Plant litter

Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen on the top layer of soil, commonly known as the litter layer or O-horizon ("O" for "organic"). Plant litter typically becomes detritus and releases nutrients into the soil when decomposed, and also forms a loose layer of covering that preserves soil moisture, reduces soil erosion and provides concealment for small epigeic and fossorial animals. It is an important factor in ecosystem dynamics, as it is indicative of ecological productivity and may be useful in predicting regional nutrient cycling and soil fertility.

Characteristics and variability

Litterfall is characterized as fresh, undecomposed, and easily recognizable (by species and type) plant debris. This can be anything from leaves, cones, needles, twigs, bark, seeds/nuts, logs, or reproductive organs (e.g. the stamen of flowering plants). Items larger than 2 cm diameter are referred to as coarse litter, while anything smaller is referred to as fine litter or litter. The type of litterfall is most directly affected by ecosystem type.

For example, leaf tissues account for about 70 percent of litterfall in forests, but woody litter tends to increase with forest age. In grasslands, there is very little aboveground perennial tissue so the annual litterfall is very low and quite nearly equal to the net primary production.