A Guide for Prescribed Fire in Southern Forests

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The Objective of this To help resource managers plan and ■ Describing the various techniques execute prescribed burns in Southern of prescribed burning. Prescribed Burning forests by: ■ Giving general information pertain- G uide ing to prescribed burning. ■ Explaining the reasons for prescribed burning. ■ Emphasizing the environmental effects. ■ Explaining the importance of weather in prescribed burning. A GUIDE FOR PRESCRIBED FIRE IN SOUTHERN FORESTS

Backing fire in young slash pine Postburn results

Rewritten in 1988 by Dale D. Wade, Photo assistance was provided by the Appreciation is expressed to the Southeastern Forest Experiment Alabama Forestry Commission; Georgia various State and Federal agencies, Station; and James D. Lunsford, Fire Forestry Commission; North Carolina private industries and other organiza- Management, Southern Region, Forest Service; USD1 Fish and Wildlife tions for their helpful reviews and USDA Forest Service Service, Piedmont National Wildlife cooperation. Refuge; South Carolina Commission of Originally written in 1966 by Merlin J. Forestry; Southeastern Forest Experi- Dixon, Southern Region, USDA Forest ment Station, Southern Region, and Service. Southern Forest Experiment Station, USDA Forest Service; Tall Timbers 1973-1979 revisions, lead author Hugh Research Station; Union Camp Cor- E. Mobley, Southern Region, USDA poration; and Westvaco Corporation. Forest Service.

This guide provides basic information needed to help you become technically proficient in the proper use of prescribed fire. A glossary toward the end of this manual will help you with unfamiliar terms. To learn more about the subject of prescribed fire, a list of suggested reading follows the glossary. Nearby State and Federal resource management agencies are also excellent sources of information. Many of these agencies provide periodic training in fire behavior and prescribed fire. Contents

ii iii Palmetto-gallberry fuel type prior to prescribed burn

Po stburn results iv introduction

The Ecology of Fire point, change is biologically necessary southern range became a custom. This to maintain a healthy ecosystem. practice, plus destructive wildfires Fire has played a major role in Resource managers have learned to after logging left millions of acres of determining the distribution of plants manipulate fire-caused changes in forest land in the south devoid of trees. across the South. Some plant com- plant and animal communities to meet The increasing wildfire problem munities such as cypress swamps sur- their needs, and those of humankind in coupled with the need for a fire-free vive for centuries between prolonged general, while at the same time preser- interval of several years to allow the droughts that finally allow stand- ving underlying natural processes and pines to become reestablished led replacement fires to enter. Other com- functions. They do this by varying the many foresters to advocate the exclu- munities such as the once vast expanse timing, frequency, and intensity of fire. sion of all fire from the woods. Others, of longleaf pine burn every few years. however, pointed out that fire might In fact some ecosystems, for example have a place in the management of the longleaf pine-wiregrass associa- Prescribed Fire History longleaf pine. Fire has been used by tion, require periodic fire for their professional foresters to reduce hazar- very survival. The use of fire in the forests of the dous fuels since the turn of the century. A basic premise of fire ecology is United States has come full cycle. Ear- The misconceptions and controversy that wildland fire is neither innately ly settlers found Indians using fire in surrounding the deliberate use of fire destructive nor constructive: it simply virgin pine stands and adopted the to achieve resource management causes change. Whether these changes practice themselves to provide better objectives have slowly been replaced are viewed as desirable or not depends access, improve hunting, and to get rid by facts. As knowledge accumulated, upon their compatibility with one's ob- of brush and timber so they could the use of prescribed fire grew. jectives. Irrespective of man's view- farm. Annual burning to "freshen up"

Depression-era photo of unproductive forest land Present Use This manual will be most useful in necessary to minimize any detrimental the lower Piedmont and Coastal Plain. effects to air quality. Potential off-site Today prescribed fire is applied to Prescribed burning in these areas has impacts such as downstream water roughly 8 million acres in the South been perfected by several generations quality should be carefully considered, each year — about half of which are of resource managers. Although the as should on-site impacts to soil and burned to achieve various forest potential of prescribed fire in the upper aesthetics. management objectives. Most of the Piedmont and mountains of the South Public opinion is another factor to remainder is for range and agricultural has been demonstrated, few guidelines consider because the general public is purposes. Prescribed burning is a exist. If you are interested in the concerned about the deterioration of desirable and economically sound emerging use of fire in the mountains, the environment. Smoke from practice on most southern pine sites. In a good source of information and help prescribed fires, as well as from many cases, prescribed burning is the is your local State or Federal forestry wildfires, is highly visible. It is our job only practical choice. Few, if any, office. as resource managers to inform the alternative treatments have been public of the differences between developed that can compete with fire I mpact of Prescribed prescribed fire and wildfire—which often from the standpoint of effectiveness Burning look identical to the untrained eye. and cost. Chemical applications Prescribed fire is a complex tool generally cost more than 10 times as A single prescribed burn can and should be used only by those trained much per acre as prescribed fire. achieve multiple benefits. For example in its use. Proper diagnosis and detailed Mechanical treatments such as disk- a prescribed burn that consumes more planning are needed for every area ing, chopping, or raking are at least 20 dead fuel than it creates will reduce the where burning is contemplated. The times more expensive. Each of these fire hazard and, with few if any incomplete assessment of any factor three alternatives also has associated modifications, will also improve can pose serious liability questions environmental costs, such as destruc- wildlife habitat. Almost any prescribed should the fire escape or its smoke tion of habitat and soil erosion. Both burn improves access. cause damage. A prescribed fire that the probability of causing damage, and Prescribed fires aren't always does not accomplish it's intended ob- the magnitude of such damage, should beneficial, however. When conditions jective(s) is a loss of both time and it occur, need to be kept in mind. are wrong, prescribed fire can severely money, and it may be necessary to In this guide, prescribed burning is damage the very resource it was in- reburn as soon as sufficient fuel ac- defined as fire applied in a tended to benefit. Prescribed fire can cumulates. Keep in mind that some knowledgeable manner to forest fuels temporarily reduce air quality, but resource management objectives can on a specific land area under selected usually to a much lesser degree than be met with a single fire, some require weather conditions to accomplish wildfire. For every prescribed fire op- several fires in fairly quick succession, predetermined, well-defined manage- portunity, there are tradeoffs that and some can only be accomplished by ment objectives. should be recognized and carefully burning periodically throughout the weighed before a decision is reached. rotation. Proper planning and execution are

2 Reasons For Prescribed Fire In Forest Resource Management

■ Reduce hazardous fuels ■ Prepare sites for seeding and planting ■ Dispose of logging debris ■ Improve wildlife habitat ■ Manage competing vegetation ■ Control disease ■ Improve forage for grazing ■ Enhance appearance ■ Improve access ■ Perpetuate fire-dependent species ■ Cycle nutrients ■ Manage endangered species

Reduce Hazardous control. The appropriate interval be- high in these vast contiguous stands. tween prescribed burns for fuel reduc- The initial hazard-reduction burn in a Fuels tion varies with several factors, young pine stand requires exacting Forest fuels accumulate rapidly in including the rate of fuel accumula- conditions of wind, humidity, and pine stands on the Coastal Plain. In 5 tion, past wildfire occurrence, values temperature. Higher wind velocities to 6 years, heavy "roughs" can build at risk, and the risk of a fire. The time and cooler temperatures minimize up, posing a serious threat from interval between fires can be as often scorch damage. Southern pine planta- wildfire to all forest resources. as every year although a 3- or 4-year tions averaging 10 to 12 feet in height Prescribed fire is the most practical cycle is usually adequate after the can be burned by experienced people way to reduce dangerous accumula- initial fuel-reduction burn. under the right conditions without tions of combustible fuels under The need to reduce hazardous fuel damage. Young plantations on in- southern pine stands. Wildfires that accumulations in the pine plantations dustrial lands arc often burned for the burn into areas where fuels have been of the South is increasing. Without fuel first time when they are 15 to 20 feet reduced by prescribed burning cause reduction, fire hazard is extremely tall using aerial ignition; close spacing less damage and are much easier to

Winter backing fire in heavy rough Damaging wildfire in heavy rough 3 of ignition spots (e.g., 2 chains by 2 chains), and cool, damp conditions with some wind are a must to avoid crown damage. Subsequent fuel reduction burns need not cover the entire area. The objective is to break up fuel continuity. Fuel reduction on 75 to 80 percent of the area is sufficient. An added advantage of "patchy" burns is that the unburned islands provide cover for wildlife. These unburned patches will not have a dangerous accumulation of fuels at the time of the next burn if they resulted from a lack of fuel during the previous fire. If, however, they were too wet to burn, these islands could result in a hot spot the next time if a heading fire was allowed to sweep through them under appreciably drier conditions. One reason excessive crown scorch should be avoided is Prescribed fire can improve wildlife habitat because, under some circumstances, it can add more fuel to the forest floor than the fire consumed. In some cases overstory pines are seed crop is inadequate, burning can left during harvest as seed trees, and in be postponed. Complete mineral soil others an unevenaged management exposure is not necessary or desirable; system such as shelterwood is used. In a thin layer of litter should remain to Dispose of Logging both situations, the logging debris can protect the soil. Generally, burning Debris still he burned, but you must take more should he done several weeks prior to After harvest, unmerchantable care to protect the remaining trees. seed fall. Timing varies with species limbs and stems arc left either scat- and locality. tered across the area or concentrated at Prepare Sites for logging decks or delimbing gates, Seeding or Planting I mprove Wildlife Habitat depending upon the method of logging. Prescribed burning is useful when Prescribed burning is highly recom- This material is an impediment to both regenerating southern pine by direct mended for wildlife habitat manage- people and planting equipment. If a seeding, planting, or natural regenera- ment where loblolly, shortleaf, wildfire occurs within the next few tion. On open sites, fire alone can ex- longleaf, or slash pine is the primary years, fireline construction can be pose adequate mineral soil and control overstory species. Periodic fire tends severely hindered; the result being competing vegetation until seedlings to favor understory species that require larger burn acreages and higher become established. Where competing a more open habitat. A mosaic of regeneration losses. Although not all vegetation cannot be adequately re- burned and unburned areas tends to large material will he consumed by a duced by fire, follow up with maximize "edge effect" which pro- prescribed fire, what is left will he ex- mechanical or chemical treatment. motes a large and varied wildlife posed so it can be avoided by tractor- The fire will improve visibility so that population. Deer, dove, quail, and plow operators. In stands that produce equipment operators can more easily turkey are game species that benefit a large amount of cull material, the see the stumps of the harvested trees, from prescribed fire. Habitat debris is often windrowed and burned. as well as any other hazards. In addi- preferences of several endangered This practice should, however, be tion, if the area is to be bedded before species, including the Florida panther, avoided whenever practical because of planting, burning first consumes much gopher tortoise, indigo snake, and red- smoke management problems and the of the debris. The result is more tightly cockaded woodpecker are also enhanced potential for site degradation. Broad- packed beds and thus better seedling by burning. Wildlife benefits from cast burning is generally a much better survival. Where herbicides are used to burning are substantial. For example, alternative. If the debris must be piled kill competition, subsequent burning fruit and seed production is stimulated. before burning, construct round will give additional vegetation control. Yield and quality increases occur in "haystack" piles when the debris and This step also permits more efficient herbage, legumes, and browse from underlying ground are both fairly dry. and easier movement of hand-planting hardwood sprouts. Openings are This step will limit the amount of dirt crews. Prescribed fire also recycles created for feeding, travel, and in the pile. Piles containing large nutrients, making them available for dusting. amounts of dirt can seldom he burned the next timber crop. efficiently. They almost always Selecting the proper size, frequency, For natural regeneration, knowledge smolder for long peroids, creating and timing of burns is crucial to the of anticipated seed crop and date of unacceptable smoke problems. successful use of fire to improve earliest seed fall is essential. If the wildlife habitat. Prescriptions should

4 recognize the biological requirements However, with the judicious use of proposition. Generally, fire is required (such as nesting times) of the preferred prescribed fire, the understory can be in combination with other treatments wildlife species. Also consider the managed to limit competition with involving heavy equipment, chemicals, vegetative condition of the stand and, desired species while at the same time or both. In many locations the prefer- most importantly, the changes fire will providing browse for wildlife. red system is a combination summer produce in understory stature and Burning is most effective in con- burn and herbicide treatment. species composition. trolling hardwoods less than 3 inches However, in the lower Appalachians of in diameter at the ground line. Periodic South Carolina. another relatively in- fires throughout the rotation can keep expensive technique is employed. All Manage Competing competing vegetation below this 3-inch residual hardwoods arc felled and the Vegetation threshold. The most desirable season area broadcast burned under exacting for burning and the frequency of burns fuel and weather conditions. Low-value, poor-quality, shade- will vary somewhat by species and tolerant hardwoods often occupy or en- physiographic region. Generally, a croach upon land best suited to grow- winter (dormant season) fire results in ing pine. Unwanted species may crowd Control Insects And less root kill than a late spring or sum- out or suppress pine seedlings. In soils mer burn. One system recommended Disease with a high clay content and in areas in both the Piedmont and Coastal Plain Brownspot disease is a fungal infec- with low rainfall during parts of the is a dormant season burn to reduce in- tion that may seriously weaken and growing season, competition for water, itial fuel mass, followed by two or eventually kill longleaf pine seedlings. nutrients and growing space may more annual (if enough fuel is present) Diseased seedlings tend to remain in significantly lower growth rates of the or biennial summer burns. the grass stage. Control is recom- overstory. Furthermore, understory If not controlled, the hardwoods mended when more than 20 percent of trees and shrubs draped with dead will form a midstory and capture the the seedlings are infected or when needles and leaves act as ladder fuels site once the pine is harvested. If a some of the diseased seedlings are allowing a fire to climb into the large pine component is wanted in the needed for satisfactory stocking. Once overstory crowns. In most situations, next rotation, these unmerchantable the seedlings become infected, burning total eradication of the understory is hardwoods must be removed during is the most practical method of disease neither practical nor desirable. site preparation — an expensive control. Any type of burning that kills

Longleaf pine infected with brownspot needle blight the diseased needles without killing the experienced personnel. Your local I mprove Forage for terminal bud is satisfactory. Burning State forestry office is a good place to the infected needles reduces the begin. Grazing number of spores available to infect the Prescribed burning seems to reduce Prescribed burning improves seedlings. Generally a fast-moving problems from Fomes annosus root grazing in open pine stands on the winter heading fire under damp condi- rot. This fungal disease is less frequent Coastal Plain. Low-intensity burns tions, as exist after passage of a strong where periodic burns have reduced the increase availability, palatability, cold front, is best. Height growth of litter. The fire alters the microenviron- quality, and quantity of grasses and the seedlings often begins the first ment of the forest floor and perhaps forbs. Dead material low in nutrient postfire growing season. destroys some fruiting bodies and value is removed while new growth Reinfection usually occurs quickly cauterizes tree stumps. high in protein, phosphorus, and if there are infected seedlings in un- Prescribed fire has been success- calcium becomes readily available. burned areas near the burned area. If fully used under very exacting fuel and These benefits are manifested in reinfection occurs, additional burns weather conditions to control cone in- increased seasonal cattle weight may be needed. However, longleaf is sects such as the white pine cone beetle gains. Cattle congregate on recently most susceptible to fire immediately (Conophthorus coniperda) while the burned areas so burn location and after it comes out of the grass stage. pest is overwintering in cones on the size must be carefully selected to pre- Therefore, a reburn will likely kill ground. Prescribed burning costs vent overgrazing. One commonly some seedlings, so such a decision mush less than traditional chemical used system is to divide the range in- should be made in consultation with control methods used to control this to three parts and burn one third beetle. 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 eleva- tion within a species' range. There- fore, observe these dates for the preferred species, and time the burn accordingly. For example, wiregrass responds much better to summer burns than it does to dormant season burns.

Enhance Appearance Prescription burning improves recreation and aesthetic values. For example, burning maintains open stands, produces vegetative changes, and increases numbers and visibility Prescribed fire improves range habitat 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 burns, 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. Warm-season grasses promoted by summer burning 6 Improve Access Burning underbrush prior to the sale of forest products improves the efficiency of cruising, timber mark- ing, and harvesting. Removing accumulated material before harvesting also provides greater safety for ti mber markers, loggers and naval stores operators due to better visibility and less underbrush. The reduced amount of fuel helps offset the greater risk of wildfire during harvesting. Moreover, the improved visibility and accessibility often increase the stumpage value of the products. Hikers and other users also benefit from easier travel and increased visibility. Hunters are more likely to get a clear shot. Limited access due to fire exclusion Perpetuate Fire- dependent Species 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 of time. Many endemics are only found the first 1 to 2 years after a fire. Changes in the "natural" fire pattern as a result 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 perpetuate Open stand resulting from annual winter burning 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.

