A basic premise of fire ecology is that wild land fire is neither innately destructive nor constructive: it simply causes change. Whether these changes are viewed as desirable or not depends upon their compatibility with one's objectives. Regardless of man's viewpoint, change is biologically necessary to maintain a healthy ecosystem. Resource managers have learned to manipulate fire-caused changes in plant and animal communities to meet their needs, and those of humankind in general, while at the same time preserving underlying natural processes and functions. They do this by varying the timing, frequency, and intensity of fire.

The use of fire in the forests of the United States has come full cycle. Early settlers found Indians using fire in virgin pine stands and adopted the practice themselves to provide better access, improve hunting, and to get rid of brush and timber so they could farm. Annual burning to "freshen up" the range became a custom. This practice, plus destructive wildfires after logging left millions of acres of forestland in the United States devoid of trees.

The increasing wildfire problem coupled with the need for a fire-free interval of several years to allow the pines to become reestablished led many foresters to advocate the exclusion of all fire from the woods. Others, however, pointed out that fire might have a place in the management of longleaf pine. Professional foresters have used fire to reduce hazardous fuels since the turn of the century. The misconceptions and controversy surrounding the deliberate use of fire to achieve resource management objectives have slowly been replaced by facts. As knowledge accumulated, the use of prescribed fire grew.

Prescribed burning is a desirable and economically sound practice on many sites. In many cases, prescribed burning is the only practical choice. Few, if any, alternative treatments have been developed that can compete with fire from the standpoint of effectiveness and cost. Chemical applications generally cost more than 10 times as much per acre as prescribed fire. Mechanical treatments such as disking, chopping, or raking are at least 20 times more expensive. Each of these three alternatives also has associated environmental costs, such as destruction of habitat and soil erosion. Both the probability of causing damage, and the magnitude of such damage, should it occur, need to be kept in mind.

A single prescribed burn can achieve multiple benefits. For example, a prescribed burn that consumes more dead fuel than it creates will reduce the fire hazard and, with few if any modifications, will improve wildlife habitat. Almost any prescribed burn improves access.

Prescribed fires aren't always beneficial, however. When conditions are wrong, prescribed fire can severely damage the very resource it was intended to benefit. Prescribed fire can temporarily reduce air quality, but usually to a much lesser degree than wildfire. For every prescribed fire opportunity, there are tradeoffs that should be recognized and carefully weighed before a decision is reached. Proper planning and execution are necessary to minimize any detrimental effects to air quality. Potential off-site impacts such as downstream water quality should be carefully considered, as should on-site impacts to soil and aesthetics.

Prescribed fire is a complex tool and should be used only by those trained in its use. Proper diagnosis and detailed planning are needed for every area where burning is contemplated. The incomplete assessment of any factor can pose serious liability questions should the fire escape or its smoke cause damage. A prescribed fire that does not accomplish its intended objective(s) is a loss of both time and money, and it may be necessary to reburn as soon as sufficient fuel accumulates. Keep in mind that some resource management objectives can be met with a single fire, some require several fires in quick succession, and some can only be accomplished by burning periodically throughout the rotation.

Prescribed fire is the most practical way to reduce dangerous accumulations of combustible fuels under southern pine stands. Wildfires that burn into areas where fuels have been reduced by prescribed burning cause less damage and are much easier to control. The appropriate interval between prescribed burns for fuel reduction varies with several factors, including the rate of fuel accumulation, past wildfire occurrence, values at risk, and the risk of a fire. The time interval between fires can be as often as every year although a 3- or 4-year cycle is usually adequate after the initial fuel-reduction burn.

Prescribed burning is highly recommended for wildlife habitat management. Periodic fire tends to favor understory species that require a more open habitat. A mosaic of burned and unburned areas tends to maximize "edge effect" which promotes a large and varied wildlife population.

Deer, dove, quail, and turkey are game species that benefit from prescribed fire. Burning enhances habitat preferences of a number of endangered species. Wildlife benefits from burning are substantial. For example, fruit and seed production is stimulated. Yield and quality increases occur in herbage, legumes, and browse from hardwood sprouts. Openings are created for feeding, travel, and dusting.

