Sentence:  Depth of litter and <WSD>duff</WSD> under the crown of each tree was measured at a point that appeared to represent average depth. Bulk samples of litter (including <WSD>duff</WSD>) were taken under four pinyons and three junipers, and ovendried. 
Meaning of the word marked with <WSD> tags:  Decaying vegetable matter on the forest floor.