There isn’t any “one size fits all” pattern to the frequency of burns on the same tract. Fields of Panicum or other grasses might be burned ever year, such as those in front of the Batsto entrance or on many WMAs. Wooded tracts might be burned on a five or six year rotation. A tract that has not been burned in recent past might get more frequent burns to reduce the fuel present, after which they get less frequent subsequent burns.
As to the effectiveness of these burns in preventing fires, it has been pretty well established that forests that have undergone prescribed burns prior to a wildfire moving through burn with much less intensity than those fully loaded with fuel, and such fires are easier to stop at a road or other fire break. It is also pretty easy to observe in a stand that has had regular burns how the lower part of the fuel ladder has been removed, and an accidental or intentional fire set on the ground will have a much harder time spreading up to the canopy, resulting in a crown fire.
A few points have been well made about prescribed burns not exactly mimicking the fires that shaped the pine barrens long ago. That is certainly true. Most are not hot enough to open up the serotinous cones in the forest canopy. But, for better or worse, these fires are not being set for ecological reasons. In fact, due to air quality laws, it is illegal to burn woodlands in New Jersey for any reason other than wildfire prevention. Even if such laws did not exist, the risk trying to manage the type of fires that caused our barrens to evolve would be too great now that human development has been interwoven with the forests to such a great degree. As we have all seen, though, a big one comes along every so often anyway. We then get to see how a pine barrens forest type is perpetuated, the old fashioned way.
As to the effectiveness of these burns in preventing fires, it has been pretty well established that forests that have undergone prescribed burns prior to a wildfire moving through burn with much less intensity than those fully loaded with fuel, and such fires are easier to stop at a road or other fire break. It is also pretty easy to observe in a stand that has had regular burns how the lower part of the fuel ladder has been removed, and an accidental or intentional fire set on the ground will have a much harder time spreading up to the canopy, resulting in a crown fire.
A few points have been well made about prescribed burns not exactly mimicking the fires that shaped the pine barrens long ago. That is certainly true. Most are not hot enough to open up the serotinous cones in the forest canopy. But, for better or worse, these fires are not being set for ecological reasons. In fact, due to air quality laws, it is illegal to burn woodlands in New Jersey for any reason other than wildfire prevention. Even if such laws did not exist, the risk trying to manage the type of fires that caused our barrens to evolve would be too great now that human development has been interwoven with the forests to such a great degree. As we have all seen, though, a big one comes along every so often anyway. We then get to see how a pine barrens forest type is perpetuated, the old fashioned way.