Desert and semi-desert zone of Russia: where it is located, map, climate, flora and fauna. Desert and semi-desert soils - how deserts arise

Speaking of deserts, the imagination pictures vast areas of sandy or rocky wasteland, not occupied by vegetation, without any signs of life. Traveling by plane and looking at the vast forested territory of Russia, with river beds and lake pits, it is difficult to imagine a place where such places exist. However, this is not so: in Russia there are deserts and semi-deserts. They are amazing, beautiful in their own way and not lifeless at all.

Deserts of Russia: geography and natural features

Semi-deserts and deserts of Russia occupy a small area in the southeast of the European part of the country, west and east from the lower Volga and to the foothills of the Caucasus range. The border runs south of Volgograd , separating the steppe and desert zones, starting from the left bank of the Volga, further to the northeast to Kazakhstan, then south to the foothills of the Caucasus and to the Terek valley.

The once significant zone of deserts and semi-deserts of modern Caspian lowland was the seabed, which left its mark on the landscape - a multi-kilometer surface, flat as a table, stretching to the very horizon. During the melting of snow or rain, water settles in small lakes on the desert surface, creating the impression of “spotting” of the earth.

The soils and flora here are different; there are alkaline, clayey and sandy areas. Semi-deserts have more benign climate and living conditions; they are used as pastures for grazing livestock. These are the western areas of semi-deserts, closer to the steep slopes of Ergeni, more relief, hilly, with semi-desert vegetation.

The hills that occur periodically on the sea plain are called salt floors. Underground rock salt deposits move under pressure rocks and are forced to the surface of the earth, forming mounds and hills and enlivening the desert landscape.

Climatic characteristics

Deserts and semi-deserts are characterized by a climate with sharp daily temperature changes and low precipitation: no more than 150 mm per year (in spring). The climate is hot and dry, water evaporates before it can be absorbed into the ground. Temperature changes are characteristic not only of the change of day and night. Winter and summer difference temperatures are also very high. The general background of weather conditions can be defined as extremely severe.

Sometimes the air temperature in deserts in summer reaches 50 degrees in the shade, and in winter the thermometer drops to minus 30 degrees!

Such temperature changes cannot but affect the formation of the flora and fauna of the semi-deserts of Russia.

Flora and fauna

The heyday of life occurs from April to June. The lack of sufficient moisture and sudden temperature changes allow only a limited number of plants to grow. The main flora is found in semi-deserts, and the closer to the deserts of the Caspian lowland, the more sparse the vegetation is.

In winter, strong winds add to the frost, which blows snow from the plains and exposes the ground. Such areas look black, they are called “Black Lands”. But that’s not the only reason they got their name. Black wormwood grows in semi-deserts: a plant with small leaves and dark branches. A certain area of ​​desert lands is set aside for a nature reserve, which is also called “Black Lands”.

What grows in semi-deserts?

The following crops grow in deserts and semi-deserts:

• Ephemeroids: plants that live only a short time, quickly wither, but leave tubers and bulbs in the soil.
• Ephemeral plants: with a short life cycle, two to three months.

Perennial herbs, cacti, ephedra, camel thorn, kendar, sand acacia and even tulips grow here. TO short cycle plants life can be attributed to bulbous bluegrass. He covers the ground with a carpet, turning it into short time desert into an oasis of life.

Grains and other plants with deep and strong roots thrive in sandy soils: volosnets, saxaul, elymus. Sandy soils absorb water well and retain it, preventing it from evaporating.

Animals of deserts and semi-deserts

Despite the harsh climate and poor flora, fauna semi-deserts are diverse. It is not easy to adapt to the scorching heat and the lack of permanent sources of water and food, but the species inhabiting deserts and semi-deserts have succeeded. Animals dig deep holes and wait out the heat in them, are able to store moisture on for a long time. It is difficult to hide among the sands and sparse vegetation: the ability to run fast and make long jumps helps to escape from predators. Birds are capable of flying over long distances.

