Litterfall,
plant litter,
leaf litter,
tree litter,
soil litter, or
duff, is dead
plant material, such as
leaves,
bark,
needles, and
twigs, that have fallen to the ground. This
detritus or dead organic material and its constituent nutrients are added to the top layer of soil, commonly known as the litter layer or
O horizon ("O" for "organic"). Litter has occupied the attention of ecologists at length for the reasons that it is an instrumental factor in ecosystem dynamics, it is indicative of ecological
productivity, and may be useful in predicting regional
nutrient cycling and
soil fertility.