Semi-deserts are characterized by the absence of forests and specific vegetation and soil cover. The semi-deserts combine elements of steppe and desert landscapes.

Semi-deserts are found in the temperate, subtropical and tropical zones of the Earth and form a natural zone located between steppe zone in the north and a desert zone in the south.

IN temperate zone semi-deserts are located in a continuous strip from west to east of Asia from Caspian lowland to the eastern border of China. IN subtropics semi-deserts are widespread on the slopes of plateaus, plateaus and uplands (Anatolian Plateau, Armenian Highlands, Iranian Highlands, Karoo, Flinders, foothills of the Andes, valleys of the Rocky Mountains, etc.). IN tropics semi-deserts occupy large spaces, especially in Africa: south of the Sahara is the Sahel zone (West Africa), which is characterized by desert savanna landscapes.

semi-desert soils

Vegetation

The highly sparse plant cover of the semi-desert often appears as a mosaic consisting of perennial xerophytic grasses, turf grasses, saltworts and wormwoods, as well as ephemers and ephemeroids. In America, succulents are common, mainly cacti. In Africa and Australia, thickets of xerophytic shrubs (see Scrub) and sparse low-growing trees (acacia, doum palm, baobab, etc.) are typical.

Animal world

Among the animals of the semi-desert, hares, rodents (ground squirrels, jerboas, gerbils, voles, hamsters) and reptiles are especially numerous; from ungulates - antelopes, bezoar goat, mouflon, kulan, etc. Small predators are ubiquitous: jackal, striped hyena, caracal, steppe cat, fennec fox, etc. Birds are quite diverse. Many insects and arachnids (karakurt, scorpions, phalanges).

Semi-desert protection

To protect and study the natural landscapes of the semi-deserts of the world, a number of national parks and reserves, including the Ustyurt Reserve, Tigrovaya Balka, Aral-Paygambar. The traditional occupation of the population is grazing. Oasis agriculture is developed only on irrigated lands (near water bodies).

Literature

Köppen classification of climate types
Class A: Tropical (af)- monsoon (Am)- Savannah (Aw, As)
Class B: Arid (BWh, BWk) - semi-desert (BSh, BSk)
Class B: Humid subtropical (cfa, cwa)- Oceanic (Cfb, Cwb, Cfc)- Mediterranean (Csa, Csb)
Class G: Humid continental (Dfa, Dwa, Dfb, Dwb)- Subarctic (Dfc, Dwc, Dfd) -
Alpine mediterranean (Dsa, Dsb, Dsc)
Class D: Polar (ET, EF)- Alpine (ETH)

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See what "Semi-desert" is in other dictionaries:

    Natural zones transitional between desert zones and steppe and savanna zones in temperate, subtropical and tropical zones. Winter air temperatures 0–10 °C, summer 20–25 °C. The annual amount of precipitation, not exceeding 300 mm, is 3-6 times less ... ... Geographic Encyclopedia

    HALOPHITE SEMI-DESTERTS- areas with very sparse vegetation "on saline soils ... Glossary of botanical terms

    Hot semi-desert zones of the world ... Wikipedia

    AND; pl. genus. tyn; and. Geographic area, By natural conditions transitional between desert and steppe. Inhabitants of deserts and semi-deserts. ◁ Semi-desert, oh, oh. New lands, steppes. * * * SEMI-DESTERN SEMI-DESERT, a biome type (see BIOME) that combines… … encyclopedic Dictionary

    Eurasia- (Eurasia) Contents Contents Name origin Geographic characteristics Extreme points of Eurasia The largest peninsulas of Eurasia General overview of nature Borders Geography History Countries of Europe Western Europe Eastern Europe Northern Europe … Encyclopedia of the investor

    This vast subfamily includes the vast majority of the considered snakes (more than 1400 species). They are characterized by a slender and long body with a small oblong head more or less clearly separated from the neck, covered with ... ... Biological Encyclopedia

    1) pov in the northeast of Africa. The name is from the ethnonym Somali. In Ptolemy, 2nd century, pov is referred to as the South Horn, today it is often called the Horn of Africa. See also Somalia, state. 2) Somali Democratic Republic, the state of the North of Africa. ... ... Geographic Encyclopedia

    People's Republic of China, PRC, state in the Center, and East. Asia. The name China accepted in Russia is from the ethnonym Kidan (they are also Kitai) of the Mong group. tribes that conquered the territory of the sowing in the Middle Ages. areas of modern China and formed the state in Liao (X ... ... Geographic Encyclopedia

    As part of the RSFSR. It was formed on December 27, 1943. It is located in the south of the Volga economic region. Area 44.1 thousand km2 Population 868 thousand people (1970). There are 10 administrative districts, 2 cities, 14 urban-type settlements in the region. City Center

    Most big mainland Earth, consisting of two parts of the world Europe (See Europe) and Asia (See Asia). Together with the islands, E. occupies an area of ​​about 53.4 million km2, of which the islands account for about 2.75 million km2. Extreme continental points E ... Great Soviet Encyclopedia

Books

  • Dynamics of agricultural lands in Russia in the 20th century and post-agrogenic restoration of vegetation and soils, D. I. Lyuri, S. V. Goryachkin, N. A. Karavaeav, E. A. Denisenko, T. G. Nefedova. The book is devoted to the dynamics and condition of Russian agricultural lands during the period from 1897 to 2004. It examines the processes of withdrawing from circulation a 1 rare lands in different ...

