Lead author Ryan Haugo, director of conservation science at The Nature Conservancy, said the new data supports the 20-year forest health strategic plan created by Washington’s Department of Natural Resources, which calls for significant increases to funding for controlled burns and forest thinning. The study found a significant decrease in low-severity fire from 1984-2015 as compared to historical models. During that period, there have been more high-intensity fires than expected in forests like those in Yakima and Kittitas counties.

“Obviously, we knew that we were getting less low-severity fire in our dry forests,” said Haugo, who moved from The Nature Conservancy office in Yakima to Portland a year and a half ago. “But we were surprised by the fact that our dry forests across the area were only getting 3 percent of their historic low-severity fires.”

Haugo said past logging practices removed large, old trees, leaving forests full of fuel and more susceptible to high intensity fires as measured by the amount of vegetation lost. Successful fire suppression added to those issues and climate change threatens to increase the occurrence of larger fires. The research from scientists with The Nature Conservancy, the U.S. Forest Service and the University of Idaho showed 1.6 million acres burned in Pacific Northwest forests from 1984-2015, far less than the expected 14.9 million to 20.6 million acres. Most of that deficit could be traced to a lack of low-intensity fires, and data showed bigger fires than expected across the region. The study’s authors recognize a return to past levels of burning would be unfeasible given the growth of human development and fire’s effects on communities. However, they emphasize the need for controlled burns and more environmentally friendly logging to improve forest health, especially since some of climate change’s future effects remain uncertain.

“Fire is inevitable in our forests across Eastern Washington and across the Pacific Northwest,” Haugo said. “This study emphasized that we need to look at all actions for how we return low and moderate severity fires into our forests.”

He noted it took two years to complete the study, which was funded by The Nature Conservancy in Oregon and Washington, the Icicle Fund, and grants from the National Science Foundation and the Northwest Climate Adaptation Science Center.