Individual trees may have serotinous or nonserotinous cones. Seed production begins at an early age. Seed production is quite regular. In nature, temperatures of this magnitude within a tree's crown are generated only by forest fires. The percentage of trees in a stand bearing serotinous cones varies greatly by region and elevation, and with stand age and fire history.
Young trees produce open cones.
In the U.S. Rockies, cone serotiny is quite variable. The percentage of trees bearing serotinous cones in a given stand ranged from 0 to 85 percent and averaged less than 50 percent. On some forests, cone serotiny increased with increasing elevation. However, on the Deerlodge National Forest, Montana, cone serotiny varied between 28 and 47 percent and did not change with elevation. Type of stand disturbance also influences cone serotiny.