the accumulated organic matter at the soil surface, including litter and unincorporated humus —note using US and Canadian soil terminologies, the floor includes the L and F soil layers and therefore excludes the H, Oa, humus layers, and coarse woody debris larger than 10 cm (3.9 in) in diameter and 1 m (3.3 ft) in length —see coarse woody debris This definition last updated 08/11/2008