Representatives of the fauna of deserts and semi-deserts:

• Mammals: sand hares, jerboas, long-eared hedgehogs, corsacs, ground squirrels, gazelles, antelopes, fennec foxes, camels.
• Reptiles: snakes, turtles, monitor lizards, lizards.
• Insects: spiders, locusts, beetles.
• Birds: bullfinches, larks, partridges, jays, sparrows.

Depending on geographical latitude areas, in deserts and semi-deserts of Russia, are formed corresponding to the climatic zone different ecosystems. The flora and fauna of these zones is also different.

Problems of deserts and their development

The ecological crisis is as follows:

Man is responsible for the desertification of lands. Cutting down trees, drying up springs, changing river beds, plowing lands, long-term use of pastures, illiterate irrigation methods, indefatigable mining of natural resources - these are just part of the list of human affairs.

Natural deserts beautiful in their own way, incomprehensible and are fraught with many mysteries. If people do not turn deserts into wastelands, they will reveal many more of their secrets to us.

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

Deserts are considered natural areas with arid climate. However, not all of them are characterized by hot weather and plenty of sunshine; there are areas that are recognized as the coldest on planet Earth. Semi-deserts represent an average landscape between desert, steppe or savanna and are formed in arid (dry) climates on all continents, excluding Antarctica.

How are they 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 that caused the formation of such natural zones are high indicators 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, up to internal regions clouds with precipitation practically do not reach. In this case, the annual norm may fall out at one time. As a result, snow deposits form over hundreds of years.

The relief in hot desert zones is varied. They are open to the wind, gusts of which carry small stones and sand, creating wave-like sediments.

They are called dunes, their common type is dunes, 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 they: 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 northern latitudes Deserts and semi-deserts of the subtropical and temperate zones are located. At the same time, there are also tropical ones - in Mexico, on the Arabian Peninsula, the southwestern United States, and the Indo-Gangetic Lowland.

Arabian Peninsula

United States of America

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

IN 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 South-West Africa, Simpson.

Namib and Kalahari

Venezuela

Victoria, Gibson, Great Sandy, Simpson deserts

Patagonia

Gran Chaco

One of the largest deserts in the world, Rub al-Khali, occupies a third Arabian Peninsula. Tourists visiting Dubai often choose safari excursions to hot places.

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

Polar natural zones are located in the periglacial regions of Eurasia, on the islands of the Canadian archipelago, in northern Greenland.

Greenland

Desert areas of Asia, Africa, Australia are located at a level of 200-600 meters above sea level, in Central Africa and North America- 1000 meters. Borders between deserts and mountains are common. They impede the progress of cyclones. Most of the precipitation falls only on one side of the mountainous area, on the other it is absent or present in small quantities.

Sources of information about how many deserts there are on earth put the number at 51, with 49 being 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 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 Astrakhan region. On the left bank of the Volga, deserts and semi-deserts stretch to Kazakhstan. Arctic zone located in the northern islands region.

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

The largest desert in Russia and Europe is called Ryn-Sands, located in the Caspian region.

Species

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

• Sand and sand-crushed stone- are formed on loose sediments 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-gravel deserts

• Rocky (hamads), gypsum, gravelly, gravelly-pebble- their location on mountain ranges, hills, low mountains, and so on. The formation of a hard surface is due to the physical weathering of material from rock cracks, which fills depressions. This species is the most common - in the Sahara it covers 70% of the territory.

  

• Salt marshes. Characterized by a high concentration of salts. The territories are covered with crust or quagmire, capable of sucking in a person or animal.

  

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

  

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

  

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

  

  Arctic snowy deserts

  

  Arctic snowless deserts

Depending on the nature of precipitation, deserts are distinguished:

The driest desert is 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 the rain, cold sea ​​waters wash the hot shores.

The Atacama is considered the driest natural zone, with an average rainfall of 1 millimeter per year. In some areas, rain occurs once every few decades. There was no significant precipitation from 1570 to 1971. Some weather stations in the desert area have never recorded rain.

In 2010, an anomalous phenomenon occurred there - snow fell, covering several cities with snowdrifts.

