Wildland Firefighting Practice Exam

What effect does a fire moving from a timber brush mix into grass have on spread speed?

1. It doubles

2. It triples

3. It decreases

4. It remains the same

The correct answer is: It triples

When a fire transitions from a timber brush mix into grass, the spread speed significantly increases. This is primarily because grass fuels are generally much lighter, drier, and more continuous than the heavier fuels often found in timber and brush mixes. When a fire reaches grass, it can catch and spread more rapidly due to these properties. Grass typically has a higher rate of combustion and less moisture content, allowing the fire to ignite quickly and spread with greater intensity. As a result, when a fire moves from the heavier timber and brush fuels to the lighter grass fuels, it effectively accelerates the fire's spread, often tripling its speed due to the change in fuel characteristics and arrangement. This dramatic increase emphasizes the importance of understanding fuel types and their behaviors in wildland firefighting, as effectively anticipating the changes in fire behavior can significantly impact firefighting strategies and safety measures.