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Desert  [ Ecology ]

Dictionary of botanic terminology - index of names

  A biome characterized by plants and animals adapted to extreme moisture scarcity. Found in regions, either hot or cold, where precipitation are insufficient to support any except xerophilous (drought resistant) vegetation; a region of extreme aridity.  

A desert is not only a hot, sandy place (as usually people think) but a desert is any place that does not get much rain. It is an area where evapotraspiration exceeds precipitation, for whatever reason.
Evapotraspiration rates will vary, according to temperature, but less than 25 centimetres of rain annually will produce a desert in almost any temperature range.  Desert soil is often composed mostly of sand and sand dunes may be present. Bottom lands may be salt-covered flats.

By the point of view of ecology a desert is a temperate or tropical biome characterized by prolonged drought, generally with extremes in temperature. As a consequence, deserts have a reputation for supporting very little life. Compared to wetter regions this may be true, although upon closer examination, desert are rarely totally without any vegetation or fauna but they give more often than not hospitality to few but highly adapted and specialized plants - like sparse shrub or grassland vegetation and animals. Approximately one-third of Earth's land surface is desert.

Most desert plants are drought or salt-tolerant, such as xerophytes. Some store water in their leaves, and stems (succulents) other remains hidden underground to preserve moisture (geophytes), Other have long tap roots that penetrate deeply in the soil to find the water. Other grow and complete their life cycle in a very sort time after an occasional rain (Ephemeral plants )
Deserts typically have a plant cover that is sparse and desert vegetation is frequently very complex and divers.
Cold deserts have grasses and shrubs as dominant vegetation.





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