Conducting Prescribed Fires

Lighting a Backfire

The use of fire in the United States has decreased since settlement of European immigrants. This decline in fire use is due to fear of fire, fragmentation of landscapes by increased human population, farming and over-use by livestock. The lack of fire has resulted in a rapid change of landscapes, from open prairies or savannahs to closed canopy forests, and in many cases monocultures of certain species, such as eastern redcedar.

In prairies and shrublands, fire suppression has resulted in an increase in both fire-tolerant woody plants that resprout, and fire-intolerant woody plants such as eastern redcedar and ashe juniper.

Not only has fire suppression caused a decline in native plant communities, but also the habitat specialist wildlife species that require these lost or declining landscapes. These species include Northern bobwhite, lesser prairie chicken and many songbirds. Fire is also very important for other wildlife species that are habitat generalists, such as wild turkey, white-tailed deer, and elk.

Soldier Beetles can have variations in coloration.

Lighting a Flank Fire

The most economically and ecologically sound tool to restore and maintain native landscapes is prescribed fire. The regular use of fire prevents invasion of eastern recedar into prairies, shrublands, and forests. Fire can also control resprouting woody plants when the frequency is at least every three years. Fire is an ecosystem driver that facilitates ecosystem processes, including nutrient cycling, water cycling, and soil health. Fire helps maintain water shed function, water quality, and water yield. In some cases, fire has been excluded for so long, that mechanical and/or chemical tools may be needed in the restoration process. In many ecosystems, fire is just as important as the soil or climate.

There are many types of mechanical treatments that will control eastern redcedar from hand tools to heavy equipment. However, mechanical treatments are very costly when compared to fire, and they do not offer the same ecosystem benefits. If fire is not part of the management plan, mechanical treatments have to be repeated very frequently, which can be very labor intensive, costly and potentially spread exotic plant species.

Small eastern redcedar infestations can be controlled by using hand-held shear/loppers, chainsaws, or brush cutters. These treatments need to be repeated at least every three years as new eastern redcedars will continue to rapidly invade.

Proper grazing management is mandatory to ensure that enough fine fuel is available to carry a fire and burn eastern redcedars. If eastern redcedar trees are not controlled, stocking rates need to be reduced frequently to account for the loss of forage. Eventually eastern redcedar will become so thick that fire will not carry across the area, except under extreme wildfire conditions.

Lighting a Headfire

Heavy infestations by eastern recedar are very expensive to control and require heavy equipment. Hydraulic saws and clippers will produce the best results, but can be time consuming unless it is hired out or most of the managers time is spent cutting. Bulldozers can be very costly and cause soil disturbance, and are not recommended unless in extreme conditions. These treatments need to be followed by fire or the manager will be in the same situation.

The use of prescribed fire is the most recommended tool for eliminating eastern redcedar. A land management plan should exist on every piece of property to ensure the land is functioning at its highest potential.

Types of Fire

There are many different techniques that can be used when lighting prescribed fires. The types of fire produced depend upon ignition technique and direction of the wind. These different types of fire are used in different areas of the burn depending on the conditions and objectives. The different types of fire include backfire, flank fire and head fire.

This image depicts the parts of a fire.

Types of Fire

A backfire is when you light off of a fire line and the flames burn into (against) the wind. Backfires are frequently used to create a line of “black,” or burned fuel, on the downwind side of the burn unit prior to lighting the flank or head fire. Backfires burn slowly and typically have short flame lengths.

A flank fire is a fire that burns perpendicular to the wind direction. Flank fires are commonly used after a backfire has been lit and let burn a safe distance, and prior to ignition of the head fire. Flank fires burn more quickly than backfires and the flames are greater in length.   

A head fire is created when the fire burns with the wind, pushing the fire towards the un-burned fuel. Head fires are used when there has already been a backfire lit on the downwind side of the burn, and flank fires lit, or if you are burning towards an area such as a large body of water, or previously burned unit with no remaining fuel. Head fires move quickly and typically have longer flame lengths than the other types and can produce intense heat.

Ignition Techniques

A strip backfire is when you light multiple lines of backfires, usually just 5-15 yards apart. This is commonly used to speed up the process of putting in “black” or burned area prior to flank or head fires.

Strip flank fires are less common, because they can turn into a “running flank fire” if the wind direction changes, and can be dangerous for the burn crew. If this technique is used, the people igniting should be alert and aware of any wind shifts.

Ringing a burn unit, is when the perimeter of the entire burn unit is lit off at once. Ringing a burn unit is not as common as other ignition techniques, and is usually only done in a small burn unit. This is a very quick method of burning because the flames from each side of the burn unit feed off of each other and suck together, but if the wind switches it can easily cause an escape. This should only be done by very experienced burn bosses and crews.

The most common process of lighting a prescribed fire begins when the backfire is lit off of the downwind fire line. Once there is a safe amount of black, a person on each side of the unit will uniformely ignite the flank fires. When they reach the respective head fire area of the unit, they pause to monitor the amount of fuel that the back and flank fires have burned. When there is a sufficient amount of “black” or burned area, the two will wither ignite the headfire from both corners and meet in the middle, or one person will ignite the head fire.

Every burn plan and ignition type is different. Use what works best for the burn unit, crew and available equipment.