The following terms have been selected from the updated FAO terminology (FAO 2003, in press.).
aerial fuel
The standing and supported live and dead fuels not in direct contact with the ground and consisting mainly of foliage, twigs, branches, stems, bark, lianas and other vines, moss and high brush. In general they easily dry out and may carry surface fires into the canopy.
agrosilvopastoral system
Land-use system in which woody perennials are used on the same land as agricultural crops and animals, in some form of spatial arrangement or temporal sequence. In fire management agrosilvopastoral systems are planned as fuelbreaks (particularly shaded fuelbreaks) to reduce fire risk by modifying understory vegetation and soil cover (cf. fuelbreak).
backfire
A fire spreading, or set to spread, into or against the wind: (1) As used in fire suppression: A fire set along the inner edge of a control line to consume the fuel in the path of a forest fire and/or change the direction of force of the fire's convection column (Note: doing this on a small scale and with closer control, in order to consume patches of unburned fuel and aid control-line construction (as in mopping-up) is distinguished as "burning out, firing out, clean burning"); (2) As used in prescribed burning: designation of fire movement in relation to wind.
backfiring
A form of indirect attack where extensive fire is set along the inner edge of a control line or natural barrier, usually some distance from the wildfire and taking advantage of indrafts, to consume fuels in the path of the fire, and thereby halt or retard the progress of the fire front.
biomass
(1) The amount of living matter in a given habitat, expressed either as the weight of organisms per unit area or as the volume of organisms per unit volume of habitat. (2) Organic matter that can be converted to fuel and is therefore regarded as a potential energy source. Note: Organisms include plant biomass (phytomass) and animal biomass (zoomass). (3) In fire science the term biomass is often used synonymously with the term "fuel" and includes both living and dead phytomass (necromass); the zoomass is usually excluded.
buffer strip / buffer zone
A fuel break on the form of a strip of land along or adjacent to roads, trails, watercourses and recreation sites, or between (separating) fuel complexes (cf. fuelbreak).
candle bark
Long streamers of bark decorticated from some gum-barked Eucalyptus species forming a firebrand responsible for long-distance spotting.
combustion
Consumption of fuels by oxidation, evolving heat and generally flame (neither necessarily sensible) and/or incandescence. Combustion can be divided into four phases: pre-ignition (or preheating), flaming, smouldering, and glowing.
control line
Comprehensive term for all constructed or natural barriers and treated fire edges used to control a fire.
dead fuel
Fuels with no living tissue in which moisture content is governed almost entirely by atmospheric moisture (relative humidity and precipitation), dry-bulb temperature, and solar radiation (cf. Live Fuel).
dispatcher
A person employed to receive reports of discovery and status of fires, confirm their locations, take action promptly to provide the firefighters and equipment likely to be needed for control in first attack, send them to the proper place and provide support as needed.
draped fuels
Needles, leaves, and twigs that have fallen from tree branches and have lodged on lower branches or brush. Comprises a part of aerial fuels.
drip torch
A hand-held apparatus for igniting prescribed fires and backfires by dripping flaming fuel on the materials to be burned. The device consists of a fuel fount, burner arm, and ignition source. Fuel used is generally a mixture of 65-80% diesel and 20-35% gasoline.
early burning
Prescribed burning early in the dry season, before the leaves and undergrowth are completely dry or before the leaves are shed; carried out as a precaution against more severe fire damage later in the fire season.
escaped fire
Fire which has exceeded or is expected to exceed initial attack capabilities or planned prescription.
fine fuel
Fast-drying dead fuels, generally characterized by a comparatively high surface area-to-volume ratio, which are less than 0.5 cm in diameter and have a timelag of one hour or less. These fuels (grass, leaves, needles, etc.) ignite readily and are consumed rapidly by fire when dry. (cf. flash fuel, medium fuel, heavy fuel).
fire behaviour
The manner in which fuel ignites, flame develops, and fire spreads and exhibits other related phenomena as determined by the interaction of fuels, weather, and topography. Some common terms used to describe fire behaviour include the following:
smouldering - A fire burning without flame and barely spreading.
creeping - A fire spreading slowly over the ground, generally with a low flame.
running - A fire rapidly spreading and with a well-defined head.
torching - Ignition and flare up of foliage of a single tree or a small clump of trees, usually from bottom to top (syn. candling).
spotting - A fire producing firebrands carried by the surface wind, a fire whirl, and/or convection column that fall beyond the main fire perimeter and result in spot fires. Note: Solid Mass or Ember Transport under Heat Transfer.
crowning - A fire ascending into the crowns of trees and spreading from crown to crown. Note: Three classes of Crown Fire under Forest Fire (1).
