Which category would stumps and slash typically fall under?

Stumps and slash are categorized as heavy fuels primarily because of their size, density, and the amount of moisture they contain compared to other types of fuels. Heavy fuels are generally defined as larger pieces of combustible material that take longer to ignite but can sustain a fire for an extended period once ignited. Stumps, being large and often containing a significant amount of moisture, along with slash—which consists of branches and debris left after tree cutting—creates a heavier fuel load that can support intense fire behavior.

In contrast, surface fuels, like grass and small twigs, are usually lighter and ignite quickly. Aerial fuels consist of materials such as branches and foliage that are elevated above the ground. Ground fuels, found underneath the surface layer, usually include organic material like roots and decomposing leaves. While all these fuel categories can influence fire behavior, stumps and slash's characteristics align more closely with the definition of heavy fuels.