Prescribed Burning= Good Wildlife Habitat Pitcher plants respond to prescribed fire 7 As a stand matures, an increasing phase of the "fell and burn" site- soils, leaching may also move minerals proportion of the nutrients on the site preparation technique commonly used through the soil layer into the ground become locked up in the vegetation in the upper Piedmont and mountains water. Generally, a properly planned and are unavailable for futher use un- should be completed by mid-September. prescribed burn will not adversely til plants die and decompose. Low- This timing allows herbaceous plants affect either the quality or quantity of intensity fires speed up this recycling to seed in and provide a winter ground or surface water in the South. process, returning nutrients back to ground cover. Burning should not be the soil where they are again available done if exposure of highly erosive Effects on Air to plants. Under many conditions, soils is likely. Prescribed fires may contribute to burning may increase nitrogen fixa- Soil should be wet or damp at the changes in air quality. Air quality on tion in the soil and thus compensate time of burning to ensure that an a regional scale is affected only when for nitrogen loss to the atmosphere organic layer will remain after a many acres are burned on the same that results from burning the litter prescribed burn. Moisture not only day. Local problems are more fre- layer. When duff layers are not com- protects the duff layer adjacent to the quent and occasionally acute due to pletely consumed, changes in soil soil, but also prevents the fire from the large quantities of smoke that can pore space and infiltration rate are consuming soil humus. If the forest be produced in a given area during a very slight. If mineral soil is floor is completely consumed, the short period of time. repeatedly exposed, rain impact may microenvironment of the upper soil Smoke consists of small particles clog fine pores with soil and carbon layer will he drastically changed, (particulate) of ash, partly consumed particles, decreasing infiltration rates making conditions for near-surface fuel, and liquid droplets. Other com- and aeration of the soil. tree roots very inhospitable. Damp bustion products include invisible A major concern of the forest soil also aids mopup after the burn. gases such as carbon monoxide, car- manager is how fires affect surface bon dioxide, hydrocarbons, and small runoff and soil erosion. On most Effects on Water quantities of nitrogen oxides. Oxides Lower and Middle Coastal Plain of nitrogen are usually produced at sites, there is little danger of erosion. The main effect of prescribed temperatures only reached in piled or In the steeper topography of the Up- burning on the water resource is the windrowed slash or in very intense per Coastal Plain and Piedmont, potential for increased runoff of rain- wildfires. In general, prescribed fires some soil movement is possible. fall. When surface runoff increases produce inconsequential amounts of However, if the burn is under a after burning, it may carry suspended these gases. Except for organic soils timber stand and some duff remains, soil particles, dissolved inorganic (which are not generally consumed in soil movement will be minor on nutrients, and other materials into prescribed burns), forests fuels con- slopes up to 25 percent. The amount adjacent streams and lakes reducing tain very little sulfur, so oxides of of soil movement will be greater after water quality. These effects seldom sulfur are not a problem either. site preparation with heavy machinery occur after Coastal Plain burns. Pro- Particulates, however, are of than after prescribed burning. blems can be avoided in hilly areas special concern to the prescribed Care must be taken when clearcut or near metropolitan water supplies burner because they reduce visibility. logging slash is burned on steep by using properly planned and con- The amount of particulate put into slopes. Until grass and other vegeta- ducted burns. the air depends on amount and type tion cover the site, surface runoff and Rainwater leaches minerals out of of fuel consumed, fuel moisture con- soil erosion may occur. The burning the ash and into the soil. In sandy tent, and rate of fire spread as deter-

Backing fires produce less smoke than heading tires mined by timing and type of firing in the day a fire is completed, the The repeated, lengthy exposure to technique used. Rate of smoke less likely it is to cause nighttime relatively low smoke concentrations dispersal depends mainly on atmos- smoke problems. More complete over many years can contribute to pheric stability and windspeed. mopup following daytime burning respiratory problems and cancer. But, Effects of smoke can be managed and nighttime burning only under the risk of developing cancer from by burning on days when smoke will very stringent prescriptions can exposure to prescribed fire has been blow away from smoke-sensitive- minimize the occurrence of these estimated to be less than 1 in a areas. Precautions must be taken problems. Your local State forestry million. when burning near populated areas, office can help with planning night- Although the use of herbicides in highways, airports, and other smoke- time burns. forest management has increased all sensitive areas. Weather and smoke chemicals are now tested before being management forecasts arc available as Effects on Human approved for use, and we arc more a guide for windspeed and direction. careful than ever to minimize their Any smoke impact downwind must Health and Welfare potential danger. Many of them break be considered before lighting the fire. Occasional brief exposure of the down rapidly after being applied. The burner may be liable if accidents general public to low concentrations Moreover, both theoretical calcula- occur as a result of the smoke. All of drift smoke is more a temporary tions and field studies suggest that burning should be done in accord- inconvenience than a health problem. prescribed fires are hot enought to ance with applicable smoke manage- High smoke concentrations can, destroy any chemical residues. ment guidelines and regulations. however, be a very serious matter, Minute quantities that may end up in During a regional alert when high particularly near homes of people smoke are well within currently- pollution potential exists, all pre- with respiratory illnesses or near accepted air quality standards. scribed burning should be postponed. health-care facilities. Threshold limit values (TLV's) are Nighttime burning should be done Smoke can have negative short- often used to measure the safety of with additional care because a tem- and long-term health effects. Fire herbicide residues in smoke. Ex- perature inversion may trap the management personnel who are exposed pected exposure rates of workers to smoke near the ground. This smoke to high smoke concentrations often various brown-and-burn combinations can create a serious visibility hazard, suffer eye and respiratory system have been compared with TLV's. especially in the presence of high irritation. Under some circumstances, They showed virtually no potential humidities (which occur on most continued exposure to high concen- for harm to workers or the general nights). In particular, smoke mixing trations of carbon monoxide at the public. with existing fog will drastically combustion zone can result in impaired There is at least one group of reduce visibility. Cool air drainage at alertness and judgement. The proba- compounds carried in smoke that can night will carry smoke downslope, bility of this happening on a prescribed have an immediate acute impact on causing visibility problems in low- fire is, however, virtually nonexistent. individuals. When noxious plants lands and valleys. On the Coastal Over 90 percent of the particulate such as poison ivy burn, the smoke Plain, nighttime air drainage often emissions from prescribed fire are can cause skin rashes. These rashes follows waterways. Conditions can be small enough to enter the human can be much more widespread on the especially hazardous near bridge respiratory system. These particulates body than those caused by direct con- crossings because of the higher can contain hundreds of chemical tact with the plants. If you breathe humidity there. Of course, the earlier compounds, some of which are toxic. this smoke, your respiratory system can also be affected. Effects on Wildlife 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 improv- ing 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 Smoke sensitive areas can be impacted by prescribed fire nests are not being used. Also, virtually all the types of prescribed fire used in the South provide ample escape routes for wildlife. For example, a large tract was operationally burned with aerially-ignited spot fires and immediately examined for wildlife mortality. Fish and game agency personnel found none, but noted deer moving back into the still-smoking burn. 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. Management of the endagered red- cockaded woodpecker presents a special problem because of the copious amounts of dried resin that stretch from the nest cavity toward the ground. The bird requires habitat historically maintained by fire, even though these pitch flows can be Generally, the more immediate un- interesting rock outcrop. The smutty ignited, carrying fire up to the cavity. favorable impacts such as smoke and appearance of the ground will "green This is unlikely, however, if short ash, topkilled understory plants, and up" fairly quickly. Any scorched needles flame lengths are prescribed. Fuel a blackened forest floor are necessary will soon drop and not be noticeable. can also be raked from around cavity to achieve two major benefits — Flowers and wildlife will increase. trees as an added precaution. increased visual variety and increased Some important points are: 1) The Prescribed fire does not benefit visual penetration. apparent size of a burn can be reduced fish habitat, but it can have adverse Variety or diversity in vegetative by leaving unburned islands to create effects. Riparian zone (streamside) cover will create a more pleasing, a mosaic pattern of burned and un- vegetation must be excluded from general visual character to the stand. burned area. 2) Where hardwood in- prescribed burns to protect high Similarly, scenic qualities of the forest clusions are retained, make sure they quality plant and animal habitat, and can be better appreciated if the stand are large enough to be relevant to the water quality. When shade is removed, can be made more transparent. An observer. 3) Observer criteria must be water temperatures will increase. example is the reduction of an under- understood if reactions to a burn are Burning conditions are often un- story buildup along a forest road that to be predicted. Personal reactions favorable along streams because of will permit the traveler to see into the will depend on observer distance, increasing fuel moisture, making line interior of the stand, perhaps to a duration or viewing time, and aspect. plowing optional. But a buffer zone landscape feature such as a pond or should always be left. If in doubt, a control line should be put in. Effects on Aesthetics The principal effect of prescribed burning on aesthetics can be sum- marized in one word: contrast. Con- trast, or change from the preburn landscape, may be postive or negative depending largely on personal opinion. What may be judged an improvement in scenic beauty by one may be considered undesirable by another. Many of the undesirable impacts are relatively short term and can be minimized by considering scenic qualities when planning a burn. For example, the increased turbulence and updrafts along roads and other forest openings will cause more intense fire with resulting higher tree trunk char and needle scorch. Aesthetics can be enhanced by prescribed fire 12 Weather and Fuel Considerations

Important Weather Elements A general understanding of the separate and combined effects of several weather elements on the behavior of fire is needed if you are to plan and execute a good burn. Wind, relative humidity, temperature, rainfall, and airmass stability are the more important elements to consider. These factors influence fuel moisture which is critical to success. Because weather and fuel factors interact, an experienced prescribed burner can conduct a successful burn even with one or more factors slightly outside the desired range as long as they are offset by other factors. You should become familiar with local weather patterns that are favorable for prescribed burning as well as local "watchout" situations. Good winter prescribed burning conditions often exist for several days after the passage of a cold front that has brought 1/4 to 3/4 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. Before starting to burn, obtain the latest weather forecast for the day of the burn and the following night. When possible, get a 2-day weather outlook. Knowledge of weather is the key to successful prescribed burning, and is mandatory for proper management of smoke produced by burning.

13 Knowledge of weather is essential for a successful burn Successful backing fires need steady winds

Sources of Weather Danger Rating System (NFDRS) Windspeed readings for most fire- Information indices which are calculated from weather forecasts are, however, taken these measurements should not he 20 feet above ground at open loca- Ordinarily, four sources of used. This system was designed to tions. Windspeeds in fire-weather weather information are available. provide a worst-case scenario for forecasts are the maximum expected Use one or more of them before and wildfire control over very large areas. and not the average for the day. The during prescription fires. The sources It was not designed as a planning tool minimum 20-foot windspeed for burning are: for prescribed burning! is about 6 mph and the maximum is ■ NATIONAL WEATHER Weather observations should be about 20 mph. These are the most SERVICE made at the prescribed burn site desirable winds for prescribed burning, ■ STATE FORESTRY AGENCIES i mmediately before, during and im- but specific conditions may tolerate ■ LOCAL OBSERVATIONS mediately after a fire. Such observa- other speeds. As a general rule ■ PRIVATE WEATHER tions are important because they higher windspeeds are steadier in FORECASTING SERVICES serve as a check on the applicability direction. Local National Weather Service of the forecast and keep the burning Relatively high winds quickly offices will furnish weather forecasts crew up-to-date on any local in- dissipate the heat of a backing fire. and outlooks via radio and television. fluences or changes. Take readings in The result is less crown scorch than Spot weather forecasts are also a similar area upwind of the fire to from a fire backing into a low-speed available, but their value depends avoid heating and drying effects of wind. In-stand windspeeds should be upon the forecaster's knowledge of the fire. Do this at 1- to 2- hour inter- in the low to middle range (1 to 2 local conditions. Inexpensive radios vals, or more often if changes in fire mph) when heading fires are used. are also available that continually behavior are noticed. Measurements With high winds, heading fires monitor National Oceanic and At- taken in an open area, on a forest spread too rapidly and become too mospheric Administration (NOAA) road, and in a stand are likely to dif- intense. On the other hand, enough weather-related information and fer widely. Easy-to-use belt weather wind must be present to keep the forecast updates. Do not rely solely kits that include a psychrometer and heat from rising directly into tree on the NOAA broadcasts because this an anemometer are available. By crowns. Mature southern pine stands information is not specific enough for using this kit and observing cloud with a sparse understory can be smoke-management planning. conditions, a competent observer can burned at very low windspeeds — The best source of information in- obtain a fairly complete picture of the just enough to give direction to the cluding current forecasts and outlooks current weather. fire. is generally the local office of your Of greater importance than wind- State forestry agency. The person you speed is the length of time the wind talk to can often help you interpret Wind blows from one direction. Presistent the forecast, give you any warnings, Underburning wind directions occur frequently dur- and pass on pertinent information Prescribed fires behave in a more ing winter, especially following such as other burns planned for that predictable manner when windspeed passage of a cold front when winds day, The prescribed burner should and direction are steady. Onsite are typically from the west or take full advantage of such services. winds vary with stand density and northwest. As these winds slowly All southern State forestry agen- crown height. Windspeed generally shift clockwise over the next few cies and national forests, as well as increases to a maximum in the early days, they become weaker and less many military bases and private con- afternoon and then decreases to a steady. Winds with an easterly com- cerns operate fire-danger stations. minimum after sunset. The preferred ponent are generally considered The basic weather parameters range in windspeed in the stand is 1 undesirable for prescribed burning. measured at these sites are very to 3 mph (measured at eye-level) for However, along the coast, sea and useful. However, National Fire most fuel and topographic situations. land breezes are often utilized. Ir-

14 respective of direction, a forecast of the movement of the smoke column. temperature and humidity. wind steadiness should always be ob- Moderate transport windspeeds allow Preferred relatiye humidity for tained. For sites near the coast, also a convection column to develop that prescribed burning varies from 30 to obtain the expected time of sea exhausts the smoke high into the 55 percent. Under special conditions, breeze arrival and departure. atmosphere where it quickly disperses a wider range of relative humidities, The most critical areas, with with a minimum impact on ground- as low as 20 percent and as high as regard to fuel and topography, should level air quality. Before setting a fire 60 percent, can produce successful be burned when wind direction is that will generate a convection col- burns. When relative humidity falls steady and persistent. Relatively easy umn, however, obtain information on below 30 percent, prescribed burning burns can be conducted under less the existing and forecast wind pro- becomes dangerous. Fires arc more desirable wind conditions. Topography, files. If an adverse profile exists, it is intense under these conditions and and local effects such as stand open- likely to result in an unacceptably spotting is much more likely; pro- ings, roads, etc. may have a bearing high spotting potential. Fire behavior ceed only with additional precau- on favorable wind conditions and characteristics are associated With tions. When the relative humidity is should always he considered when various wind profiles. They are 60 percent or higher, a fire may leave planning a burn. described in Byram's publication, unburned islands or may not burn hot listed in the Suggested Reading enough to accomplish the desired section. Once the fire has died down result. PREFERRED IN-STAND WIND: and smoke production is from The moisture content of fine, dead 1 MPH to 3 MPH smoldering combustion, surface wind fuel such as pine needles and dried is necessary to ensure good smoke grasses responds rapidly to changes dispersion. in relative humidity. However, there Debris Burning is a timelag involved for fuels to Winds are stronger in open areas Relative Humidity achieve equilibrium with the moisture than they are in the forest. Because Underburning condition of the surrounding at- there is no overstory to protect, wind Relative humidity is an expression mosphere. Also, previous drying and is not needed to cool the heated com- of the amount of moisture in the air wetting will influence fuel moisture. bustion products. However, from a compared to the total amount the air Therefore, the relative humidity and smoke management standpoint, the is capable of holding at that temperature fuel moisture must be assessed stronger the wind the better the and pressure. Each 20° rise in temp- independently. dispersion—provided there are no erature (which often occurs during downwind smoke-sensitive areas that the morning hours on a clear day) will be impacted. When broadcast reduces the relative humidity by PREFERRED HUMIDITY: burning, eye-level winds over 3 to 4 about half, and likewise, each 20° 30 TO 55 PERCENT mph can create containment problems drop in temperature (which often oc- if a heading fire is used. With piled curs in early evening) causes relative or windrowed debris, eye-level winds humidity to roughly double. When a Debris Burning of 8-10 mph can be tolerated by ad- cold front passes over an area, the air Relative humidity (along with justing the firing pattern. behind the front is cooler and drier temperature) controls fuel moisture Wind direction may change than the old airmass it is replacing. content up to about 32 percent. substantially with height, but it is The result is a drop in both Liquid moisture such as rain or dew these transport winds that regulate

