Firefighter 1C Wildland Practice Exam

Do fires spread more quickly in fine fuels or in heavy timber and brush?

1. It depends on the temperature.

2. It depends on the quantity.

3. Fires spread more quickly in heavy timber and brush.

4. Fires spread more quickly in fine fuels.

The correct answer is: Fires spread more quickly in fine fuels.

Fires spread more quickly in fine fuels due to their lower moisture content, smaller size, and high surface area-to-volume ratio. Fine fuels, such as grass, leaves, and small twigs, ignite easily and burn rapidly, allowing the fire to move swiftly across the landscape. These fuels catch fire at lower temperatures and require less heat to sustain combustion, which leads to a rapid increase in fire intensity and spread. In contrast, heavy timber and brush consist of larger and denser materials that tend to burn slower because they require more heat for ignition and to sustain the fire. This results in a slower rate of fire spread as the flames struggle to penetrate and consume the larger fuel masses. Heavy fuels may also retain moisture longer, particularly in cooler or shaded areas, further slowing the combustion process. Therefore, the characteristics of fine fuels facilitate a quicker spread of fire compared to heavier fuels.