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Definitions |
History |
Reasons to Burn |
Weather Effects |
Smoke Management |
Firing Techniques |
Planning the Rx Burn Red Flag Situations | Rx Fire Certification |
What Is Prescribed Fire DefinitionPrescribed fire (Rx fire) is defined as fire applied in a knowledgeable manner to forest fuels on a specific land area under selected weather conditions to accomplish predetermined, well-defined management objectives.
Early American settlers found Native Americans using fire in pine stands and adopted the practice themselves to provide better access, improve hunting, and get rid of brush and timber so they could farm. Annual burning became a custom .
Reduce hazardous fuels - forest fuels accumulate rapidly in pine stands. In 5 to 6 years heavy roughs can build up, posing a serious threat from wildfire to all forest resources. Prescribed fire is the most practical way to reduce dangerous accumulation of combustible fuels under southern pine stands. Wildfires that burn into areas where fuels have been reduced by Rx fire cause less damage and are much easier to control. Prepare sites for seeding and planting - Rx fire is useful when regenerating southern pine by direct seeding, planting, or natural regeneration. On open sites, fire alone can expose adequate mineral soil and control competing vegetation until seedlings become established. Improve wildlife habitat - Rx fire is highly recommended for wildlife habitat management where loblolly, shortleaf, longleaf, or slash pine is the primary overstory species. Periodic fire tends to favor understory species that require a more open habitat. A mixture of burned and unburned areas tends to maximize "edge effect", which promotes a large and varied wildlife population. Deer, dove, quail, and turkey are some of the game species that benefit from Rx fire. Manage competing vegetation - low-value, poor quality, shade tolerant hardwoods often occupy or encroach upon land best suited to growing pines. Unwanted species may crowd out or suppress pine seedlings. In most situations, total eradication of understory is neither practical nor desirable. However, with the careful use of Rx fire the understory can be managed to limit competition with desired species while at the same time providing browse for wildlife. Control insects and disease - brownspot disease is a fungal infection that may seriously weaken and eventually kill longleaf pine seedlings. Once the seedlings become infected, burning is the most practical method of disease control. Any type of burning that kills the diseased needles without killing the terminal bud is satisfactory. Rx fire has been successfully used under very exacting fuel and weather conditions to control cone insects such as the white pine cone beetle, while the pest is overwintering in cones on the ground. Rx burning costs much less than traditional chemical control methods used to control this beetle. Improve forage for grazing - Rx burning improves grazing in open pine stands on the Coastal Plain. Low intensity burns increase availability, palatability, quality, and quantity of grasses and forbs. Enhance appearance - Rx burning improves recreation and aesthetic values. Burning maintains open stands, produces vegetative changes, and increases numbers and visibility of flowering annuals and biennials. Rx burning also maintains open spaces such as mountain balds, and creates vistas. Improve access - Burning underbrush prior to the sale of forest products improves the efficiency of cruising, timber marking, and harvesting. The reduced amount of fuel helps offset the greater risk of wildfire during harvesting. Moreover, the improved visibility and accessibility often increases the stumpage value of the product.
Knowledge of weather is the key to successful Rx burning, and is mandatory for proper management of smoke produced by burning. An understanding of weather and its effects on fire is essential to any Rx burn. The more important elements to consider for executing a good burn are. • Wind • Relative Humidity • Temperature • Rainfall Good winter Rx burning conditions often exist for several days after the passage of a cold front that brings ¼ to ¾ inch of rain. During this time, persistent winds, low relative humidities, cool temperatures and sunny days can be anticipated. Weather conditions for summer burning are much less predictable but summer burns can be successful with careful planning.
Sources of weather information • Georgia Forestry Commission (GFC) fire weather forecast • Media (television, radio, newspaper) • National Weather Service • Local Observation • Private Weather Forecasting Services
Preferred weather conditions • Wind - in-stand wind speeds 3- 5 mph • Humidity - 30-55 percent • Temperature (winter) - below 60 degrees Fahrenheit • Fine fuel moisture - 10 to 20 percent (see GFC fire weather maps ) • Keetch-Byram Drought Index (KBDI) between 250 and 400 KBDI is the measure of moisture in the duff or upper soil layers. It ranges from 0 (very wet) to 800 (drought conditions). Low KBDI relates to very wet conditions, which would make it difficult for a fire to carry in the understory. High KBDI readings relate to dry conditions and may cause the fire to burn too deeply into the duff layer causing damage to root systems as well as possible soil damage. See GFC fire weather maps for up to date KBDI reading.
Smoke ManagementRx burning helps achieve many desired resource objectives, but nevertheless produces smoke that can cause irritation to neighbors, schools, hospitals and nursing homes. Smoke can also settle on highways causing reduced visibility that could lead to accidents. These areas are described as smoke sensitive areas. The Rx burner could be held liable for damages caused from his/her smoke. Using fire weather forecasts, guidelines to reduce the impact of smoke have been established and should be followed. Smoke management weather factors • Dispersion Index - should be between 41 and 80 • Mixing Height - should be at least 1650 feet. Mixing height is described as the lid on the available volume of atmosphere. This is the height at which the smoke will begin to travel horizontally. • Transport Wind Speed - should be at least 9 mph. Transport wind speed is the average wind speed within the mixing height • Low Visibility Occurrence Risk Index (LVORI) - should be 6 or 7 • Turner Stability Index - describes atmospheric stability. Should be about 3 to 5 • Wind - wind is required to move smoke. The more the better to an extent. Too much wind could lead to control problems. All weather factors can be obtained from your local GFC office or through the GFC fire weather forecast web site. Residual smoke is a major problem. Be sure to have a plan in place to extinguish all smoldering stumps, logs, etc. before leaving your Rx fire. Check for smoke sensitive areas and avoid delivering smoke in their direction. You may need to wait for a shift in wind direction before executing your burn.
Firing TechniquesVarious firing techniques can be used to accomplish a burn objective. The technique chosen must be correlated closely with burning objectives, fuels, topography, and weather factors. The proper technique can change as these factors change. Based on behavior and spread, fires either move with the wind (heading fires) against the wind (backing fires) or at right angles to the wind (flanking fires). The movement of any fire can be described by these terms. Listed below are some of the firing techniques used in Rx fires:
Check with local GFC office or other certified Rx burners for assistance in proper Rx burn techniques.
Planning the Rx BurnThe first step to a successful burn is to have a good written plan. The written plan is the prescription for your stand and outlines your objectives. Pre-planning of firebreaks whether natural or man-made is also a part of the written plan. A map of the tract may need to be attached identifying the location of firebreaks. Contact your local GFC office for assistance in installing pre-suppression firebreaks. A written plan is also a record of your past accomplishments and helps guide you the next time you prepare to burn the same stand. A written plan may be a short simple document, others may be quite complex. As long as your objectives are outlined and understood your plan will be a good one.
Maps
A map should be drawn showing your burn unit. You can draw a map using topographical maps, aerial photos, or simply draw a map on your own.
The map should show at least the following:
Red Flag SituationsIf any of the following conditions exist, analyze further before burning:
If any of the following conditions exist STOP burning and extinguish existing fire:
smoke in smoke sensitive areas Source - USFS publication A Guide for Prescribed Fire in Southern Forest
Rx Fire CertificationThe Georgia Forestry Commission offers a certification program for those who practice prescribed burning. The certification program requires applicants to meet a prerequisite of having been the person in charge of five prescribed burns. Applicants may attend one of several training sessions scheduled through out the year where they will receive a comprehensive study manual and instruction on subjects such as fire behavior, fire weather and fire tactics. The applicants must pass a written test in order to become certified prescribed burn managers.
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