July 26, 2017, 2:31 pm
Prescribed Burning
Written by Dan Scheffing

In the “pine barrens” most of the day.  Low, level sandy tracts; the pines wide apart; the sunny spaces between full of beautiful abounding grasses. liatris, long, wand like solidago, saw palmettos, etc., covering the ground in garden style.  Here, I sauntered in delightful freedom, meeting none of the cat clawed vines, or shrubs of the alluvial bottoms.”

John Muir

The above quote was part of Muir’s diary as he walked the Southeast on his epic journey across the United States.  What Muir saw is as appealing to many land managers today as it was to him then.  What he saw was the result of fire.

Fire plays a significant role in the distribution of plants and animals in the forests of the South.  Communities such as the longleaf pine – wire grass ecosystem require periodic fire to survive.  Historically, fire from lightning or Native Americans, occurred in the uplands every three to five years.  The interspersed lowlands of cypress and gum ponds may have burned only once every ten to fifteen years in times of drought.  Later, settlers used fire to clear the land and it ranged beyond their borders regularly, mimicking the natural occurrence.

Land managers use fire today, under prescription, to influence the distribution of plants.  Known as prescribed fire and managed prudently, its use can result in the view that Muir described in his diary.

Prescribed burning is used to reduce the amount of fuel available for wildfire thus reducing the chance of catastrophic fire.  The same fire also improves access to the forest and generally improves browse for wildlife.  Managing the plant community is the principal tool in managing wildlife.

The damage to individual plants caused by fire is a function of temperature and exposure.  Some plants (most southern pines) are resistant to fire.  Their thicker bark and needle structure provides insulation that allows them to survive fire that may kill other, less resistant, species.  Most hardwood trees are more susceptible to fire damage.

Timing is important in the application of fire.  Generally, dormant season (winter) burns are used to reduce fuel and the associated fire hazard.  They have lees impact on species composition.  Growing season burns have a greater impact on plant communities.  Fire during the spring/summer will usually result in greater mortality among hardwood trees and other herbaceous vegetation.  That will allow the warm season grasses to populate the forest floor.  Burns during the growing season may emulate the effects of natural summer lightning fires.

Land managers use fire to keep the understory vegetation low.  A more open aspect allows the growth of grasses and forbs.  Fires rarely burn the entire stand.  The vagaries of wind and fuel usually result in unburned “islands” scattered through the burned area.  These islands increase “edge effect”.  The increased diversity is positive for white tailed deer, turkey and quail, as well as many non-game species such as neo-tropical songbirds.

Several endangered species also benefit from regular burning.  The gopher tortoise, indigo snake, red-cockaded woodpecker and flatwood salamander all require conditions best maintained by a regular fire regime.

Experienced fire managers should be able to predict the vegetative changes that result from the application of a specific fire at a specific time.  The prescription should recognize the biological requirements, such as nesting times, and identify the desired outcome when planning a burn.

Fire managers have three main safety considerations when planning a burn.  Unintended damage to the area being burned is controlled and the burn should be contained within the planned area.  The fire manager is also responsible for the smoke generated from the burn so that becomes part of the planning process as well.  These concerns are all weather dependent.

Temperature and exposure are the keys to managing plant communities through fire.  Choosing the right time of year (dormant or growing season) is important to accomplish the desired objectives.  Choosing the appropriate day to have the safest wind direction, wind speed and favorable dispersion is equally important.

Limiting the area of the burn is generally accomplished through the use of firebreaks.  These breaks are generally along property lines, roads, stream or wet bottomland.  Fire breaks can be used as area access) or they may be used as wildlife food plots. Well maintained adequate fire breaks are essential to managing a controlled burn.

Managing the smoke is a function of fuels and wind.  Burns are generally designed to be out before dark when nighttime temperature inversions are the rule in our coastal areas.  Smoke generated during the day may resettle and hug the ground at night.  Such smoke may restrict visibility on roads and become a hazard.

Frequency of prescribed burns is dependent upon the objective.  For hazard reduction, burns at an interval of three to five years in pine stands is generally effective.  Fuels build up rapidly in our coastal forests.  Low intensity, frequent burns will keep the fuels down limiting the threat of catastrophic wildfire.  For competition reduction, later season or growing season burns on a more frequent basis until the species composition goal is met may be desirable, after which a program of burning for hazard reduction will maintain the stand objective.

Prescribed fire is an invaluable tool for land managers.  Properly conducted by Certified Prescribed Fire Managers, it can achieve stand level objectives and maximize the forest owner’s goals.