Last month, a heat wave persisted for days in the Chilean coastal city of Viña del Mar. The landscape, already affected by an El Niño-supercharged drought, was baked dry. So, when wildfires sparked, they ripped through densely populated and mountainous terrain. In just a few days, the fires — the deadliest in Chile’s history — burned 71,000 acres and killed at least 134 people.

Devastating wildfires like these are becoming increasingly common. Climate change is partly to blame — while research has found that both El Niño and climate change have contributed to intense wildfires in Chile in recent years, scientists disagree whether climate change had a statistically significant impact on these particular February fires. But the Chilean fires also underscore another ominous dynamic: Grasses, shrubs, and trees that humans have introduced to new ecosystems are increasing wildfire occurrence and frequency.

In central Chile over five decades, timber companies have converted natural forests to homogenous, sprawling plantations of nonnative eucalyptus and Monterey pine that grow rapidly in the country’s Mediterranean climate. These trees contain an oily resin that makes them especially flammable but coupled with hotter and drier conditions due to climate change, they can be explosive, says Dave McWethy, an assistant professor at Montana State University.

Our relationship with such nonnative species is fraught. We enable the spread of nonnatives by purposely transporting species to landscapes that haven’t previously existed with them. Take English ivy, a popular choice for stabilizing soil as an ornamental plant. Or the Norway maple, which was introduced to the East Coast of the US in 1756,........

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