In fire-dependent forests of the western United States, tree species adapt in several ways to survive fire. In low-elevation forests that evolved with frequent, low-severity fire, many species have thick bark protecting the living tissues of cambium and phloem from wildfires’ destructive heat. Longer, thicker needles or those enclosed in thick scales protect growing buds. Some tree species even shed their lower branches, which reduces the chance of fire climbing into their crowns. Still other tree species are easily killed by fire but can readily resprout, or their seeds survive to quickly regenerate burned areas.
Collectively, these adaptive measures allow species survival in fire-prone areas. However, highintensity wildfires can generate temperatures that overwhelm a tree’s adaptations to survive fire. The result: thousands of acres of Federal, Tribal, State, and private forests filled with trees having charred bark and burned crowns. And the sight can be distressing.
U.S. Forest Service Rocky Mountain Research Station
September 2019 | Issue 36 Science You Can Use Bulletin