"The farther south you go, the less herbaceous cover becomes. The steppe gradually turns into a huge belt of deserts that stretches across Central Asia from west to east. You repeatedly cross low mountain ranges, and between them again lie endless expanses of flat sandy and rocky desert where you will not see an antelope or any other animal for days on end.This area looks waterless and bare, covered with stones and rubble, and in places sand or loess-like loam. a few grasses and ugly bushes grow in the gullies. giant hedgehogs with splayed needles.

Behind the last eastern mountain spurs of the Gobi Altai dominates sandy desert. Only knotty, as if dead, trunks of saxaul here and there stick out of the soil" * .

* (Unfortunately, this part of the quote could not be identified.)

“All day long you walk among the endless sandy sea: dune after dune, like giant waves, rise before the eyes of a weary traveler, opening short, yellow horizons. Even climbing to a higher peak, you see nothing - all sand, sand and sand. not seen and not heard, only heavy, rapid breathing of camels and the rustle of their wide paws is heard. A beautiful giant snake meanders along the sands of a camel caravan, now climbing the crests of dunes, now plunging between their capricious slopes ... "*

* (Kozlov P.K. Mongolia and Kam, part 1, 1905, p. 126.)

The above descriptions belong to the famous Russian explorer of Central Asia, P.K. Kozlov, who crossed the Gobi Desert at the end of the last century. But the Gobi is only one of the areas of the desert zone, covering the entire globe.

Geographical position. The zone of semi-deserts and deserts is well represented mainly in the northern hemisphere, where it extends between 15 and 50°N. sh. in the form of a belt, in different places having an unequal width. The zone occupies over a quarter of the entire land surface of the Earth. There are subtropical hot deserts and semi-deserts and moderately hot, but cold winters. The first ones reach 30 - 35 °C. and yu. sh. Their northern border coincides with the northern border of date palm cultivation. Deserts and, first of all, semi-deserts - vast transitional areas to real deserts - are gradually replaced by a wide variety of plant communities. Towards the equator from subtropical deserts and semi-deserts there are communities of tropical savannahs, thorn-shrub steppes, thorny woodlands and communities of tropical grasses, and towards the poles - areas with a wet winter period, which are characterized by communities of hard-leaved plants and subtropical winter-green steppes. Moderately hot but cold winter time The desert and semi-desert years (desert steppes) border mainly on the steppes, which are also cold in winter.

Let us name the most important subtropical deserts and semi-deserts of the northern hemisphere: the North African-Arabian deserts (of which the Sahara alone occupies an area only slightly inferior to the area of ​​​​the whole of Europe), the deserts of the Iranian-Pakistani-Indian region (Dashte-Lut and Thar), as well as the deserts and semi-deserts of the south -West of North and Central America (Sonoran Desert). In the southern hemisphere: the Chilean-Peruvian coastal desert South America, the coastal Namib Desert, the Kalahari Desert and the Karoo semi-desert in southwest Africa, as well as the semi-deserts of Central and South Australia. The cold winter dry regions of the middle latitudes of Asia include the Central Asian deserts and semi-deserts of the Irano-Turan desert region (Northern Iran, the Aral-Caspian lowland with the Karakum and Kyzylkum deserts), the Kazakhstan-Jungar region of semi-deserts with the Hungry Steppe (Kazakhstan from the lower Volga and further to the east through the territories adjacent to the Aral Sea to Lake Balkhash), the Central Asian desert region of Mongolia and northern China (the deserts of the Gobi, Takla-Makan, Beishan, Alashan, Ordos and Tsaidam), as well as the cold high-altitude deserts of Tibet (cold deserts). In North America cold in winter semi-desert is located in the Great Basin Highlands region between the Rocky Mountains and the Sierra Nevada range. And finally, in the southern hemisphere, a cold winter semi-desert is located in Argentina; this is a vast Patagonian shrubby semi-desert, occupying territories poor in precipitation (to the west of them are the Andes).

