What is classified as surface fuel in fire suppression?

Surface fuel refers to the combustible materials that are found on the ground or near the surface of the earth, which can ignite and contribute to the spread of a fire. Grass and shrubs fit this definition perfectly, as they are directly in contact with the ground and can easily catch fire, especially during dry conditions.

In contrast, tree crowns are classified as aerial fuels because they are elevated above the ground and consist of the branches and leaves of trees. Deep soil and underground roots are not classified as fuel at all; they serve more as a structure in the environment rather than as materials that can sustain combustion. The primary concern with surface fuels is their ability to ignite and spread fire rapidly across the landscape, making the recognition of these materials vital in fire suppression efforts.