The belt weather kit and additional wind meter must contact a fuel for moisture con- high. Temperatures below freezing, winds, and low humidities will tent to rise above 32 percent, and the on the other hand retard fire intensity generally result in several days of increase depends upon duration as because additional heat is required to good prescribed fire conditions with well as the amount of precipitation. convert ice to liquid water before it adequate soil protection. Recently-cut pine tops have a dry- can be vaporized and driven off as On clay soils, such as are found in ing rate that is somewhat independent steam. Consequently, it does not take the Piedmont, much of the rainfall is of relative humidity as long as the much moisture under these conditons lost through surface runoff, and dura- mositure content of fresh tops to produce a slow-moving fire that tion is more important than amount. (needles still green) is above about 32 will leave unacceptably large areas For example, 1 inch of rain occurring percent. Once this material initially unburned. in 1/2 hour will not produce as large dries to a moisture content below 32 a moisture gain as 1/2 inch falling percent, it behaves as a dead fuel and over a 2 hour period. becomes much more responsive to PREFERRED WINTER daily fluctuations in relative humidity. TEMPERATURE: The response to changes in relative BELOW 60°F PREFERRED SOIL humidity is much more rapid in fine MOISTURE: DAMP dead fuels suspended above the ground than in those that have Debris Burning become part of the litter layer. These Cleared areas are often burned Debris Burning elevated needles and other suspended when ambient air temperatures are dead materials are not in contact with Generally, rain has a much greater high. There is no overstory present to effect on fuel moisture in cleared the damp lower litter and are more worry about and surface heating from exposed to the sun and wind. areas than under a stand because direct sunlight usually increases the none is intercepted by tree canopies. When burning piled debris, once mixing height which helps disperse the larger-diameter fuels ignite, in- However, fuels also dry much faster the smoke. creases in relative humidity have little in cleared areas because of increased It is particularly important to use effect on fire behavior during the ac- sunlight and higher windspeeds. This an ignition pattern such as center differential drying can often be used tive burning phase. Low humidities tiring when ambient air temperatures (below 30 percent), however, will to advantage from a fire-control are high. This tactic draws the heat promote spotting and increase the standpoint. Burn the cleared area into the cleared area and prevents several days after a hard rain while likelihood of tire spreading between heat damage to trees in adjacent piles. fuels in the surrounding forest are stands. still damp. Burning under these con- Temperature Rainfall and Soil ditions assures good soil moisture. However, when burning cleared Underburning Moisture areas, soil damage is as much a func- The average instantaneous lethal Underburning tion of fire intensity and duration as temperature for living tissue is about Because rainfall affects both fuel it is of soil moisture. Intense, long- 145°F. Air temperatures below 60°F moisture and soil moisture, you duration fires will bake the soil are recommended for winter under- should have some idea of the amount regardless of the moisture present. burns because more heat is needed to of rain falling on the area to be Both the chemical and physical prop- raise foliage or stem tissue to lethal burned. In winter, rainfall is fairly erties of the soil can be altered. This temperature levels. When the objec- easy to forecast throughout the South. type of fire should be avoided, tive is to control undesirable species, In summer, when shower activity especially on clay soils and steep growing-season burns with ambient prevails, predicting rainfall at in- slopes. These undesirable fire effects air temperatures above 80°F are dividual locations is much more are often produced when burning recommended. These conditions in- difficult. The only reliable method to windrowed or piled debris, and are crease the likelihood of reaching kill- determine the amount of precipitation one reason piling or windrowing ing temperatures in understory stems that actually falls is to place an slash prior to burning are and crowns. Of course, the overstory inexpensive rain gauge on the site. discouraged. pines must be large enough to escape The importance of adequate soil injury. Larger trees have thicker bark moisture can't be overemphasized. Fine-fuel Moisture and their foliage is higher above the Damp soil protects tree roots and flames, which allows more room for Underburning microorganisms. Even when burning Fine-fuel moisture is strongly in- the hot gases to cool before reaching to expose a mineral soil seedbed it is the crowns. fluenced by rainfall, relative humidity, desirable to leave a thin layer of and temperature. The preferred range Temperature strongly affects organic material to protect the soil moisture changes in forest fuels. in actual (not calculated) fine-fuel surface. Burning should cease during moisture of the upper litter layer (the High temperatures help dry fuels periods of prolonged drought and quickly. When fuels are exposed to surface layer of freshly fallen needles resume only after a soaking rain of and leaves) is from 10 to 20 percent. direct solar radiation, they become at least 1 inch. As soil moisture con- much warmer than the surrounding Burning when fine-fuel moisture is ditions improve, less rain is needed below 6 or 7 percent can result in air. Moisture will move from the before burning. If recent precipitation warmer fuel to the air even though damage to plant roots and even the has been near average, 1/4 to 1/2 inch soil. When fine-fuel moisture ap- the relative humidity of the air is of rain followed by sunny skies, brisk

16 Fuel-moisture sticks Effects of humidity and days since rain on fine-fuel moisture proaches 30 percent, fires tend to estimates can be obtained just before On-the-ground knowledge of fuels burn slowly and irregularly, often ignition. These values will differ must be incorporated into the resulting in incomplete burns that do slightly from actual fine-fuel prescription. not meet the desired objectives. moistures, but are fairly represen- Fuel moisture also influences However, when areas with very heavy tative of most southern fuel types. smoke production. When very damp fuel buildups or extensive draped They are much closer to actual fine- woody fuels burn, large amounts of fuels are burned, moisture content fuel moistures than are calculated or characteristic white smoke are given should be 20 to 25 percent to keep tabular values. off. Much of the visible smoke plume fire intensity manageable, especially Lower litter should always be is actually condensed water vapor. if aerial ignition techniques are used. checked before burning to make sure Fine-fuel moisture values obtained it feels damp. This will help ensure from NFDRS tables on fire-behavior that some remains, even though char- PREFERRED FINE-FUEL models are considerably less than red, to leave a protective covering MOISTURE: these actual values. over the soil. Generally, the moisture 10 TO 20 PERCENT Some experienced practitioners content increases from the litter sur- can accurately estimate fuel moisture face down through the duff layer to by examining a handful of litter. the soil. Exceptions can occur after a However, the only sure way to tell is light shower, or in the morning after Debris Burning to take a sample and ovendry it. a heavy dew. In these cases, fires Harvested areas should be burned Tables and equations in the National often burn more intensely than would when fuels are dry. They will ignite Fire Danger Rating System and be expected from just looking at the easier, burn more quickly and com- BEHAVE can be used to estimate upper-litter-layer moisture content. pletely, shortening the time necessary fine-fuel moisture, but the results are When burning on organic soils this to complete the burn. Less mopup invariably underestimates (because phenomenon can have drastic conse- will he required and the impact on they are worst-case values designed quences. If the fire dries the moist air quality will be reduced. The short for use in predicting wildfire surface layer of peat, the organic soil but severe summer droughts common behavior). One simple test that will will ignite. These fires can impact an throughout much of the South pro- give a very rough estimate of the area for many weeks in spite of con- vide ideal burning conditions on upper-litter-layer moisture content is trol efforts, causing extensive smoke cleared areas, provided soil moisture to pick up a few pine needles and in- problems. does not get too low. dividually bend each in a loop. If the The speed with which fine fuels To avoid the possibility of un- needles snap when the width of the respond to changes in humidity necessary damage to the site, debris closing. loop is about 1/4 to 1/2 inch, depends on fuelbed characteristics should be burned as it lies (broadcast their moisture content is between 15 such as whether the fuelbed consists burned) rather than piled. Because and 20 percent. If they do not snap of compacted hardwood leaves or fuels on logged areas receive full in two, they are too wet to burn well. jack-strawed pine needles. Different solar radiation, they dry before sur- If they crumble into small pieces they fuel types can reach different moisture rounding forest fuels do. It takes at are exceedingly dry and even if the contents under the same humidity least several weeks after cutting for lower litter is moist, the fire may conditions. For example, grassy the severed tree tops to cure. Once cause damage and be difficult to con- openings containing cured material the needles turn a greenish-yellow trol. Fuel moisture sticks that respond can be burned within hours of a to weather changes like 10-hour fuels drenching rain if good drying condi- are available. With a good set of tions exist. Because of these natural scales and proper placement of the variations, recommended fine-fuel Prescribed Burned Forests sticks, acceptable fuel moisture moisture values are only guidelines. are More Productive

17 and the hardwood leaves wither, the windspeeds above 9 mph arc because of the large temperature dif- debris is ready to burn. Cleared areas desirable for good smoke dispersion. ference between the smoke and sur- can then be safely burned soon after Some prescribed burners on the rounding air. The column will con- a rain, before adjacent forest fuels Ozark Plateau believe their fires tinue to build in height as long as it dry enough to burn well. Ten-hour become difficult to control when the remains relatively stationary and is fuel moisture (fuels 1/4 to 1 inch in mixing height is greater than 6,500 heated by new combustion products diameter, such as branches and small feet. faster than it is being cooled. The stems) is a better indicator of burning The old adage that hot air rises is stronger the convective activity, the conditions in slash fuels than is fine- true but only as long as it is warmer stronger the indrafts into the fire. fuel moisture. Fuel moisture sticks than the surrounding air. Thus, stable This effect increases fire intensity by will give excellent results. One set of air tends to restrict convection col- producing even stronger convective "sticks" can be placed on the area to umn development and produces more activity. Eventually spotting, crown- be burned and another in the nearby uniform burning conditions. ing and other indicators of erractic undisturbed forest. Let the sticks However, combustion products are fire behavior develop. Supress such a become acclimated for at least 2 held in the lower layer of the at- fire as quickly as possible to hold weeks before reading. Many mosphere (especially under damage to a minimum. With adequate managers consider the area ready to temperature inversions). Visibility is planning, this situation rarely develops burn when the moisture content of li kely to be reduced because of when underburning, using conven- the sticks on the logged area reaches smoke accumulation. As the earth tional ground-ignition techniques. about 10 percent while that of those cools each night, the air near the However, when using aerial ignition in the forest is still above 15 percent. ground is cooled more than the air techniques at the high end of the If the burn objective is to consume above, forming a stable layer. prescription window, you can ignite larger fuels (over 2 to 3 inches in Because this cold air is denser, it too much area too quickly. This ac- diameter), piling will probably be drains into low-lying areas such as tion results in severe damage to the necessary. Piling in wet weather swamps and bottomlands, carrying overstory. The behavior of the first should be avoided. Keep the piles with it smoke from smoldering row or two of spots should warn the small and free of dirt. Allow fresh stumps, branches and other debris. burning boss to halt ignition and logging debris to cure for several When the atmosphere is unstable, observe fire behavior before making a weeks before piling because drying the decrease in temperature with decision to adjust the ignition pattern, conditions are exceedingly poor in height exceeds 5.5°F per 1,000 feet. change firing techniques, or terminate the middle of a pile, especially if it is Once a parcel of air starts to rise, it the burn. compacted or contains much dirt. will continue to rise until it cools to Much of the smoke problem associated the temperature of the surrounding with burning piled debris is caused air. Such conditions promote convec- by inefficient combustion of damp, tion and rapid smoke dispersion but, PREFERRED STABILITY: soil-laden piles. These piles may if severe, can make fire control SLIGHTLY UNSTABLE OR smolder for days or weeks. difficult. NEUTRAL A neutral atmosphere is one in Airmass Stability and which a rising parcel of air remains at the same temperature as its sur- Atmospheric Dispersion PREFERRED MIXING HEIGHT: rounding environment (i.e., the Underburning temperature decrease with altitude 1,700 TO 6,500 FEET ABOVE Atmospheric stability is the equals the dry adiabatic lapse rate of GROUND resistence of the atmosphere to vertical 5.5°F per 1,000 feet). Smoke disper- motion. When the atmosphere is sion in a neutral atmosphere can be stable, temperature decreases slowly adequate if windspeed is sufficiently as altitude increases (less than 5.5°F PREFERRED TRANSPORT high. But remember, you need to ac- per 1,000 feet). Under very stable WINDSPEED: count for the effect of the wind on conditions, inversions may develop in 9 TO 20 MPH fire control. which temperature actually increases Obtain forecasts of mixing height, with height. The distance from the transport windspeed, and atmospheric ground to the base of this inversion stability, but also observe local in- Debris Burning layer is called the mixing height. dicators at the fire site. Indicators of Strong convection over cleared Under less stable atmospheric condi- a stable atmosphere arc steady winds, areas burned for site preparation or tions, other factors beyond the scope clouds in layers, and poor visibility slash disposal helps vent smoke into of this discussion determine the the upper atmosphere. A convection height of the mixing layer. In either due to haze and smoke hanging near the ground. Unstable conditions are column will continue to rise until it case, the mixing layer is defined as cools to the temperature of the sur- the layer of air within which vigorous indicated by dust devils, gusty winds, clouds with vertical growth, and rounding air or until it reaches the mixing of smoke and other pollutants base of an inversion layer. A well- takes place. The average windspeed good visibility. A prescribed fire generates vertical developed convection column produces throughout the mixing layer is called strong indrafts which help confine the transport windspeed. Mixing motion by heating the air. If the atmosphere is unstable, the hot com- this type fire to its prescribed area. heights above 1,700 feet and transport bustion products will rise rapidly Care must be taken to ensure that all

18 burning materials sucked into the convection column burnout before being blown downwind and dropping to the ground to act as firebrands. Whenever a burn site is in hilly terrain, diurnal slope winds must be considered. As soon as a slope is heated by the morning sun, an upslope breeze results. This breeze will increase to a maximum (<8 mph) during the early afternoon and end as the slope cools in the evening. As the slope continues to cool, a downslope wind will develop, reaching a maximum (<5 mph) after midnight. This breeze will end after sunup as the slope again begins its daily heating cycle. If you ignite a tire at the base of a slope during the day, differential heating will be greatly increased. The fire will rapidly spread uphill, giving High fuel moistures produce lots of smoke the combustion products added lift to help vent them into the atmosphere. However the nighttime downslope wind will have the opposite effect, concentrating any drift smoke in low areas.

Weather is the Vital Element of Prescribed Burning -- Use the Weather Forecasts

Stable conditions or a low mixing height keep smoke near the ground

Unstable conditions and/or a high mixing height provide for rapid smoke dispersion 19 Firing Techniques

General compensates for its faster movement. the heading fire would be greater. In Generally, backing fires consume a backing fire, the released heat Various firing techniques can be more forest floor fuels than do energy is concentrated closer to the used to accomplish a burn objective. heading fires. The total heat applied ground. The technique chosen must be corre- to a site may be roughly equal for lated closely with burning objectives, both heading and backing fires, as fuels, topography, and weather factors long as additional fuels are not in- to prevent damage to forest resources. volved. This result can be expected The proper technique to use can change even though the fireline intensity of as these factors change. Atmospheric conditions should be favorable for smoke to rise into the upper air and away from smoke-sensitive areas such as highways, airports, and urban areas. Based on behavior and spread, fires either move with the wind (heading fire), against the wind (backing fire), or at right angles to the wind (flanking fire). The movement of any fire can be described by these terms. For example, a spot fire would exhibit all three types. Heading fire is the most intense because of its faster spread rate, wider flaming zone, and longer flames. Backing fire is the least intense, having a slow spread rate regardless of windspeed. This type of fire has a narrow flaming zone, and short flames. Flanking fire intensity is intermediate. The slope of the land has an effect on rate of spread similar to that of wind. If you encounter slight variations in fuel volumes or weather conditions, consider combining two or more firing techniques to achieve the desired result. A solid line of fire always spreads faster and thus builds up intensity quicker than does a series of spot ignitions spaced along the same line. Intensity increases abruptly when two fires burn together. The magnitude of this increase is greater when fires converge along a line rather than along a moving point. The line of crown scorch often seen paralleling a downwind control line delineates the zone where a heading fire and a backing fire met. Residence time is the time it takes the flaming zone to move past a given point. The residence time of heading and backing prescribed fires is often about the same because the deeper flame depth of a heading fire Heading fire may be used with light fuel loadings 20 Backing Fire A backing fire is started' along a baseline (anchor point), such as a road, plow line, stream or other barrier, and allowed to back into the wind. Variations in windspeed have little effect on the rate of spread of a fire burning into the wind. Such fires proceed at a speed of 1 to 3 chains per hour. Backing fire is the easiest and safest type of prescribed fire to use, provided windspeed and direction are steady. It produces minimum scorch and lends itself to use in heavy fuels and young pine stands. Major disadvantages are the slow progress of the fire and the increased potential for feeder-root damage with increased exposure to heat if the lower litter is not moist enough. When a large area is to be burned, it often must be divided into smaller blocks with interior plow lines (usually every 5 to 15 chains). All blocks must be ignited at about the same time to complete the burn in a timely manner. In-stand winds of 1 to 3 mph at eye level are desirable with backing fires. These conditions dissipate the smoke and prevent heat from rising directly into tree crowns. When the relative humidity is low, a steady wind is blowing, and fuels are continuous, an excellent burn can be anticipated once the fire backs away from the downwind control line. Under such conditions, however, extra care must be taken to make sure the initial fire doesn't spot across the line.

Factors Associated with Backing Fires: ■ Must be ignited along the down- Young wind control line. Reproduction ■ Use in heavy roughs. ■ Use in young stands (minimum basal diameter of 3 inches) when air temperature is below 45°F. ■ Normally result in little scorch. ■ Costs are relatively high because of additional interior plow lines and extended burning period resulting from slower movement of the fire. ■ Not flexible to changes in wind direction once interior lines are plowed. ■ Requires steady in-stand winds (optimum: 1 to 3 mph). ■ Will not burn well if actual fine- fuel moisture is above 20 percent. ■ Requires good fuel continuity to carry well. Backing fire technique ■ A single torch person can progressively ignite lines. 21 Strip-Heading Fire Factors Associated with Strip- ■ Needs just enough wind to give heading Fires In strip-headfiring, a series of direction (1 to 2 mph in-stand). ■ Secure the downwind base line lines of fire are set progressively up- ■ Cost is lower than other line- before igniting a heading fire. wind of a firebreak in such a manner firing techniques because fire pro- ■ that no individual line of fire can Do not use in heavy roughs. Con- gress is rapid and few plow lines are sider alternative techniques if fire- develop to a high energy level before required. free interval exceeds 3 years. it reaches either a firebreak or ■ The technique can accommodate another line of fire. A backing fire is ■ Winter use is best because cool wind shifts up to about 45 degrees. weather (below 60°F) helps avoid generally used to secure the base line ■ Flame lengths increase whenever and the remainder of the area then crown scorch. heading fire converges with a backing ■ Use in medium-to-large treated with strip-heading fires. Strips fire, thereby increasing the possibility sawtimber. May be used for annual are often set 1 to 3 chains apart. The of crown scorch. plantation maintenance burns after in- distance between ignition lines is ■ A single torch person can pro- itial fuel reduction has been determined by the desired flame gressively ignite strips. accomplished. length. This distance can be varied ■ Do not force a burn on a marginal ■ Can be used in "flat" fuels such as within a fire to adjust for slight day at the low end of the prescription hardwood leaves. changes in topography, stand density, window. The fire may burn slowly ■ Is a good method for brownspot weather, or the type, amount or until after the crew leaves, then pick control. distribution of fuel. Compensation up intensity and escape. ■ Because fire movement is fast, for minor wind direction changes can large blocks can be burned. he made by altering the angle of strip fire with the base line. Treat major ■ Can be used with high relative changes in fuel type separately. An humidity (50 to 60 percent) and high actual fine-fuel moisture (20 to 25 effective method of reducing fire in- percent). tensity is to use a series of spots or short 1- to 2-foot-long strips instead of a solid line of fire. An added advantage of these short strips or spots is that driptorches will not have to be filled as often. Strip-heading fires permit quick ignition and burnout, and provide for smoke dispersal under optimum conditions. However, higher intensities will occur wherever lines of fire burn together, increasing the likelihood of crown scorch. Occassionally, on areas with light and even fuel distribution, a heading fire may be allowed to move over the entire area without stripping to better accomplish the objective(s). This method reduces the number of areas of increased fire intensity that occur each time two fires burn together. Caution: Be sure the fire will not escape control. First set a backing fire along the downwind control line and allow it to burn out.a strip wide enough to control the heading fire.