Climate and soils. Deserts and semi-deserts are characteristic of arid regions the globe. The latter differ from other areas in the insignificant amount of precipitation and strong evaporation of moisture: here the amount of moisture evaporating from the open water surface during the year exceeds the annual amount of precipitation falling on the same area. In areas with an arid climate, soil salinization (saline soils) often occurs due to the predominance of the upward flow of soil water. Endorheic lakes and channels of temporary (drying) streams are also often found. Quite large rivers can also be found in deserts and semi-deserts, but their sources are outside the arid zones. They often flow into endorheic lakes. Consequently, semi-deserts and deserts are self-draining territories that do not have surface water runoff.

Their climate is very different. First of all, as we have already said, according to the temperature regime, they are divided into hot subtropical and moderately hot, but with cold winters, as well as cold high-altitude deserts and semi-deserts. In terms of the amount of precipitation, they are also very different: from extremely arid areas where there is no rain at all or they are extremely rare and irregular, to arid areas with a summer rainy period and winter drought, or, conversely, with rainy winters and dry summers; there are areas with two short wet periods and those whose moistening occurs almost exclusively by fogs.

The existence of areas poor in precipitation, especially characteristic of the subtropical zone, is explained by the presence in them of more or less permanent areas of high atmospheric pressure; downstreams air masses clouds disperse, and therefore dryness occurs. Dry trade winds blow throughout the year. This subtropical belt of dry regions, which is mainly dependent on air circulation, located in the western parts of the continents (Baja California and the west of South America, the Sahara and southwestern Africa, as well as Southwestern Australia), behind high, precipitation-retaining mountains, goes far into temperate latitudes, for example, in the Great Basin of the American Rocky Mountains, in the Patagonia closed by the Andes, as well as in the desert and semi-desert Central Asian regions surrounded by high mountain ranges.

The sky over deserts and semi-deserts is almost always cloudless, which leads to extremely sharp temperature fluctuations during the day. So, at noon, the ground layers of air can warm up to 60 ° C and above, and at night the temperature can drop to several degrees above zero, daily temperature fluctuations of 40-50 ° C are not uncommon here.

Along with the macroclimate, the microclimate also plays an important role in determining the nature of the vegetation cover in areas where precipitation is extremely low, depending on the features of the terrain. Differences in relief, as well as soils and parent rocks, cause a significant diversity of plant communities of the same desert or semi-desert. And since water here turns out to be a factor limiting the development of vegetation cover, in this zone, along with the features of the relief, the ability of soils to better or worse retain moisture is no less important.

The water regime of some soils in arid regions is directly opposite to the regime of the same soils in humid regions of middle latitudes, where there is a lot of precipitation. There, clay soils are the wettest, with the greatest ability to retain water (film water), and the driest are sandy and stony soils. In arid regions, however, scanty precipitation never moistens the soil to its full depth and does not saturate them with water, therefore, in clayey and loess soils, only the surface layers become moist immediately after rains. The subsequent intensive evaporation of moisture contributes to the rapid drying of the upper soil layer and the appearance of cracks in it as a result of shrinkage, while sandy soils, into which water easily seeps, accumulate a lot of soil moisture. Large pores between soil particles separate soil capillaries filled with water, so only the topmost layer dries out, while the bulk of rainwater remains inside the soil. In stony soils, rainwater seeps into cracks filled with fine soil particles, where evaporation is minimal and conditions for moisture retention are favorable. It should hardly be surprising that in arid regions there are almost no plants on clay habitats, while on even sandy ones there are herbaceous or dwarf shrubs. plant communities, and even trees often grow on rocky habitats. That is why in deserts and semi-deserts, even where precipitation is extremely low, plants still develop in many places, but there is no dense vegetation cover. In dry valleys sandy deserts there are favorable conditions for the development of plants, since groundwater is at a relatively shallow depth. Here, for the growth of plants, optimal conditions are available at the places where they come to the surface. fresh water, that is, near sources; such places are called oases.

In general, soil formation almost does not occur in regions poor in precipitation. The reasons for this are wind erosion, which manifests itself very strongly due to the openness of the vegetation cover, the insignificant participation of plants in soil-forming processes (for example, humus does not appear) and almost complete absence soil organisms. Since moistening is only periodic and, moreover, short-term, water also hardly contributes to soil formation. Consequently, the properties of such soils are almost entirely determined by their granularity (granulometric composition of the solid substrate). Certain geological rocks and their derivatives, during the formation of which physical weathering predominates (due to lack of water, chemical and biological processes play a subordinate role), and determine the types of deserts - sandy, pebbly, stony, clay and loess (the latter are more often saline deserts ).

Plant growth forms. In all arid regions of the globe, a regularity can be traced: in the direction from the steppes and savannahs surrounding semi-deserts and deserts, towards the centers of deserts, the vegetation cover becomes more and more rare. Its density is proportional to the decrease in precipitation. Where there is a lack of moisture, there are much fewer plants in a certain area than in places with a lot of moisture. In deserts, vegetation develops better in habitats with favorable conditions for plants. water regime, such as the foot of the slopes, valleys and lowlands. But if in semi-deserts plants are still relatively evenly scattered over the soil surface, then in deserts there are large areas where there are no plants at all.

