Challenging What We Think We Know: Wildfires Reveal the Power of Science

Large wildfires make headlines that spread across the world. This certainly does nothing to lessen the negative stigma attached to them.

That is why it was so interesting to come across a study examining the impact of wildfires in the western United States on air quality in other parts of the country. The researchers’ hypothesis was that wildfires would worsen air quality simply because of smoke transport.

However, the hypothesis turned out to be incorrect. Ma and colleagues showed that extreme wildfires in the West actually reduce fine particle concentrations in the eastern United States by roughly the same amount as they increase them in the West.

This surprising result was explained by the fact that heat-induced convection from the fires weakens eastward transport of smoke and enhances the removal of air pollutants through precipitation. In fact, this mechanism reduces human mortality and economic losses nationwide!

Of course, it is welcome news that the health effects of wildfires may not be as dramatic as feared. Yet in my view, the real lesson of this study lies elsewhere. It once again demonstrates that ordinary and seemingly logical assumptions people make do not necessarily correspond to reality. At the same time, it helps to highlight why systematic science is very likely one of humanity’s most important institutions.

Previous thoughts on the same topic:
Control of Douglas fir beetles by woodborer beetles
Forests in Indonesia and Finland
Scientific misconduct on prevailing theories is too attractive

Control of Douglas fir beetles by woodborer beetles

Wildfires and bark beetles have interacted for centuries—and even millennia—to shape diverse and resilient forest ecosystems. However, the record-breaking wildfires of recent years in western North America have raised concerns that the vast areas of damaged and dead trees—essentially easily exploitable resources—might promote the growth of insect populations.

The Douglas-fir beetle, the primary mortality agent of Douglas-fir trees, often experiences population increases following wildfires. The same applies to many other phloem-feeding insects, such as various woodboring beetles, which are attracted to burned areas and colonize fire-injured trees.

In a recent study, Canadian researchers investigated the interactions between Douglas-fir beetles and woodboring beetles that exploit the phloem of fire-injured trees. More specifically, their hypothesis was that the rapid colonization of bark beetle niches by woodborers following wildfires might restrict Douglas-fir beetle population growth through interspecific competition beneath the bark.

The hypothesis was tested in three mature Douglas-fir forests in British Columbia that burned in 2017. The researchers found that both Douglas-fir beetles and woodborers preferentially colonized mature stands containing large-diameter trees with moderate fire damage.

When woodborers were absent, the Douglas-fir beetle’s reproductive rate was sufficient to cause a local population outbreak. In contrast, in stands where woodborers were abundant (more than 50% of trees infested), Douglas-fir beetles were unable to reproduce at outbreak levels.

These results indicate that competition from woodboring beetles can significantly limit Douglas-fir beetle outbreaks in fire-injured forests. From a forest management perspective, this suggests that forests should be managed in ways that support the success of economically harmless phloem-feeding insects—such as many woodboring beetle species—since their presence may help reduce the risk of bark beetle outbreaks following wildfires.

Previous thoughts on the same topic:
The EU Needs Innovations That Drive Climate Neutrality
Forests in Indonesia and Finland
Why are boreal forest fires on the rise everywhere but in Finland?

Forests in Indonesia and Finland

According to a new research paper, Indonesia has lost one quarter of its old-growth forest since 1990, with its intact forest area (natural forest undisturbed by human activity) declining by 45%. Nearly half of Indonesia’s deforested land had no detectable land use five years after clearing.

This was caused by fires, long assumed to be Indonesia’s principal idle land driver, and by deliberate mechanical clearing, an understudied phenomenon despite its large deforestation footprint. When idle areas were converted to productive uses, the majority were planted with oil palms, which covered 28% of Indonesia’s deforested land by 2020.

Oil palms were the only major land use for which lagged conversion was the norm; other major drivers such as smallholder agriculture were typically established immediately after clearing.

This can be compared to boreal forestry in Finland, where practically all clear-cut forests are regenerated within a couple of years—mostly within one year—using local tree species selected based on their soil requirements. Forest fires do occur but are quickly extinguished, so the burned areas very rarely exceed one hundred hectares. Even then, they are regenerated very soon.

The amount of wood in Finnish forests has increased continuously since the 1960s, despite the country’s strong forest industry, which contributes almost one-fifth of its export value. At the same time, the area of protected forests has increased year after year, and there are currently 73 old-growth forest reserves established on state-owned lands.

The lesson to be learned is that forests can be used efficiently in two ways: sustainably or destructively. But what should we do to make the first option so attractive that it would be practiced everywhere?

Previous thoughts on the same topic:
Defense Minister Prabowo Subianto aligned Indonesia on the wrong side of world history
A new justification is needed for environmental activists
They want to wipe out from Finland what is good for Africa