Fuel Categories

Fuels can be classified into four broad categories based on their vertical distribution:

• Ground fuels: organic soils, forest floor duff, stumps, dead roots, and buried fuels
• Surface fuels: litter layer, downed woody materials, and dead and live plants to 2 m (6 ft.) height
• Ladder fuels: vine or liana fuels and draped foliage fuels
• Canopy fuels: tree crowns

These fuel categories are not to be confused with the fuel types used in fuel models (such as grasses, brush, timber litter, and logging slash). Fuel models are more specific classes of fuels used in fire behavior modeling.