Selecting the proper size, frequency, and timing of burns is crucial to the successful use of fire to improve wildlife habitat. Prescriptions should recognize the biological requirements (such as nesting times) of the preferred wildlife species. Also, consider the vegetative condition of the stand and, most importantly, the changes fire will produce in understory stature and species composition.

Periodic fires throughout the rotation can keep competing vegetation below a management decided threshold. The most desirable season for burning and the frequency of burns will vary somewhat by species and physiographic region. Generally, a winter (dormant season) fire results in less root kill than a late spring or summer burn. One system recommended in both the Piedmont and Coastal Plain is a dormant season burn to reduce initial fuel mass, followed by two or more annual (if enough fuel is present) or biennial summer burns.

Brownspot disease is a fungal infection that may seriously weaken and eventually kill longleaf pine seedlings. Diseased seedlings tend to remain in the grass stage. 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. Burning the infected needles reduces the number of spores available to infect the seedlings.

Prescribed burning seems to reduce problems from Fomes annosus root rot. This fungal disease is less frequent where periodic burns have reduced the litter. The fire alters the microenvironment of the forest floor and perhaps destroys some fruiting bodies and cauterizes tree stumps.

Prescribed fire has been successfully used under very exacting fuel and weather conditions to control cone insects such as the white pine cone beetle (Conophthorus coniperda) while the pest is overwintering in cones on the ground. Prescribed burning costs are much less than traditional chemical control methods used to control the beetle.

Low-intensity burns increase availability, palatability, quality, and quantity of grasses and forbs. Dead material low in nutrient value is removed while new growth high in protein, phosphorus, and calcium becomes readily available. One commonly used system is to divide the range into three parts and bum one third every year.

A plant may become more - or less - abundant after a fire. The result depends on the stage in the plant's life cycle at the time of the fire. Flowering dates vary among species and with latitude and elevation within a species' range. Therefore, observe these dates for the preferred species, and time the bum accordingly. For example, wiregrass responds much better to summer burns than it does to dormant season burns.

Prescription burning improves recreation and aesthetic values. For example, burning maintains open stands, produces vegetative changes, and increases numbers and visibility of flowering annuals and biennials. Burning also maintains open spaces such as mountain balds, and creates vistas. Unburned islands increase vegetative diversity, which attracts a wider variety of birds and animals. A practical way to maintain many visually attractive vegetative communities and perpetuate many endangered plant species is through the periodic use of prescribed fire.

Using fire to manage landscapes and enhance scenic values requires judiciously planned and executed bums, especially where exposure to the public is great. Burning techniques can be modified along roads and in other heavily used areas to ensure low flame heights, which in turn will reduce crown scorch and bark char while still opening up the stand and giving an unrestricted view.

Many plants have structural adaptations, specialized tissues, or reproductive features that favor them in a fire-dominated environment. Such traits suggest a close association with fire over a very long period. Many such plants are only found the first 1 to 2 years after a fire. Changes in the "natural" fire pattern because of attempted fire exclusion have led to dramatic decreases in many of these fire-tolerant or fire-dependent species. Many picturesque flowers, including several orchids, currently listed as threatened or endangered are benefited by fire.

Prescribed burning, however, does not automatically help these plant and animal species because fires are not necessarily conducted during the same season in which the site historically burned. The interval between prescribed fires as well as fire intensity may also differ from those of the past. The individual requirements of a species must therefore be understood before a fire can be prescribed to benefit that species.

Noxious weeds and exotic plant species are an increasing concern. Any wild or prescribed burning occurring or planned in areas subject to noxious plant invasion should be evaluated from that standpoint.

The main effect of prescribed burning on the water resource is the potential for increased runoff of rainfall. When surface runoff increases after burning, it may carry suspended soil particles, dissolved inorganic nutrients, and other materials into adjacent streams and lakes reducing water quality. These effects seldom occur after Coastal Plain bums. Problems can be avoided in hilly areas or near metropolitan water supplies by using properly planned and conducted burns.

