Fighting Fire with Fire
From The Bugwood Network
Forest fuels accumulate rapidly in pine stands on the Coastal Plain. In 5 to 6 years, heavy "roughs" can build up, posing a serious threat from wildfire to all forest resources.
Prescribed fire is the most practical way to reduce dangerous accumulations of combustible fuels under southern pine stands. Wildfires that burn into areas where fuels have been reduced by prescribed burning cause less damage and are much easier to control. The appropriate interval between prescribed burns for fuel reduction varies with several factors, including the rate of fuel accumulation, past wildfire occurrence, values at risk, and the risk of a fire. The time interval between fires can be as often as every year although a 3- or 4-year cycle is usually adequate after the initial fuel-reduction burn.
The need to reduce hazardous fuel accumulations in the pine plantations of the South is increasing. Without fuel reduction, fire hazard is extremely high in these vast contiguous stands. The initial hazard-reduction burn in a young pine stand requires exacting conditions of wind, humidity, and temperature.
Higher wind velocities and cooler temperatures minimize scorch damage. Southern pine plantations averaging 10 to 12 feet in height can be burned by experienced people under the right conditions without damage. Young plantations on industrial lands are often burned for the first time when they are 15 to 20 feet tall using aerial ignition; close spacing of ignition spots (e.g., 2 chains by 2 chains), and cool, damp conditions with some wind are a must to avoid crown damage.
Subsequent fuel reduction burns need not cover the entire area. The objective is to break up fuel continuity. Fuel reduction on 75 to 80 percent of the area is sufficient. An added advantage of "patchy" burns is that the unburned islands provide cover for wildlife. These unburned patches will not have a dangerous accumulation of fuels at the time of the next burn if they resulted from a lack of fuel during the previous fire. If, however, they were too wet to burn, these islands could result in a hot spot the next time if a heading fire was allowed to sweep through them under appreciably drier conditions. One reason excessive crown scorch should be avoided is because, under some circumstances, it can add more fuel to the forest floor than the fire consumed.