fire belt
A strip, cleared or planted with trees, maintained as a firebreak or fuelbreak.
firebreak
Any natural or constructed discontinuity in a fuelbed utilized to segregate, stop, and control the spread of fire or to provide a control line from which to suppress a fire; characterized by complete lack of combustibles down to mineral soil (as distinguished from fuelbreak).
fire climax
A plant community at a stage of succession maintained by periodic fires.
fire control
All activities concerned with protection of vegetation from fire.
fire cycle
The number of years required to burn over an area equal to the entire area of interest.
fire danger
A general term used to express an assessment of both fixed and variable factors of the fire environment that determine the ease of ignition, rate of spread, difficulty of control, and fire impact; often expressed as an index.
fire danger rating
A component of a fire management system that integrates the effects of selected fire danger factors into one or more qualitative or numerical indices of current protection needs.
fire-dependent species
Plant and animal species which require regular fire influence which triggers or facilitates regeneration mechanisms, or regulates competition. Without the influence of fire these species would become extinct.
fire ecology
The study of the relationships and interactions between fire, living organisms, and the environment.
fire exclusion
Planned (systematic) protection of an ecosystem from any wildfire, including any prescribed fire, by all means of fire prevention and suppression in order to obtain management objectives (cf. fire control).
fire frequency
The average number of fires or regularly occurring fire events per unit time in a designated area.
fire hazard
(1) A fuel complex, defined by volume, type, condition, arrangement, and location, that determines the degree both of ease of ignition and of fire suppression difficulty; (2) a measure of that part of the fire danger contributed by the fuels available for burning. Note: Is worked out from their relative amount, type, and condition, particularly their moisture contents.
fire history
The reconstruction and interpretation of the chronological record, causes and impacts of fire occurrence in an ecosystem in relation to changes of past environmental, cultural and socio-economic conditions. Fire history evidence is based on analysis of charcoal deposits in soils, sediments, and ice, dendrochronology (fire scar analysis), historical documents, and fire reports.
fire information system
An information system designed to support fire management decisions. Advanced fire information systems integrate different sources of information required (e.g., vegetation conditions including fire history, topography, fire weather, fire behaviour models, real-or near-real time fire detection and monitoring data, fire management resources, infrastructures and pre-suppression information) on the base of a Geographic Information System (GIS) and allows real-time distribution or access via telecommunication.
fire interval or fire-return interval
The number of years between two successive fires documented in a designated area (i.e., the interval between two successive fire occurrences); the size of the area must be clearly specified.
fire management
All activities required for the protection of burnable forest and other vegetation values from fire and the use of fire to meet land management goals and objectives. It involves the strategic integration of such factors as a knowledge of fire regimes, probable fire effects, values-at-risk, level of forest protection required, cost of fire-related activities, and prescribed fire technology into multiple-use planning, decision making, and day-to-day activities to accomplish stated resource management objectives. Successful fire management depends on effective fire prevention, detection, and pre-suppression, having an adequate fire suppression capability, and consideration of fire ecology relationships.
fire management plan
(1) A statement, for a specific area, of fire policy and prescribed action; (2) The systematic, technological, and administrative management process of determining the organization, facilities, resources, and procedures required to protect people, property, and forest areas from fire and to use fire to accomplish forest management and other land use objectives (cf. fire prevention plan or fire Campaign, pre-suppression planning, pre-attack plan, fire suppression plan, end-of-season appraisal).
fire pre-suppression
Activities undertaken in advance of fire occurrence to help ensure more effective fire suppression; includes overall planning, recruitment and training of fire personnel, procurement and maintenance of fire fighting equipment and supplies, fuel treatment, and creating, maintaining, and improving a system of fuelbreaks, roads, water sources, and control lines.
fire prevention
All measures in fire management, fuel management, forest management, forest utilization and concerning the land users and the general public, including law enforcement, that may result in the prevention of outbreak of fires or the reduction of fire severity and spread.
fire protection
All actions taken to limit the adverse environmental, social, political, cultural and economical effects of wildland fire.
fire regime
The patterns of fire occurrence, size, and severity - and sometimes, vegetation and fire effects as well - in a given area or ecosystem. It integrates various fire characteristics. A natural fire regime is the total pattern of fires over time that is characteristic of a natural region or ecosystem. The classification of fire regimes includes variations in ignition, fire intensity and behaviour, typical fire size, fire return intervals, and ecological effects.
fire season
(1) Period(s) of the year during which wildland fires are likely to occur and affect resources sufficiently to warrant organized fire management activities; (2) a legally enacted time during which burning activities are regulated by State or local authority.
fire suppression
All activities concerned with controlling and extinguishing a fire following its detection. (Syn. Fire Control, Fire Fighting).
