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Prescribed Burning Glossary

Posted May 1, 1998

While prescribed burning is recognized as a valuable tool by many land managers, many are unfamiliar with the vocabulary associated with it. In an effort to rectify this situation, I would like to take this opportunity to present a glossary of some terms commonly used when describing or discussing prescribed burning. I realize the winter/spring burning season is quickly drawing to a close, but if you are like many "pyro-practitioners" I know whose activities were dampened this year by El Niño and an early green-up, committing these terms to memory during the offseason may offset some of the frustration.

Backfire - A fire that backs into unburned fuel against the wind. This is generally the slowest, coolest and easiest to control of the types of fires. The technique of "backfiring" is often used to establish adequate fireguards around a target area.

Black line - A type of fireguard that is actually a burned area. A black line is often created several days in advance of the prescribed burn by "burning out" the fireguard and extinguishing it as one moves on.

Disked fireguard - A fireguard created by disking and exposing the soil.

Drip torch - A tool used to distribute fire. It consists of a canister with a tubular looped spout. The loop prevents fire from going up the loop and into the canister. Fuel for the drip torch consists of a 60%-75% diesel and 25%-40% gasoline mixture.

Fire boss - The person in charge of the burn. There is only one fire boss. This person is ultimately responsible for the burn and makes the final decisions on what actions should be taken.

Fire crew - All of the personnel working on a prescribed burn (often distinguishable by lack of facial hair).

Fireguard - A barrier around the target area. There are many different kinds of fireguards (see black line, disked fireguard, green fireguard, mowed fireguard and natural fireguard).

Fire plan - The plan of attack. It is important that everyone involved with the burn is familiar with the plan. The fire plan takes into consideration the personnel available, equipment available, weather conditions (i.e. relative humidity, temperature and wind direction and velocity), fuel load and goals of the burn.

Flank fire - A fire that is quartering into unburned fuel. The relative intensity of this type of fire is between that of a head fire and a backfire. Flank fires are also used to establish adequate fireguards around a target area.

Four-letter words - Expletives uttered upon sudden wind shifts or to prod crew members into action.

Fuel load - Refers to the amount of combustible material. When used in reference to prescribed burning, fuel load generally refers to dry herbaceous material or leaf litter (fine fuel).

Green fireguard - A green fireguard is created by stimulating the growth of cool-season annuals. For a late winter/early spring burn, this may be done by mowing, disking, planting or concentrating grazing activity in late August or early September prior to the burn.

Head fire - A fire being pushed by the wind into unburned fuel. This is the fastest, hottest and most difficult to control of the types of fires.

Mowed fireguard - This generally refers to an area that is mowed prior to the burn, but not with sufficient time to produce a green fireguard.

Natural fireguard - Structures or land features not created by man that may be used as fireguards. These include rivers, creeks, cattle or game trails, etc.

Pasture burn - A fire often set with good intentions, but with little or no effort expended toward controlling the fire. These fires often turn into wildfires and should not be confused with a prescribed fire.

Prescribed burn - A prescribed burn is a burn implemented in accordance with a fire plan and restricted to a specific area to achieve specific landscape goals. A prescribed burn is a controlled burn.

Spot firing - Starting several to many individual fires within a target area. This technique is often used when fuel loads are discontinuous and the fire is not carrying well. This technique is used only after perimeter fireguards are well established.

Strip firing - Setting two to several parallel lines of fire. This technique is often used to expedite "burning out" fireguards in low fuel load areas.

Volatile fuel - Types of fuel that actually contain oils or compounds that combust when heated sufficiently. Examples of volatile fuels include eastern red cedar and greenbriar. If volatile fuels are present near the perimeter of the fire, extra caution should be taken to prevent fire escape.

Wet line - A temporary fireguard created by wetting vegetation adjacent to the fuel to be ignited. A wet line is often used in conjunction with less than optimal fireguards (e.g. mowed fireguards) to improve their efficiency. To be effective, a wet line must be made immediately prior to ignition and for relatively short distances.

"Where there is smoke, there's fire" - An old saying that should be heeded as it pertains to the perimeter of a prescribed burn. The perimeter of a burn should always be extinguished before leaving it. If there is smoke coming from the perimeter, that means that something is still burning and needs to be addressed.

Wildfire - A wildfire is a fire out of control. Any fire can become a wildfire including "a prescribed burn gone bad." Wildfires are often a result of not following a fire plan.