Terrestrial Biome – Desert
Desert biomes cover about one fifth (20 percent) of the earth’s land area. There are four different types of desert biomes – hot and dry, semi arid, coastal and cold deserts. The different desert types are scattered around the world on different continents. The four major North American deserts are the Chihuahuan, Sonoran, Mojave and Great Basin, these are hot and dry deserts.
Others outside the U.S. include the Southern Asian realm, Neotropical (South and Central America), Ethiopian (Africa) and Australian deserts.
Some deserts get both very hot during the day and very cold during the night, when temperatures can drop well below freezing. Some deserts, however, are always cold, for example, the Gobi Desert in Asia and the desert on the continent of Antarctica. As with all biomes, the desert climate is determined by geographic conditions. Geographic conditions such as location, high atmospheric pressure and proximity of mountain ranges determine just what type of desert it is.
Hot and Dry Deserts
These deserts are hot and dry all year round. These receive very little rainfall in winter months. The largest hot and dry desert is northern Africa’s Sahara Desert, it covers roughly 3,500,000 square miles (9,065,000 square kilometres).
Semi Arid Deserts
The major deserts of this type include the sagebrush of Utah, Montana and Great Basin. They also include the Nearctic realm (North America, Newfoundland, Greenland, Russia, Europe and northern Asia). The summers are moderately long and dry and like hot deserts, the winters normally bring low concentrations of rainfall. Summer temperatures usually average between 21 – 27° Centigrade. Temperature do not normally go above 38° Centigrade and evening temperatures are cool, at around 10° Centigrade. Cool nights help both plants and animals by reducing moisture loss from transpiration, sweating and breathing.
These deserts occur in moderately cool to warm areas such as the Nearctic and Neotropical realm. A good example is the Atacama of Chile. The cool winters of coastal deserts are followed by moderately long, warm summers. The average summer temperature ranges from 13 – 24° Centigrade and winter temperatures are 5° Centigrade or below. The maximum annual temperature is about 35° Centigrade and the minimum is about -4° Centigrade. In Chile, the temperature ranges from -2 to 5° Centigrade in July and 21 – 25° Centigrade in January. The average rainfall measures 8 – 13 centimetres in many areas. The maximum annual precipitation over a long period of years has been 37 centimetres with a minimum of 5 centimetres.
These deserts are characterized by cold winters with snowfall and high overall rainfall throughout the winter and occasionally over the summer. They occur in the Antarctic, Greenland and the Nearctic realm. Cold deserts have short, moist and moderately warm summers with fairly long, cold winters. The mean winter temperature is between -2 to 4° Centigrade and the mean summer temperature is between 21 – 26° Centigrade. The winters receive quite a bit of snow. The Antarctic desert is the largest cold desert in the world, measuring 14,000,000 kilometres squared.
Animals that live in the Desert Biome
Different animals live in the different types of deserts. Animals that live in the desert have adaptations to cope with the lack of water, the extreme temperatures and the shortage of food. To avoid daytime heat, many desert animals are nocturnal. They burrow beneath the surface or hide in the shade during the day, emerging at night to eat. Many desert animals do not have to drink at all, they get all the water they need from their food. Most desert animals are small.
Rarer, but important, are physiological adaptations such as aestivation (dormancy during summer), the absence of sweat glands, the concentration of urine, localized deposits of fat in tails or humps and salt glands to secrete salt without loosing fluids.
Reptiles with their waterproof skin, production of uric acid instead of urine, hard-shelled eggs and ability to gain body heat directly from the sun and to retreat to shade or underground to avoid heat are exceptionally well adapted to drylands and, not surprisingly, diverse there.
There are relatively few large mammals in deserts because most are not capable of storing sufficient water and withstanding the heat. Deserts often provide little shelter from the sun for large animals. The dominant animals of warm deserts are nonmammalian vertebrates, such as reptiles.
Below are just a few of the animals that inhabit the Desert biome. The animals below are featured in our World Wildlife section.
Asia/South West Africa
- Boreal or Taiga Forests
- Chaparral or Scrub
- Grassland (Savanna)
- Temperate Forests
- Tropical Rainforests
- Other Biomes