22 Flanking Fire This method of firing can stand Factors Associated with Flanking little variation in wind direction and The flanking-fire technique con- Fires: requires expert crew coordination and ■ Always secure downwind base line sists of treating an area with lines of timing. For safety, all lines of flank first. fire set directly into the wind. The fire should be ignited simultaneously ■ Fuel loading should be light to lines spread at right angles to the and all torch people should keep wind. This technique requires con- medium—less than 8 tons per acre. abreast of one another. If only one or siderable knowledge of fire behavior, ■ Wind direction must be steady. two torch people are available, this ■ particularly if used by itself. It is Best used in medium-to-large technique is usually altered to set the sawtimber. used quite often to secure the flanks ignition lines 45 degrees into the wind. of a strip-heading fire or backing fire ■ Allows fast area ignition. In the Piedmont, any ignition line ■ Needs few control lines. as it progresses. It is sometimes used that drops perpendicularly off a ridge ■ In areas with a high understory, to supplement a backing fire in areas creates a flanking fire under no-wind of light fuel or under more humid multiple torch people are needed and conditions. If several lines are ignited weather conditions. It is useful on a coordination is very important. Use off the end of a ridge or knoll, the radio communications whenever torch small area or to facilitate burning a pattern looks like a chevron or maple people cannot see one another. large area in a relatively short ti me leaf. ■ Useful in securing flanks of other when a line-heading fire would be fire types. too intense.

Flanking fire technique 23 Point Source Fires tent by changing the time between ig- poral and spatial changes in fuel and nition points within a line, the weather. A prudent burning boss will often distance between points, and the Intensity is decreased by widening switch from strip-heading fires to distance between lines. Thus the the interval between ignition points point source fires as the day pro- balancing act between spacing and along a line. If fireline intensity is gresses and continuous lines of fire timing has to be continually adjusted still too high after doubling this inter- become too intense. When properly as fire behavior reacts to both tem- val while maintaining a 2-chain executed, a grid of spot ignitions will produce a fire with an intensity much greater than that of a line-backing fire but somewhat less than that of a line-heading fire. Timing and spacing of the individual ignition spots are the keys to the successful application of this method. First a line backing fire is ignited across the downwind side of the block and allowed to back 10 to 20 feet into the block to increase the effective width of the control line. A line of spots is then ignited at some specified distance upwind of the backing fire and the process continued until the whole block has been ignited. To minimize crown scorch, ignition-grid spacing is selected to allow the spots along a line to head into the rear of the spots along the downwind line before the flanks of the individual spots merge to form a continuous flame front. The merger Point source ignitions of successive ignition lines thus takes place along a moving point rather than along a whole line at the same time. Merger along a moving point can be ensured by beginning with a closely spaced square grid (2 chains by 2 chains is recommended). Close spacing between lines helps the individual spots develop, but ensures that the head of one spot will burn into the rear of the downwind spot before the heading fire's potential flame length and intensity are reached. Of course, the closer the spacing, the more merging points you have. You must be aware that a large number of small fires burning simutaneously can produce the same kind of explosive convective energy as a single large fire because too much heat energy is released too rapidly. This situation is discussed more fully under the section on Aerial Ignition. Rectangular grids with wider spacing between lines than within a line should not be used initially because such a pattern may allow the spots along a line to merge into a line of heading fire before running into the rear of the downwind spots. Once the first few lines have been ignited and fire behavior has been assessed, intensity can be regulated to some ex- Grid or point source ignition technique 24 distance between lines, firing should throughout the day. Burn until fires containing potassium permanganate. be halted. Allow the area to burn verge on getting "too hot'.' Then either The balls are injected with ethylene with a backing fire or plow it out. quit burning or resort to backing glycol and immediately jettisoned Although intensity at the head of an fires only. before the chemicals react thermally individual spot is increased by widen- ■ Continually modify the ignition to produce a flame that consumes the ing the distance between lines, the grid to take advantage of topography ball. The dispensing machine can be average intensity of the burn as a and changes in understory fuels. mounted in small airplanes or whole is usually somewhat lower. ■ Costs are low because firing is helicopters. The ping-pong ball Check to see that convergence-zone rapid and no interior control lines system works best in continuous fuels flame lengths are within tolerable need to be constructed. or in areas where a mosaic burn pat- li mits, and that other fire behavior tern is desired. parameters appear satisfactory. If Aerial Ignition The helitorch is simply a giant everything is within prescription, you driptorch and drum of gelled gasoline can increase both between- and When ground ignition techniques mounted or slung under a helicopter. within-line distances. This step will are used, the downwind spots will The helitorch is well suited for reduce ignition time, and decrease usually coalesce and burn out before discontinuous fuels such as those in the number of ignitors used. The the whole block has been ignited. In clearcuts because this system emits a number of convergence areas with contrast, aerial firing permits ignition steady stream of burning fuel globs. their higher intensities will also be of a block to be completed before the It is very difficult to effectively decreased. downwind spots have burned out. regulate the spacing between these Experience to date shows grids up This does not present a problem at fuel globs. At least one gadget that to 4 chains by 4 chains (one ignition the damp end of the prescribed burn- apparently solves this problem is point every 1.6 acres) can produce ing window when actual fine-fuel being marketed. Any helitorch not excellent results. The time needed to moisture is near 20 percent. Rapid modified to effectively control the complete the burn can be reduced by ignition of a block reduces both flying timing between the globs of burning offsetting successive ignition lines by ti me and the time needed to complete fuel should be considered a line- one half of the within-line spacing. the burn. However, when using aerial firing device. The heading fires from one line will ignition techniques under "traditional" Both types of aerial ignition then come up between the backing ideal burning conditions for line- dramatically reduce the time needed fires on the next line. backing fires with actual fine-fuel for an area to burn out. Although moisture near 10 percent, rapid igni- roughly the same amount of smoke is Factors Associated with Point tion of the entire area can result in an produced, it is emitted over a shorter Source Fires increase in fire intensity to unaccep- period and more of it is entrained in ■ Assume much of the area will be table levels. You would then have the convection column. Thus, the im- burned by heading and flanking fires little recourse except to let the area pact of any adverse air quality effects and very little by backing fires. burn out and hope that damage is is much reduced. ■ If conditions are ideal for tradi- limited to just a loss in overstory growth. tional line-backing fires, point source Factors Associated with Aerial Some experienced burners start fires may be too intense. Ignition firing early in the day, before the fuel ■ Preferred burning conditions in- ■ Rapid firing and burnout allows is dry enough to carry fire well. clude low (1-2 mph) in-stand wind- use of a much smaller prescription speeds. Wind direction can he They reduce the distance between window. spots within a line to less than 2 variable. Actual fine-fuel moisture ■ Damp, fine fuels are of critical chains by 2 chains. The increased should be above 15 percent. i mportance. Actual fine-fuel number of ignitions creates more heat ■ When underburning, start with a moistures of 15 to 25 percent are and helps dry the surface fuels, square ignition grid (equal distance preferable. between spots within a line and between especially when a helitorch is used. ■ Requires an experienced burning flight lines). Two chains by 2 chains The distance between spots must be boss to make ignition grid adjust- is often used. expanded as the morning progresses ments and to determine when to halt ■ Always secure the downwind base and burning conditions improve. ignition due to conditions. line first. Otherwise, the spots will merge ■ Although not likely under ■ Be careful when underburning laterally forming lines of heading fire prescribed fire conditions, too much stands with a flammable understory that get too intense before reaching heat energy released over too short a or a heavy rough. the next downwind line of ignition period will result in a sudden, ■ Severe crown scorch is likely if points. The distance between lines dangerous increase in fire intensity. fuel is too dry. can also be increased as necessary to ■ Large acreages can be safely ■ Under the same weather condi- maintain a square ignition grid. burned in a single burning period. Current aerial ignition techniques tions, fires in Piedmont fuel types ■ Many widely dispersed tracts can can be separated into two major tend to spread slower and be less in- be burned during a single day. types: the DAID (Delayed Aerial tense than those in Coastal Plain fuel ■ A contingency plan is essential in Ignition Device) or ping-pong ball types. the event the aircraft is reassigned or system, and the helitorch or flying ■ The usual changes in weather dur- equipment breaks down during driptorch system. The ping-pong ball ing a typical winter day may require operation. modification of ignition patterns system utilizes small plastic spheres

25 Factors Assoicated with Ping -pong Ball (DA ID) System ■ Best suited for continuous fuels or when a mosaic pattern is desired. ■ Ignition spacing within and between Tight lines can be easily adjusted. ■ A 2 by 2 chain to 4 by 4 chain grid (one ignition point every 0.4 acre to one every 1.6 acres) works well in both palmetto/gallberry and Piedmont fuel types. ■ When underburning Coastal Plain fuel types, actual fine-fuel moisture should be 20 to 25 percent (even higher in very heavy fuels) and the air temperature should be low, preferably below 50°F. ■ In Piedmont fuel types, actual fine-fuel moisture contents between 10 and 15 percent and air temperature below 55°F work well. ■ Make sure no DAID's are Device) dispenser mounted in helicopter DAID (Delayed Aerial Ignition mistakenly dropped outside the burn as the helicopter turns at the end of each line.

Factors Associated with Helitorch System ■ Not as safe as the DAID system, but less expensive. ■ If the torch and fuel tank is slung under rather than attached to the helicopter, a larger crew will be required. ■ Creates disposal problems. ■ Very difficult to regulate spacing within a flight line. ■ Fuel-mixing viscosity is sometimes inconsistent due to temperature changes which, in turn, further aggravate in-line spacing of ignition spots. ■ The most efficient firing technique for large, cleared areas with discontinuous fuels, including piled or windrowed debris. ■ Use extreme caution when underburning Coastal Plain fuel types. Try to keep within-line ignition point interval to at least 2 chains.

26 Center and Circular (Ring) Firing This technique is useful on cut- over areas where a hot fire is needed to reduce or eliminate logging debris prior to seeding or planting. It works best when winds, if any, are light and variable. This procedure should never be used for underburning because of the likelihood of severe tree damage as the flame fronts merge As with other burning techniques, the downwind control line is the first line to be ignited. Once the base line is secured, the entire perimeter of the area is ignited and the flame fronts allowed to converge. One or more spot fires are often ignited near the center of the area and allowed to develop before the perimeter of the block is ignited. The convection generated by these interior fires creates indrafts that help pull the outer circle of fire toward the center. This tiring method can generally be used in any season, and weather conditions are not as critical. However, caution is in order, particularly when the atmosphere is unstable. This type of fire tends to develop a strong con- Ignite backing fire first, then center, and then perimeter vection column which can cause spotting a considerable distance Center firing technique downwind. Pile and Windrow The biggest deterrent to windrow some areas. burning, however, is that it causes a Although it generally costs more Burning high percentage of all smoke incidents. to pile than to windrow, piles are The objective of piling logging Large volumes of fuel, including preferable to windrows because access debris before burning it is to prolong larger pieces that contain a lot of within the area is no problem, plant- fire residence time on a restricted moisture, are consumed. However, ing is easier, burning is safer and, area so that larger materials have oxygen for good combustion is lack- most important, smoke problems are time to be consumed. Some areas ing, especially in large piles and wide significantly reduced since piles burn will contain an unacceptable amount windrows. Large amounts of soil are out much quicker! Generally, piles of large, scattered debris that must be often mixed in, further compounding contain less dirt and dry faster. Burn- concentrated to ensure consumption. the problem. The result is a fire that ing piles can easily be "humped" to This material should be piled and not continues to smolder for days or remove any dirt and pushed in to in- windrowed. Windrowing can reduce weeks, creating air quality problems crease consumption. The whole area site quality by removing topsoil. because the smoke produced by can then be utilized. Piedmont soils are also susceptible to smoldering combustion is not hot Keep piles small and minimize the compaction from the heavy equip- enough to rise into the atmosphere. amount of soil in them so surface ment used, especially during wet The smoke stays near the ground water can pass through, and the weather. Full exposure of the soil to where it cools even more, dirifting debris can dry quickly. Always pile the sun and rain bakes the top layer. and concentrating in low areas when the ground surface is dry; less Furthermore, the direct force of rain- because of cool air drainage. To soil compaction will take place, and drops will clog soil pores and often make matters worse, the smoke often considerably less soil will end up in results in erosion on steep slopes. mixes with humid air to produce fog the piles. Allow fresh logging debris The area beneath the windrows is lost which further reduces visibility. to cure first and to dry after rain. to production because the debris is Coupled with these problems is the Then "shake" the debris while piling rarely consumed completely and what fact that the weather changes from to remove as much soil as possible. If remains makes planting difficult or day to day making it impossible to material is piled while green or wet, impossible. Even when windrows predict, and thus manage, the smoke the centers of the piles take an ex- contain breaks spaced every couple of for more than a day or two. For these ceedingly long time to dry. Piles that chains, they still present a barrier to reasons, air quality regulations pro- contain little soil and are constructed firefighting equipment and wildlife. hibit pile and windrow burning in to allow some air movement will

27 Tractor-mounted firing device for piled-debris ignition Piles burn more efficiently than windrows

result in a burn that consumes (backing a drag-load of trees between ■ Burns can continue to smolder for significantly more of the debris and two posts) tend to concentrate much many weeks. produces less smoke. More efficient of the debris at the logging deck. ■ Smoke produced at night tends to burning and greater heat output will Piles created in this manner are stay near the ground. lift smoke higher, reducing smoke. generally free of soil (providing log- ■ Cannot be readily extinguished concentrations near the ground. Burn ging was suspended in wet weather) after ignition. If extinguished, even when the atmosphere is neutral to and can be burned as is. more effort is required to reignite slightly unstable, but not unstable Techniques used in burning piled them the next day. enough to create control problems. debris are somewhat fixed because of ■ Can burn in light or variable Forest managers can take many the character and placement of fuel. winds. steps to minimize these debris pro- Traditionally, each pile is ignited ■ Usually safe and easy to control, blems. Much of the larger material along its perimeter, but burnout can provided piles are not next to the left after harvest is cull hardwood, be speeded up considerably by igniting edge of the area and are not left unat- and periodic use of underburns during the pile center. A helitorch is often tended, particularly when burning the rotation will reduce the number used because burning globs of gelled during periods of high fire danger. of large hardwoods at harvest. Some gas penetrate deep into piled fuels ■ Piles should be as free of soil as of the cull material can often be sold and provide a "large" heat source. possible. or given away as firewood. Sites Tractor-mounted ignition devices that ■ Fuel should be dry. often can be prepared for seeding or help burning fuel penetrate down ■ Burn area should be as small as planting by a broadcast burn without toward the center of a pile have also economically practical. piling the debris. Trees should be cut been fabricated. ■ Need neutral to unstable condi- close to the ground, leaving low tions for good smoke dispersion — stumps. Factors Associated with Pile and which generally do not occur after Advances in harvesting equipment Windrow Burning: sunset. and methods have also helped. Large ■ A large majority of all smoke- ■ Need good mixing heights and mobile harvesters chip the whole related incidents are caused by this transport winds. tree, increasing utilization and reducing type of burning. the need for site preparation. Tree- ■ Produces the most smoke of all length logging and gate delimbing firing techniques.

Dirt in windrows can aggravate smoke management Windrows can smolder for long periods of time problems 28 Smoke Management

Prescribed burning helps achieve well as fire behavior. If the forestry if the Dispersion Index is calculated many desired resource objectives, but weather outlook does not agree for your area, it is a better indicator it nevertheless pollutes the air. We reasonably well with the radio/TV (see table 1). Reassess a decision to therefore have an obligation to mini- forecast, find out why. burn when the daytime Dispersion mize adverse environmental effects. If C. Don't burn during pollution Index value is below 41. this obligation is disregarded, pre- alerts or stagnant conditions.— F. Use caution when near or upwind scribed burners can be held liable for Smoke will tend to stay near the of smoke-sensitive areas. — Burning damages from accidents or problems ground and will not disperse readily. should be done when wind will carry resulting from their actions. Use the Many fire-weather forecasters include smoke away from public roads, air- following guidelines to reduce the this in their regular forecasts. ports, and populated areas. Do not impact from smoke. D. Comply with air pollution control burn if a smoke-sensitive area is regulations. — Know the regulations within 1/2 mile downwind of the pro- A. Define objectives. — Be sure you that apply at the proposed burn site posed burn. have clear resource objectives and when you make the prescription. G. Use caution when smoke- have considered both on-site and off- Check with your State fire control sensitive areas are down drainage. site environmental impacts. agency. B. Obtain and use weather and E. Burn when conditions are good smoke. Use aggressive mopup as smoke management forecasts. for rapid dispersion.— Ideally, the necessary. I atmosphere should be thermally weather and smoke management neutral to slightly unstable so smoke forecasts are available to all resource will rise and dissipate, but not so managers through State forestry unstable as to cause a control prob- agencies. Be sure to use them. Such lem. Again, your local forestry agency Prescribed Fire Reduces A ir information is needed to predict can help. Some States use Category smoke generation and movement as Day based on the ventilation rate, but Pollution From Wildfires

TABLE 1.—Relationship of Dispersion Index to On-the-Ground Burning Conditions

Dispersion Index Burning conditions

>100 Very good — Burning conditions may be so good that fires may be hazardous and present fire control problems. Reassess decision to burn. 61 - 100 Good — preferred range for prescription burns. 41 - 60 Generally OK — climatological afternoon values in most inland forested areas fall in this range. 21 - 40 Fair — stagnation may be indicated if accompanied by low windspeeds. Reassess decision to burn. 13 - 20 Generally poor — do not burn. Stagnant if persistent, although better than average for a night value. 7-12 Poor — do not burn. Stagnant during the day, but near or above average at night. 1 - 6 Very poor — represents the majority of nights at many locations.

