Hot Deserts

Abstract

Hot deserts occur in two global belts north and south of the equator, at latitudes where calm air and a stable atmosphere dominate. Desert rainfall occurs in the form of highly unpredictable pulses followed by long periods of drought, and many plants and animals are finely adapted to these cycles of abundance and scarcity. Water‐storing succulents and short‐lived ephemeral plants are some of the most common life forms in these highly variable and strongly pulsating environments. In spite of their apparent barrenness, the hot deserts of the world harbour unique and rare biotas with impressive biological adaptations. As a result of evolution in isolation from each other, the world's deserts have high levels of endemism and harbour rare and unique life forms, a fact that makes them ecologically fragile and highly vulnerable to biological extinction.

Key Concepts:

  • Large deserts occur in the mid‐latitudes of the world, north and south of the equator, where the atmosphere is highly stable and calm air dominates.

  • Smaller rain shadow deserts often develop in the leeward side of mountain ranges, which capture moisture before it reaches the downwind side.

  • Coastal fog deserts, such as Atacama or the Namib, owe their aridity to cold ocean currents, and their moisture oscillates with oceanic ‘El Niño’ cycles.

  • A panoply of morphological and physiological adaptations have evolved in desert environments, which allow plants and animals to survive the harsh desert conditions.

  • Some plants store water in fleshy tissues, others develop extremely long roots to tap water in the deep soil aquifer, while others simply die as the drought sets‐in and survive long periods in the form of seed.

  • Animals may migrate into areas where rain has fallen, and have a complex set of morphological and physiological traits that allows them to regulate their temperature without losing water.

  • The harsh conditions of deserts have promoted the evolution of a complex set of positive relations among desert organisms, such as ‘nurse’ plants, and elaborate pollination and seed dispersal interactions.

Keywords: adaptations; aridity; deserts; sky‐islands; xerophytes

Figure 1.

Satellite composite image of the Earth, showing the two hot desert belts north and south of the equator. Taken from NASA's ‘Earth Observatory’ website (http://earthobservatory.nasa.gov/). © NASA.

Figure 2.

Only 40 km apart, two weather stations in the deserts of the narrow Baja California peninsula show the effect of oceanic currents on winter and summer rains: In Benito Juárez, near the Pacific coast and under the influence of the California Current, rains come during the coldest months of the year (a). In El Mezquital, near the hot Gulf of California and facing the continental mainland, rains arrive in summer in the form of tropical thunderstorms (b).

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References

Allan JA, Warren A, Tolba M and Allan T (1993) Deserts: The Encroaching Wilderness (A World Conservation Atlas). Oxford: Oxford University Press.

Cloudsley‐Thompson JL (1979) Man and the Biology of Arid Zones. London: Edward Arnold.

Cloudsley‐Thompson JL (1996) Biotic Interactions in Arid Lands. Berlin, Heidelberg: Springer.

Davis W (1998) Shadows in the Sun Travels to Landscapes of Spirit and Desire. Washington, DC: Island Press.

Dimmit MA (2000) Biomes & communities of the Sonoran Desert region. In: Phillips SJ and Comus PW (eds) A Natural History of the Sonoran Desert, pp. 3–18. Tucson, AZ: Arizona‐Sonora Desert Museum and University of California Press.

Ezcurra E and Mellink E (2013) Desert ecosystems. In: Levin SA (ed.) Encyclopedia of Biodiversity, 2nd edn, vol. 2, pp. 457–478. Waltham: Academic Press.

Ezcurra E, Mellink E, Wehncke E et al. (2006) Natural history and evolution of the World's deserts In: Ezcurra E (ed.) Global Deserts Outlook, pp. 1–26. Nairobi: United Nations Environment Programme (UNEP).

Goudie A and Wilkinson J (1977) The Warm Desert Environment. Cambridge: Cambridge University Press.

Gutterman Y (1993) Seed Germination in Desert Plants, 253 pp. Berlin: Springer.

Louw GN and Seely MK (1982) Ecology of Desert Organisms. London: Longman.

Mares MA (1980) Convergent evolution among desert rodents: a global perspective. Bulletin of the Carnegie Museum of Natural History 16: 1–51.

McGinnies WG, Goldman BJ and Paylore P (eds) (1977) Deserts of the World. Tucson, AZ: University of Arizona Press.

Morton RR (1979) Diversity of desert‐dwelling mammals: a comparison of Australia and North America. Journal of Mammalogy 60: 253–264.

Mulroy WT and Rundel PW (1977) Annual plants: adaptations to desert environments. BioScience 27: 109–114.

Noy‐Meir I (1973) Desert ecosystems: environment and producers. Annual Review of Ecology and Systematics 4: 25–41.

Pianka ER (1986) Ecology and Natural History of Desert Lizards. Analysis of the Ecological Niche and Community Structure. Princeton, NJ: Princeton University Press.

Pipes R (1998) Hot Deserts (World Habitats). New York, NY: Raintree.

Ricciuti ER (1996) Desert (Biomes of the World). New York, NY: Benchmark Books.

Robichaux RH (ed.) (1999) Ecology of Sonoran Desert Plants and Plant Communities. Tucson, AZ: University of Arizona Press.

Schmidt‐Nielsen K (1964) Desert Animals; Physiological Problems of Heat and Water. Oxford: Clarendon Press.

Further Reading

Ezcurra E (ed.) (2006) Global Deserts Outlook, 148 pp. Nairobi: United Nations Environment Programme (UNEP).

Mares MA (1999) Encyclopedia of Deserts, 672 pp. Norman, OK: University of Oklahoma Press.

Phillips SJ and Comus PW (eds) (1999) A Natural History of the Sonoran Desert, 628 pp. Tucson, AZ: University of California Press/Arizona‐Sonora Desert Museum Press.

de Villiers, Marc and Hirtle S (2002) Sahara: A Natural History, 320 pp. London: Walker & Company.

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Ezcurra, Exequiel, Mellink, Eric, and Martínez‐Berdeja, Alejandra(Sep 2014) Hot Deserts. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0003178.pub2]