When the evergreen trees turned red, it was hard not to worry. The die-offs started in Alaska about 20 years ago, and soon conifers were perishing en masse across western North America. Life drained from millions of hectares of forest so quickly it was as if they had been abruptly unplugged, like a Christmas tree before bedtime.
The killers: tiny insects called bark beetles. Many people worried that the dead, dry trees would give birth to huge, damaging wildfires. To prevent infernos, some U.S. lawmakers pushed expensive, controversial policies to aggressively log beetle-damaged trees. “We are battling a huge insect epidemic that is destroying our forests” and creating “prime real estate for forest fires,” warned then-Representative John Salazar, a Democrat from Colorado, on the floor of the U.S. House of Representatives in 2006. To some casual observers, the prediction seemed to come true as blazes such as the 2012 High Park Fire near Fort Collins, Colorado, set records for hectares burned and homes destroyed.
But that fire, like others, burned green forest as well as beetle-killed trees. And now, a growing body of research—including a study published last week—is challenging the notion that beetle-killed forests are more vulnerable to severe fires than forests that have escaped infestation. The findings are highlighting the complex causes of western wildfires and raising new questions about policies that promote the removal of insect-damaged trees to reduce fire risks. Contrary to popular belief, says forest ecologist Thomas Veblen of the University of Colorado (CU), Boulder, the science suggests that “healthy forests [can] include fire, and bark beetles, and lots of dead trees.”