29 nighttime smoke patrol is often Screening System for necessary. Managing Smoke P.Anticipate down-drainage smoke flow.—Atmospheric conditions tend to Most southern States have either become stable at night. Stable condi- voluntary or mandatory smoke tions tend to keep smoke near the management guidelines that should ground. In addition, downslope winds be followed when planning a pre- generally prevail at night. Thus, smoke scribed burn. Your local State forestry will flow down drainage and concen- office can advise you of recommended trate in low areas. When relative or required procedures. Many of humidity rises above 80 percent and these guidelines use a term called the ventilation rate or ventilation factor smoke is present, the formation of fog becomes increasingly likely as which estimates the atmosphere's moisture condenses on the smoke capacity to disperse smoke. Another particles. There seldom are satisfac- way to estimate this capacity is to use tory solutions to these problems, so the Dispersion Index (see table 1) they should be avoided entirely developed at the Southern Forest Fire Laboratory. This calculated index is whenever possible. Q. Mopup along roads. — Start mopup better able to incorporate diurnal along roads as soon as possible to changes in the lower atmosphere. reduce impact on visibility. Ex- If you will be burning in a State tinguish all stumps, snags and logs. that has not issued guidelines, use the Mopup should be particularly ag- Southern Forestry Smoke Management (see Suggested Reading gressive whenever roads are in areas Guidebook where smoke could travel downslope section, second listing under U.S. or up or down a drainage. Department of Agriculture). This R. Have an emergency plan. — Be guidebook tells you how to predict prepared to extinguish a prescribed smoke concentrations at any distance burn if it is not burning according to downwind. An improved and com- PRESMOK, plan or if weather conditions change. puterized version, called Have warning signs available. If wind simplifies use of this prediction direction changes, be prepared to system. Copies are available from the quickly contact the local law enforce- Southern Forest Fire Laboratory. Use ment agency and to direct traffic on of this smoke screening system does affected roads until traffic control not take precedence over State personnel arrive. guidelines. The full system cannot be discussed here, but an updated version of the Initial Screening System based on the Guidebook is presented below. This system has five steps: (1) Plot direction of the smoke plume, (2) Caution: Check For Down Identify smoke-sensitive areas, (3) Drainage Smoke Flow At Night! Identify critical smoke-sensitive areas, (4) Determine fuel type, and (5) Minimize risk.

30 Step 1. Plot Direction of the Smoke Step 2. Identify Smoke-Sensitive the size of the area to be burn- Plume Areas ed by approximately one half, A. Use maps on which the locations of Identify and mark any smoke- complete burn at least 3 hours smoke-sensitive areas can be iden- sensitive areas (such as airports, before sunset, and aggressively tified. Plot the anticipated down- highways, communities, recreation mopup and monitor, or wind smoke movement a distance areas, schools, hospitals, and factories) 3. Use an alternative other than of: 5 miles for grass fuels within the impact zone plotted in step 1. burning. regardless of fire type; 10 miles These areas are potential targets for for palmetto-gallberry fuels when smoke from your burn. C. If no critical smoke-sensitive areas using line-backing fires or spot A. If no potential targets are found, are found, or criteria B1 or B2 is fires; 20 miles for palmetto- you may burn as prescribed. met, continue the screening system. gallberry fuels using line-heading B. If the area to be burned contains fires; 30 miles for all logging organic soils that are likely to debris fires; 5 miles for line back- ignite, do not burn. Step 4. Determine Fuel Type ing fires in all other fuel types; C. If any targets are found, continue The smoke produced may vary and 10 miles for line-heading fires this screening system. greatly by type, amount, and condi- in all other fuel types, or burns of tion of fuel consumed. 250 acres or more. First locate A. From the list below determine the planned burn area on a map which broad type best fits your and draw a line representing the Step 3. Identify Critical Smoke- fuel. centerline of the path of the Sensitive Areas I. Grass (with pine overstory) smoke plume (direction of A. Critical smoke-sensitive areas are: 2. Light brush transport wind) for the distance 1.Those that already have an air 3. Pine needle litter indicated. If the burn will last 3 pollution or visibility problem. 4. Palemetto-gallberry or more hours, draw another line 2. Those within the probable 5. Windrowed logging debris showing predicted wind direction smoke impact area as determined 6. Scattered logging debris or at completion of the burn. below. If the distance determined small dry piles B. To allow for horizontal dispersion in step 1 was: of smoke as well as shifts in wind B. Review fuel categories or direction, draw two other lines a) 5 miles, any smoke-sensitive combinations. from the fire at an angle of 30 area within 1/2 mile is critical, 1. If the fuel type is described by degrees from the centerline(s) of both downwind and down- one of the above categories, observed wind direction (45 drainage. continue. degrees if forecast wind direction b) 10 miles, any smoke-sensitive 2. If your fuel type is not com- used). If tire is represented as a area within 1 mile is critical. parable to any of the above, spot, draw as in figure A. If c) 20 miles, any smoke-sensitive pick the fuel type for which larger, draw as in figure B. The area within 2 miles is critical. fire behavior and smoke pro- result is your probable daytime d) 30 miles, any smoke-sensitive duction most nearly compare smoke impact area. area within 3 miles is critical. with yours and proceed with C. Now go down-drainage for one- B. If any critical smoke-sensitive EXTREME CAUTION on the half the distance determined areas are located, DO NOT first few burns. above, but do not spread out except BURN under present prescription! to cover any valleys or bottoms. 1.Prescribe a new wind direction C. If the fuel type is windrowed log- The result is your probable night- that will avoid such targets and ging debris, and you have identi- time impact area, providing the Teturn to the beginning of this fied smoke-sensitive areas, DO burn will be completed at least 3 screening system, or NOT BURN under present hours before sunset, and providing 2. If smoke-sensitive area is in last prescription. Smoke production is the forecast night winds are light half of distance criteria, reduce great and can last for weeks. and variable.

31 1.Prescribe a new wind direction 2. If greater than 10 tons per acre, Many variables affect the behavior to avoid all smoke-sensitive refer to the Southern Forestry and resulting smoke from a prescribed areas and return to the beginning Smoke Management burn. The above system works best in of the system. Guidebook or double the flat terrain and was not designed for 2. If you cannot avoid all smoke- distance determined in step IA. use in mountainous country. It does sensitive areas, you will need a Use 1 1/2 times the distance if not attempt to consider all the variables: better procedure than this sim- close to 10 tons. it can only offer broad guidelines. If ple screening system. Refer to your prescribed fire complies with all the Southern Forestry Smoke Step 5. Minimize Risk conditions in these five steps, you Management Guidebook or To meet your smoke management should be able to safely burn without use PRESMOK. obligations when any smoke-sensitive causing a smoke problem. If you area may be affected by your burn, have any marginal answers, areas that D. If the fuel type is scattered log- you must meet all of the following are especially sensitive to smoke, ging debris or small, essentially criteria to minimize any possible heavy fuel loadings or wet fuels, use dirt-free, dry piles, the following adverse effects. the prediction system mentioned in conditions should be met: the Southern Forestry Smoke 1. Size of area to burn less than ■ Height of mixing layer (mixing Management Guidebook. You must 100 acres. height) is 1,650 feet (500 meters) make the final judgement. 2. No major highways within 5 or greater. miles down drainage. ■ Transport windspeed is 9 mph (4 3. No other smoke-sensitive areas meters per second) or greater. within 3 miles down drainage. ■ Background visibility is at least 5 4. If relative humidity is predicted miles within the plotted area. CAUTION: Be Sure Atmospheric to stay below 80 percent and ■ If rough is older than 2 years, use Conditions Are Conducive surface winds above 4 m.p.h. a backing fire. If burn can be To Good Dispersion! all night, the distances in 2 and completed 3 hours before sunset, 3 above can be cut in half. or if no smoke-sensitive areas are located in the first half of the E. If your comparable fuel type is impact area, other firing techni- one listed in 4A above, determine ques can be used. your total per-acre fuel loading. ■ Promptly mopup and monitor to See below or Southern Forestry minimize smoke hazards. Smoke Management Guidebook ■ If a smoke-sensitive area is in the for tables to assist you. overlapping trajectory of two 1. If less than 10 tons per acre, smoke plumes, it should be 1 mile continue. Generally, the total from either source (2 miles if one fuel loading will be less than is from logging debris). 10 tons in the fuel types listed ■ For night burns, backing fires below when age of rough is: with surface windspeed greater a. Grass (with pine overstory), than 4 mph and relative humidity any age. Also wheat fields under 80 percent should be and other agricultural burns. prescribed. b. Light brush, 7 years old or ■ If it appears that stumps, snags, less (10 years if basal area is or logs may cause a residual under 100 square feet per smoke problem, take steps to keep acre). them from burning. If they do c. Loblolly pine with ignite, extinguish them. a. palmetto-gallberry ■ Daytime value of the Dispersion understory, 7 years or less Index between 41 and 60 is ade- if basal area is under 150 quate for small fires and low levels square feet per acre. of burning activity. As either size b. little or no understory, 15 of individual fires or level of burning years or less if basal area activity increases, the Dispersion is under 150 square feet Index value should also increase. per acre. d. Slash pine with a. palmetto-gallberry understory, 5 years or less if basal area is under 150 square feet per acre. b. little or no understory, 8 years or less if basal area is under 150 square feet per acre.

32 Planning the Prescribed Burn

The first step to a successful given day can be increased drama- sist of a series of blocks in the same prescribed burn is a stand-by-stand tically if aerial ignition is used. If compartment or management unit as analysis of your forest lands. Deter- you have several blocks to burn, set long as the same objectives apply and mine the needs of each stand and what priorities. Specifically designate any the fuel is similar. acitons should be taken to meet these planned burns that require exacting Break large areas into 1-day burning needs. Prescribed fire as well as other weather conditions. Considerations blocks or smaller areas. Use existing alternatives should be addressed here include heavy fuels, small trees, harriers such as roads and creeks as and a decision reached regarding the potential smoke problems, etc. Indi- possible, but be sure these barriers preferred treatment. cate all blocks to be burned on an are effective at the time of the burn. Prescription burning is a highly administrative map. When the burns technical job requiring knowledge of are completed, record the dates on tire behavior, suppression techniques, the map. The Written Plan and environmental effects of fire. A written prescribed-burning plan A prepared form with space for all Well in advance of the burning season, prepared by a knowledgeable person needed information is best. The form scout stands that may need a fire is needed for each area to be burned. will serve as a checklist to be sure treatment and choose those to burn. Complete the plan before the burning you have not overlooked some aspect Overplan the number of acres to be season and be prepared to burn when or potential impact. Sample forms for burned by 10 to 25 percent so substi- the prescribed weather occurs. Some both understory burns and postharvest tutions can be made if necessary, and plans may be quite short and simple burns can be found on pages 34, 35, so additional areas can be burned if while others will be complex. Indivi- and 36. The "simple" form can be favorable weather continues. The dual blocks can vary from a few used on small burns within a large number of suitable burning days acres to over 1,000, but topography, landholding that does not contain varies widely from year to year and and amount and type of fuel in a unit public roadways. Contents of the writ- the acreage that can be burned on a should be similar. Your plan can con- ten plan should include:

TABLE 3 — Effects of Age of Rough on Some Common Fire Parameters

Assume a 20-year-old southern pine plantation on the Coastal Plain with no understory present. Table values will increase as the amount of understory increases. In the Piedmont and mountains, an understory is likely to have an opposite effect ekcept during severe drought.

1 = Backing fire with rate-of-spread of 100 feet per hour and fuel consumption of 60 percent. 1-1 = Heading fire with rate-of-spread of 660 feet per hour and fuel consumption of 40 percent. 'Ambient temperature of 50°F and windspeed of 2mph. Lower temperatures and higher windspeeds will decrease scorch height.

Required Signatures Provide spaces for signature(s) of person(s) who prepared the plan. This identifies the people who know the most about the plan.

Purpose and Objective(s) Include in the written plan the reason(s) for prescribing a fire. Examples include: prepare seedbed, control insects or disease, reduce hazard, improve wildlife habitat, control understory, improve forage, increase accessibility, and enhance aesthetics. In addition, give a specific quantifiable objective. State exactly what the fire is to do — what it should kill or consume, how much litter should be left, etc. Also con- cisely describe the expected fire behavior, including the desired range in flame length and fireline intensity. In case prescribed weather conditions do not materialize, this description may allow the objective(s) to still be achieved by varying the firing technique. Such information will also be useful in determining success of a burn.

Map of the Burning Unit A detailed map of each burning unit is an important part of the burning plan. The map should show the boundaries of the planned burn, adjacent land owners, topography, control lines (both existing and those to construct), anticipated direction of the smoke plume, smoke-sensitive areas, holding details, and other essential information. Plowed control lines are often not necessary. Consider expanding the planned burn to employ existing firebreaks and natural barriers. For example, use fuel type boundaries such as occur near creek bottoms where the fire will go out as it encounters fuels with a higher moisture content. Show areas that should be excluded or protected such as improvements, young reproduction, sawdust piles, etc. Sub- divide each area to be burned into logical, I-day burning blocks, or smaller areas if smoke management needs dictate.

Equipment and Personnel and ignition pattern to use. Species fraction of the fuel will burn. Lower List equipment and personnel needed involved and height of overstory will temperatures are desireable with more on site and on standby. Assign duties. determine the maximum intensity that intense fires, especially when under- can be tolerated. Where large amounts story fuels are tall. Fire Prescription of fuel arc present, cooler burns can A series of user-friendly computer The amount of fuel, weather condi- be accomplished by burning when programs called BEHAVE has been tions and desired intensity of the burn humidity and fuel moisture are near developed to predict the behavior of a will determine the firing technique the high end of the range so a smaller fire. They are based on a specific set 37 of fuel data and prescribed weather Time of Day Alternative Prescriptions conditions. These programs will run Normally, plan burning operations Consider alternative sets of weather on a hand-held calculator with a fire so the entire job can be completed conditions (wind, relative humidity, behavior CROM (Custom Read Only within a standard workday. Prescribed and/or fuel moisture) and methods of Memory). You can use them in the fires usually are ignited between 10 burning that will produce a fire of field to make instant decisions as a.m. and noon, after sunshine has about the same intensity and accomplish burning conditions change. A version evaporated any early morning dew. If the desired objectives. Two separate called MICRO BEHAVE, compatible an inversion occurred the previous burns may be necessary to eliminate with IBM PCs, is also available at night, wait until daytime heating heavy volumes of fuel without damage very low cost from Forest Resources eliminates it before igniting the fire. If to the overstory. Systems Institute (FORS), Courtview the forecast is for poor nighttime Towers, Suite 24, 201 N. Pine Street, dispersion, halt ground ignition before Preparation Work and Protection of Florence, AL 35630; telephone (205) 3 p.m. standard time (ST). Halt aerial Sensitive Features 767-0250. ignition before 4 p.m. ST, to allow Include fire lines to be constructed, Always think about smoke adequate time for the fire to burn out snags to be lined or felled, special management. Make sure your burning before atmospheric dispersion condi- features to be protected and the instal- plan passes a smoke management tions deteriorate. lation of any monitoring equipment. system. Burning conditions are usually bet- Give instructions for the protection of ter during the day than at night because sensitive areas. Consider historical Season windspeed is higher and wind direc- and archeological sites, streams, Winter — Most understory burning tion steadier. Smoke management is habitats of threatened and endangered is done during the winter dormant also much easier during the day. At species, and fragile soils. season. Acceptable relative humidity, night smoke tends to stay close to the Notification of Intent to Burn temperature, fuel moisture, and steady, ground and collect in depressions. List the names and telephone numbers persistent winds most often occur Also, relative humidity usually in- of the local State fire protection officer then. creases at night, resulting in spotty and other officials who should be Spring — More variable weather burning and an increased likelihood contacted prior to the burn. Make and generally higher fire danger dic- that fog will form. direct contact with all homes and tate smaller burns in the spring. However, on winter nights when a businesses in the area likely to be Check with local wildlife specialists to strong cold front moves across an i mpacted by the burn. Offer to avoid periods when prescribed burning area, winds remain strong and persis- evacuate anyone with respiratory prob- could harm nesting wildlife. Pine tent and relative humidity does not lems during the burn. Put them up in buds are more exposed and thus more rise greatly. These conditions can pro- a local motel if necessary. Consider susceptible to heat damage during vide good prescribed burning weather, written notification explaining the elongation. especially when cooler temperatures reasons for the burn and encouraging Summer — Hot weather during the are needed. Whenever night burning individuals with respiratory ailments summer means much less heat is is done, keep a close check on wind, to contact you — include a 24 hour needed to raise the temperature of humidity, and smoke drift. telephone number. Establish respon- plant tissue to lethal levels. For this sibility for burn-day contacts and how reason, summer burns are used to kill Firing Plan they will be made. Consider a news- undesirable hardwoods — usually a Key parts of a successful prescribed paper article describing the reasons series of burns after an initial winter burn are plans for firing and holding for the burn if you expect to produce burn. Care must be taken not to a burn. This plan should consist of a lots of smoke or anticipate any severely scorch overstory crowns. narrative section and a detailed map. negative reactions. Postharvest burns to dispose of log- The burning unit map is ideal for this ging debris can be conducted year- purpose because it already contains round, but conditions are especially much pertinent information. Add the good in mid to late summer because following items: Establish Burn Acreage Goals the high ambient temperatures help ■ Firing technique, ignition pattern, But NOT Quotas! dry out the larger materials. and planned ignition time. Fall — Exercise special care when ■ Manpower and equipment burning in early fall just prior to the needed, and planned distribution dormant season. Both loblolly and for setting, holding, patrolling, slash pines are more likely to die if and mopping up the fire and severely scorched or root damaged at managing the smoke. this time. ■ Location and number of reinforce- ments and equipment that can be mobilized rapidly if fire escapes. ■ Instructions for all supervisory personnel, including complete description or illustration of assignment, and forces needed to fire out, hold, and mopup the fire.

