SciWorks Radio is a production of 88.5 WFDD and SciWorks, the Science Center and Environmental Park of Forsyth County, located in Winston-Salem. Follow Shawn on Twitter @SCIFitz.

Shawn Fitmaurice
This tree was injured by fire in 1920. This kind of injury is called a fire scar. As the tree recovered it slowly grew over the damage, a little bit each year, resulting in the curving growth rings see in subsequent years. Credit Shawn Fitzmaurice

Fire is a natural part of a forest ecosystem. Today we live in and around the forests, so fires can become deadly. Controlled, or prescribed, burns are often conducted to get rid of the dead wood and underbrush that can fuel a fire.

By setting fires regularly, you prevent fuel build-up, which makes the unanticipated fire less likely, and less frequent. We want fire to happen when we have some hope of controlling it. If we don't do it, it will catch on fire at some point, from a lightning strike or something else, and then we'll have bigger trouble on our hands.

That's Dr. Dane Kuppinger, Assistant Professor of Biology at Salem College in Winston-Salem. In a visit to Pilot Mountain State Park with his undergrad Conservation Biology Class, after the 2012 prescribed fire that went out of control, Dr.Kuppinger learned that the fire history of Pilot Mountain was unknown. Knowing this history could be key in fire management, so he and his students began an investigation.

Basically what it entails is hunting through the woods for trees that have scars on the surface. When a tree is injured by a fire, over time the tree will grow over the dead layer. In doing so, it covers up and encapsulates the char, and makes a very distinctive growth pattern in the tree. We take entire cross sections. Each year the tree puts on a growth ring, so you can count back through the years and figure out when that scar happened. Do that across a whole bunch of trees, and you can figure out how often fire came to these forests as far back as your trees will go.

This tree experienced multiple fires causing successive scars on the tree. The tree survived the first fire, and grew around the original point of damage. Five more fires also damaged the growing tissue. Those scars are seen on the right side of the tree. The damage of each fire resulted in an additional curl in the subsequent growth of the tree.
Credit Shawn Fitzmaurice

Dating an event using tree rings is called dendrochronology. On Pilot Mountain, the record goes back more than a century and a half.

Our oldest tree is from the 1850s. We've got a pretty solid collection of trees all the way up through 2013. We have a few trees that show pretty frequent fires, but most of these trees only show spotty fires. So you don't get all fires recorded in one tree, the tree has to be injured. So you have to gather together lots of different trees to get a close-to-complete record.

Dr. Kuppinger and his students determined that the frequency of fire on Pilot Mountain is consistent with nearby forests, such as the Smoky Mountains in Western North Carolina and Brushy Mountain in Virginia.

We have fires that come through at about 7 to 14 years, with a few exceptions of trees that seem to have experienced fire every couple of years. The best estimate is that it is due to the use history of the park. So, it was first a private preserve, and before that it was logged and farmed, and so it's had a lot of heavy human usage. Our sense is that these were in spots where people like to start fires; either because it's where you're having your campfires, or burning your brush. So these are measures of human influences. But across the majority of our trees, we have this slightly larger fire interval that falls in line with what we found elsewhere.

Dr. Dane Kuppinger, Assistant Professor of Biology at Salem College in Winston-Salem.

Fires have always been part of forest ecosystems. So what is the benefit?

So, for this ecosystem in particular, it has species that require fire; so we have pines that only open their cones and disperse their seeds after fire. Table Mountain pine only occurs in this region. And it only occurs in spots that have frequent fires. If we managed to stop fire from burning in Pilot Mountain, the community as a whole would change from a pine- dominated to a hardwood- dominated forest. So the character of the forest will change in that way.

But there is more work to be done by Dr. Kuppinger's future classes.

So that's the next step we haven't gotten to yet, going back and matching each of these fire scars with historical records to show, yes, our dating is actually on target. I think it's really important for me as a professor to involve students. That's how I got interested in the sciences, through my experiences as an undergraduate. This sort of research experience, I think, is really important for undergraduates because it is a really great avenue for getting young people involved in science. You know, how are we going to find the next generation of scientists if we don't inspire them at this age?

This Time Round, the theme music for SciWorks Radio, appears as a generous contribution by the band Storyman and courtesy of

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