University of Arizona finds fewer forest fires lead to worse blazes

Research indicates forests are burning less frequently than before, potentially leading to more severe and destructive wildfires.

Recent research has uncovered a surprising paradox in North American forest fires—they occur less frequently now than in centuries past. This unexpected finding, published in Nature Communications, suggests that our modern approach to fire management may be contributing to more destructive blazes when they do occur.

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Historical fire patterns reveal a changing landscape

Analysis of tree-ring data shows that North American forests historically experienced regular fires every 10-20 years. These fires were typically less severe than today’s devastating infernos, according to Donald Falk, a fire ecologist and professor at the University of Arizona who co-authored the study.

The research, funded by the U.S. Geological Survey’s John Wesley Powell Center, demonstrates how natural fire cycles play a crucial role in maintaining healthy forest ecosystems. Regular burns would clear undergrowth and maintain balanced tree density, creating more resilient forest environments. “As a result, today’s extreme wildfires are more likely to harm people and communities, while exposing forests to damaging effects on soils and natural vegetation, from which they may not recover,” Falk explained.

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Reading nature’s fire record

Researchers utilized the North American Tree-Ring Fire Scar Network to reconstruct historical fire patterns. These fire scars, preserved within tree rings, serve as natural records of past forest fires, allowing scientists to track fire frequency and timing across centuries.

The comprehensive study examined data from more than 1,800 sites across North America, spanning diverse forest types from Alaska to southern Mexico. This extensive dataset revealed that recent fires, while devastating to human communities, are not unprecedented in size.

Centuries of data reveal surprising patterns

Sean Parks, lead researcher and ecologist at the USDA Forest Service Rocky Mountain Research Station noted: “In recent history, between 1984 and 2022, wildfires in 2020 seemed like they were unprecedented in terms of the area they burned, but historically speaking, they were not. There were several years between 1600 and 1880 where much more fire burned than what we experienced in 2020.”

A related study has also identified strong connections between wildfire patterns and climate phenomena like El Niño, adding another layer to our understanding of forest fire dynamics. Falk notes, “The more we can do to make our forests more resilient to that inevitable fire, the better off we’re going to be.” Combined, this research suggests that 140 years of fire suppression has led to overgrown forests more susceptible to catastrophic fires.