38 Impact of Smoke Escaped-Fire Plan List any sensitive areas near to, Identify potential fire escapes and Give Prescribed Burning FIRST downwind, or down drainage of the specify actions to take should such Priority When Weather Conditions burn. Include smoke management occur. Designate who will be in Are Favorable strategies of avoidance, emission charge of suppression action and what reduction, dispersal, or all three, to personnel and equipment will be minimize any adverse smoke impacts. available. Attach the smoke management plan (e.g. screening system calculations) as Control and Mopup part of the burning plan. A plan must include necessary safeguards to confine the fire to the Legal Requirements prescribed area and reduce smoke List any legal requirements that might impact. Mopup promptly and com- apply, and what the prescribed burner pletely. Emphasize protection of all must do to comply. Remember, the adjacent land. Consider and make person who conducts the prescribed plans for any variation in forecasted burning operation may not be the one weather that may change a prescribed who made the analysis and prepared fire into a damaging wildfire, increase the prescription. Follow all applicable the pollution in smoke-sensitive areas, statutes, regulations, and agency pro- or create visibility problems on adja- cedures. Needs for a written prescribed cent roads. burning plan, documentation of devia- tions from the plan, and good judge- Evaluation ment cannot be overemphasized. Er- Include space for a written evalua- roneous forecasts, unforeseen local tion of the prescribed burn. A record influences, and accidents occur despite of actual weather conditions, behavior our best efforts to prevent them. Pro- of the fire, and total environmental per documentation will help establish effects of the burn is essential. This that the prescribed fire was conducted information is used to determine the in a prudent and professional manner. effectiveness of the prescribed burn If a prescribed fire results in damage and in setting criteria for future burns. or bodily harm and you cut corners, At the beginning of the prescribed neglected any mandatory require- burn, record windspeed and direction, ments, or acted with disregard to the fuel moisture, humidity, burning in- welfare of others, you are likely to be dex, temperature, days since and held responsible, regardless of whether amount of last rain, and dampness of compliance would have changed the soil and lower litter. Also record fire outcome. For more information see behavior data such as type of fire the summary article, Legal Implica- used, length of flames, and forward tions of Prescribed Burning in the rate of spread. Continue to record South by William C. Seigal, listed in applicable weather and fire-behavior the Suggested Reading section. parameters at 2- to 3-hour intervals throughout the burn. After the burn, record amount of crown scorch, consumption of brush, litter, and duff, and any other evidence of fire intensity such as unburned areas, exposed mineral soil, and cracks in bark or cupping on the lower bole due to bark consumption. Also include a short narrative on success of the burn.

Prescribed Fires Often Behave Erratically A t Edges Of Openings

Steps to Be Considered Good preparation is the key to successful burning. It is essential in realizing maximum net benefits at acceptable cost. Preparation consists of all steps necessary in making the area ready for firing and of having all needed tools and equipment in operating order and ready to go. This preburn work is often done by a crew consisting of a leader, a tractor operator, and a cleanup person. The leader should be trained and experienced in prescribed fire. The job is to locate and establish control lines to best accomplish the objectives of the burning plan. To do this job skillfully, the leader must have personal knowledge or information available about: ■ Weather elements involved Establishing a control line in heavy rough ■ Fire behavior ■ Smoke management All site-specific information ■ Subdivide large areas into logical ■ Amount and type of fuel on the should be included in the written I-day burning jobs. area prescription. Before starting work, ■ Avoid leaving dense timber stands ■ Location of natural and manmade the leader should inspect the area by or heavy fuel pockets near lines. fire barriers walking over it and should give safety ■ Degree of risk and hazard present instructions to the crew. After Plow Lines are ■ Burning technique and intensity of Established fire to be used Establishing Control ■ Remove any material above the ■ Burning objectives for the par- Lines line that could carry fire across the ticular area control line such as vines and ■ Restrictive measures dictated by ■ Plow in advance of burning, overhanging brush. law or local custom preferably after leaf fall, to reduce ■ Fall snags near line (inside and ■ Fire suppression safety effect of fallen material on prepared outside). ■ Location of any improvements lines. ■ Construct water bars and leadoff which could he endangered ■ Use natural barriers such as ditches in steeper terrain to prevent ■ Areas within the prescribed unit streams, logging roads, or cultivated soil erosion. that may need to be excluded from fields whenever possible. ■ Seed and fertilize exposed soil on fire, such as: ■ Hold plowlines to a minimum, plow lines in steep topography to pre- — areas with extreme mopup or keeping them shallow and on the con- vent soil erosion. breakover potential (sawdust tour as much as possible in hilly piles, snags, etc.) country. Consider igniting from wet highly scenic areas lines. Use skid trails and logging Burning-unit Map —highly erodible areas roads where feasible. ■ Locate all control lines on the map — streamside zones ■ Keep control lines as straight as noting any changes from the original —areas harboring special-quality possible. Bend them around excluded plan. wildlife or plant community areas, avoiding abrupt changes in ■ Note on the map any danger spots habitat that would be damaged direction. along control lines having potential for by fire ■ Avoid rock outcrops and boggy fire escape. —desirable hardwood areas ground. timber and grass areas sus- ■ Double or widen plow lines at ceptible to fire damage hazardous places.

41 Executing the Burn

There are few days of good Radios for communication are maximum time for rnopup and patrol prescribed burning weather during essential for aerial ignition and for of the lines. Normally, plan to com- the year. When these days arrive, any large burn. Behavior of a plete any one job within a standard give top priority to burning. With prescribed burn will vary because of workday. The burning boss must adequate preparation, burning can roads or other openings in the timber make sure the crew has the proper begin without loss of opportunity. stand, varying fuel conditions, chang- clothing and safety equipment and is A prescribed burning crew con- ing weather, and the firing technique in good physical shape. Proper sisting of a burning boss and 3 to 6 used. Two vehicles are essential to clothing includes long-sleeve fire crew members can handle a burn of permit maximum mobility of the resistant or cotton shirts, pants several hundred acres. The leader burning boss and crews. Chain saws without cuffs, leather boots with non- should be an experienced prescribed are useful additions to the equipment skid soles, safety glasses, hardhat, burner with an understanding of fire supply. gloves, and plenty of drinking water. behavior. Such a crew often consists The burning boss should have the During the summer, the possibility of of 3 torch people equipped with hand crew ready to fire the area as early in heat exhaustion and heat stroke must tools, and a tractor operator with a the day as conditions permit, leavin be considered. plow unit for emergency use. If aerial ignition is used, the ground crew often consists of a tractor-plow unit and a 2-person crew with 2 pickups. The aerial crew generally consists of a pilot and machine operator when the ping-pong ball system is used. If the pilot is not an experienced fire behavior observer, the burning boss should also be in the helicopter (as allowed) where he/she will have a relatively unobstructed view of the developing fire. Use of the helitorch can require 2 to 3 additional ground support people to mix the fuel and position the drums depending upon torch configuration and company/ agency policy. Disposal of any unused helitorch fuel mix can present additional logistical problems; alumagel is toxic and should never just be dumped.

Examples of prescribed burning equipment

Post smoke warning signs Check fuel moisture of duff and litter 42 Checklist ■ Instruct crew on procedures, in- cancel the burn if you are not com- cluding safety precautions and the fortable with the observed behavior. ■ Make sure all equipment is in proper operation of equipment and ■ Inform crew of starting point and working order and safe to use. use of hand tools. firing sequence. Give each member a ■ Carry burning plans and maps to ■ Post signs on public roads and be map. the job. prepared to control traffic if potential ■ Have a means of instant com- ■ Check the weather before starting exists for smoke to reduce visibility. munication with all crew members. to burn and keep updated throughout ■ Check duff and soil for dampness. Portable radios are very useful. the day. ■ Test burn with a small fire before ■ Be alert to changing conditions, ■ Check all control lines, clean out firing; check the fire and smoke and be prepared to change burning needles and leaves, and reinforce as behavior to make sure the fire is techniques or plow the fire out if an necessary. burning as expected. If it is not, emergency arises. ■ Notify adjoining property owners decide whether the observed behavior ■ Burn so the wind will carry and local fire control organizations is acceptable. This is the time to smoke away from sensitive areas. before starting fire. ■ Mopup and patrol perimeters con- stantly during the operation, and thereafter until there is no further danger of fire escape or smoke problems.

"Give Prescribed Burning TOP PRIORITY When Burning Weather Arrives"

Small test fire to check behavior of fire and smoke

Prompt mopup will minimize residual smoke Evaluating the Burn

The purposes of a burn evaluation If more than 15 percent of a southern needles burned off, but still having a are to determine how well the stated pine tree's needles are actually con- protective sheath of green needles objectives of the burn were met and sumed by flames, the tree's chances around the unharmed terminal bud. to gain information to be used in of survival would be poor even if future burns. An initial evaluation very little of the rest of the crown is Soil and Root Damage should be made immediately after the scorched. Young vigorous trees are Burning under prescribed conditions burn, perhaps the following morning. more likely to survive severe crown in the South generally does not expose A second evaluation should be made damage than are older individuals. bare soil. If duff remains after a during or after the first postfire Magnitude and duration of growth burn, the physical properties of the growing season. responses in southern pines due to soil probably were not harmed. If various levels and seasons of defolia- mineral soil is exposed, especially on Points to be Considered tion are not well documented. Both steep slopes, soil movement and ■ Was preburn preparation properly negative and positive responses have deterioration of site quality may occur. done? been observed, but the preponderance Root damage is likely whenever ■ Were objectives met? of evidence shows a direct relation- the organic layer is completely con- ■ Was burning plan adhered to? ship between diameter and height sumed. It should also be expected Were changes documented? growth loss and crown scorch. whenever burns are conducted over ■ Were weather conditions, fuel Providing no crown consumption dry soils (drought conditions) or conditions, fire behavior, and smoke took place, the following table will when a deep litter layer is present, dispersion within planned limits? help in estimating potential growth even though some duff remains. New ■ What were effects on soil, air, loss in loblolly and slash pines over root growth in vigorously growing vegetation, water, and wildlife? 3 inches dbh. These "ball park" pines can usually offset these losses, ■ Was fire confined to intended estimates can be used for other but older trees, having survived such area; any escapes? southern pines as well, until more fires without crown damage, often die ■ Was burning technique correct? specific results become available. six months to a year later for no ■ Were costs commensurate with A good indicator of hardwood apparent reason. benefits derived? control is a series of bark cracks ■ How can similar burns be extending into the cambium near ground Air Quality improved? level. This indicates sufficient heat Smoke behavior must be continually was applied to penetrate the bark and evaluated from the time the fire is I ndications and kill the cambium. Although large hard- ignited until smoldering ceases. Guidelines woods can be damaged by periodic Unusual or unexpected smoke effects fires they are difficult to kill. should be noted and correlated with Needle Scorch Judge the success of burning for other parameters of the burn for future The best indicator of crop tree brownspot control by the number of use. Any public complaints should be damage is percent foliage discolora- longleaf seedlings with all infected recorded as part of the evaluation. tion. Assuming that buds and branch- lets are not heat-killed, even crown scorch approaching 100 percent generally will not kill trees unless secondary factors such as insect attack or drought materialize. If, Percent Damage however, loblolly pine stands are Crown Scorch burned in the fall (September or 0 to 33 Some volume growth loss may occur the first October), after the trees have postfire growing season but it will be minor. undergone their last needle flush of the growing season but prior to the 34 to 66 Volume growth loss usually less than 40 percent onset of dormancy, research indicates and confined to first postfire growing season. that 100 percent crown scorch is like- 67 to 100 Reduction may be as high as a full year's ly to kill them. Slash pine appears to volume growth spread over 3 years. be more tolerant of severe crown scorch during the fall. 44 Timing and Points to Evaluate Evaluation should take place i mmediately after the burn and again during the first posture growing season. In the case of late summer prescribed tires, the second evaluation should take place the following spring after the next growing season has begun.

Points in First Evaluation ■ Amount of overstory foliage discoloration. ■ Amount of consumption and top- kill of understory vegetation. ■ Consumption of infected needles on longleaf seedlings without injury to terminal bud. ■ Amount of litter remaining on forest floor. ■ Smoke dispersion into upper atmosphere and success in avoiding smoke-sensitive areas. ■ Protection of areas not to be burned. ■ Any escape of fire. ■ Any adverse public comment or reaction prior to, during, or immediately after the burn.

Points in Future Evaluation Future evaluation can best be made after the start of the growing season to determine the following: ■ Resin exuding from pine trees, an indicator of cambium damage or insect attack. ■ Other signs of beetle attack. ■ Mortality of timber or other desirable vegetation. ■ Sprouting vigor of undesired vegetation. ■ Recovery of longleaf seedlings free of brownspot. ■ Remaining duff layer, mineral soil exposed, and any soil movement. ■ Public expression for or against the burning program.

45 Coordination of

Burning These guidelines are general and will not fit all situations.

PURPOSE TIME OF BURN SIZE OF BURN TYPE OF FIRE FREQUENCY REMARKS

REDUCE FUELS Winter Large enough to Not critical. Do 2 to 4 years Use line-backing fire, or point- break fuel not ring fire. source fires under moist conditions continuity for initial burn. Grid-firing technique excellent for maintenance burns.

1 MPROVE General — Protect transitional or W1LDL1FE fringe areas. Do not burn stream HAB1TAT bottoms. Deer Winter preferred Small or leave Backing fire or 2 to 4 years Want to promote sprouting and unburned areas point-source fires keep browse within reach. Repeat summer fires may kill some rootstocks. Turkey Winter preferred; Small or leave Backing fire or 2 to 4 years Avoid April through June nesting summer burns in unburned areas point-source fires season. July - August Quail Late winter 25+ acres Not critical. Do 1 to 2 years Avoid April through June nesting not ring fire season. Leave unburned patches and thickets. Dove Winter Not critical Not critical. Do Not critical Leave unburned patches and not ring fire thickets. Waterfowl Late fall or winter Not critical Heading fire 2+ years Marshland only. Do not burn in hardwood swamps.

CONTROL Heavy roughs in Not critical. Not critical. Do 2 to 8 years Summer burns result in higher COMPET1NG winter, otherwise not ring fire. rootstock kill and affect larger VEGETAT1ON not critical stems. Exclude fire from desirable hardwoods in pine-hardwood type.

1 MPROVE Winter through Not critical but Not critical. Do 3 years Split range and burn one-third FORAGE FOR late spring for will be damaged not ring fire. each year. Individual herbs and GRAZ1 NG most situations by overuse if too grasses respond differently to small for herd. fire and season of burn. Consult expert.

1 MPROVE Will vary with Varies with in- Depends on As needed Coordinate with other resource ob- ACCESS1B1L1TY understory and dividual situation amount of fuel jectives. They will dictate size, tim- desired use present ing and frequency of burn.

CONTROL Brownspot, Depends on size Strip-heading or 2 to 3 years Burn when humidity is above 500/0. D1SEASE winter of infected area. heading fire Avoid leaving unburned pockets of Include a buffer infected seedlings within or adja- strip cent to burn.

46 PURPOSE TIME OF BURN SIZE OF BURN TYPE OF FIRE FREQUENCY REMARKS

ENHANCE Late fall through Varies with each Backing fire or 1 + years Requires precise prescription to APPEARANCE late winter situation point-source fire protect vegetative type changes. Know effect of fire frequency and season of burn on both annual and biennial flowering plants. Provide pleasing visual lines.

PERPETUATE Will vary with Will vary but Will vary with fuel Will vary with Fire intensity, timing and frequency F1RE species usually fairly conditions and species all dictated by species DEPENDENT small species requirements. SPEC1ES requirements.

YOUNG P1NE Winter Varies with size Backing fire 2 to 4 years Pine diameter 3 inches or more at STANDS of stand ground. Pine height above 10 ft. Burn only after a strong cold front with rain.

D1SPOSE OF Not critical Small areas Center firing with — — Smoke management is a must! LOGG1NG mean fewer helitorch Take care not to damage soil or DEBR1S nighttime smoke preferred water resources with these hot problems fires. If a broadcast burn will not meet objectives, pile - do not windrow debris.

PREPARE S1TES Natural seeding, Large enough to Not critical. Do — — Be careful not to kill seed trees. If FOR SEED1NG summer to early prevent concen- not ring fire logging debris present, manage fall prior to seed trations of birds & your smoke. fall. rodents (usually 10 acres or more).

Direct seeding, Large enough to Not critical. If logging debris present, smoke fall to late winter prevent concen- Center firing with management is a must! Take care for spring sowing. trations of birds & helitorch prefer- not to damage soil or water Previous winter rodents (usually red if slash resources with these hot fires for fall sowing of 10 acres or present. longleaf. more).

PREPARE S1TES Growing season Large enough to Not critical. — — If logging debris present, smoke FOR PLANT1 NG for hardwood prevent concen- Center firing with management is a must! Take care control. trations of birds & helitorch pre- not to damage soil or water rodents (usually ferred if slash resources with these hot fires 10 acres or present. more).