Plants in arid regions have a variety of adaptations that allow them to provide themselves with water; they are able to maximize the use of available water and conserve it by reducing the rate of evaporation (transpiration). By reducing the surface of the leaves, desert plants develop more root systems. Plants with widely grown root systems often live here, and the roots occupy many times more area than the above-ground organs. Thanks to this, they are able to quickly absorb rainwater from large areas. Other plants, especially sandy desert shrubs, on the contrary, form roots (or widely branched root systems) that go deep into many meters: this gives them the opportunity to use groundwater. The most striking example is the genus Juzgun (calligonum) from the buckwheat family; in these shrubs, common from the Sahara to the Gobi Desert, the roots go as deep as 30 m. Finally, there are plants with large leaves spread above the ground, which, despite the negligible humidity of the air, are able to absorb morning dew.

In addition to adaptations that ensure the absorption of water, desert plants have another feature: they are able to tolerate even long-term drought. Desert plants can be divided into several environmental groups. The first includes the so-called annual ephemera. These are plants that live for a short time; they develop from seeds immediately after the rains fall and often complete the entire development cycle up to the formation of seeds in a few days. At this time, a rare phenomenon occurs - the desert blooms, which can be seen in the figure below. The seeds of these plants remain viable during long periods of drought (the so-called latent existence).

The group of ephemeral geophytes includes perennial plants with typical underground storage organs (tubers and bulbs). They develop leaves and reproductive organs above the ground only for a short time immediately after the rains. Drought, which can last for years, these plants survive in the form of underground storage organs that are at rest.

The third group includes desert plants that can exist with periodic moisture (they are called poikilohydric); it is par excellence lower plants, such as some blue-green algae and lichens, as well as mosses, a few species of mosses (Selaginella) and ferns and even very few flowering plants. All of them are able to tolerate drought at rest, being severely dehydrated. After the rains, they turn green, grow and multiply for a while, and then dry up again.

A widely represented group of desert plants are xerophytes. Their above-ground organs remain alive during dry periods. In deserts and semi-deserts, xerophytes are mainly represented by hard-leaved shrubs (sclerophilic xerophytes), which, thanks to their highly branched and deeply penetrating root systems, receive required amount water and during drought. To reduce evaporation of moisture, their leaves are densely pubescent or greatly reduced. IN extreme cases assimilation is carried out by shoots that look like leafless rods or thorns. To limit water evaporation, some of these plants shed their leaves and even entire branches during the dry season. With a lack of moisture, their stomatal gaps close. Typical examples of such xerophytic plants of deserts and semi-deserts are representatives of the genera comb (Tamarix) from the comb family (Tamaricaceae), juzgun (calligonum) from the buckwheat family (Polygonaceae) (Zygophyllum) from the parnolistnikovy family (Zygophyllaceae), and in addition, many species from the families of ephedra (Ephedraceae) and caper (Capparidaceae).

Finally, a group of succulents should be mentioned. True (not halophilic) succulents contain a supply of water in leaves, branches, trunks or in underground organs, replenished during rains. During dry periods, the evaporation of moisture both into the atmosphere and into the soil is extremely limited. At the same time, metabolic processes are greatly slowed down and, as a result, plant growth is greatly slowed down. Typical representatives of real succulents: cacti (family Cactaceae) of the American semi-deserts, as well as morphologically similar plants from other families (Europhorbia, Crassula, species of the genera Senecio and Aloe, etc.), which are especially common in the South African Karoo semi-desert.

In deserts, and especially in sandy ones, under the action of the wind, there is an intensive movement of particles of the substrate on which plants live. In order for perennial plants to exist in such conditions, special adaptations are required. Like our dune grasses, these plants must also resist falling asleep; so their shoots grow quickly. These shrubs and grasses should rise above the wind-blown sands deposited around them.

For plants in arid areas, along with a lack of moisture and strong wind erosion great importance has soil salinity. As a result of intensive evaporation of water, the soils of both periodically and constantly moistened habitats accumulate easily soluble salts. This primarily applies to areas where groundwater occurs close to the surface and an upward flow of moisture occurs in the soil, to habitats located in lowlands, where puddles form for some time after rains, as well as to drainless desert lakes. Thus, all the most water-provided habitats of deserts and semi-deserts are threatened by salinization (salinization) of soils. The same pattern is observed in areas with artificial irrigation. Many arid areas are characterized by vast areas located in the lowlands with solonetzic and solonchak soils. Most often they contain sodium chloride and magnesium chloride, as well as calcium sulfate (gypsum). But the latter is poorly soluble in water and therefore, when soils are salinized, it is of secondary importance. Halophyte plant communities typical for such places develop on saline soils. In order to survive, halophytes must adapt to the relatively high salt content of soils. This is facilitated by the salt tolerance of their cytoplasm inherent in halophytes, associated with the entry of salts into the cell sap and their accumulation in it. So, in the cell sap of halophytes growing on soils containing chlorides, a high content of sodium chloride is found. Chlorides cause swelling of the cytoplasm, which leads to an increase in the volume (hypertrophy) of cells. This is what explains the fleshiness (succulence) of plants in this group. Succulence is also noted in halophytes growing on alkaline soils, while halophytes developing on soils containing sulfates do not show succulence, since the protoplasm shrinks under the action of sulfates. The content of soluble salts in halophytes reaches 35% of the dry matter weight of plants.

