Figure 2 Leaning lodgepole pine within a family unit campsite poses a threat to visitor safety. This tree should be removed. These trees are a threat only when the lean is the result of structural damage. Trees that lean naturally usually are reinforced by compensatory growth. The greater the lean of damaged trees, the greater the probability of failure during wind gusts or snow loads.
Roots function as an anchor, providing the major resistance to windthrow.
Any agent causing root damage increases the chance for failure. Figure 3 Aspen infected with root decay fungus, Ganoderma applanatum , failed. Note absence of supporting root system. Figure 4 Aspen infected with root and butt decay fungus, Ganoderma applanatum , is highly susceptible to failure and should be removed. Location and frequency of reported tree failures in recreational areas listed for softwoods and hardwoods, USDA Forest Service 1965-1980.