47 Rules of Thumb

1.Obtain and use latest weather and 9. Heading fires produce about three 18.Estimate background smoke con- smoke management forecasts. times more particulate than back- centration [micrograms per cubic 2. Relative humidity will roughly ing fires. meter] in the absence of high halve with each 20°F rise in 10.Burn when fuels are dry, but not humidities by dividing 500 by the temperature and double with each too dry. Wet fuels produce visibility in miles. 20°F drop in temperature in a substantially more particulate 19. If nighttime Dispersion Index given air mass. than do dry fuels. forecast is poor or very poor 3. Expect increased spotting when 11.Start burning logging debris by [less than 13], stop burning by relative humidity drops below 30 midmorning. 3 p.m. ST. percent. Do not burn when the 12. Site prep burning behind chop- 20. Doubling the Dispersion Index relative humidity is below 25 ping or other mechanical treat- implies a doubling of the atmos- percent. ment gives best results if done 10 pheric capacity to disperse smoke 4. Burn when mixing height is to 15 days after treatment. within a 1,000 square mile area. above 1,650 feet [500 meters]. 13.Windrows are the most polluting 21. Assuming 1 ton of fuel per acre 5. Do not burn under temperature of all southern fuel types. is being consumed by smoldering inversions. 14.Broadcast burn scattered debris if combustion during poor nighttime 6. Burn areas with low fuel loadings possible. dispersion conditions, expect and large-sized trees on marginal 15.Do not pile when either ground visibility in the smoke to be less days at the high end of the or debris is wet. than 1/2 mile within 11/2 miles of prescription window. 16.Dirt in piled debris will increase the fire. 7. Never underburn during a the amount of smoke produced by drought. Soil moisture is needed up to four times. Shake out dirt to protect tree roots and lower while piling "bump" piles while litter. burning, and repile as necessary. 8. Don't burn on organic soils unless 17.Use a smoke management plan. the water table is very close to Consider smoke sensitive areas. the surface. Look several miles downwind and down-drainage for potential targets.

48 Red Flag Situations

If any of the following ■ Behavior of test fire not as If any of the following conditions exist, prescribed ■ A smoke-management system conditions exist, analyze further before has not been used stop burning and plow burning. ■ Smoke-sensitive area downwind out existing fire. or down drainage Underburning: ■ Fire behavior erratic ■ Organic soil present ■ Spot fire or slop-over occurs ■ No written plan ■ Daytime Dispersion Index and is difficult to control ■ No map below 40 ■ Wind shifting or other unfore- ■ No safety briefing ■ Not enough personnel or seen change in weather ■ Heavy fuels equipment available to control ■ Smoke not dispersing as ■ Dry duff and soil an escaped fire predicted ■ Extended drought ■ Personnel on fire not qualified ■ Public road or other sensitive ■ Inadequate control lines to take action on escaped fire. ■ No updated weather forecast area smoked in for area ■ Burn does not comply with all laws, regulations, and standards ■ Forecast does not agree with Debris burning - in addition to the prescription ■ Large fuels igniting and burn- above: ing, not enough personnel to ■ Poor visibility ■ Area contains windrows ■ Personnel or equipment mopup before dark and likely to ■ A lot of dirt in piles smoke in a smoke sensitive area stretched thin ■ Poor nighttime smoke disper- ■ Burning large area using sion forecast ground ignition ■ Have not looked down drainage ■ Communications for all people ■ Mixing height is below 1,650 not available feet (500 meters) ■ No backup plan or forces ■ Debris was piled when wet available ■ Pile exteriors are wet ■ No one notified of plans to burn

49 Glossary

Aerial Fuels—Standing and sup- Belt Weather Kit—Belt mounted Catface—Defect on the surface of a ported live and dead forest com- canvas case with fitted pockets for tree resulting from a wound where bustibles not in direct contact with anemometer, compass, sling healing has not re-established the the ground consisting mainly of psychrometer, slide rule, water bottle, normal cross-section. foliage, twigs, branches, cones, bark, pencils, and book of weather report Center Firing—A method of stems, and vines (See Draped Fuels, forms. broadcast burning in which fire(s) are Ladder Fuels). Blackline—Preburning of fuels, set in the center of the area to create Aerial Ignition—Ignition of fuels by either adjacent to a control line a convection column with strong dropping incendiary devices or before igniting the main prescribed surface indrafts. Usually additional materials from aircraft. fire, or along a roadway as a fires are then set progressively nearer Age of Rough—Time in years since deterrent to human-caused fires. the outer control lines as the indraft the forest floor was last reduced by Blackline denotes a condition in builds up, to draw the flames and fire. which there is no unburned fine fuel. smoke toward the center of the burn. Air Stagnation Advisory (ASA) — Broadcast Burn—Prescribed fire Chain —Unit of measure in land A statement issued by a National that burns over a designated area, survey equal to 66 feet; 80 chains Weather Service office when generally in the absence of a equal 1 mile. atmospheric conditions are stable merchantable overstory, to consume Clearcutting—Removal of the entire enough that the potential exists for debris that has not been piled or standing, merchantable timber crop. windrowed. pollutants to accumulate in a given Cold Front—The leading edge of a area. Brown & Burn—Application of mass of air that is colder and drier Anemometer—General name for herbicide to desiccate living than the air mass being replaced. vegetation prior to burning. instruments designed to measure Control Line—Comprehensive term windspeed. Brownspot Control—A prescribed for all constructed or natural fire Area Ignition—Igniting, throughout burn to control a fungal infection barriers and treated fire edges used to an area to be burned, a number of (brownspot disease) of longleaf pine control a fire. in the "grass" (small seedling) stage. individual fires either simultaneously Convection Column—The rising or in rapid succession and so spaced Buildup—Cumulative effects of long- column of gases, smoke and debris that they soon influence and support term drying on current fire danger. produced by a fire. The column has a each other to produce a hot, fast- Buildup Index (BUI)—A relative strong vertical component indicating spreading fire throughout the area. number expressing the cumulative that buoyant forces override the Aspect—Direction toward which a effect of daily drying factors and ambient surface wind (See Smoke slope faces. precipitation on fuels with a 10-day Plume). Atmospheric Stability—A measure timelag constant. Convergence Zone—The area of of the degree to which the Burning Boss—Person responsible increased flame heights and fire atmosphere resists turbulence and for managing a prescribed fire from intensity produced when two or more vertical motion. In prescribed fire ignition through mopup. flame fronts burn together. activities the atmosphere is usually Burning Index (BI)—A relative Crown Scorch—Browning of needles described as stable, neutral, or number related to the contribution or leaves in the crown of a tree or unstable. fire behavior makes to the amount of shrub caused by heat from a fire. Available Fuel—That portion of the effort needed to contain a fire within total fuel that would actually be Cured—Debris or herbaceous a given fuel type. A doubling of the vegetation that has dried and lost its consumed under a specific set of BI indicates twice the effort will be green color. burning conditions. needed to contain a fire in that fuel Backing Fire—A fire spreading or type as was previously required. DAID (Delayed Aerial Ignition set to spread into (against) the wind, Device)— See Ping-pong Ball Category Day—A numerical index System. or downhill. (See Flanking Fire, related to the ability of the atmos- Heading Fire). phere to disperse smoke. For Debris Burning—In this publication, BEHAVE —A system of interactive example, in South Carolina the defined as any prescribed fire used to computer programs for modeling fuel current scale, based on Ventilation dispose of scattered, piled, or and fire behavior comprised of two Factor, ranges from 1 (poor) to 5 windrowed dead woody fuel in the subsystems: BURN and FUEL. (excellent). absence of an overstory. Such a burn often accomplishes the objectives of a Site Prep Burn as well. 50 Dew Point—Temperature to which air Duff—The layer of decomposing Fireline Intensity (Byram's must be cooled to reach saturation at organic materials lying below the Intensity)— The rate of heat release a constant atmospheric pressure. The litter layer and immediately above the per unit time per unit length of fire dew point is always lower than the mineral soil. It is comprised of the front. Numerically, it is the product wet-bulb temperature, which in turn Fermentation (F) and Humus (H) of the heat yield, the quantity of fuel is always lower than the dry-bulb layers of the forest floor. consumed in the Fire Front, and the temperature. The only exception to Edge—As used in this manual, the rate of spread. this is when the air is saturated (i.e., boundary between two fairly distinct Fire Plow—Heavy-duty share or disk relative humidity is 100 percent), in fuel types. plow designed to be pulled by a which case all three values are equal. Emission Factor—The amount of tractor to construct Firebreaks. Dispersion—The decrease in pollution (pounds per ton) released to Fire Rake—A long-handled concentration of airborne pollutants the atmosphere per unit weight of dry combination rake and cutting tool, as they spread throughout an fuel consumed during combustion. the blade of which is usually increasing volume of atmosphere. Emission Rate—The quantity of constructed of a single row of 4 Dispersion Index—As used in this pollutant released to the atmosphere sharpened teeth. manual, a numerical index developed per unit length of fire front per unit Firing Technique—The type(s) of by Lee Lavdas (Southern Forest Fire time. fire resulting from one or more Laboratory). This index is an ignition(s), e.g., backing fire, estimate of the atmosphere's capacity Equilibrium Moisture Content (EMC)—The moisture content that a flanking fire, heading fire, (See Grid to disperse smoke from prescribed Ignition, Ignition Pattern). burns over a 1,000-square-mile area. fuel would eventually attain if It is related to the Ventilation Factor, exposed for an infinite period to Flame Depth —The depth of the Fire but also considers the rate of specified constant values of Dry-bulb Front at the fuel surface. pollutant dispersion. Temperature and Relative Humidity. Flame Length—The distance between Draped Fuels—Needles, leaves, Fine Fuels (Flash fuels) — Fast- the flame tip and the midpoint of the twigs, etc., that have fallen from drying, dead fuels which have a Flame Depth at the base of the flame above and have lodged on lower Timelag constant of 1 hour or less. (generally at the ground surface). branches and brush. Part of aerial These fuels ignite readily and are Flanking Fire—A Fire Front fuels. consumed rapidly when dry. Included spreading, or set to spread at roughly are grass, leaves, draped pine right angles to the prevailing wind. Drift Smoke—Smoke that has been needles, and small twigs. transported from its point of origin Flash Fuels—See Fine Fuels. Fire Behavior—A general term that and in which convective motion no Flying Drip Torch—See Helitorch. longer dominates. refers to the combined effect of fuel, weather and topography on a fire. Fuel Moisture Content—Water Drip Torch—Hand-held apparatus content of a fuel expressed as a used to ignite fires by dripping Firebrand—Any flaming or smoldering material such as leaves, percentage of the ovendry weight of flaming liquid fuel, at an adjustable the fuel. rate, on the materials to be burned. pine cones, or glowing charcoal that The fuel is generally a mixture of 65 could start another fire. Fuel Moisture Indicator Sticks—A to 80 percent diesel and 20 to 35 Firebreak—Any natural or specially manufactured set of sticks percent gasoline. constructed discontinuity in a fuelbed of known dry weight continuously used to segregate, stop, or control the exposed to the weather and Drought Index (Keetch-Byram periodically weighed to determine Drought Index)—A numerical rating spread of fire or to provide a control line from which to suppress a fire. changes in moisture content. The of the net effect of evapotranspiration changes are an indication of changes and precipitation in producing Fire Effects—Physical, biological in the moisture status and relative cumulative moisture depletion in and ecological impacts of fire on the flammability of dead fuels that deep duff or upper soil layers. environment. roughly correspond toTen-hour Dry-bulb Temperature—The Fire Front—The strip within which Timelag Fuels. temperature of the air. continuous flaming occurs along the Grid Ignitions—Method of igniting fire perimeter (See Flame Depth). fires in which ignition points are set individually at predetermined spacing with predetermined timing throughout the area to be burned (see Ping-pong Ball System). 51 Dew Point—Temperature to which air Duff—The layer of decomposing Fireline Intensity (Byram's must be cooled to reach saturation at organic materials lying below the Intensity)— The rate of heat release a constant atmospheric pressure. The litter layer and immediately above the per unit time per unit length of fire dew point is always lower than the mineral soil. It is comprised of the front. Numerically, it is the product wet-bulb temperature, which in turn Fermentation (F) and Humus (H) of the heat yield, the quantity of fuel is always lower than the dry-bulb layers of the forest floor. consumed in the Fire Front, and the temperature. The only exception to Edge—As used in this manual, the rate of spread. this is when the air is saturated (i.e., boundary between two fairly distinct Fire Plow—Heavy-duty share or disk relative humidity is 100 percent), in fuel types. plow designed to he pulled by a which case all three values are equal. Emission Factor—The amount of tractor to construct Firebreaks. Dispersion—The decrease in pollution (pounds per ton) released to Fire Rake—A long-handled concentration of airborne pollutants the atmosphere per unit weight of dry combination rake and cutting tool, as they spread throughout an fuel consumed during combustion. the blade of which is usually increasing volume of atmosphere. Emission Rate—The quantity of constructed of a single row of 4 Dispersion Index—As used in this pollutant released to the atmosphere sharpened teeth. manual, a numerical index developed per unit length of fire front per unit Firing Technique—The type(s) of by Lee Lavdas (Southern Forest Fire time. fire resulting from one or more Laboratory). This index is an ignition(s), e.g., backing fire, estimate of the atmosphere's capacity Equilibrium Moisture Content (EMC)—The moisture content that a Clanking fire, heading fire. (See Grid to disperse smoke from prescribed Ignition, Ignition Pattern). burns over a 1,000-square-mile area. fuel would eventually attain if It is related to the Ventilation Factor, exposed for an infinite period to Flame Depth —The depth of the Fire but also considers the rate of specified constant values of Dry-bulb Front at the fuel surface. pollutant dispersion. Temperature and Relative Humidity. Flame Length—The distance between Draped Fuels—Needles, leaves, Fine Fuels (Flash fuels) — Fast- the flame tip and the midpoint of the twigs, etc., that have fallen from drying, dead fuels which have a Flame Depth at the base of the flame above and have lodged on lower Timelag constant of 1 hour or less. (generally at the ground surface). branches and brush. Part of aerial These fuels ignite readily and are Flanking Fire—A Fire Front fuels. consumed rapidly when dry. Included spreading, or set to spread at roughly are grass, leaves, draped pine right angles to the prevailing wind. Drift Smoke—Smoke that has been needles, and small twigs. transported from its point of origin Flash Fuels—See Fine Fuels. Fire Behavior—A general term that and in which convective motion no Flying Drip Torch—See Helitorch. longer dominates. refers to the combined effect of fuel, weather and topography on a tire. Fuel Moisture Content—Water Drip Torch—Hand-held apparatus content of a fuel expressed as a used to ignite fires by dripping Firebrand—Any flaming or smoldering material such as leaves, percentage of the ovendry weight of flaming liquid fuel, at an adjustable the fuel. rate, on the materials to be burned. pine cones, or glowing charcoal that The fuel is generally a mixture of 65 could start another fire. Fuel Moisture Indicator Sticks—A to 80 percent diesel and 20 to 35 Firebreak—Any natural or specially manufactured set of sticks percent gasoline. constructed discontinuity in a fuelbed of known dry weight continuously used to segregate, stop, or control the exposed to the weather and Drought Index (Keetch-Byram periodically weighed to determine Drought Index)—A numerical rating spread of fire or to provide a control line from which to suppress a fire. changes in moisture content. The of the net effect of evapotranspiration changes are an indication of changes and precipitation in producing Fire Effects—Physical, biological in the moisture status and relative cumulative moisture depletion in and ecological impacts of fire on the flammability of dead fuels that deep duff or upper soil layers. environment. roughly correspond toTen-hour Dry-bulb Temperature—The Fire Front—The strip within which Timelag Fuels. temperature of the air. continuous flaming occurs along the Grid Ignitions—Method of igniting fire perimeter (See Flame Depth). tires in which ignition points are set individually at predetermined spacing with predetermined timing throughout the area to he burned (see Ping-pong Ball System). 51 Hazard Reduction—Treatment of Line Ignition—Setting a line of fire Ping-pong Ball System—A method living and dead forest fuels to reduce as opposed to individual spots. of igniting fires with the use of a the likelihood of a fire starting, and Litter—The top layer (L layer) of the Delayed Aerial Ignition Device to lessen its damage potential and forest floor directly above the (DAID). The device is a polystyrene resistance to control. fermentation layer (F layer), ball, 1.25 inches in diameter that Heading Fire—A Fire Front composed mainly of recently fallen contains a combustible chemical. The spreading or set to spread with the leaves and pine needles, but also balls are fed into a dispenser, wind or upslope. includes dead twigs, bark fragments, generally mounted in a helicopter, etc. (See Duff). where they are injected with another Helitorch (Flying Drip Torch) —A chemical and drop through a chute specialized drip torch hung from, or Logging Debris—Unwanted tree leading out of the helicopter. The mounted on a helicopter that parts remaining after harvest, chemicals react thermally and ignite dispenses globs of ignited gelled including tree crowns, unutilized in about 30 seconds. The space gasoline. logs, and uprooted stumps. between ignition points on the ground Herbaceous Fuels—Grasses and Low-Level Jet—See Wind Profile. is primarily a function of helicopter speed, gear ratio of the dispenser, other plants that contain little woody Midflame Wind—See In-stand wind. tissue. and the number of chutes used (up to Mineral Soil—Soil layers below the 4) (See Grid Ignition). Humus—The layer of decomposed predominantly organic horizons. organic matter on the forest floor PM-10—Particulate with an aero- beneath the partially decomposed Mixing Height —The height to which dynamic diameter smaller than or litter layer (F layer) and directly relatively vigorous mixing of the equal to 10 micrometers. atmosphere occurs. above the soil. Prescribed Burning—The controlled Hygrothermograph—An instrument Mopup—Extinguishing or removing application of fire to wildland fuels that continuously records Dry-bulb burning material, especially near in either a natural or modified state, Temperature and Relative Humidity. control lines after an area has burned under specified environmental to make it safe, or to reduce residual conditions which allow the fire to be Ignition Pattern—The manner in smoke. confined to a predetermined area and which a Prescribed Fire is ignited. at the same time produce the The distance between ignition lines Muck—See Organic Soil. intensity required to attain planned or points and the sequence of igniting National Fire Danger Rating resource management objectives. them, as determined by fuel, topo- System (NFDRS)—The method graphy, weather, ignition system, currently used by the USDA Forest Psychrometer—The general name for firing technique, and other factors Service, and many other instruments designed to determine the influencing fire behavior and the organizations to integrate the effects moisture content of air. A psychro- objectives of the burn (See Firing of topography, fuels, and weather into meter consists of dry-and wet-bulb Technique). numerical indices of fire danger on a thermometers that give the Dry-and Wet-bulb Temperatures, which in turn In-stand Wind (Midflame Wind)— day-to-day basis. are used to determine Relative Windspeed within a stand at about One-Hour Timelag Fuels—Fine Humidity and Dew Point. eye level. fuels consisting mainly of dead Relative Humidity—The ratio, Inversion—In this publication, herbaceous plants, roundwood less expressed as a percentage of the defined as a layer of the atmosphere than about 1/4-inch in diameter, and the uppermost Litter Layer. amount of moisture in the air, to the through which the temperature maximum amount of moisture the air increases with increasing height. Organic Soil—Any soil or soil is capable of holding under the same horizon containing at least 30 percent conditions. Keetch-Byram Drought Index—See organic matter; examples are peat Drought Index. and muck. Residence Time —The time (seconds) Ladder Fuels—Fuels that provide required for the Fire Front to pass a Particulate (Total Suspended stationary point at the surface of the vertical continuity between the ground Particulate (TSP))—Any liquid or and tree crowns, thus creating a fuel. Numerically, it is the Flame solid particles temporarily suspended Depth divided by the rate of spread. pathway for a surface fire to move into in the atmosphere. See PM-10. the overstory tree crowns. Residual Smoke — Smoke produced Peat—See Organic Soil. by smoldering material behind the actively burning Fire Front.

