such as the popular "Smokey the Bear" advertisements.
According to the press release, Lafon has discovered that the tree rings can show not just whether or not a fire occurred, but also - through cross-referencing multiple samples - can pinpoint the exact year in which the event took place. He also notes that some trees, like the Table Mountain Pine even require such fires to occur so that they can reproduce.
"The bottom line is that fire scars can tell us a lot about ecological changes," he concluded. "We can tell when a fire occurred and often how severe that fire was, and we can learn how forests changed as fire frequency varied over time“¦ Today, agencies like the U.S. Forest Service, the National Park Service, The Nature Conservancy and private landowners use controlled burning to try to restore the fire-associated vegetation. They are applying our fire history research to guide these efforts."
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