Methods of suppression are:
direct attack - A method whereby the fire is attacked immediately adjacent to the burning fuel.
parallel attack - A method whereby a fireguard is constructed as close to the fire as heat and flame permit, and burning out the fuel between the fire and the fireguard.
indirect attack - A method whereby the control line is strategically located to take advantage of favourable terrain and natural breaks in advance of the fire perimeter and the intervening strip is usually burned out or backfired.
hot spotting - A method to check the spread and intensity of a fire at those points that exhibit the most rapid spread or that otherwise pose some special threat to control of the situation. This is in contrast to systematically working all parts of the fire at the same time, or progressively, in a step-by-step manner.
cold trailing - A method of determining whether or not a fire is still burning, involving careful inspection and feeling with the hand, or by use of a hand-held infrared scanner, to detect any heat source.
mop-up - The act of extinguishing a fire after it has been brought under control.
fire weather
Weather conditions which influence fire ignition, behaviour, and suppression. Weather parameters are dry-bulb temperature, relative humidity, wind speed and direction, precipitation, atmospheric stability, winds aloft.
flammability
Relative ease of igniting and burning of a given fuel under controlled conditions, with or without a pilot flame. Flammability of a fuel is characterised quantitatively by the ignition delay of a sample of fuel exposed to a normalised radiation source.
flash fuel
Fuels, e.g. grass, ferns, leaves, draped (i.e., intercepted when falling) needles, tree moss, and light slash, that ignite readily and are consumed rapidly by fire when dry; generally characterized by a comparatively high surface-to-volume ratio.
forest fire
I. Definition of forest fire
Any wildfire or prescribed fire that is burning in a forest, variously defined for legal purposes. The FAO Forest Resource Assessment 2000 aims towards global standardization of the terminology:
forest: Land with tree crown cover of more than 10 percent and area of more than 0.5 hectares. The trees should be able to reach a minimum height of 5 meters at maturity.
other wooded land: Land either with a crown cover of 5-10 percent of trees able to reach a height of 5 meters at maturity; or a crown cover of more than 10 percent of trees not able to reach a height of 5 meters at maturity; or with shrub or bush cover of more than 10 percent.
other land: Land with less crown cover, tree height, or shrub cover as defined under "Other wooded land". Indication is desired if recurring wildfires affect "Other land" by inhibiting regeneration to the "Forest" and "Other wooded land" categories.
I. Typology
ground fire: A fire that burns in the ground fuel layer (syn. Subsurface fire, below surface fire).
surface fire: A fire that burns in the surface fuel layer, excluding the crowns of the trees, as either a head fire, flank fire, or backfire.
crown fire: A fire that advances through the crown fuel layer, usually in conjunction with the surface fire. Crown fires can be classified according to the degree of dependence on the surface fire phase:
intermittent crown fire: A fire in which trees discontinuously torch, but rate of spread is controlled by the surface fire phase (syn. Passive Crown Fire).
active crown fire: A fire that advances with a well-defined wall of flame extending from the ground surface to above the crown fuel layer. Probably most crown fires are of this class. Development of an active crown fire requires a substantial surface fire, and thereafter the surface and crown phases spread as a linked unit (syn. Dependent Crown Fire).
independent crown fire: A fire that advances in the crown fuel layer only (syn. Running Crown Fire).
forest protection
That section of forestry concerned with the management of biotic and non-biotic damage to forests, arising from the action of humans (particularly unauthorized use of fire, human-caused wildfires, grazing and browsing, felling), natural wildfires, pests, pathogens, and extreme climatic events (wind, frost, precipitation).
fragmentation
The process of transforming large continuous vegetation or landscape patterns into smaller patches by disturbance. Natural agents of fragmentation are fire, landslides, windthrow, insects, erosion. Human-induced fragmentations include land use (e.g., agriculture, grazing, forestry), construction of residential areas, roads and other infrastructures. Fragmentation involves change of fire regimes due to alteration and discontinuity of fuels.
fuel
All combustible organic material in forests and other vegetation types, including agricultural bio-mass such as grass, branches and wood, infrastructure in urban interface areas; which create heat during the combustion process.
fuel accumulation
Process or result of build-up of those elements of a vegetation complex which are not subject to biological decay, reduction by fire, animal grazing and browsing, or harvest by humans; used in characterizing fuel dynamics between two fires and implications on fire behaviour.
fuel arrangement
The horizontal and vertical distribution of all combustible materials within a particular fuel type.
