Desert biomes cover about one fifth of the Earth's surface and are defined to occur where rainfall is less than 50 centimeters per year. Although most deserts, such as the Sahara of North Africa and the deserts of the southwestern USA, Mexico, and Australia, occur at low latitudes, another kind of desert, cold deserts, occur in the basin and range area of Utah and Nevada and in parts of western Asia. Most deserts have a considerable amount of specialized vegetation, as well as specialized vertebrate and invertebrate animals. Soils often have abundant nutrients because they need only water to become very productive and have little or no organic matter. Disturbances are common in the form of occasional fires or cold weather, and sudden, infrequent, but intense rains that cause flooding.
WWF Terrestrial Ecoregions Collection
The Mojave Desert is the smallest of the four North American deserts. While the Mojave lies between the...
Madagascar spiny thicketsLast Updated on 2015-06-25 20:16:56
WWF Terrestrial Ecoregions Collection
The Madagascar spiny thickets or spiny desert of southern Madagascar, also referred to as deciduous thicket, is a globally distinctive ecoregion. This ecoregion is part of the Deserts and Xeric Shrublands biome, within the Afrotropics Realm. While the island of Madagascar is notable for exceptional levels of endemic plants and animals, the spiny thicket is particularly distinctive with 95 percent of the plant species endemic to the ecoregion. Members of the endemic Didiereaceae family present dominate the thicket, which have similar xeric adaptations to New World cacti, such as small leaves and spines, but with the Madagascar spiny thickets displaying more woody rather than succulent characteristics.
There are a total of 288 recorded vertebrate taxa in the Madagascar spiny thickets, including several endemic... More »
CactusLast Updated on 2015-04-08 23:49:44Cactus is a family of plants that are specially adapted to survive arid conditions, most often having leaves reduced to spines, and succulent characteristics. The scientific family name Cactaceae is applied to this group comprising 121 different genera. This plant family is concentrated in the Americas and has a surprisingly broad latitude range in both the Northern and Southern Hemispheres.
A considerable number of cacti species are threatened, chiefly due to habitat loss to agriculture, trampling by illegal human immigration into the southwestern USA, large-scale desert solar power projects, as well as overcollecting.
The cactus family is generally considered native to the Americas. A notable exception is Mistletoe cactus, Rhipsalis baccifera, which is thought to have spread, fairly recently, from the American tropics to the subtropics and the deserts of the... More »
NamibiaLast Updated on 2014-07-07 16:10:29Namibia is a nation of over two million people in southern Africa, bordering the South Atlantic Ocean, between Angola to the north and South Africa to the south.
Namibia is mostly high plateau with the Namib Desert along the coast and the Kalahari Desert in east. It is one of the least densly populated nations in the world.
Namibia's major environmental issues include:
limited natural fresh water resources;
habitat fragmentation; and,
land degradation which has led to few fully protected intact conservation areas.
Most of the country is susceptible to prolonged periods of drought.
South Africa occupied the German colony of Southwest Africa during World War I and administered it as a mandate until after World War II, when it annexed the territory.
In 1966 the Marxist Southwest Africa People's... More »
Registan-North Pakistan sandy desertLast Updated on 2014-06-28 00:07:20The Registan-North Pakistan sandy desert is an ecoregion spanning southern Afghanistan; the extreme eastern portion of Iran; part of northwest Pakistan, covering a total land area of approximately 107,100 square miles. This ecoregion is classifed within the Deserts and Xeric Shrublands biome.
There is considerable vertebrate species richness within the Registan-North Pakistan sandy desert, although endemism among this group is only represented by five reptilian taxa.
Situated in the southernmost portion fo Afghanistan, the far east of Iran and along part of the northwest Pakistan border area, this ecoregion is an arid element of the palearctic landscape. The Khash Desert is a major feature ot the ecoregion.
The Registan-North Pakistan sandy desert includes:
Zohary’s Iranian steppes of Artemisietea herbae-albae iranica east of the Kuh-e Gamsidzai and the Kuh-e Palangan;... More »
Desert grassesLast Updated on 2014-06-25 15:41:10Desert grasses are those plants from the family poaceae that have adapted to desert biomes.The Plants that are most conspicuous in desert communities are long-lived trees, such as Foothill palo verde (Cercidium microphyllum), and cacti, such as the saguaro (Carnegiea gigantea), with grasses usually not so noticeable. Yet grasses are surprisingly numerous and play important ecological roles in desert communities.
Many plants lose parts in times of stress. In temperate and tropical forests, deciduous trees drop their leaves once a year in response to cold or drought. Ocotillo (Fouquieria splendens) loses its leaves with drought, but leafs out several times a year depending on rainfall. Desert trees and shrubs such as creosote bush (Larrea tridentata), foothill palo verde, triangleleaf bursage (Ambrosia deltoidea), and many others, actually lose branches during drought or... More »
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