Duff - Partially decomposed organic matter lying beneath the litter layer and above the mineral soil. Includes the fermentation and humus layers of the forest floor (Oa and Oe soil horizons).
Leaf Litter - Leaves not showing excessive decomposition.
Green Herbaceous Growth - Vegetation dominated by nonwoody plants (i.e., grasses, broad-leafed plants, etc.).
1-hour time-lag fuels - Dead fuels comprised of herbaceous plants or woody plants less than about 0.25 inch (6.4 mm) in diameter.
10-hour time-lag fuels - Dead fuels comprised of wood from 0.25 to 1 inch (0.6-2.5 cm) in diameter.
100-hour time-lag fuels - Dead fuels comprised of wood from 1 to 3 inches (2.5-7.6 cm) in diameter.
1,000-hour time-lag fuels - Dead fuels comprised of wood from 3 to 8 inches (7.6-20.3) in diameter.