fuelbreak
Generally wide (20 - 300 meters) strips of land on which either less flammable native vegetation is maintained and integrated into fire management planning, or vegetation has been permanently modified so that fires burning into them can be more readily controlled (as distinguished from firebreak). In some countries fuelbreaks are integrated elements of agro-silvopastoral systems in which the vegetative cover is intensively treated by crop cultivation or grazing. Some fuelbreaks contain narrow firebreaks which may be roads or narrower hand-constructed lines. During fires, these firebreaks can quickly be widened either with hand tools or by firing out. Fuelbreaks have the advantages of preventing erosion, offering a safe place for firefighters to work, low maintenance, and a pleasing appearance (cf. control line, agrosilvopastoral system, buffer strip/zone).
fuel consumption
The amount of a specified fuel type or strata that is removed through the fire process, often expressed as a percentage of the pre-burn fuel weight (or fuel load). It includes available fuel plus fuel consumed after the fire front passes.
fuel loading
The amount of fuel present expressed quantitatively in terms of weight of fuel per unit area. This may be available fuel (consumable fuel) or total fuel, usually expressed as ovendry weight.
fuel management
Act or practice of controlling flammability and reducing resistance to control of wildland fuels through mechanical, chemical, biological, or manual means, or by fire, in support of land management objectives.
fuel reduction
Manipulation, including combustion, or removal of fuels to reduce the likelihood of ignition, the potential fire intensity, and/or to lessen potential damage and resistance to control.
greenbelt
(1) A fuelbreak maintained by the cultivation of strips of less flammable plants within a zone of high fire hazard, e.g., an irrigated, landscaped, and regularly maintained fuelbreak put to some additional use (e.g., golf course, park, playground).
hazard reduction
Treatment of living and dead forest fuels to reduce the likelihood of a fire starting, and to lessen its damage potential and resistance to control (cf. Fuel Treatment). Activity gaining special importance in residential/wildland interface areas.
Incident Command System
A standardized on-scene emergency management concept specifically designed to allow its user(s) to adopt an integrated organizational structure equal to the complexity and demands of single or multiple incidents, without being hindered by jurisdictional boundaries. (element of the Incident Command System [ICS]).
Integrated Forest Fire Management (IFFM)
Designation of fire management systems which include one or both of the following concepts of integration: (1) Integration of prescribed natural or human-caused wildfires and/or planned application of fire in forestry and other land-use systems in accordance with the objectives of prescribed burning; (2) Integration of the activities and the use of the capabilities of the rural populations (communities, individual land users), government agencies, NGOs, POs to meet the overall objectives of land management, vegetation (forest) protection, and smoke management including “community-based fire management” or CBFiM. The term IFFM is common for fire management approaches in less developed regions including forest and non-forest ecosystems. Note: In case of absence of forests in the area concerned the term Integrated Fire Management (IFM) is used instead (cf. prescribed burning).
ladder fuel
Fuels which provide vertical continuity between strata and allow fire to carry from surface fuels into the crowns of trees or shrubs (torching, crowning) and support continuation of crown fires (cf. crown fuel, ground fuel, and surface fuel).
late burning
Prescribed burning activities towards the end of the dry season.
low intensity fire
Fire which burns with a relatively low intensity, e.g. a prescribed surface fire as opposed to a high-intensity crown fire.
pre-attack plan
A plan detailing predetermined fire suppression strategy and tactics to be deployed following fire occurrence in a given land management unit. A pre-attack plan contains data on fuel types and topographic conditions including fuelbreaks, access routes and travel times, water supply sources, lakes suitable for skimmer aircraft, and existing heliports. It also includes information on existing and/or proposed locations for control lines (including the types and number of fire suppression resources that may be required and probable rates of fireguard construction, and possible constraints), base and line camps, helispots, and the priorities for construction and/or improvement of pre-suppression facilities (syn. pre-attack planning, pre-attack, cf. fire management plan, fire suppression plan, pre-suppression planning).
prescribed burning
Controlled application of fire to vegetation in either their natural or modified state, under specified environmental conditions which allow the fire to be confined to a predetermined area and at the same time to produce the intensity of heat and rate of spread required to attain planned resource management objectives (cf. Prescribed Fire). Note: This term has replaced the earlier term "Controlled Burning".
prescribed fire
A management-ignited wildland fire or a wildfire that burns within prescription, i.e. the fire is confined to a predetermined area and produces the fire behavior and fire characteristics required to attain planned fire treatment and/or resource management objectives. The act or procedure of setting a prescribed fire is called prescribed burning (cf. Prescribed Burning). A wildfire burning within prescription may result from a human-caused fire or a natural fire (cf. prescribed natural fire, integrated forest fire management, wildfire).
