[Wikipedia] Fire-Dependent Species: Pinus contorta is a fire-dependent species, requiring wildfires to maintain healthy populations of diverse ages. The thin bark of the lodgepole pine minimizes its defense to fire, although the heat of fire opens the cones to release the seeds. This allows the species to regenerate and maintain its place in the forest habitat. It otherwise fares poorly in crowds as other species are more shade tolerant, although some (e.g. firs) are more susceptible to fire. (link added by Mary Ann Machi)