52 Ring FireA tire started by igniting Spot Weather Forecast—Special Wet li ne —A line of water, or water the perimeter of the intended burn prediction of atmospheric conditions and chemical retardant, sprayed along area so that the ensuing Fire Fronts at a specific site, sometimes requested the ground and which serves as a converge toward the center of the by the Burning Boss before igniting a temporary control line from which to block. prescribed fire. ignite or stop a low-intensity fire. Rough—The live understory and dead Stagnant Conditions—Conditions fuels that build up on the forest floor under which pollutants build up faster Wind Direction—Compass direction over time. than the atmosphere can disperse from which the wind is blowing. Scorch Height (Scorch Line)—The them. Wind ProfileA plot of windspeed average height to which foliage has Strip-Heading FireA series of over height above the earths surface. been browned by fire. lines of fire upwind (or downslope) A rapid increase with height to a of a firebreak or backing fire that maximum windspeed within 1,000 Site Prep Burn A fire set to expose feet above ground and then a slow adequate mineral soil and control will burn with the wind toward the firebreak or backing fire. decrease above that peak is commonly competing vegetation until seedings called a low-level jet and is one of of the desired species become Ten-Hour Time lag Fuels—Dead several adverse wind profiles. established (See Debris Burning). roundwood 1/4 to 1 inch in diameter Windrow—Woody debris that has Slash—Debris resulting from such and, to a rough approximation, the top 3/4 inch of the litter layer. been piled into a long continuous natural events as wind, tire, or snow row. breakage, or such human activities as Timelag—The drying time, under logging or road construction . specified conditions, required for a Smoke Concentration—The weight dead fuel to loose about 63 percent of combustion products (micrograms of the difference between its initial per cubic meter) found in a given moisture content and its Equilibrum volume of air. Moisture Content. Providing conditions remain unchanged, a fuel Smoke Management—Application of will reach 95 percent of its EMC knowledge of fire behavior and after four timelag periods. meteorological processes to minimize air quality degradation during Tractor-Plow—Any tracked vehicle, Prescribed Burning. with a plow for exposing mineral soil, with transportation and Smoke Plume—The gases, smoke, personnel for its operation. and debris that rise slowly from a fire while being carried along the Transport WindspeedA measure ground because the buoyant forces of the average rate of the horizontal are exceeded by those of the ambient movement of air throughout the surface wind (See Convection mixing layer. Column). Underburning— Prescribed burning under a timber canopy. Smoke-sensitive Area (SSA)—An area in which smoke from outside Ventilation Factor—An indicator of sources is intolerable. the lower atmospheres potential to diffuse and disperse smoke. Smoldering Combustion Phase— Numerically, it is the product of the Combustion associated with residual Mixing Height and the Transport burning of forest fuels behind the Windspeed (See Dispersion Index). Fire Front. Emissions are at least twice that of the Fire Front, and Wet-bulb Temperature—Technically, consist mainly of tars. the temperature registered by the wet- bulb thermometer of a Psychrometer. Spot Fire—Fire ignited outside the It is the lowest temperature to which perimeter of the main fire by a Fire air can be cooled by evaporating Brand. water into it at a constant atmospheric pressure.

53 Suggested Reading

Abercrombie, James A.,Jr; Sims, Golden, Michael S. 1987. Johansen, R.W. 1984. Prescribed Daniel H. 1986. Fell and burn for Development and evaluation of low- burning with spot fires in the Georgia low-cost site preparation. Forest cost systems for artificial regeneration Coastal Plain. Ga. For. Res. Pap. 49. Farmer. 46(1): 14-17. of pine. Ga. For. Res. Pap. 71. Macon, GA: Georgia Forestry Andrews, Patricia L. 1986. Macon, GA: Georgia Forestry Commission. 7 p. BEHAVE: Fire behavior prediction Commission. 12 p. Johansen, R.W. 1985. Is aerial and fuel modeling system-burn Grano, Charles X. 1970. Eradicating ignition a panacea to the southern subsystem, part 1. Gen Tech. Rep. understory hardwoods by repeated prescribed burner? In: Shoulders, INT-194. Ogden, UT: U.S. prescribed burning. Res. Pap. SO-56. Department of Agriculture, Forest Eugene, ed. Proc. 3rd biennial New Orleans, LA: U.S. Department southern silvicultural research Service, Intermountain Forest and of Agriculture, Forest Service, conference; 1984 November 7-8; Range Experiment Station. 130 p. Southern Forest Experiment Station. Atlanta, GA. Gen. Tech. Rep. SO-54. 11 p. Boyer, William D. 1987. Volume New Orleans: U.S. Department of growth loss: a hidden cost of periodic Greene, Thomas A.; Shilling, Agriculture, Forest Service, Southern prescribed burning in longleaf pine. Charles L. 1987. Predicting girdling Forest Experiment Station: 514-518. Southern Journal of Applied Forestry. probability for pine and hardwood Johansen, Ragnar W. 1987. Ignition 11(3): 154-157. saplings in low-intensity backfires. patterns & prescribed fire behavior in Forest Science. 33(4): 1010-1021. Brown, A.A.; Davis, K.P. 1973. southern pine stands. Ga. For. Res. Forest fire: control and use. 2d ed. Hough, W.A. 1968. Fuel Pap. 72. Macon, GA: Georgia New York: McGraw-Hill. 584 p. consumption and fire behavior of Forestry Commission. 6 p. hazard reduction burns. Res. Pap. Burgan, Robert E.; Rothermel, Johansen, Ragnar W.; McNab, W. SE-36. Asheville, NC: U.S. Richard C. 1984. BEHAVE : Fire Henry 1977. Estimating logging Department of Agriculture, Forest behavior prediction and fuel modeling residue weights from standing slash Service, Southeastern Forest system - fuel subsystem. Gen. Tech. pine for prescribed burns. Southern Rep. INT-167. Ogden, UT: U.S. Experiment Station. 7 p. Journal of Applied Forestry. 1(2): 2-6. Department of Agriculture, Forest Hough, W.A.; Albini, F.A. 1978. Johansen, R.W.; Wade, D.D. 1987. Service, Intermountain Forest and Predicting fire behavior in palmetto- An insight into thinning young slash Range Experiment Station. 126 p. gallberry fuel complexes. Res. Pap. pine stands with tire. In: Proceedings SE-174. Asheville, NC: U.S. Byram, George M. 1954. of the fourth biennial southern Atmospheric conditions related to Department of Agriculture, Forest silvicultural research conference; 1986 blowup fires. Station Pap. 35. Service, Southeastern Forest November 4-6; Atlanta, GA. Gen. Experiment Station. 44 p. Asheville, NC: U.S. Department of Tech. Rep. SE-42. Asheville, NC: Agriculture, Forest Service, Hughes, Ralph. 1975. The native U.S. Department of Agriculture, Southeastern Forest Experiment vegetation in south Florida related to Forest Service, Southeastern Forest Station. 34 p. month of burning. Res. Note. SE-222. Experiment Station. 103-106. Asheville, NC: U.S. Department of Countryman, Clive M. 1971. This Johansen, Ragnar W.; Wade, Dale Agriculture, Forest Service, South- humidity business: whats its all about D. 1987. Effects of crown scorch on eastern Forest Experiment Station. and its use in fire control? Berkeley, survival and diameter growth of slash 8 p. CA: U.S. Department of Agriculture, pines. Southern Journal of Applied Forest Service, Pacific Southwest Johansen, R.W. 1968. Fire control Forestry. 11(4): 180-184. Forest and Range Experiment Station. considerations in pine plantations. In: Johnson, Von J. 1984. Estimating 15 p. Proceedings seventh forestry forum; moisture content in litter. Southern 1968 June 12-13; Auburn, Auburn Croker, Thomas C., Jr. 1967. Crop- Journal of Applied Forestry. 8(4): University, AL: 14-19. seedling method for planning brown- 197-201. spot burns in longleaf pine. Journal of Johansen, Ragnar W. 1981. Forestry. 65(7): 488. Windrows vs. small piles for forest debris disposal. Fire Management Notes. 42(2): 7-9.

54 Lavdas, Leonidas G. 1986. An McNab, W. Henry. 1976. Prescribed Sandberg, D.V. (and others). 1979. atmospheric dispersion index for burning and direct-seeding old Effects of fire on air: a state of prescribed burning. Res. Pap. SE-256. clearcuts in the Piedmont. Res. Note knowledge review. Gen. Tech. Rep. Asheville, NC: U.S. Department of SE-229. Asheville, NC: U.S. WO-9.Washington: U.S. Department Agriculture, Forest Service, South- Department of Agriculture, Forest of Agriculture, Forest Service, 40 p. eastern Forest Experiment Station. Service, Southeastern Forest Schroeder, Mark J.; Buck, Charles 33 p. Experiment Station. 4 p. C. 1970. Fire weather. Agric. Handb. Lewis, Clifford E.; Harshbarger, McPherson, Guy R.; Rasmussen, 360. Washington: U.S. Department of Thomas J. 1986. Burning and grazing G. Allen; Wright, Henry A.; Agriculture, Forest Service. 229 p. effects on bobwhite foods in the Britton, Carlton M. 1986. Getting Seigel, William C. 1985. Legal southeastern Coastal Plain. Wildlife started in prescribed burning. implications of prescribed burning in Society Bulletin. 14(4): 455-459. Management Note 9. Lubbock: Texas the South. In: Proceedings on Lilieholm, Robert J.; Hu, Shih- Tech University, Texas Tech Range Prescribed Fire and Smoke and Wildlife Manage. Dept. 5 p. Chang. 1987. Effect of crown scorch Management in the South Conference; 1984 September 12-14; Atlanta, GA. on mortality and diameter growth of Mobley, Hugh E.; Kerr, Ed. 1973. Asheville, NC: U.S. Department of 19-year-old-loblolly pine. Southern Wildfire versus prescribed fire in the Agriculture, Forest Service, Journal of Applied Forestry. 11(4): southern environment. Atlanta: U.S. 209-211. Southeastern Forest Experiment Department of Agriculture, South- Station: 77- 85. Lotan, James E. (and others). 1981. eastern Area, State and Private Effects of fire on flora: a state of Forestry. 6 p. Tiedemann, Arthur R. (and others). 1979. Effects of fire on water: a state knowledge review. Gen. Tech. Rep. Paul, James T.; Lavdas, Leonidas of knowledge review. Gen. Tech. Rep. WO-16. Washington: U.S. Department G.; Wells, Wesley. 1987. Use of WO-10.Washington: U.S. Department of Agriculture, Forest Service. 71 p. general weather and Dispersion Index of Agriculture, Forest Service. 28 p. Lansford, James. 1987. Prescribed to minimize the impact of smoke on fire in the Southeast-five steps to a highway visibility. Ga. Forest Res. U.S. Department of Agriculture, successful burn. Fire Management Pap. 69. Macon, GA: Georgia Forest Service, Southeastern Forest Notes. 48(3): 30-35. Forestry Commission. 10 p. Experiment Station. Prescribed burning symposium. 1971 April 14-16. Lyon, L. Jack (and others). 1978. Prescribed Fire and Fire Effects Charleston SC. Asheville, NC. 160 p. Effects of fire on fauna: a state of Working Team, National Wildfire knowledge review. Gen. Tech. Rep. Coordinating Group. 1985. U.S. Department of Agriculture, WO-6. Washington: U.S. Department Prescribed fire smoke management Forest Service, Southeastern Forest of Agriculture, Forest Service, 22 p. guide. Publication 420-1. NFES No. Experiment Station. 1976. Southern Martin, Robert E. (and others). 1279. Boise, ID: Boise Interagency forestry smoke management 1979. Effects of fire on fuels; a state Fire Center. 28 p. guidebook. Gen. Tech. Rep. SE-l0 Asheville, NC. 140 p. of knowledge review. Gen. Tech. Pap. Rothermel, Richard. 1983. How to WO-13. Washington: U.S. Department predict the spread and intensity of U.S. Department of Agriculture, of Agriculture, Forest Service, 64 p. forest and range fires. Gen Tech. Rep. Forest Service. 1977. Fire by McKevin, Martha R.; McKee, INT-143. Ogden, UT: U.S. prescription symposium; 1976 October 13-15; Atlanta. Washington. 127 p. William H., Jr. 1986. Long-term Department of Agriculture, Forest prescribed burning increases nutrient Service, Intermountain Forest and U.S. Department of Agriculture, uptake and growth of loblolly pine Range Experiment Station. 161 p. Forest Service, Southeastern Forest seedlings. Forest Ecology and Sackett, Steven S. 1975. Scheduling Experiment Station. 1985. Prescribed Managment. 17(4): 245-252. prescribed burns for hazard reduction fire and smoke management in the McMinn, James W. (and others). in the Southeast. Journal of Forestry. South: Proceedings of a symposium; 1987. Pre-harvest estimation of logging 73(3): 143-147. 1984 September 12-14; Atlanta, GA. residues in middle Georgia. Ga. For. Asheville, NC. 194 p. Res. Pap. 73. Macon, GA: Georgia Forestry Commission. 6 p.

55 U.S. Department of Agriculture, Wade, Dale D.; Wilhite, Lawrence P. For information about articles, Forest Service, Southern Region. 1981. Low intensity burn prior to contact: USDA Forest Service, 1988. Draft environmental impact bedding and planting slash pine is of Southern Region, Fire and Aviation statement: vegetation management in little value. In: Proceedings, 1st Staff Unit, 1720 Peachtree Road NW, the Costal Plain/Piedmont. Vol. I and southern silvicultural research Atlanta, GA 30367 or USDA Forest II. Mange. Bull. R8-MB 15. Atlanta. conference; 1980 November 6-7; Service, Southeastern Forest Van Lear, D.H; Danielovich, S.J. Atlanta, GA. Gen. Tech. Rep. SO-34. Experiment Station, P.O. Box 2680, 1988. Soil movement after broadcast New Orleans: U.S. Department of Asheville, NC 28802 burning in the southern Appalachians. Agriculture, Southern Forest Southern Journal of Applied Science. Experiment Station: 70-74. 12(1): 49-53. Waldrop, Thomas A. (and others). Villarrubia, CR.; Chambers J.L. 1987. Long term studies of prescribed 1978. Fire, its effect on growth and burning in loblolly pine forests of the survival of loblolly pine, Pinus taeda Southeastern Coastal Plain. Gen. L. Louisiana Academy of Science. 41: Tech. Rep. SE-45. Asheville, NC: 85-93. U.S. Department of Agriculture, Forest Service, Southeastern Forest Wade, Dale D. 1983. Fire Experiment Station. 23 p. management in the slash pine ecosystem. In: Proceedings, the Weise, David R.; Johansen, R.W.; managed slash pine ecosystem. 1981 Wade, Dale D. 1987. Effects of spring June 9-11; Gainesville, FL. defoliation on first-year growth of Gainesville, FL: University of young loblolly and slash pines. Res. Florida, School of Forest Resources Note SE-347. Asheville, NC: U.S. and Conservation, 203-227, 290-294, Department of Agriculture, Forest 301. Service, Southeastern Forest Experiment Station. 4 p. Wade Dale D. 1986. Linking fire Wells, Carol G. (and others). 1979. behavior to its effects on living plant Effects of fire on soil: a state of tissue. In: Proceedings of the 1986 knowledge review. Gen. Tech. Rep. Society of American Foresters WO-7. Washington: U.S. Department National Convention; 1986 October of Agriculture, Forest Service. 34 p. 5-8; Birmingham, AL. Bethesda, MD: Society of American Foresters. 112-116. Wade, Dale D.; Johansen, R.W.l986. Effects of fire on southern pine: observations and recommendations. Gen. Tech. Rep. SE-41. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station. 14 p. Wade, Dale D.; Lewis, Clifford E. 1987. Managing southern grazing ecosystems with fire. Rangelands. 9(3): 115-119.

56 Five Steps to a Successful Prescribed Burn

ANALYSIS

PRESCRIPTION

PREPARATION

EXECUTION

EVALUATION