Some fires burn with extreme fire behavior and rapid rates of spread. These large, fast moving fires send plumes of smoke thousands of feet into the air and receive much of the public’s attention. These large fires (>100 acres) occur less than 10% of the time in the park. Frequency of Fire. Fire return intervals since European American settlement have ranged from 20–25 years for shrub and grasslands on the northern range to 300 years or more for lodgepole pine forests on the central plateau and subalpine whitebark pine stands. Fire scars on old Douglas-fir trees in the Lamar River valley indicate an average frequency of one fire every 25–60 years.