Сухе опале листя

Leaf litter

Leaf litter is also called plant litter, tree litter, soil litter, litterfall or duff. When it decomposes, plant litter typically becomes detritus and releases nutrients into the soil. Many organisms of the forest floor, such as fungi, are decomposers. Plant litter also forms a loose covering that preserves soil moisture and reduces soil erosion.

Soil scientists describe three litter layers: L, with relatively undecomposed plant material; F, with partly decomposed organic matter; and H, with fully decomposed organic matter. The portion of the litter that is not readily decomposable is known as humus. The litter layer varies in thickness, decomposition rate and nutrient content, and is affected by season, plant species, climate, soil fertility, elevation and latitude.

Leaf color

Some leaves appear brown, which can be due to the colors of chlorophyll and anthocyanin combining during early senescence or to the polymerization of quinones during cell death in late senescence. In late summer, as days shorten and temperatures cool, leaf senescence begins and the plant starts to recover its nutritional investment in the leaves. Anthocyanins, which give the reds and purples of autumn foliage, are not present in the leaf all season but are produced actively towards the end of summer.

Tannins and slow decomposition

Condensed tannins are found in virtually all families of plants and make up to 50% of the dry weight of leaves. Ecologists increasingly recognize tannins as important controllers of decomposition and nitrogen cycling. Leaf litter and other decaying parts of kauri, a tree species found in New Zealand, decompose much more slowly than those of most other species. Kauri bears substances such as waxes and phenols, most notably tannins, that are harmful to microorganisms. Highly water-soluble tannins leaching from decaying leaves along a stream may produce what is known as a blackwater river.

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