Rainwater leaches minerals out of the ash and into the soil. In sandy soils, leaching may also move minerals through the soil layer into the ground water. Generally, a properly planned prescribed burn will not adversely affect either the quality or quantity of ground or surface water in the South.

Prescribed fires may contribute to changes in air quality. Air quality on a regional scale is affected only when many acres are burned on the same day. Local problems are more frequent and occasionally acute due to the large quantities of smoke that can be produced in a given area during a short period.

Effects of smoke can be managed by burning on days when smoke will blow away from smoke-sensitive areas. Precautions must be taken when burning near populated areas, highways, airports, and other smoke-sensitive areas. Weather and smoke management forecasts are available as a guide for windspeed and direction. Any smoke impact downwind must be considered before lighting the fire. The burner may be liable if accidents occur because of the smoke. All burning should be done in accordance with applicable smoke management guidelines and regulations. During a regional alert when high pollution potential exists, all prescribed burning should be postponed.

Occasional brief exposure of the public to low concentrations of drift smoke is more a temporary inconvenience than a health problem. High smoke concentrations can, however, be a very serious matter, particularly near homes of people with respiratory illnesses or near health-care facilities.

Smoke can have negative short and long-term health effects. Fire management personnel who are exposed to high smoke concentrations often suffer eye and respiratory system irritation. Under some circumstances, continued exposure to high concentrations of carbon monoxide at the combustion zone can result in impaired alertness and judgment. The probability of this happening on a prescribed fire is, however, virtually nonexistent.

Over 90 percent of the particulate emissions from prescribed fire are small enough to enter the human respiratory system. These particulates can contain hundreds of chemical compounds, some of which are toxic. The repeated, lengthy exposure to relatively low smoke concentrations over many years can contribute to respiratory problems and cancer. But, the risk of developing cancer from exposure to prescribed fire has been estimated to be less than 1 in a million.

Although the use of herbicides in forest management has increased, all chemicals are now tested before being approved for use. Many of them break down rapidly after being applied. Moreover, both theoretical calculations and field studies suggest that prescribed fires are hot enough to destroy any chemical residues. Minute quantities that may end up in smoke are well within currently accepted air quality standards. Threshold limit values (TLV's) are often used to measure the safety of herbicide residues in smoke. Expected exposure rates of workers to various brown-and-burn combinations have been compared with TLV's. They showed virtually no potential for harm to workers or the public.

There is one group of compounds, carried in smoke, which can have an immediate impact on individuals. When noxious plants such as poison ivy burn, the smoke can cause skin rashes. These rashes can be much more widespread on the body than those caused by direct contact with the plants. If you breathe this smoke, your respiratory system can also be affected.

The major effects on wildlife are indirect and pertain to changes in food and cover. Prescribed fires can increase the edge effect and amount of browse material, thereby improving conditions for deer and other wildlife. Quail and turkey favor food species and semi-open or open conditions that can be created and maintained by burning. Burning can improve habitat for marshland birds and animals by increasing food production and availability.

The deleterious effects of prescribed fire on wildlife can include destruction of nesting sites and possible killing of birds, reptiles, or mammals trapped in the fire. Fortunately, prescribed fires can be planned for times when nests are not being used. Also, virtually all the types of prescribed fire used provide ample escape routes for wildlife. The ill-advised practice of lighting all sides of a burn area (ring firing) is a primary cause of animal entrapment and has no place in underburning. It also results in unnecessary tree damage as the flame fronts merge in the interior of the area.

Prescribed fire does not benefit fish habitat, but it can have adverse effects. Riparian zone (streamside) vegetation must be excluded from prescribed burns to protect high quality plant and animal habitat, and water quality. When shade is removed, water temperatures will increase. Burning conditions are often unfavorable along streams because Of increasing fuel moisture, making line plowing optional. But a buffer zone should always be left. If in doubt, a control line should be put in.