Insect and Disease
In addition to fire; insects, diseases, and weeds act as important disturbance agents in Utah forest ecosystems. Fire suppression has altered the occurrence, severity, and intensity of fire. This may have contributed to increased insect and disease activity in certain forest types. Noxious and invasive weeds in Utah are spreading at an alarming rate, displacing native species and disrupting the normal functioning of ecosystems.
Insects and diseases play an important role in the function and nutrient cycling of forest ecosystems. In a healthy forest, endemic levels of insects and diseases remove weakened and stressed trees, thus thinning the forest and reducing competition for light, water, and nutrients. Dead trees provide habitat for a variety of wildlife species. For example, raptors use dead trees for perches and decayed trees provide homes for cavity nesting birds. The vigor of trees is an important factor in determining their susceptibility to attack by insects or diseases. Forests that are over-mature or over-dense often become susceptible to insect and disease outbreaks, creating considerable fuel and increasing susceptibility of stands to fire.