Wildland Firefighting Practice Exam

At approximately what temperature does woody fuel burst into flame, assuming sufficient oxygen is present?

1. 400 degrees

2. 500 degrees

3. 540 degrees

4. 600 degrees

The correct answer is: 540 degrees

Woody fuels, such as trees and shrubs, undergo a series of thermal changes as they are heated. The temperature at which woody fuel actually bursts into flame tends to be around 540 degrees Fahrenheit. At this temperature, the lignin and cellulose fibers within the wood begin to Pyrolyze, breaking down to produce volatile gases that can ignite. For combustion to occur, not only must the temperature reach this ignition point, but there must also be sufficient oxygen present, which is critical for sustaining the flame. Understanding this ignition point is crucial for wildland firefighters, as it informs them about the fire behavior they might expect in a particular area based on fuel type and environmental conditions. Higher temperatures, such as those listed in the other choices, can definitely contribute to the combustion process but do not represent the point of ignition for woody fuels.