Anthropogenic Ignition Sources

Wildfires ignited by humans can be either accidental or deliberate. Nationally, a major source of accidental human-caused wildland fire is burning yard waste or trash (debris burning) that becomes uncontrollable. Other major sources of accidental ignition include escaped campfires, discarded cigarettes, fireworks, sparks from railroad equipment, and highway/off-road vehicles. Railroad equipment may cause fires in a variety of ways: improperly maintained tracks may cause sparks during transit (especially on steep grades); maintenance equipment (such as cutting and grinding tools) may cause sparks; brake pads may shed embers and sparks in periods of high stress. Vehicles, either highway or off-road, cause fires through hot exhaust systems, either through contact with dry vegetation (when parked) or through the production of sparks during normal operation (some vehicles have been outfitted with spark-arrestors to reduce this risk) (Baxter 2002). Most accidental fires caused by discarded cigarettes, railroad equipment, and vehicles occur in extremely dry, low humidity situations–a common condition in the Southeastern U.S. during dry spring and fall periods.

Deliberate anthropogenic fires fall into two major categories: arson and prescribed fires.

• Arson or incendiary fires are intentionally ignited utilizing a variety of methods: dropping incendiary devices (matches, flares, etc) or arranging simple solar heating systems. Approximately 25% of wildfires are intentionally set in the United States.

• Prescribed fires are used in the Southeast to meet specific land management objectives and to maintain natural ecosystems. Qualified land managers set these fires under specific conditions of humidity, wind, and fuel moisture. Prescribed fire is applied to more acreage of land in the Southeast than in any other region of the United States.