prescribed natural fire
Naturally ignited fires , such as those started by lightning, which are further used to burn under specific management prescriptions without initial fire suppression and which are managed to achieve resource benefits under close supervision (cf. prescribed fire, wildfire).
prescription
Written statement defining the objectives to be attained as well as the conditions of temperature, humidity, wind direction and speed, fuel moisture, and soil moisture, under which a fire will be allowed to burn. A prescription is generally expressed as acceptable ranges of the prescription elements, and the limit of the geographic area to be covered.
rate of spread
The speed at which a fire extends its horizontal dimensions, expressed in terms of distance per unit of time (m/min or km/h) (syn. fire spread, cf. rate of area growth, rate of perimeter growth).
reclamation burning
Prescribed burning for restoration of ecosystem characteristics and functioning (cf. restoration).
rehabilitation
The activities necessary to repair damage or disturbance caused by wildfire or the wildfire suppression activity (cf. restoration).
residence time
(1) The time required for the flaming zone of a fire to pass a stationary point. (2) The time an emission component is in the air between emission and removal from the air or change into another chemical configuration.
residential / wildland interface
The transition zone between residential areas and wildlands or vegetated fuels (cf. Urban, Urban/Wildland Interface, Wildland, Wildland Fire, Rural Urban Interface).
restoration
Restoration of biophysical capacity of ecosystems to previous (desired) conditions. Restoration includes rehabilitation measures after fire, or prescribed burning where certain fire effects are desired (cf. rehabilitation, reclamation burning).
ring fire
A fire started by igniting the full perimeter of the intended burn area so that the ensuing fire fronts converge toward the centre of the burn.
risk
(1) The probability of fire initiation due to the presence and activity of a causative agent. (2) A causative agent.
rural fire protection
Fire protection and firefighting problems that are outside of areas covered by municipal Fire & Rescue Services and its Fire Ordinance; these areas are usually remote from public water supplies and require all terrain vehicles to reach.
serotiny
Storage of seeds in closed seed containers in the canopy of shrubs and trees. For instance, serotinous cones of Lodgepole Pine do not open until subjected to temperatures of 45 to 50°C, causing the melting of the resin bond that seals the cone scales.
slash
Debris (fuels) resulting from natural events (wind/ fire) or human activities like forest harvesting.
slash disposal
Treatment of slash to reduce fire hazard or for other purposes (cf. Fuel Management).
smoke haze
An aggregation (suspension) in the atmosphere of very fine, widely dispersed, solid or liquid particles generated by vegetation fires giving the air an opalescent appearance.
smoke management
The application of knowledge of fire behaviour and meteorological processes to minimize air quality degradation during prescribed fires.
spot fire
(1) Fire ignited outside the perimeter of the main fire by a firebrand (by flying sparks or embers transported by air currents, gravity, or fire whirls). (2) A very small fire which jumped over the fireline, that requires little time and resources to extinguish by air currents, gravity, and/or fire whirls (cf. Long-Range Spotting).
stand replacement fire
Fire which kills all or most living overstory trees in a forest and initiates secondary succession or regrowth.
underburning
Prescribed burning with a low intensity fire in activity-created or natural fuels under a timber canopy.
urban / wildland interface
The transition zone (1) between cities and wildland (cf. urban, wildland, wildland fire), (2) where structures and other human development meets undeveloped wildland or vegetative fuels (syn. residential/wildland interface, wildland/urban interface, rural urban interface).
values-at-risk
Natural resources, developments, or other values that may be jeopardized if a fire occurs.
wilderness
(1) A wild, uncultivated, uninhabited region, vegetated and non-vegetated. (2) Area of remarkable natural beauty and ecological diversity. (3) Area established to conserve its primeval character and influence for public enjoyment, under uncultivated conditions, in perpetuity.
wildfire
(1) Any unplanned and uncontrolled wildland fire which regardless of ignition source may require suppression response, or other action according to agency policy. (2) Any free burning wildland fire unaffected by fire suppression measures which meets management objectives (cf. wildland, wildland fire, prescribed natural fire, prescribed fire).
wildland
Vegetated and non-vegetated land in which development is essentially non-existent, except for roads, railroads, powerlines, and similar transportation facilities; structures, if any, are widely scattered. In fire management terminology this general term includes all burnable vegetation resources including managed forests and forest plantations (cf. residential/wildland interface, wildfire).
wildland fire
Any fire occurring on wildland regardless of ignition sources, damages or benefits (cf. wildland, wildfire, residential/wildland interface).
1 For additional fire terms please refer to the revised FAO Wildland Fire Management Terminology. FAO Forestry Paper 70. FAO, Rome 2003. In press.