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

Atacama is famous for a mysterious discovery - 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. For external resemblance with an alien creature, she was called the “humanoid Atacama”.

However, scientists in their reports after research are inclined to the earthly origin of the mummy girl. She probably suffered from the disease 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 "Tarapaca", the Giant. The creators are unknown; the entire image can be viewed from an airplane.

The largest hot desert is the Sahara

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

Its definition of “Queen of the Deserts” is due to its huge territory (9,065,000 square kilometers). Many areas of the zone are uninhabited; settlements are observed only near reliable sources of water and vegetation.

Sahara is full of secrets and mysteries.

It is known for mirages that lead travelers astray and doom them to death. People imagine oases, lakes and even entire cities, but it is impossible to get closer to them - they move away until they disappear completely.

The version that explains the phenomenon calls a mirage a kind of lens that visually brings objects closer that are actually much further away.

Made for tourists special cards indicating the places where phantom images are likely to appear.

In the Sahara on the territory of Mauritania, astronauts discovered an amazing object - a ring with a diameter of 50 kilometers, called the “Eye of Africa” or “Richat Structure”.

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

The largest cold desert is the Antarctic

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

IN winter period the air temperature drops to -70 degrees, in summer the typical level is from -30 to -50 (not higher than -20). On the coast of the Antarctic Peninsula, it is possible that in summer the indicators may rise to 10-12 degrees.

Precipitation is in the form of snow, its amount varies from 30 mm to 1000 mm per year. Strong winds, storms and blizzards are typical. Nature is poor, the flora and fauna are sparse 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 among tourists; there are major cities Lancaster, St. George, Henderson and, of course, gambling Las Vegas.

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

Even an experienced tourist finds it difficult to navigate such diversity. Poisonous snakes, spiders, scorpions, coyotes will not let you lose your vigilance.

Description of desert places

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

People also inhabit hot zones, farm, and find ways to interact with nature. However, in large areas due to harsh conditions external environment there is no life, existence there becomes impossible for almost all organisms.

Soil

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

Gray-brown soil is characteristic of high plains.

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

Groundwater predominantly mineralized. When reaching the soil surface they are located in its top layer, forming salinity.

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

In northern Africa, South and North America, gray soils are found in deserts.

Climate

The climate in deserts and semi-deserts depends on its location. It is arid, hot, the air is poorly humidified, and 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, at night the temperature decreases markedly, since heat is not retained in the atmosphere.

Daily amplitudes in deserts tropical zone up to 40 degrees, in moderate temperatures - up to 20. The latter are characterized by significant seasonal fluctuations. Hot summers are observed with temperatures in the range of +50 degrees and harsh winter, at which the thermometer drops to -50, while the snow cover is small.

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

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

They transport material located on the surface, forming sandy and dust storms.

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

The evaporation of precipitation exceeds the amount of precipitation; it is mainly observed in spring and summer.

Characterized by strong winds, dust storms and dry winds.

There are no transition seasons in Arctic deserts. The polar night lasts 90 days, winter comes with temperature conditions up to -60 degrees. Then summer comes with the polar day. It does not last long, and the temperature is within +3 degrees. The 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.

When exposed to cold or heat, they hide in burrows and feed on insects and underground parts of plants.

jungle cat

Carnivorous animals of desert zones include fennec foxes, jungle cats, pumas, and coyotes.

In the semi-desert you can meet a tiger.

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

Inhabits North America and Asia large number reptiles: lizards, snakes, insects, including poisonous ones.

The large mammal saiga is also considered an inhabitant of hot natural zones.

In the Chihuahuan Desert, located on the border of Texas, New Mexico and the Mexican states, pronghorn are 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, and Somali gazelle live, feeding on sparse vegetation.

Wild donkey

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

sand hare

Among the predators there are steppe fox, ferret, wolf.

