Issue 7

What Can Experimental Forests Teach Us About Fire In The Wildland-Urban Interface?

Since the 1920s, the USDA Forest Service has maintained a system of experimental forests to test hypotheses and collect long-term data about the ecological effects of fire, grazing, insect infestations, air pollution, and other disturbances. In the South, researchers from Federal agencies and universities use 15 active experimental forests for studies ranging from the practices needed to maintain healthy forests, to the water filtration functions of forests, to habitat restoration for endangered species.

Experimental forests are some of the few places in the United States where longterm data are collected about forests and how they change over time. These living laboratories also serve as demonstration sites where cooperators and landowners can see the results of different forest management options.

Located in the Georgia Piedmont near Juliette, GA, the Hitchiti Experimental Forest (Hitchiti) was established by President Franklin D. Roosevelt in 1939 on abandoned farmland purchased by the Federal Government. The 4,735-acre experimental forest has hosted more than 30 years of research on loblolly pine—and more recently, prescribed fire. It is also known as the Brender Demonstration Forest, which was established in 1987 by the SRS, the Georgia Forestry Commission, and the Southern Industrial Forest Research Council to showcase pine management for nonindustrial private landowners.

Prescribed fire may not seem like a wildland-urban interface issue, but with 6 to 8 million acres burned annually, planned burning is an important forest management tool that often runs counter to the needs of the increasing number of homeowners who live near forests in the South. Research on the most efficient methods to conduct and manage prescribed burns allows resource managers to continue this important practice as population grows in the southern region.

The Piedmont, roughly defined as the area between the Appalachian Mountains and the Atlantic Coastal Plain, extends from Maryland to Alabama. In the 1800s, much of the region was cleared for farming, resulting in extensive erosion and in some areas, soil depletion from cotton production. Areas abandoned in the 1900s were recolonized by a mixture of native hardwood and pine trees, with significant acres in loblolly pine—often called old-field pine because it could produce dense seedling stands from a few mature fencerow trees. Today about one-third of Piedmont forestland is covered by stands of loblolly or shortleaf pine. Hardwood-dominated forests, mainly oak and hickory, cover another third of the region; another 20 percent is dominated by a mixture of oak and pine.

Back to the Burn

Most of the Hitchiti is in secondand third-growth forest, with stands containing loblolly and shortleaf pine mixed with hardwoods. Yellow-poplar and black walnut plantations are also found on the experimental forest. Centuries before, Native Americans maintained the pine-dominated stands of the Georgia Piedmont by frequent burning. Lightning-ignited fires were actually rare, since most of the storms in the area come with significant rainfall. A period of fire suppression followed reestablishment of forests in the 1930s, when pine stands were often replaced by hardwoods or developed dense hardwood understories. Prescribed burning is again being used to restore open pine forests for key species such as the redcockaded woodpecker and to reduce fuels for wildfire.

Though the use of prescribed fire to maintain the health of southern forests, promote seed production in fire-dependent plants, and benefit wildlife is almost universally accepted, the practice has become increasingly difficult as more people move closer to forests. Prescribed burning does have negative impacts, mostly related to the smoke it produces. Smoke particles can aggravate health problems, lower regional air quality, and reduce visibility on roads and bridges. Though some people question the continued use of burning, stopping or even limiting its use would quickly lead to more of the thick forest undergrowth that feeds destructive wildfire. Scientists from multiple SRS research units work with a wide range of cooperators to find the best and safest ways to use fire to restore and maintain forests.

In 1989, a team of scientists led by SRS researcher Dale Wade established a series of plots on the Hitchiti to test burning regimes—using different seasons and frequencies—on fuels and the understory and overstory composition of Piedmont forests. They tested responses to six different treatments in a stand of naturally regenerated loblolly and shortleaf pines that had not been burned in over 50 years, tracking results by periodic measurements and surveys. Each treatment was replicated four times, with the 15-year measurements taken in 2004. Kenneth Outcalt, SRS research plant ecologist based in Athens, GA, took over management of the study when Wade retired in January 2003. “There are only a handful of studies like this in the South,” says Outcalt. “This is the only one that I am aware of in the Piedmont, or in these mixed pine and hardwood stands.”

Visual Proof of Benefits

Because the plots are located along a major road—and next to the popular Hitchiti Hiking Trail—researchers and foresters use the research plots to demonstrate the effects of prescribed burning to the public, the difference readily apparent between plots where fire has been excluded and those that have been burned frequently at low intensities. A competitive grant from the Joint Fire Science Program was used to fund a permanent outdoor display, individual treatment plot signs, and a fact sheet for a selfguided tour of the prescribed burn study.

The 15-year measurements showed that even infrequent burning will control the hardwood saplings and woody undergrowth that begin to take over forest understories. Burning also increases the herbaceous cover in the understory, often a desirable goal in restoration and wildlife recovery efforts—and it doesn’t affect the large pines that house the red-cockaded woodpecker. Though prescribed fire will not reduce a hardwood midstory, the practice gives managers a starting point for other options. “Burning every 3 to 4 years is all managers need to do to keep fuel loads down and reduce wildfire hazard,” says Outcalt. “If a manager wants to create red-cockaded woodpecker habitat, they need to thin overstory, remove midstory, and burn on a regular basis.”

As a demonstration forest, the Hitchiti has an on-site manager and staff who provide outreach and tours to interested groups. The prescribed burn study is a featured stop on tours conducted for other researchers, land managers, foreign scientists, students, State and Federal employees, and the interested public. The experimental forest also includes an arboretum of native Georgia trees, two interpretive walking trails, and the Hitchiti Natural Area. –ZH

For more information:

Ken Outcalt at 706–559–4309 or koutcalt@fs.fed.us.