It seems everyone is grasping for some “solution” to big fires. And one of the common assertions is that more prescribed burning would reduce fire spread and allow firefighters to knock down a blaze.
Increasingly we also hear that tribal people kept fires from becoming large by the frequent burning of the landscape–as if this was a secret tool no one in the fire fighting agencies knew about. The evidence suggests that tribal burning likely reduced fuels in the immediate area around villages but seldom influenced the larger landscape fire rotation.
A prescribed burn, whether done by Indians for cultural purposes or a firefighter with a drip torch, may reduce fuels for a short period. And if a fire were to encounter the burn when fuels were reduced, it might influence fire spread. However, one of the problems with prescribed burning (as well as thinning forests) is the likelihood that any blaze will encounter a “fuel reduction” when it may be effective at influencing fire spread is exceedingly rare. So most prescribed burns (as well as thinning) have no influence whatsoever.
In addition, the very fire people are anxious to stop or control are those burning under extreme fire conditions. These conditions include high temperatures, low humidity, drought and most importantly high winds. High winds, often blow embers over and through “fuel reductions” like prescribed burns. In other words, even if such prescriptions worked under low to moderate fire weather conditions, fuel reductions including thinning and prescribed burning typically fail to alter fire spread due to wind transport of embers.
Just burning enough of the landscape to have any influence on wildfires is also problematic. The window when burning is safe is frequently very narrow. Concerns about smoke dispersal add to the limitations.
Furthermore, there is always a chance that a prescribed burn will get away and burn far more of the landscape, including homes, prescribed burning increases the chances of fire losses. Due to the low possibility that any blaze will encounter a prescribed burn during the period when it could change fire behavior whether you would reduce the acreage charred is questionable. A prescribed burn could get away from fire fighters and burn significant acreage as occurred with the Cerro Grande prescribed burn that destroyed homes in Los Alamos.
The other problem with prescribed burning is that in many ecosystems, burning stimulates plant growth. This additional biomass results from the removal of competing vegetation lease more nutrients, water, and sunlight for the remaining plants. Consequently, within a few years of a prescribed burn, you will often get more fine fuels like grass, shrubs, and small trees than before the burn.
I repeatedly see around the West that agencies will perform a prescribed burn and never bother with the follow-up maintenance. While prescribed burning could be effective if strategically located by communities and repeated continuously, this seldom occurs.
The following two photos demonstrate this idea. The first photo was taken a week after the Bridger Foothills Fire swept across forests, hayfields, and pastures in September 2020. Note that the hayfield has very little grass after being mowed. But strong winds drove the fire across even one-inch stubble. The second photo taken in nearly the exact location shows how rapidly the grass regrew after a fire. In other words, without continuous “maintenance,” the burn would have little impact on slowing or stopping a fire.
All this said I don’t oppose the strategic use of prescribed burning so long as people recognize the limitations. Reducing fuels around communities and homes can be effective if and when a blaze threatens structures. However, the idea that somehow prescribed burning is an effective panacea that can reduce or preclude climate-driven blazes is questionable.