What type of fuel is classified as surface fuels?

Surface fuels refer to any flammable materials located on the surface of the ground, which are primarily those that can easily ignite and support fire on or near the ground level. Grass and small shrubs are excellent examples of surface fuels because they are typically low to the ground and can quickly catch fire, especially under dry conditions. These types of fuels contribute significantly to the spread of fire, particularly in wildfire scenarios, where they provide a continuous source for flames to travel rapidly across the landscape.

On the other hand, heavy timber, downed logs, and litter layers represent different categories of fuels. Heavy timber may be considered part of the canopy or ladder fuels rather than surface fuels, as they are generally located higher above the ground. Downed logs, while they can contribute to fire spreading, are typically larger and may not burn as readily as grasses or smaller shrubs. Litter layers, which consist of decomposed organic matter from leaves and small branches on the ground, can support fires but are not the primary components defining surface fuels when considering immediate fire spread characteristics.