Desert
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The Desert: Land of Little Rain
Of all the biomes of the world, the desert biome has the driest climate.
The great expanses of the world's desert lie between 20 degrees to 30 degrees north and south latitude. It is here that equatorial air falls down toward the Earth's surface and rainfall is rare because rain usually occurs when air begins to rise, not fall. The equatorial air that is falling prevents most air from rising. North Africa, southwestern North America, the Middle East, and Australia support the largest deserts, but there are smaller deserts in other regions such as on the Pacific coast of South America (the Atacama) and the Atlantic coast of southern Africa (the Namib), where moisture from cold water currents is evaporated immediately by the hot land masses adjacent to the currents.
Rainfall in the desert often totals a few inches yearly or, in some regions, there is absolutley none. Desert soils are often salty because whatever little rain that does fall quickly evaporates from the ground, leaving salt and other minerals behind.
| Important Fact |
| The Sahara Desert is expanding southwards, engulfing degraded grasslands, at a rate of 30 miles every year. |
Since rainfall is so scarce, plants in the desert are almost always drought-tolerant, meaning they can survive without water for a long time. With unique features such as, thick or waxy leaves, large root systems, and water storage systems-like in the cactus, these adaptive plants are built to store water, find water quickly or live with the littlest amount of water possible. The vegetation in deserts varies tremendously. The mojave desert in California is known for it's unique Joshua trees, in the Sonoran Desert there is the thorn-covered Ocotillo and the giant Saguaro Cactus. Sagebrush covers the Great Basin in the western United States and the Chihuahua Desert (in between Mexico and Texas), is well known for its mesquite trees.
The animals which live in this arid biome are usually light-colored and use camouflage to blend into their surroundings, and possibly for protection against predators. Being more active at night and around dawn and dusk, allows them to escape the scorching heat. During the day they often lay in burrows or under rocks. Different species of life in the desert include jackrabbits (North America), kangaroo rats, owls, snakes, lizards and tortoises.
Because of our carelessness, deserts are spreading over regions where there was once green, fertile land. This is mainly due to misuse of the planet. However, the desert expansion can be stopped through anti-desertification projects, and better land and agricultural management. This will turn the deserts back, by making the soil stronger with the roots of plants embedded into them, and replenishing the soil with nutrients and minerals.
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