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Fuel Characteristics

Subsurface Fuels include roots, peat, and other decomposed organic matter.

Surface Fuels include needles, twigs, brush, leaves, small trees, and logging slash. Flashy fuels would be twigs, needles, and grasses the ignite and burn rapidly. Ladder fuels are tree boughs, brush or limbs that are touching the ground. This allows the fire to reach aerial fuels above.

Aerial Fuels include brush over 6 feet, leaves/needles on trees, etc. Air is able to circulate between the fuel and the ground. This allows the fire to burn at a rapid rate. The rate is dependent on the proximity to other aerial fuels, winds, and environment.

Fuel Size is classified at light, medium, or heavy. This is important to know to determine what type of heat transfer and possible change in moisture content. This will influence the forward spread of the fire.

Light Fuels (Fine fuels, flashy fuels, or flash fuels). Short grasses and light brush up to 2 feet that burn rapidly. Moisture levels can change substantially in this category.

Medium Fuels are brush up to 6 feet and often include patchy fuels with grass. The rate of spread is usually slower but it can burn at a moderate to very high intensity.

Heavy Fuels are continuous brush more than 6 feet and includes slash. The rate of spread is low to moderate but it is a high intensity type of burn.