Desert biome
Desert biomeDESERT BIOME
Any barren region that supports very little life may be called a desert. The cold expanses of Antarctica, extreme northern Asia, and Greenland are therefore true, but cold, deserts. Most commonly, however, the term desert is used for regions that are barren because they are arid, or dry. Arid deserts receive little precipitation and are characterized by specialized plants that tolerate drought conditions and salty soils, and by distinctive land features. Most desert areas get less than 5 inches (13 centimeters) of rain in a year. The rainfall is not only scanty but also uncertain. "Records at Iquique in northern Chile showed no rain for a period of four years. The fifth year brought 0.6 inches (1.5 centimeters), making a five-year average of 0.12 inches (0.3 centimeter). At another time 2.5 inches (6.4 centimeters) fell in a single shower. " (Compton's Encyclopedia)
Temperatures range widely in deserts. The greatest daily fluctuations occur in deserts near the equator. Temperatures above 100o F (38o C) occur regularly in summer. "Azizia, 25 miles (40 kilometers) southwest of Tripoli, in Libya, holds the record with 136.4o F (58o C), while Death Valley, Calif., comes close with 134o F (56.7o C). "(Genius book of world records 2000) Winters are cold in middle-latitude deserts, located far from the equator. "At Luktchin in central Asia the average temperature in July is 90o F (32o C), while the January average is 13o F (-10.6o C)--a range of 77 Fahrenheit degrees (42.6 Celsius degrees)"(Compton's Encyclopedia). The temperature drops sharply in the desert night. Dry air, cloudless skies, and bare, dry earth furnish ideal conditions for the cooling of air after sunset. A 24-hour range of 25 to 45 Fahrenheit degrees (14 to 25 Celsius degrees) is common, and it may be as great as 60 to 70 Fahrenheit degrees (33 to 39 Celsius degrees).
In the deserts, ordinary wells can usually tap a supply of good water. Oasis settlements therefore are most often found where wadis are numerous. Ergs into which many wadis drain may have a water supply. Desert shrubs in the hollows between the dunes signal its presence. Desert soils are usually productive when given water. They are coarse textured and highly mineralized. Most widely cultivated are the water-transported soils of floodplains and alluvial fans. Plants of the desert depend on sources of water or the adaptations they have developed. Few parts of the desert are entirely barren. Where water seeps toward the surface, a great variety of plants spring up. After a rain low shrubs and grasses come to life. At blooming time, the...
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