July 09, 2020
When our grandfathers were raising cattle and cotton in the piney woods of the Southeast a hundred years ago, they burned the woods regularly. They knew that putting a fire through the piney woods didn't hurt the trees; it killed all the brushy hardwoods and encouraged new growth of the native grasses cattle love.
This effort mimicked the historical fire regime of the Southeast. For centuries prior, lightning-struck fires burned millions of acres of southern piney woods yearly, keeping mature pinelands open. Cattle farmers in the early part of the twentieth century accomplished the same thing, providing a landscape that benefited quail and other native wildlife.
Then the U.S. Forest Service, in its understandable zeal to eliminate destructive wildfires from the woods, went too far and outlawed all controlled burning. The removal of fire from the woods drastically changed the piney woods habitat, making it unsuitable for many pineland species of both plants and animals, allowing brush to build up and creating a situation where fires would burn much hotter than they had historically.
At the same time, patterns of land use were changing. Around the turn of the last century, much of the landscape was broken up into small farms. The landscape became one of small fields and woodlots, with strips of rough, weedy habitat types between the fields. Not surprisingly, all these changes combined to create a climate where accidental fires became wildfires, destroying forests and structures and causing millions of dollars in damage.
As it became clear that the Smokey Bear mindset ("Only YOU can prevent forest fires.") was creating hazardous conditions, and as new research showed the importance of fire on the southeastern landscape, attitudes about fire shifted. Forest managers increased the use of prescribed burning to manage timberlands in more desirable ways, which reduced the fuel load in managed forests.
Determining a Prescription
Steven Mitchell is the upland game bird coordinator for the Alabama Department of Conservation and Natural Resources. He says when he undertakes a prescribed burn on one of the state’s Wildlife Management Areas (WMAs), his overall goal is to improve wildlife habitat.
"Depending on the type of prescription that you’re putting on the landscape, the fire can reclaim an overgrown area or it can maintain an area," he says. "There are different levels of fire."
For example, if wildlife managers want to clean up an area that’s overgrown with hardwood brush, shrubs and vines, and is too thick to walk through, they might choose to use a growing-season fire to kill a lot of the brush and improve the habitat.
"If you’re just maintaining a habitat that’s already looking pretty good, where you have broomsedge and other grasses that you want to keep, you’ll do a dormant-season fire," Mitchell says. "When everything is dormant, you’re not going to kill anything. You use different fires for different reasons."
The frequency of controlled burns also is determined by the objective, Mitchell says. "If you’re managing for bobwhite quail you want most of your fires on a two-year rotation. That keeps the plant succession where you want it. If you’re managing for whitetail deer you may want to be on a three- to five-year rotation to let some areas get thicker for bedding cover. The length of rotation is species-dependent."
Biologists at national wildlife refuges also use prescribed fires to manage a wide variety of plant and animal communities. According to The Nature Conservancy, the frequency of fire varies between three broad ecosystem categories: fire-dependent, fire-sensitive, and fire-independent. Fire-dependent ecosystems, like grasslands and pine forests, are those for which fire is essential. Those are the systems that are regularly burned.
Considering the Variables
Randy Brents, the prescribed fire manager for the Arkansas Game & Fish Commission (AGFC), says that overall, AGFC burns about 25,000 acres of land on the state’s WMAs each year.
"We possess a little less than 400,000 acres, so we’re sitting around 10 percent of our available burn acres each year," he says. "We have a lot of land that’s in waterfowl habitat that historically would not have had fire on it, as well as some hardwood forests, and we don’t burn that. But of our upland hardwood sites, we burn about 10 to 20 percent of our acreage every year.”v
That doesn’t mean that AGFC burns the same 25,000 acres each year. "We’re on a cycle that depends on what the objectives are for each unit," Brents says. "If it’s an area we’re managing for quail, it would see a more frequent burn rotation. If it’s an area that’s being managed for deer habitat, you might see a five- to 10-year return interval."
The goal, Brents says, is to maintain the habitat for wildlife. "We want forest sustainability and viability, coupled with the wildlife side."
Arkansas has several ecoregions. The Ozark Highlands and Boston Mountains ecosystems are predominantly oak/hickory forests. In the river valleys are a lot of oak/shortleaf pine forests.
"As we move into the Ouachita Mountains, it’s pine-dominated oak forest," Brents says. "When you get down into the southern part of the state, there’s a lot of industrial forest land that’s dominated by shortleaf pine and loblolly pine."
According to Brents, the AGFC burns some WMA lands in all the ecoregions. "We’ve burned in the Delta and in the flatwoods. But the bulk of our burning is in our Ozark mountains WMAs, which are hardwood dominated. Some of that is just because our larger WMAs are situated in that part of the state."
From an ecological perspective, Brents says, biologists typically are trying to return forests to their historical conditions.
"Historically, the oak woodlands and savannas in the northern part of the state were intermixed with glades," he says. "The south-facing slopes had lower tree densities and more short-leaf pine, and the north-facing slopes would have had higher densities. Our goal is to manage the forests with those historical perspectives in mind and keep sunlight on the forest floor for plant regeneration.”