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Ecosystems

Desert life

Cape fox in the Kalahari desertCape fox in the Kalahari desert A desert is an area of land which has very little or no rainfall. Many deserts are hot places, bare and rocky or sometimes covered with sand. There are also cold deserts, such as the Gobi in Asia, where winters are bitterly cold. In hot deserts, temperatures can soar to over 50°C (120°F) during the day. There, high mountains act as a barrier to any warm, moist air currents, and temperatures can fall to –20°C (–4°F) in winter. There are no trees to give shade and very few places to find water. Even so, some kinds of plants and animals are still able to survive.


Wildlife in the desert of southwestern USAWildlife in the desert of southwestern USA
Euphorbia virosa, a xerophyteEuphorbia virosa, a xerophyte

Plant life

Many deserts are bare and rocky with areas of sparse scrubland, where only the hardiest plants can grow. As plants need water to survive, they must conserve as much as they can. Some desert plants can take in water that condenses from dew or fog. Desert plants such as cacti have adapted the way they carry out photo­synthesis, opening their stomata (pores) to take in carbon dioxide only in the cool of the night. Their thick, swollen stems also help to reduce water loss. Other desert plants keep most of their bulk in root systems underground, out of the sun’s heat. Plants adapted to desert conditions are called xerophytes.

An oasis in the Sahara desertAn oasis in the Sahara desertSome hot deserts are sandy, and the wind sweeps the sand into huge wave-like dunes. In these arid, bare landscapes, the sand is mostly too unstable to support plant life. Sometimes an underground water source comes close to the surface, creating an oasis, where plants can grow, and people can live.
 

Saguaro cactuses may live up to 200 years, but grow slowly. At 9 years old, they are, on average, 15 cm (6 inches) high; they may develop their first branches at 50–70 years.

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