These ecosystems are either barren or with scanty vegetation consisting of
mainly thorny bushes. Deserts are classified as warm (hot) and cold (temperate)
deserts.
The hot deserts are the Sahara in Northern Africa, Kalahari in Southern
Africa, Thar in India, Atacama in South America, deserts of Mexico and
Australia.The deserts of Iran and Turkey, Gobi desert of Mongolia, some
deserts of Argentina are recognised as temperate or cold deserts.
Characteristics of Desertsi) Most deserts receive some rain every year
but not uniform.
ii) Light green covering of annuals is seen just after rains.iii) Have
scanty vegetation, clear skies, hot days and extremely cold nights.
iv) Soil is rocky and encrusted with sand or salt.v) Long periods without
precipitation and extreme temperature (50 - 60oC) conditions (arid
lands) impose considerable restraints on the flora and fauna which inhabit
there.
vi) Sandy storms are very frequent.vii) Occur generally in rain shadow
areas.
Flora1) Includes succulents such as Cacti and Euphorbias, which can
store water in their tissues.
2) Trees with long spreading roots such as Acacia, Prosopis, Phoenix (dates)
are found.3) Ephemerals (short lived) such as Boerhaavia repens are seen
only during rainy season.
FaunaMost desert animals are nocturnal and avoid the heat of the day by
burrowing into the cooler soil. Animals include ants, locusts, lizards, Gila
monster, coral snake, rattle snake, burrowing owls, Gambel's quail, kangaroo
rats, rabbits, camel, skunk, badger foxes, jackals and desert cats.
In general, the organisms having specialised structural and physiological and
behavioural adaptations to withstand the extreme temperatures only can survive
in a desert.