In geography, an area with an annual precipitation of less than 10 inches is defined as a desert. By that logic, around ⅕ or 20 percent of the total surface area of the Earth is covered by deserts. Owing to its magnitude, it is virtually impossible for us to understand each and every aspect of this biome. Some of the well-known deserts of the world are the Sahara desert, Kalahari desert, Gobi desert, Atacama desert, Great basin desert, etc.
The Desert Biome
Other than precipitation, even evaporation has a crucial role to play in determining whether an area qualifies as a desert or not. There do exist some areas wherein the annual rainfall exceeds 10 inches, but large-scale evaporation makes them very dry, and thus, they are considered a part of the desert biome. One of the best example of this is Tucson, Arizona, where the annual rainfall is around 12 inches and evaporation is around 100 inches. The abiotic conditions of a region play an important role in determining the species of plants and animals which are likely to inhabit that region.
Many people are left confused when they see the continent of Antarctica top the list of deserts of the world in terms of area. That, however, isn't at all surprising, considering that it's a normal tendency to picture a desert as some hot, dry place, with lots of sand and no trees. So, the first thing that you need to keep in mind is that there are two types of deserts: hot deserts and cold deserts.
In hot deserts, the daily temperature can reach around 113 °F during the day and fall to 32 °F at night. In cold deserts, on the other hand, the daily temperature fluctuates between −130 °F and 59 °F. Though hot deserts are also characterized by absolutely low temperatures at night, the fact that there is no snow in these deserts differentiates them from cold deserts that are found in polar areas and at high altitudes.
Precipitation, as we mentioned earlier, is virtually non-existent in this biome, and all these factors combined result in harsh conditions wherein human habitation is very difficult.
While the desert biome vegetation is predominantly characterized by the presence of cacti, other species are also found in this biome. Besides the cacti species like the barrel cactus, saguaro cactus, old man cactus, etc., the list of desert plants also includes species like the brittle bush, creosote bush, desert ironwood, Joshua tree, Mojave aster, ocotillo, soaptree yucca, triangle-leaf bursage, etc.
Water retention ability happens to be one of the most crucial adaptations in desert plants, which helps them survive the harsh conditions prevailing in this biome. More importantly, these plants form an important component of the desert ecosystem with several animals depending on them directly for their energy requirements.
The lengthy list of animals that you are likely to come across in deserts includes species like camels, dingoes, Arabian horses, jackrabbits, vultures, desert iguanas, gerbils, hyenas, porcupines, rattle snakes, coyotes, jackals, sidewinders, scorpions, bighorn sheep, jerboas, oryxes, kangaroos, gila monsters, bobcats, desert tortoises, as well as numerous species of bats, beetles, and lizards.
As in the case of plants, even animals found in deserts sport superb adaptation skills that help them survive the harsh conditions of this biome. Some of the most common adaptations in desert animals include the ability to store water in fatty tissues, pale-colored skin to absorb less heat, long body parts to facilitate heat dissipation, etc.
While adaptations like nocturnal behavior and burrowing to avoid the harsh Sun are seen in most desert animals, other species resort to specialized adaptations. The sidewinder, for instance, keeps minimal contact with the ground when moving over hot sand, while jackrabbits use their long ears to dissipate heat.
Though the desert biome is not the richest biome in terms of species, it is definitely one of the most amazing biomes. Though extreme, this is surely one of the most useful biomes for those who intend to study the biodiversity of the planet.