Fire was frequent in the past, and an important shaper of vegetation in the Appalachian forest – along with the rest of North America.
These weren’t the catastrophic forest fires we see in the news today. They generally were moderate fires that burned through grasses, shrubs, and dry leaves. With the implementation of fire prevention and suppression practices in the 20th Century, the vegetation has changed in ways that are harmful for certain species. Some of these species include oak and pine trees, which have great value for timber and wildlife.
Dr. Charles Lafon, Professor and Assistant Department Head in the Department of Geography at Texas A&M University, has been studying the history of fire since 2002. This research entails sawing cross-sections from fire-scarred trees and using the trees’ annual growth rings to determine in which years the scars were formed. He recently partnered with colleagues from the University of Arizona, University of Tennessee, and U.S. Forest Service to put together the publication, Fire History of the Appalachian Region: A Review and Synthesis. This publication synthesizes fire history studies that used fire-scarred trees as well as other types of evidence, such as charcoal fragments retrieved from soil or lake sediments. The report was funded by the Consortium of Appalachian Fire Managers and Scientists (CAFMS).
According to Lafon, evidence shows that fire prevention has seriously altered the vegetation and environment of the Appalachian region.
“The fires prepared the environment like we prepare a garden,” explains Lafon. “In the last few hundred years, fires occurred frequently (every few years) up until the 1930’s – and then pretty much stopped. The vegetation has changed as a consequence.”
Some refer to this post 1930’s period as the “fire suppression era,” because the U.S. Forest Service and other agencies have contained more fires through active suppression – such as fire lines and helicopters.
However, Dr. Lafon explains that suppression isn’t the only reason for the decline in fire.
“Another important reason is fire prevention. Think Smokey The Bear. Prevention has been a major campaign, with a goal of reducing the number of fires that are ignited in the first place. So, prevention and suppression have worked in tandem to virtually exclude fire from the landscapes of the eastern United States. Other factors have also contributed to the decline in fire – such as social and economic changes, and landscape changes,” he added.
The consequence? The vegetation is now much thicker, and very different, than it was in the past.
“The forest has become a lot more dense. So instead of woodlands with grass and diverse vegetation, now we have a pretty dense forest with a lot of shade, and a lot of shrubs,” said Lafon.
Species like maple trees, which couldn’t thrive under frequent burning, are now overtaking the fire-tolerant vegetation.
“We like maples, they’re pretty. But in terms of a wildlife perspective or timber perspective, they’re just not as a valuable as the oaks and pines. They’ve grown a lot more dense and they’re outcompeting these fire-dependent species for resources,” explained Lafon.
He continued, “At one time the trees that loved moist sites were constrained to the stream-side areas, and the more fire-dependent, drought-tolerant, species were up on the ridges. So now, without fire, the stream-side species have moved up on the ridges.”
As the older pines and oaks die, they’re being replaced – and the forest has transitioned into something different. The once open forest, which was favorable for species like pines and oaks, has changed.
“The forest has shifted in terms of what species live there, how abundant certain species are, how dense the forest is, a change in wildlife and habitat, and change in the timber quality,” added Lafon.
This story by Andrew Vernon was originally posted on the College of Geosciences website.
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