This, in brief, is a general description of the living conditions of plant organisms in deserts and semi-deserts, as well as the specific adaptations of plants to these conditions. Let's move on to a description of the main deserts and semi-deserts of the Earth and the conditions for the existence of plant communities characteristic of them.

Deserts and semi-deserts are characterized by severe weather conditions, unique natural phenomena. Here there are animals and plants that practically do not use water, moving hills - dunes, evidence of the existence of ancient civilizations.

Deserts are natural areas with an arid climate. However, not all of them are characterized by hot weather and abundance sunlight, there are areas that are recognized as the coldest on planet Earth. Semi-deserts represent an average landscape between desert, steppe or savannah and form in arid (dry) climates on all continents except Antarctica.

How are formed

Predisposing factors for the emergence of deserts and semi-deserts are individual for each of them and include territorial location (continental or oceanic), features of the atmosphere and land structure, uneven distribution of heat and moisture.

The reasons for the formation of such natural zones are high rates solar radiation and radiation, little or no precipitation.

Cold deserts appear for other reasons. In the Arctic and Antarctica, snow mainly falls on the coast; clouds with precipitation practically do not reach the inner regions. In this case, the annual rate can fall for 1 time. As a result, snow drifts form over hundreds of years.

The relief in hot desert zones is diverse. They are open to the wind, the gusts of which carry small stones, sand, creating undulating sediments.

They are called dunes, their common type is a dune, the height of which reaches 30 meters. Ridge dunes grow up to 100 meters and have a length of up to 100 meters.

Where are: location on the map

Deserts and semi-deserts are located in the tropical, subtropical and temperate zones. Natural areas on planet Earth are presented on a map with names.

Mira

In the northern latitudes there are deserts and semi-deserts of the subtropical and temperate zones. At the same time, tropical ones are also present - in Mexico, on the Arabian Peninsula, the southwestern United States, and the Indo-Gangetic lowland.

Arabian Peninsula

USA

In Eurasia, desert zones are located in the Caspian lowland, on the Central Asian and South Kazakh plains, Central Asia, and the Near Asian highlands.

In the southern hemisphere, natural areas are less common. This includes a list of names: Namib in the Republic of Namibia, desert zones of Peru and Venezuela, Gibson, Atacama, Victoria, Kalahari, Patagonia, Gran Chaco, Great Sandy, Karoo in Southwest Africa, Simpson.

Namib and Kalahari

Venezuela

Deserts Victoria, Gibson, Great Sandy, Simpson

Patagonia

Gran Chaco

One of the largest deserts in the world, Rub al-Khali occupies a third of the Arabian Peninsula. Tourists visiting Dubai often opt for a safari tour of hot spots.

The vast deserts of Israel are presented on the map - these are the Judean and Negev.

Polar natural zones are located in the near-glacial regions of Eurasia, on the islands of the Canadian archipelago, in the north of Greenland.

Greenland

The desert regions of Asia, Africa, Australia are located at a level of 200-600 meters above sea level, Central Africa and North America - 1000 meters. The borders of deserts with mountains are widespread. They prevent the advance of cyclones. Most of the precipitation falls on only one side highlands, on the other they are absent or are present in a small volume.

Sources of information about how many deserts there are on earth give the number 51, while 49 are real (not icy).

Russia

The country occupies a vast area with different types of climate, so the answer to the question of whether there are deserts in Russia is in the affirmative. There are not only hot zones, but also cold ones. On the territory of Russia, deserts and semi-deserts are distributed from the Caspian lowland to China, in the east of Kalmykia and in the southern part of the Astrakhan region. On the section of the left bank of the Volga, deserts and semi-deserts stretch to Kazakhstan. The Arctic zone is located in the region of the northern islands.

As you can see in the picture, semi-deserts are located in the northern part, they are characterized by a steppe landscape. To the south, the climate becomes arid, the vegetation cover thins out. The desert zone begins.

The largest desert in Russia, Europe is called the Ryn-sands, located in the Caspian Sea.

