With wildfires often in the news, Charles Lafon, associate professor of geography, has studied the fire history of forests throughout the southern and central Appalachian Mountains. He says trees can reveal key information about fire events, and some trees have a lot to tell — one tree he examined endured 14 separate fires through its lifetime. He has published the research in Applied Vegetation Science and Physical Geography.
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. More examinations showed that trees in the area had sustained numerous fires over the past centuries.
"We found one tree that has had at least 14 fires, and we found many other trees that had endured multiple fires," he explains. 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. He found some trees with scars dating back to the mid-1600s. So far, they have not discovered any trees old enough to provide a record of even earlier fires.
"The fires probably were ignited by a combination of humans and lightning strikes," Lafon adds.
"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 says. "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 says that interestingly, fires showed a dramatic decrease after the 1930s.
"That's about the time the U.S. Forest Service and other agencies started to increase public awareness of forest fires, and they introduced the 'Smokey the Bear' campaign to tell people that they could prevent forest fires," he says. "And when a wildfire did occur, they suppressed it to halt its spread. Their efforts worked — the trees show that it did because they are fewer fires in the last 50 to 70 years."
Lafon says tree rings can show if a fire occurred, and by taking several samples and cross-referencing them to other trees, it is possible to determine the precise year — and even the time of year — when a particular fire occurred. The trees, in turn, have adapted to fires.
"Many tree species that inhabit fire-prone areas have thick, protective bark," he points out. "Some trees depend on fires for their own reproduction. One such tree is the Table Mountain Pine. Through a feature called serotiny, its cones often will not open to release the seeds unless they are heated by a fire, ensuring that the new seedlings emerge at an optimal time to survive and grow — right after a fire has cleared away the competing vegetation."
Likewise, the seeds of the Peters Mountain Mallow, a herbaceous plant related to cotton, require high temperatures, such as those produced by a fire, for germination, Lafon explains. Without fire, its reproductive efforts fail. In the early 1990s, the plant hovered on the brink of extinction before The Nature Conservancy began conducting controlled burns to restore it.
One of Lafon's graduate students used fire-scarred trees growing near the mallows to estimate how often fires burned the mallows in the past. The Nature Conservancy is using that research to guide their controlled burning program.
"The bottom line is that fire scars can tell us a lot about ecological changes," he notes. "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. The decline in fire frequency during the 20th century, for example, permitted tree species like red maple to encroach into pine and oak forests. Now the pines, oaks and other fire-associated species like the Peters Mountain mallow are declining in abundance, reducing the commercial value of the timber and diminishing the quality of wildlife habitat.
"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."
The project was funded by the Joint Fire Science Program, which is affiliated with the Department of the Interior and the Department of Agriculture.
About Research at Texas A&M University: As one of the world's leading research institutions, Texas A&M is in the vanguard in making significant contributions to the storehouse of knowledge, including that of science and technology. Research conducted at Texas A&M represents an annual investment of more than $630 million, which ranks third nationally for universities without a medical school, and underwrites approximately 3,500 sponsored projects. That research creates new knowledge that provides basic, fundamental and applied contributions resulting in many cases in economic benefits to the state, nation and world.
Keith Randall | EurekAlert!
Plasma-zapping process could yield trans fat-free soybean oil product
02.12.2016 | Purdue University
New findings about the deformed wing virus, a major factor in honey bee colony mortality
11.11.2016 | Veterinärmedizinische Universität Wien
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine