The whitebark pine historic plant association occurs at the highest elevations in the park. This association is in a narrow band around the rim of the lake and on high, wind-exposed ridges and mountainsides. Tree species included in this association are whitebark pine, mountain hemlock, and lodgepole pine. Elevation typically ranges from 7,000 to 8,000 feet. Because of the cold temperatures in winter, exposure to high winds, long periods of snow cover, and frost in summer, the growing environment is harsh.
Whitebark pine is moderately fire resistant and can survive moderately intense fires and slow-moving ground fires. These types of fires kill other associated tree species that are more shade tolerant and more sensitive to fire. Studies of fire scars have shown that fires occurred infrequently (intervals of 50 to 300 years) in whitebark pine communities (Arno, 1980; Fischer and Clayton, 1983). Regeneration occurs in openings that probably were caused by fire. As a result of fire suppression activities, whitebark pine stands are older and more susceptible to pine beetle epidemics, which advance the succession toward dominantly shade-tolerant species (Arno, 1986). Whitebark pine is also susceptible to white pine blister rust (Cronartium ribicola). Because infected trees do not produce cones or the trees die before they reach cone-bearing age, blister rust inhibits the regeneration of whitebark pine.
The ecological site in the whitebark pine association is whitebark pine/woodrush-carex (Pinus albicaulis/Luzula-Carex).