Kinds

Depending on the type of soil and soil, there are types of deserts:

  • Sandy and sandy-gravel- are formed on loose deposits of ancient alluvial plains. In different territories they are called differently: in Africa - ergs, in Central Asia- kumami, in Arabia - nefudami. At the same time, sands do not occupy the largest part of the desert zone. For example, in the Sahara they make up only 10%.

    sandy deserts

    Sand and gravel deserts

  • Stony (hamadas), gypsum, gravel, gravel-pebble- their location on mountain ranges, uplands, low mountains, and so on. The formation of a solid surface is due to the physical weathering of material from cracks in the rocks, which fills the depressions. This species is the most common - in the Sahara, 70% of the territory belongs to it.

  • Saline. They are characterized by a high concentration of salts. Territories are covered with a crust or bog that can suck a person or animal.

  • clayey- the surface of the territory is a clay layer, characterized by low mobility and low water properties (dry quickly, do not allow moisture to penetrate under the clay).

  • Loess- are formed in areas of accumulation of dusty, porous particles. They are characterized by a heterogeneous relief, the presence of a network of potholes, ravines.

  • arctic- allocate snowy and snowless (dry). The former occupy 99% of the area of ​​the Arctic deserts.

    Arctic snow deserts

    Arctic snowless deserts

Depending on the nature of precipitation, deserts are distinguished:


The driest desert - Atacama

Atacama is located on the west coast of South America in Chile. The coastal desert is located at the foot of the mountains, covering it with ridges from rain, cold sea ​​waters washed by hot shores.

Atacama is considered the driest natural area, with an average rainfall of 1 millimeter per year. In some areas, rain is observed 1 time in several decades. Significant precipitation was absent from 1570 to 1971. Some weather stations in the desert zone have never recorded rain.

In 2010 there happened anomalous phenomenon- Snow fell, filling several cities with snowdrifts.

In Atacama, there is a famous eleven-meter sculpture "Hand of the Desert", depicting a human palm, which protrudes three quarters from the sand. It symbolizes loneliness, grief, injustice, helplessness.

Atacama is known for a mysterious find - a humanoid mummy discovered in 2003 in the village of La Noria. Its size is 15 centimeters, instead of the usual 12 ribs, there are only 9, the skull has a pronounced elongated shape. Behind resemblance with the alien being, she was given the name "Atacama humanoid".

However, scientists in their reports after the research are inclined to the earthly origin of the mummy girl. She probably suffered from progeria (rapid aging) and died either in the womb or after birth. There is a version that she lived for 7 years - this is due to the age of the skeleton.

In the desert on Mount Cerro Unica, there is the largest anthropomorphic geoglyph - a drawing 86 meters long, whose age is about 9 thousand years. He is called "Tarapaka", the Giant. The creators are unknown, it is possible to fully view the image from the aircraft.

The largest hot desert - Sahara

The natural zone is located on the territory of 10 states: Algeria, Egypt, Morocco, Libya, Mali, Niger, Mauritania, Chad, Sudan.

Her definition of "Queen of the Desert" is due to the huge area of ​​\u200b\u200bthe territory (9,065,000 square kilometers). Many areas of the zone are uninhabited, settlements are observed only at reliable sources of water and vegetation.

The Sahara is full of secrets and mysteries.

She is known for mirages that lead travelers astray and doom them to death. People see oases, lakes and even entire cities, but it is impossible to get closer to them - they move away until they disperse altogether.

The version explaining the phenomenon calls the mirage a kind of lens that visually approximates objects that are actually much further away.

For tourists, special maps have been compiled indicating the places where phantom images are likely to appear.

In the Sahara, on the territory of Mauritania, astronauts discovered amazing object- a ring with a diameter of 50 kilometers, called the "Eye of Africa" ​​or "Rishat Structure".

Its age is estimated at 500-600 million years, the origin is unknown.

The largest cold desert - Antarctica

In terms of the area occupied by the territory, it is recognized as the leader among all desert places, ahead of even the Sahara. According to Wikipedia, the area of ​​the polar zone is 13,828,430 square kilometers. It is located on the island and mainland land of Antarctica.

In winter, the air temperature drops to -70 degrees, in summer the characteristic level is from -30 to -50 (not higher than -20). On the coast of the Antarctic Peninsula, it is possible to increase the indicators in summer up to 10-12 degrees.

Precipitation is presented in the form of snow, their amount is from 30 mm to 1000 mm per year. Characterized by strong winds, storms, snowstorms. Nature is poor, vegetable and animal world poor and monotonous.

The most popular desert is the Mojave

Located in the southwestern United States of America, most of the territory is uninhabited.

However, the desert is popular with tourists, here are the major cities of Lancaster, St. George, Henderson and, of course, gambling Las Vegas.

famous museums, National parks, nature reserves in the Mojave. Death Valley stands out among them. This national park, where bizarre forms of salt flats, canyons, sand dunes, and valleys are presented.