Steppe fox

Spiders also live in natural areas: karakurt and tarantula. Birds include the steppe eagle, white-winged lark, white heron, and so on.

steppe eagle

In the polar deserts the fauna is sparse. Its representatives feed on seafood and vegetation. Polar bears, musk ox, arctic fox, seals, walruses live here, 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, the flora is not rich and includes prickly cacti, date palm, hard-leaved grasses, acacia, saxaul, psammophyte shrubs, ephedra, soap tree, and edible lichen.

Date palm

Psammophyte shrubs

Sandy natural areas are characterized by oases - “islands” with rich vegetation and reservoirs.

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

Feather grass of Sarepta

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

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

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

In the Taklamakan Desert in western China, most of the territory is completely devoid of vegetation cover; only in rare areas of groundwater do thickets of tamarisk and reeds appear; camel thorn, saxaul, and poplar grow along the river valleys.

camel thorn

IN arctic desert vegetation is practically absent. In summer, the surface of the earth is covered with moss and lichens, there are sedges 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 highlight pastoralism.

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

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

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

The most severe conditions for economic activity are found in rocky and gravelly deserts, where agriculture is practically absent.

When there is a shortage of water, local residents are developing various ways to obtain it. For example, in the driest Atacama Desert, natives use “fog eliminators” - human-sized cylinders - to collect moisture. The fog condenses on the walls of the vessel, made of nylon threads, and flows into the barrel. With its help 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. A Bedouin and his family roam on a camel, which carries a portable home and utensils.

Reserves

Human intervention 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 - oil and gas - are extracted in these areas.

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

Anthropogenic impact in the Arctic is contributing to the melting of ice, reducing the area of ​​cold deserts. Her disappearance will cause death large number representatives of the flora and fauna of the natural area.

In Russia and all over the world, environmental work is being carried out, national parks and reserves are being created.

Deserts and semi-deserts of Eurasia extend from the Caspian lowland to China. In Russia, this occupies the territory of the southeastern regions of the country. The Arctic desert is located in the northern territories. Distinctive feature Deserts and semi-deserts are characterized by high fluctuations in winter and summer temperatures. Semi-deserts are located in the northern part of the natural zone. The climate here is milder, so they are characterized by a steppe landscape. Closer to the south, where it becomes arid and the vegetation cover practically disappears, there is a desert zone.

Geographical location and natural conditions

Arctic desert, as well as deserts and semi-deserts on the map of Russia

In the area of ​​the left bank of the Volga, deserts and semi-deserts stretch to Kazakhstan. The lands from the right bank of the river extend to the foothills of the Caucasus. The territories lie on the Caspian lowland, which is a flat area. Millions of years ago there was a seabed here. Most of the deserts are flat earth's surface, and only in the west are there steep slopes.

Climate

The natural zone is located in an area of ​​sharply continental climate. Rain and snow fall infrequently, making the climate dry but harsh. Most precipitation occurs in spring and summer. The level of evaporation exceeds the amount of precipitation.
The desert experiences strong daily and annual temperature ranges. During the day, the temperature difference can reach thirty degrees Celsius. In winter, the thermometer drops to -30°C and the winds rage. Their gusts blow away the snow cover from the soil, causing it to take on a black tint. Summer temperatures exceed +40°C. It rains rarely, but dust storms and dry winds often occur.

Flora

The soils in semi-deserts are saline because they are based on ancient marine rocks. Wormwood-grass vegetation grows in semi-deserts. The lands contain little humus, and as a result of human economic activity they turn into shifting sands, and therefore are infertile. Nevertheless, the vegetation cover of the natural area is variegated. Feather grass, fescue, white wormwood, black wormwood, desert wheatgrass, and viviparous bluegrass grow here. From April to November, semi-desert lands are used as pastures. In June, with the onset of the dry period, the vegetation disappears, and the semi-desert becomes like a desert.

Closer to the south, the climate becomes arid, and the lands turn into a real desert. It is usually divided into two subzones: northern and southern. In the northern part the climate is mild. Subshrubs dominate here: saltmarsh barnacle, gray quinoa, and redberry. adapt to living conditions, many of them are leafless to reduce moisture evaporation. Vegetation in one form or another is located throughout the desert. In the southern part there are small trees and shrubs: sand acacia, Richter's solyanka, white saxaul. These areas also serve as pastures.

