Until recent years forest fires have been viewed as a destructive influence on forests and extreme measure were taken to put them out and keep them from spreading. It has since been learned, however, that fire plays an important role in a healthy ecosystem and in fact that fire suppression can have a number of negative effects:
- Woody debris that would otherwise burn in a forest fire will accumulate, slowing the return of nutrients in the the wood to the soil. Furthermore, when wildfires do occur, they are far more destructive because of the large amount of exceptionally flammable debris on the ground, killing even fire-tolerant vegetation.
- Some plants require fire for reproduction and are consequently endangered by fire prevention. An example is the sand pine, whose cones normally store a large quantity of seeds. When the cone is cracked open by the heat of a fire, the seeds take advantage of the conditions immediately after a burn to grow.
- Certain species such as cherries, elderberries, and blackberries grow primarily in successional areas (which grow out of a burned habitat), producing copious amounts of fruit. The loss of these post-fire areas and consequently a large food source for fruit-eating birds and animals can affect animal populations and migration patterns.
- In some areas fire suppression can result in the invasion of woody species and displacement of herbaceous species, which in turn affects animal populations and the rest of the ecosystem.
Despite the overwhelming evidence that fire suppression is generally deleterious to the ecosystem, we continue to put out most forest fires. In general only natural (lightning-induced) fires are allowed to burn, and then only in well defined boundaries to minimize any threat to human developments. Indeed, only in rare cases can a completely natural fire process be achieved (examples include the Alaskan wilderness and large parks like Yellowstone).