Enemies of the forest include insects, disease, wildfire, air pollution and poor land-use practice. While a certain level of insect and disease damage is natural, humans have unintentionally introduced many diseases, insects and plants into the forest from foreign areas. These forest pets are called invasive exotics because they spread quickly and displace native forest vegetation. As mentioned above, wildfire is a natural part of many forest ecosystems.
However, in some forests, humans have suppressed fires for many years and large quantities of woody debris have collected on the forest floor. Fires that ignite in such forests often grow into massive and uncontrollable wildfires. These large wildfires burn most vegetation, dislocate wildfire, expose the forest soil and cause soil erosion. Large wildfires can be avoided by allowing small wildfires to burn and by setting intentional debris-reducing fires. Air pollution from burning fossil fuels has resulted in acid rain and the decline of forest health in some areas.
