Wildland Firefighting Practice Exam

What does a fire transition from timber to grass generally result in?

1. Quadruplication of speed

2. Doubling of speed

3. Tripling of spread speed

4. Decreased spread speed

The correct answer is: Tripling of spread speed

When a fire transitions from timber to grass, it typically results in a significant increase in the rate of spread. This is because grass fuels are usually much less dense and less moisture-laden compared to timber, allowing fires to spread more rapidly through these fuels. The correct answer reflects that the transition from a heavier, slower-burning fuel type (like timber) to a lighter, faster-burning one (like grass) can lead to a dramatic increase in the speed of the fire, often viewed in practical terms as tripling the spread speed. This is due to several factors, including the lower heat content and shorter flame lengths in grass fuels that allow them to ignite and sustain combustion more easily, compared to the more substantial biomass found in timber. Hence, recognizing how fire behavior changes with fuel types is critical for effective firefighting strategies and understanding the dynamics of wildfire spread.