Return of Trees to Eastern U.S. Is Fueling a Surge in Wildfires

Trees and shrubs have proliferated in unmanaged forests in the eastern U.S. This growth, which marks a return of trees to the region after centuries of deforestation, is fueling a new surge in wildfires, a study finds.

Over the last four decades, the eastern U.S. has seen a marked uptick in tree cover, and in some areas the number of large wildfires has grown as much as tenfold.

For a new analysis, researchers compared the growth of trees and shrubs with the spread of wildfires, finding that for every 1 percent increase in woody cover, the odds of a wildfire in the next year rose by 3.9 percent. The link between woody growth and fires was strongest in Texas and Appalachia. In the Northeast, researchers found no link between recent plant growth and fires.

The study, published in Geophysical Research Letters, shows that, like the western U.S., the East is seeing increasingly dense forests succumb to more frequent fires. Authors say that officials may need to thin forests to curb the risk of burning.

Curiously, the return of trees to the eastern U.S. has also kept warming in check by supplying shade and water vapor, a recent study found. Over the last century, the U.S. as a whole warmed by 1.2 degrees F, but across much of the East, temperatures actually dropped, by 0.5 degrees F.

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