Animal world

In the zone of semi-deserts and deserts there are many that have adapted to harsh conditions. Animals dig deep holes to wait out the heat of the day in them. Optimal conditions To survive in the harsh conditions of the natural zone, jerboas, gophers, mice and voles have evolved.

During the polar night, which lasts 90 days, winter begins. Summer comes with a polar day. There are no transition seasons. Winter temperatures low, up to -60°C. There is little precipitation. Winds blow snow cover off the soil. Summer doesn't last long. The air temperature in July is +3°C. During the polar day, the sun does not warm the air well. The snow does not melt for 300 days a year, and winter comes overnight.

Trees and bushes are completely absent. In summer the lands are covered with lichens and mosses. Sedge and cereals grow on rocky soil. In the Arctic desert in summer you can find green oases with polar poppy, saxifrage, buttercup and Arctic pike.

The soil thaws to a depth of 40 cm. Iron oxides accumulate in the upper part, causing the soil to acquire a brown tint. There is sand and stones on the surface. Spherical formations, spherulites, are a landmark of cold deserts.

The fauna is scarce. Animals living in the Arctic desert feed on seafood. Polar bears leading semi-aquatic image life, breed off the coast of Chukotka, on Franz Josef Land. IN arctic reserve"Wrangel Island" dens have been created for them. Arctic foxes, lemmings, hares, and reindeer come from here in the summer. Seals and walruses set up their rookeries on the coast. Birds are considered the most numerous class. Bird markets are organized by eider ducks, gulls, tundra partridges, guillemots, and terns. When the polar day arrives, snow geese, geese, plovers and dunlins flock to the Arctic.

Ecological problems of deserts and semi-deserts of Russia

The main threat to turning deserts into wastelands is human intervention. Recent scientific research has shown that these areas contain oil and natural gas. Due to technological progress, the need for them is constantly growing. Oil production pollutes nearby areas more than others. The entry of “black gold” into the environment entails an environmental disaster.

The desert and semi-desert zone of Russia is home to many different types animals, some of them are listed in the Red Book. Poaching puts the survival of valuable animals into question. The process of desertification itself causes damage to agriculture. The number of pastures is decreasing.

Due to anthropogenic influence, ice in the Arctic is melting, as a result of which the Arctic desert zone itself is shrinking. If it disappears, a large number of flora and fauna will disappear from the face of the Earth. Snowmobiles and other ground vehicles pollute with exhaust emissions. Ozone holes negatively affect animal life. destroys mining, waste, . Large fish species are under threat of extinction. Their food, small fish and seafood, is caught on an industrial scale.

Deserts and semi-deserts need our protection. Already today there are nature reserves in the territories, but this is not enough. Work to protect natural areas must be controlled at the state level. Every effort should be made to resolve existing problems so that new ones do not arise.

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HOW DO DESERT AND SEMI-DESERTS ARISE? There are many reasons why deserts arise. For example, the Atacama Desert receives little rainfall because it is located at the foot of the mountains, which cover it from rain with their ridges. Ice deserts formed for other reasons. In Antarctica and the Arctic, the bulk of the snow falls on the coast; snow clouds practically do not reach the interior regions. Precipitation levels generally vary greatly; one snowfall, for example, can result in a year's worth of precipitation. Such snow deposits form over hundreds of years. Hot deserts have a wide variety of topography. Only some of them are completely covered with sand. The surface of most is strewn with pebbles, stones and other different breeds. Deserts are almost completely open to weathering. Strong gusts of wind pick up fragments of small stones and hit them against the rocks. IN sandy deserts the wind carries sand across the area, creating wave-like deposits called dunes. The most common type of dunes is dunes. Sometimes their height can reach 30 meters. Ridge dunes can be up to 100 meters high and extend for 100 km.