Even an experienced tourist is not easy to navigate in such a variety. Poisonous snakes, spiders, scorpions, coyotes will not let you lose your vigilance.

Description of desert places

Natural zones are characterized by a variety of landscape and climate. Despite the harsh conditions, adapted species of animals, plants, and insects live in deserts and semi-deserts.

People also inhabit hot zones, run a household, find ways to interact with nature. However, over vast areas, due to harsh conditions external environment life is absent, the existence there for almost all organisms becomes impossible.

The soil

In desert zones, a weak development of soils is noted, in which water-soluble salts predominate over organic components. Vegetation covers less than 50% of the surface or is completely absent.

The gray-brown soil is characteristic of the elevated plains.

In deserts and semi-deserts, solonchaks with 1% concentration of easily soluble salts are often found.

Groundwater is predominantly mineralized. Upon reaching the surface of the soil, they are located in its upper layer, forming salinization.

The soil in subtropical deserts and semi-deserts is orange and brick red. Such soil is called red soil and yellow soil.

In the north of Africa, South and North America, gray soils are found in the deserts.

Climate

The climate in deserts and semi-deserts depends on its location. It is arid, hot, the air is slightly humidified, practically does not protect the soil from solar radiation.

The average temperature is +52 degrees, the maximum is +58. Excessive heating is associated with the lack of clouds and, accordingly, protection from direct sunlight. For the same reason, the temperature decreases markedly at night, since heat is not stored in the atmosphere.

Diurnal amplitudes in deserts tropical zone up to 40 degrees, in moderate - up to 20. The latter are characterized by significant seasonal fluctuations. There are hot summers with temperatures in the range of +50 degrees and harsh winters, when the thermometer drops to -50, while the snow cover is small.

In hot deserts, rain is rare, but sometimes there are heavy downpours in which water is not absorbed into the soil. It flows into dry channels called wadis.

A characteristic feature of deserts - strong winds at a speed of 15-20 meters per second, sometimes more.

They transport surface material, forming sand and dust storms.

The desert zones of Russia are characterized by a sharply continental climate: dry and harsh with strong daily and seasonal temperature fluctuations. In summer, the level reaches more than +40 degrees, in winter it drops to -30.

Evaporation of precipitation exceeds the amount of precipitation, they are mainly observed in spring and summer.

Strong winds, dust storms and dry winds are typical.

IN arctic deserts no transitional seasons. The polar night lasts 90 days, winter comes with temperature regime up to -60 degrees. Then summer comes with the polar day. It does not last long, while the temperature is within +3 degrees. Snow cover is constant, winter comes in 1 night.

Animal world

Living organisms living in deserts and semi-deserts have managed to adapt to harsh conditions.

From cold or heat, they hide in burrows, feed on insects, underground parts of plants.

reed cat

The carnivorous animals of the desert zones include the fennec fox, reed cats, cougars, and coyotes.

In the semi-desert you can meet a tiger.

Some representatives of the animal world have a developed system of thermoregulation. They withstand fluid loss up to a third of their own body weight (camel, gecko), and certain types of invertebrates - up to two-thirds of their weight.

North America and Asia inhabited by a large number of reptiles: lizards, snakes, there are insects, including poisonous ones.

A large mammal, the saiga is also considered an inhabitant of hot natural areas.

In the Chihuahua Desert, located on the border of Texas, New Mexico and Mexican states, pronghorn is often found, feeding on all plants, including poisonous ones.

In the hot natural zone of Danakil, where the air temperature can rise to +60 degrees, wild donkeys, Grevy's zebra, Somali gazelle live on sparse vegetation.

wild donkey

In the deserts and semi-deserts of Russia, there are sandstone hares, hedgehogs, kulans, goitered gazelle, snakes, jerboas, ground squirrels, mice, and voles.

sandstone hare

Among predators, the steppe fox, polecat, and wolf are distinguished.

steppe fox

Spiders also live in natural areas: karakurt and tarantula. Among the birds there are the steppe eagle, white-winged lark, white heron and so on.

steppe eagle

In the polar deserts, the animal world is scarce. Its representatives feed on seafood, vegetation. Here live polar bears, musk ox, arctic fox, seals, walruses, reindeer, hares.

Polar bear and walruses

Reindeer

Among the birds, eiders, gulls, terns, penguins and so on stand out.

Penguins

Plants

In deserts and semi-deserts vegetable world is not rich and includes thorny cactus, date palm, hard-leaved grasses, acacia, saxaul, psammophyte shrubs, ephedra, soap tree, edible lichen.

Date palm

Psammophyte shrubs

Sandy natural zones are characterized by oases - "islands" with rich vegetation and reservoirs.

In the Russian deserts and semi-deserts, there are white and black wormwood, fescue, sarepta feather grass, viviparous bluegrass. The soil is not fertile.

