We explain what the desert is and the different climates that predominate in this biome. In addition, the flora and fauna that it can host.
What is the desert?
Desert is understood as a bioclimatic landscape (or biome ) characterized by its very low precipitation rates (rains) and therefore very narrow margins of humidity , which translates into dry climates, extreme temperatures and arid soils.
Traditionally they have been thought of as places devoid of life , although this is not necessarily so: there is a flora (xerophilous) and a fauna (and also human populations) that has adapted to these harsh living conditions.
Currently the deserts occupy almost a third of the surface of our planet , which represents a total area of more or less 50 million km2, of which 53% correspond to hot deserts (such as the Sahara) and the rest to frozen deserts (like Antarctica).
They are distributed throughout the five continents, the best known regions being those of North Africa, northern Mexico, the Russian tundra, the icy plains of Greenland and Alaska, as well as northern Chile and the southern Argentina
In the deserts, wind erosion (wind) and solar radiation tend to be very intense, so the soil is usually sandy, stony or rocky ; and in the case of the polar deserts of the Antarctic, it is constituted by a dense layer of frozen soil (permafrost). The degree of intensity of these factors will depend on many desert characteristics, such as the type of sand formed or the climatic dynamics that it presents.
It is possible to recognize three different climatic types in the deserts, according to their average annual rainfall, which in any case is usually lower than in the rest of the regions of the planet. Can we talk about:
- Climate s emiárid or s (estepari or s) . They have an average of 250 to 500 mm of rain per year and constitute 15% of the Earth’s surface. They are usually found only at the outer edges of the deserts proper.
- Climes a rid o s . With annual rainfall between 25 and 250 mm (maximum), they cover 16% of the planet’s surface and are found in the bulk of known deserts.
- Climate h iperárid or s . The drought in these regions is such that it does not usually rain for years. Luckily they make up only 4% of the planetary surface, and are limited to polar deserts (too icy for liquid water ) or to the very heart of large warm deserts.
Desert temperatures tend to be extreme, with huge thermal variation between day and night. In the hot deserts a maximum of more than 40 degrees Celsius can be recorded during the day and at night descend below zero .
If we refer to polar deserts, the temperature always remains very low (around -40 ° C) and depending on the stationary cycle it can rise during the summer to almost 0 ° C.
The flora of the deserts is very particular, and in principle scarce, due to the very low humidity indices: without water it is impossible to carry out photosynthesis .
However, life has adapted to such adverse conditions: xerophilous vegetation has a predominance of prickly, fleshy and resistant plants , similar to the cactus (cactus), with large storage capacity of the water received. From the rest weeds predominate and, in the best case, shrubs of short stature.
In the eventual oases, on the other hand, the enriched water allows a greater proliferation of plant life, and it is possible to observe palm trees and bushes of greater height, including fruit trees such as dates or coconut.
Contrary to what one used to think, there are animals in the desert, adapted to the environment and concentrated on the preservation of their body moisture.
In the hot deserts, reptiles (snakes, lizards), insects (ants, beetles) and arachnids (scorpions, spiders) abound. There are also numerous desert rodents, which take refuge in burrows to get away from the daytime sun , from which they emerge only at night when everything cools. They feed on birds of prey and scavengers. Finally, it is possible to find camelids (camels, dromedaries) of very high drought resistance.
The frozen deserts, on the other hand, are less generous with life, and apart from mosses and bacterial life, there aren’t usually too many animals. In the outermost regions of the same, on the other hand, it is possible to find polar fauna: bears, seals and other mammals with insulated skin and a lot of stored fat, killer whales and whales, and fish, plankton and penguins that make them food.