Understory


Understory

Understory (or understorey) is the term for the area of a forest which grows in the shade of the emergent or forest canopy. Plants in the understory consist of a mixture of seedlings and saplings of canopy trees together with understory shrubs and herbs. Young canopy trees often persist as suppressed juveniles for decades while they wait for an opening in the forest overstory which will enable their growth into the canopy. On the other hand, understory shrubs are able to complete their life cycle in the shade of the forest canopy. Also some small trees such as dogwood and holly rarely grow tall and are generally understory trees.

Forest understories have lower light intensities. The wavelengths of light that are available are only a subset of those that are available in full sunlight. Understory plants must therefore be shade tolerant—they must be able to photosynthesize successfully with the limited amount of light that is available. They are often able to use wavelengths not available to canopy trees. In temperate deciduous forests understory seedlings "leaf out" before the canopy trees do. This is important because it allows the understory plants a window in which to photosynthesize without the canopy present. This brief period (usually 1–2 weeks) is often a crucial period which allows the plant to maintain a net positive carbon balance over the course of the year.

Forest understories also have higher humidity than exposed areas. The forest canopy reduces solar radiation, so the ground does not heat up as rapidly. Consequently, the understory dries out more slowly than does more exposed areas. The greater humidity allows fungi and other decomposers to flourish. This drives nutrient cycling, and provides favorable microclimates for many animals and plants.

ee also

*Overgrazing
*Rainforest#Rainforest layers


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Look at other dictionaries:

  • understory — (n.) in reference to forest vegetation, also understorey, 1945, from UNDER (Cf. under) + STORY (Cf. story) …   Etymology dictionary

  • understory — [un′dər stôr΄ē] n. [ UNDER + STORY2] the smaller trees, saplings, and, sometimes, shrubs that grow beneath the large trees in woods or forests …   English World dictionary

  • understory — noun Date: 1902 1. an underlying layer of vegetation; specifically the vegetative layer and especially the trees and shrubs between the forest canopy and the ground cover 2. the plants that form the understory …   New Collegiate Dictionary

  • understory — ˈ ̷ ̷ ̷ ̷ˌ ̷ ̷ ̷ ̷ noun Etymology: under (III) + story 1. : a foliage layer lying beneath and shaded by the main canopy of a forest 2. a. : the plants (as seedlings, shrubs …   Useful english dictionary

  • understory — /un deuhr stawr ee, stohr ee/, n. the shrubs and plants growing beneath the main canopy of a forest. [1900 05; UNDER + STORY2] * * * …   Universalium

  • understory — noun The layer of plants that grow in the shade of the canopy of a forest …   Wiktionary

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