Sarepta feather grass

Semi-deserts from April to November serve as pastures for livestock.

In some periods, natural areas flourish, filled with rich vegetation. For example, the Kyzylkum desert (“red sands”), which belongs to Uzbekistan, Kazakhstan, and partly Turkmenistan, blooms in spring with a bright carpet of flowers and herbs.

Subsequently, they disappear under the rays of the scorching summer sun.

In the Takla-Makan desert in western China, most of the territory is completely devoid of vegetation cover, only in rare areas of groundwater occurrence thickets of tamarisk, reed appear, camel thorn, saxaul, and poplar grow along river valleys.

Camel-thorn

IN arctic wilderness vegetation is practically absent. In summer, the surface of the earth is covered with moss and lichens, there are sedge and cereals, polar poppy, saxifrage, buttercup, and so on.

locals

People living in hot natural areas are forced to adapt to the conditions environment. In economic activity, pasture cattle breeding is distinguished.

Agriculture is used only in the valleys of large rivers, irrigation is used.

Oil and gas are produced in many natural areas. This is especially true for Asia.

In the deserts and semi-deserts of Russia, irrigated agriculture is practiced in the floodplains and deltas of large rivers (Volga, Syrdarya, Amudarya). A large number of wells and wells have been created for watering cattle, places for their wintering.

The most severe conditions for economic activity are noted in stony and gravelly deserts, here Agriculture practically absent.

With a lack of water locals develop various ways for her prey. For example, in the driest Atacama Desert, the natives use "fog eliminators" - cylinders the size of a person to collect moisture. The fog condenses on the walls of the vessel, made of nylon threads, and flows into the barrel. With it, it is possible to collect up to 18 liters of water per day.

The nomadic inhabitants of Arabia, the Near and Middle East are called Bedouins.

Their culture is based on the invention of the tent and the domestication and breeding of camels. The Bedouin, together with his family, roams on a camel, which carries a portable dwelling and utensils.

reserves

Human interference is recognized as the main threat to deserts and their inhabitants. In addition to hunting for rare and endangered species of animals and birds, natural resources are being extracted in these zones - oil and gas.

Technological progress increases the need for them, which leads to an increase in the development of deposits. Mining pollutes nearby areas, causing an environmental disaster.

Anthropogenic impact in the Arctic contributes to the melting of ice, reducing the territory of cold deserts. Its disappearance will cause the death of a large number of representatives of the flora and fauna of the natural zone.

Environmental work is being carried out in Russia and throughout the world, national parks and reserves are being created.


Semi-desert natural zones are land areas characterized by a dry climate with significant daily temperature fluctuations and low average annual precipitation (about 150 mm / year). These territories are arid, characterized by poor surface water runoff, which determines the increased salt content in the soil. Often, reservoirs and rivers in these areas are prone to drying up; during the period of drought, their bottom is covered with a layer of salts. In the semi-desert zone, vegetation mainly consists of grasses and low-growing shrubs.

Characteristics of the natural zone of semi-deserts.

Semi-deserts are located on all continents, except Antarctica, in three climatic zones: temperate, tropical and subtropical. They are dominated by landscapes formed as a result of the action strong winds, the steppe relief is interspersed with stone mounds or hills.


Another map showing the location of semi-deserts.

Semi-deserts of the temperate zone in Eurasia stretch from the Caspian lowland to the borders of China. In North America, this zone is found in the foothills of the Rocky Mountains and in the lowlands of the Great Basin. In South America, it is located east of the Andes. Climate characterized by low winter temperatures (up to -25 degrees) and high summer temperatures (up to +30 degrees). Soils brown and light chestnut (Fig. 1 (1)), with a low content of humus (about 2%), they contain gypsum and a large amount of salts, solonetzes and solonchaks are common in places (Fig. 1 (2, 3)), which can be used for agricultural turnover only under the condition of artificial irrigation and salinity reduction.

The tropical semi-desert zone in Africa combines the features of a savannah and a desert, located south of the Sahara, in the humid zone of the Namibia desert, in the northeast of the Kalahari desert, it is also located in India and Pakistan, on the Arabian Peninsula, in South America on the Brazilian plateau, in Australia. The maximum summer temperatures reach 50 degrees, the minimum winter temperatures are about 12-15 degrees above zero. Red-brown clayey soils, subject to erosion processes, predominate. (Fig.2)

The subtropical semi-desert zone is located in the mountains of North and South America, Australia, the Iranian Highlands, North and South Africa. The climate is temperate continental with summer temperatures up to 25 degrees, winters are characterized by a drop in temperatures to 0 degrees with rather rare snowfalls. The soils are poor gray-brown and sierozem with inclusions of crushed stone. (fig.3)


Salt Lake.


Semi-desert in the foothills of the Colorado Plateau.