Across the western U.S., wildfires are becoming larger and more severe — and even trees that initially survive are dying in subsequent years, making it harder for forests to regenerate, according to new research from Portland State University. Building on previous research exploring fire refugia — the green islands of live trees that remain after forest fires — researchers in PSU’s Global Environmental Change lab mapped annual changes in the extent of live tree cover up to three years after the unprecedented 2020 Labor Day fires in Oregon’s western Cascades. The study quantifies changes in the spatial distribution and attributes of fire refugia as a result of delayed tree mortality. …there is potential for delayed fire effects to cause trees to die in subsequent years, including direct burn injuries as well as a combination of direct and indirect effects related to climate, insects, pathogens and heatwaves.