Prescribed Burn Terminology
Prescribed fire (also called controlled burning) is an important tool that can be used to reduce the risk of large uncharacteristically severe wildfires, increase public and firefighter safety, as well as meet a variety of integrated natural resource management objectives. Examples of natural resource management objectives that can be achieved with prescribed fire include; habitat restoration, restore or maintain ecosystem health, and maintenance of vegetation treatments.
A technically reviewed and agency approved prescribed fire burn plan must be completed prior to the ignition of all planned prescribed fires. All prescribed fires are ignited by trained, qualified and experienced personnel. Prescribed fires are either ignited by hand using a drip torch (a hand-carried device that pours out a small stream of burning fuel mix) or by helicopters carrying a gelled fuel torch (helitorch) or a sphere dispenser machine that drops or dispenses a fuel mixture to the surface to ignite the surface fuels and vegetation. The method of ignition for each prescribed burn unit depends on personnel safety, current and predicted weather, topography, vegetation and the intensity of the fire needed to meet the resource objectives of the burn. Common types of prescribed fire are:
- Pile Burning: A prescribed fire used to ignite hand or machine piles of cut vegetation resulting from vegetation or fuel management activities. Piles are generally burned during the wet season to reduce damage to the residual trees and to confine the fire to the footprint of the pile. Pile burning allows time for the vegetative material to dry out and will produce less overall smoke by burning hot and clean. Swamper burning is a modified form of pile burning where personnel feed material (or swamp material) into small ignited burn piles. The result is fewer piles per acre and can be used to lessen impact on fragile soils and plant and animal species.
- Understory burning/Underburning: A prescribed fire ignited under the forest canopy that focuses on the consumption of surface fuels but not the overstory vegetation. Underburning is generally used following a pre-treatment such as thinning and /or pile burning to further reduce the surface fuels, help maintain the desired vegetation conditions and enhance the overall health and resiliency of the stand.
- Broadcast burning: A prescribed fire ignited in areas with little or no forest canopy present. Broadcast burning is used in grasslands, shrublands, and oak woodlands for habitat restoration and fuels reduction purposes. This type of burning can be beneficial for protecting and enhancing sage grouse habitat and mule deer and elk winter ranges.
- Jackpot burning: A modified form of underburn or broadcast burn where the target fuels to be ignited are the concentrations (or jackpots) of vegetative fuel. The result is a mosaic burn pattern. This technique works well when surface fuels loading is very high following vegetation treatments such as juniper encroachment removal used to improve rangeland ecosystems.
When the environmental conditions allow for a prescribed burn, a "window" of opportunity is referred to as the burn window or when the burn is in prescription. The burn window depends on many variables including the resource objectives, current and predicted weather, fuel moisture, personnel and equipment availability to carry out the burn,
mop-up, and patrol. The most common burn windows occur outside of wildfire season in the spring and fall. When the objective is to reduce live vegetation such as grasslands and shrublands the prescribed burn is likely to take place in the fall prior to the wet season. When the main fuel to consume is timber litter or dead fuel the prescribed burn could take place in the winter or spring. Pile burning generally takes place when the vegetation around the pile is too wet to carry fire and mainly takes place during the fall/winter wet season.
Prescribed Fire Plan
A prescribed fire plan is required for each prescribed fire ignited by land management agencies. Burn plans are official site-specific implementation documents prepared by trained and qualified personnel, approved by the agency administrator and include criteria for the conditions under which the fire will be conducted to meet the resource objectives.
Prescribed Fire Burn Boss
A burn boss is a trained and qualified person in charge of the prescribed burn. The burn boss is responsible for the writing of burn plans, determining when the burn is in prescription, obtaining smoke clearance and weather forecasts, notifying officials of the upcoming burn, obtaining all qualified personnel and equipment needed to conduct and patrol the burn. The burn boss must also ensure all operations are conducted in a safe manner and considers personnel and public safety during and after the burn.
Smoke from prescribed fires must be managed and monitored to ensure the smoke does not enter designated smoke sensitive areas. Clearance to burn must be granted from the State smoke management officials at the Oregon Department of Forestry (ODF) or Washington Department of Natural Resources (DNR) prior to ignition. During the months that prescribed burning occurs, a daily smoke management forecast and burning instructions are issued by an air quality forecaster from ODF or DNR, which is used by the burn boss to help determine the best day and time to burn. Final permission to burn comes from either the written smoke management forecast instructions or verbally from the State smoke management forecaster.
Vegetative fuel on or near the ground surface, consisting of leaf and needle litter, grass, dead branch material, downed logs, bark, tree cones and low grown vegetation.
Vegetative fuel (small trees and shrubs) which provide vertical continuity between the ground surface and the forest canopy. These fuels can provide a ladder for the fire to reach the forest canopy.
Mop-up and Patrol
As soon as a prescribed fire is ignited resources will be patrolling the control lines and mopping up hot spots as necessary. Mop-up is the term used to describe the extinguishing of the fire where needed. Mop-up is usually done around the perimeter of the prescribed fire to keep it contained and controlled. Active patrol of the control lines (fire edge) will continue until the prescribed fire is completely out. After that periodic patrol will continue to ensure no latent smoke and/or heat is detected.
Contain and Control
In a wildfire situation containment or "boxing in" of a fire is done by using natural and/or constructed barriers such as fireline, roads, trails, lakes, green fields, etc. Control of a fire means is has been contained and put out. In a prescribed fire the fire is contained prior to ignition and is under control the entire time until it is put out. The barriers that hold a prescribed fire in place are identified and constructed before ignition and are known to all personnel doing the burn.