Planning and preparation for prescribed burns should start several months or even a year prior to a burn. The following issues represent the most common problems we encounter regarding well-intended, but poorly prepared or executed burns:
- Little training and experience
- Inadequate fine fuel
- Absence of a well-prepared burn plan
- Poorly prepared fireguards
- Coarse or volatile fuels too close to fireguards
- Impatience (related to poor decisions)
Lack of training can be overcome by attending prescribed burning workshops and courses taught by qualified personnel, such as extension, universities, Natural Resources Conservation Service, the Noble Foundation, etc., and reading appropriate publications prepared by such entities. Experience can be obtained by helping on several burns conducted by knowledgeable, well-trained burn managers and asking questions while helping.
Inadequate fuel is generally a result of inadequate rest from grazing, low rainfall, infertile soils, poor range condition and/or excessive amounts of some woody species. Although inadequate fuel makes it difficult or impossible to accomplish burning objectives, it is seldom a safety or containment problem, unlike these other issues.
Well-prepared burn plans require time, study and thought, but force managers to carefully and thoroughly plan burns and adequately prepare for contingencies. After a good burn plan is completed for a tract of land, future burns on the same tract of land require only minor tweaking of the original plan.
Appropriate fireguard preparation depends on the quantity of fine fuels present, proximity and volume of coarse fuels, environmental conditions allowed in a burn prescription, skill of a burn crew, size of a burn, erodibility of soils and types of fire suppression equipment available. For example, two miles of 8-foot-wide disked backfire and flank fireguards through ungrazed tallgrass prairie would be inadequate for an inexperienced burn crew to accomplish a burn safely within five hours using a small volume power sprayer, such as a typical cattle/herbicide sprayer, with 40 percent relative humidity and 10-mile-per-hour winds. However, a burn with these parameters probably could be accomplished safely with a 12-foot disked fireguard adjacent to the fine fuels and 12-20 feet of short-mowed vegetation along the outside of the disked strip. Mowing should occur several weeks or months prior to a burn to allow most clippings adequate time to disperse and/or decompose. Sometimes, additional mowing or raking is necessary to break up clumps and scatter clippings.
Coarse and volatile fuels too close to backfire and flank fireguards are probably the most common problems that we encounter with inexperienced burn managers. Coarse fuels include things such as brush piles, logs, dead trees, hollow live trees, clumps of mowed grass or hay, and clumps or turnrows of mixed soil and grass. Volatile fuels include things such as eastern red-cedar trees and Ashe juniper trees. Volatile fuels too close to a fireguard can throw embers considerable distances beyond a fireguard. When burning several acres at a time, fuels next to a fireguard should burn out quickly and safely, so a burn crew can move on without risk of embers blowing across a fireguard. Preferably, coarse fuels and juniper trees should not exist in a burn unit within 50 yards from the outside edge of backfire and flank fireguards (farther for elevated coarse fuels such as dead or hollow trees).
An example of impatience would be a burn manager’s decision to burn outside of a written prescription because he/she wants to accomplish a burn by a certain date or is nearing the end of a burning season. A major purpose of a burn prescription is to define the conditions when a burn can be conducted safely. Burning outside of a prescription invites problems. Impatience also pertains to ignition crews traveling too quickly while igniting backfires and flank fires. Ignition crews traveling along backfires and flank fires should create adequately wide blackened areas along the fireguards behind them as they progress.
There is much to learn and experience before a person becomes a skilled burn manager. However, most people can become proficient if they are willing to commit the time and effort.
This article was contributed by Mike Porter of the Samuel Roberts Noble Foundation.