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| Deserts |
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| These ecosystems are either barren or with scanty vegetation consisting of mainly thorny bushes. Deserts are classified as warm (hot) and cold (temperate) deserts. |
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| 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. |
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| The deserts of Iran and Turkey, Gobi desert of Mongolia, some deserts of Argentina are recognised as temperate or cold deserts. |
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| i) Most deserts receive some rain every year but not uniform. |
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| ii) Light green covering of annuals is seen just after rains. |
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| iii) Have scanty vegetation, clear skies, hot days and extremely cold nights. |
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| iv) Soil is rocky and encrusted with sand or salt. |
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| v) Long periods without precipitation and extreme temperature (50 - 60oC) conditions (arid lands) impose considerable restraints on the flora and fauna which inhabit there. |
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| vi) Sandy storms are very frequent. |
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| vii) Occur generally in rain shadow areas. |
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| 1) Includes succulents such as Cacti and Euphorbias, which can store water in their tissues. |
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| 2) Trees with long spreading roots such as Acacia, Prosopis, Phoenix (dates) are found. |
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| 3) Ephemerals (short lived) such as Boerhaavia repens are seen only during rainy season. |
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| Most 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. |
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| In general, the organisms having specialised structural and physiological and behavioural adaptations to withstand the extreme temperatures only can survive in a desert. |
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