On October 17th, 2017 we learned about

Optimistic findings about preventing fires by reducing the amount of flammable fuel in forests

With yet another wildfire filling our skies with smoke, it’s starting to feel like California will never stop burning. The state experienced an unusually rainy winter that thankfully helped fend off a multi-year drought, spurring new plant growth at the same time. Unfortunately, all that vegetation was dried out in record-setting summer heat. From that perspective these fires feel somewhat inevitable, since we can’t stop the rain and many people in power seem intent on avoiding doing much to curb climate emissions that help make more extreme temperatures. However, there’s still opportunities to reduce our fire risks by thinning out the forests themselves, either mechanically or with controlled burns. These aren’t easy tasks to take on, but studies suggest that strategic thinning may reduce some of the costs and logistics associated with wildfire prevention.

For millions of years, forests have occasionally caught fire. In this time, they’ve adapted to make the most of blazes naturally caused by things like lightning strikes, in some cases even evolving pine cones that only open in a fire’s extreme heat. Humans have thrown this balancing act off a bit though, as we both help start fires more often with sparking cars, campfires and cigarettes, but also rush to put those fires out as soon as possible. The result is that forests are now denser than before, not just with living plants but also dry, dead branches, pine needles and more. This means that when a fire does start up, it’s got a lot more fuel to burn, and can get out of control much more quickly.

Small burns aren’t bad

A controlled burn certainly works, because it’s intended to be a safer version of a good lightning strike. Burning a small area ideally clears out dry tinder, but can then be contained before it becomes a problem. Detractors to this method have worried about the fires getting out of control, but also about unintended damage to the environment. To see if prescribed burns were harming plants or animals, the U.S. Forest Service and six universities embarked on detailed studies of the flames’ effects on the affected environment. While there’s obviously smoke and soot after a burn, a smaller fire caused no measurable harm. If anything, plant diversity increased and trees seemed more resilient to things like bark beetles after a small fire. This makes sense, because the more frequent fires of the past would have been smaller on average, and thus something these ecosystems have been able to adapt to.

Mechanical thinning, for less money

Mechanical thinning doesn’t risk running out of control like a fire, and aside from some diesel exhaust, shouldn’t introduce widespread threats to the environment. Instead, detractors bring up the prices and logistics of sending in personnel to clear brush and remove trees, as it can become a huge task in a large forest. Real world experiments were, appropriately, cost prohibitive, so biologists from the University of New Mexico ran simulations of two approaches to mechanical thinning. One option tested the effectiveness thinning vast ranges of land, while the other looked at scenarios where only areas that were considered to be higher risk were dealt with. With all other things being equal, both strategies reduced the severity of simulated fires by as much as 60 percent. This may sound inconclusive until you compare the difficulty of either approach, and realize that the much simpler, cheaper option of thinning only high-risk areas of a forest offers the same benefits for a much smaller price. This means that well-planned mechanical thinning may be more affordable than people previously understood.

If these last two weeks are anything to go by, it looks like we’ll unfortunately have ample opportunities to put these prevention methods to work in the coming years.

Source: Fighting Fires Before They Spark, Scienmag

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