Proper fireguards (fire breaks) can prevent a fire from escaping the burn unit during a prescribed burn. So what types of fireguards are best for your burn unit? The answer to that question is the one that every biologist loves to give: it depends. It depends on available equipment, slope, soil type, labor, and amount and type of fuel. There are many types of fireguards, and understanding the strengths and weaknesses of each type can help determine which one to use for a given situation. Additionally, you might already have some fireguards in place and not even know it.
Bare Soil Fireguard
This is probably the most popular type of fireguard. They can be created with a disk, plow, blade or bulldozer, and are effective at stopping backfires and flank fires. Bare soil fireguards require little to no water when igniting along them, but can cause erosion in areas that have a significant slope. Also if it rains prior to or during a burn, vehicles and tractors may have difficulty traveling on bare soil fireguards.
These can be paved, gravel, dirt or two-track roads. Roads are good fireguards because they require little to no preparation and provide a good base for vehicles. They are effective at stopping backfires and flank fires with little water needed. Using roads as fireguards has some limitations; a land manager is restricted to the location of the road and might be required to burn around fire-sensitive areas.
In areas with a significant slope, green fireguards can be used as an alternative to bare soil fireguards to reduce erosion. Winter crops can serve as green fireguards. Green fireguards also limit the chance of getting stuck after a rain. However, green fireguards require months or even years of advance planning. For more info on green fireguards, refer to the July 1996 Ag News and Views article Green Fireguards or contact any Noble Foundation wildlife and fisheries consultant.
These can be lakes, ponds, rivers, creeks, cliffs, bluffs or gullies. In certain situations, water and topographic features can be very effective at stopping a fire and require little to no preparation. On the downside, if a fire jumps a natural feature, access to and containment of a spot fire can be very difficult.
Mowed or Hayed Line
These can be useful in areas with significant slope because there is still vegetation on the ground to reduce erosion, and they provide a firm base for vehicles after rain. Mowed/hayed lines only slow fire movement across the fire line so fire can be more easily extinguished with a sprayer. This technique requires a lot of water and labor because the crew is constantly extinguishing the fire as it creeps across the mowed/hayed line. Regardless of fireguard type used, it is a good idea to have a back-up sprayer, because if the first one breaks down, it can be very hard to stop a fire from crossing the fire line. This technique usually results in very slow ignition progress, so it is not desirable on larger burns.
These are strips along the edge of the burn unit that have been pre-burned. Black lines can be used to widen existing fireguards to more effectively contain a fire. They can be difficult to implement due to weather variables and the labor required prior to the scheduled burn date for the entire unit.
To learn more about fireguards and prescribed burning in general, plan on attending the Noble Foundation Prescribed Burn Workshop on Jan. 26, 2010, in Ardmore, Okla. Contact Tracy Cumbie at 580-224-6292 or firstname.lastname@example.org to register for this event. You can also register online at www.noble.org/events.