TEMPERATURE REGIME The climate of deserts and semi-deserts is quite diverse. In some regions, daytime temperatures can reach 52 degrees. C. This phenomenon is associated with the absence of clouds in the atmosphere, thus nothing saves the surface from direct sunlight. At night, the temperature drops significantly, which is again explained by the absence of clouds that can trap the heat emitted by the surface. In hot deserts, rain is a rare occurrence, but sometimes heavy downpours occur here. After rain, water does not soak into the ground, but quickly flows from the surface, washing away particles of soil and stones into dry channels called wadis.

LOCATION OF DESERTS AND SEMI-DESERTS On continents located in northern latitudes, there are deserts and semi-deserts of the subtropical and temperate zones. Sometimes tropical ones are also found - in the Indo-Gangetic Lowland, Arabia, Mexico, and the southwestern United States. In Eurasia, extratropical desert areas are located in the Caspian lowland, on the Central Asian and South Kazakh plains, in the Central Asian basin and in the Western Asian highlands. Central Asian desert formations are characterized by a sharply continental climate. In the southern hemisphere, deserts and semi-deserts are less common. Here are located such desert and semi-desert formations as the Namib, Atacama, desert formations on the coast of Peru and Venezuela, Victoria, Kalahari, Gibson Desert, Simpson Desert, Gran Chaco, Patagonia, Great Sandy Desert and Karoo Semi-Desert in southwest africa. Polar deserts are located on the mainland islands of the periglacial regions of Eurasia, on the islands of the Canadian archipelago, in northern Greenland.

ANIMALS Animals of deserts and semi-deserts, over many years of existence in such areas, have managed to adapt to harsh climatic conditions. They hide from cold and heat in underground burrows and feed mainly on underground parts of plants. Among the fauna there are many species of carnivores: fennec fox, jungle cats, pumas, coyotes and even tigers. The climate of deserts and semi-deserts has contributed to the fact that many animals have developed a well-developed thermoregulation system. Some desert inhabitants can withstand fluid loss of up to a third of their weight (for example, geckos, camels), and among invertebrates there are species that are capable of losing water up to two-thirds of their weight. In North America and Asia there are a lot of reptiles, especially lizards. Snakes are also quite common: ephas, various poisonous snakes, boas. Large animals include saiga, kulans, camels, pronghorn, and Przewalski's horse has recently disappeared (it can still be found in captivity). Animals of the desert and semi-desert of Russia are a wide variety of unique representatives of the fauna. The desert regions of the country are inhabited by sand hares, hedgehogs, kulan, jaiman, and poisonous snakes. In the deserts that are located in Russia, you can also find 2 types of spiders - karakurt and tarantula. They live in polar deserts polar bear, musk ox, arctic fox and some species of birds.

VEGETATION If we talk about vegetation, then in deserts and semi-deserts there are various cacti, hard-leaved grasses, shrubs, sammophytes, ephedra, acacia, saxaul, soap tree, date palm, edible lichen and others.

DESETS AND SEMI-DESERTS: SOIL The soil is, as a rule, poorly developed, and water-soluble salts predominate in its composition. Among the soil-forming rocks, ancient alluvial and loess-like deposits, which are reworked by winds, predominate. Gray-brown soil is typical for elevated flat areas. Deserts are also characterized by salt marshes, that is, soils that contain about 1% of easily soluble salts. In addition to deserts, salt marshes are also found in steppes and semi-deserts. Groundwater, which contains salts, when reaching the soil surface is deposited in its upper layer, resulting in soil salinization. Completely different types of soils are characteristic of such climatic zones, like subtropical deserts and semi-deserts. The soil in these regions has a specific orange and brick-red color. Due to its shades, it received the corresponding names - red soils and yellow soils. IN subtropical zone in northern Africa and in South and North America there are deserts where gray soils have formed. In some tropical desert formations, red-yellow soils have developed. deserts semi-deserts soil Natural areas of deserts and semi-deserts are a huge variety of landscapes, climatic conditions, flora and fauna. Despite the harsh and cruel nature of the deserts, these regions have become home to many species of plants and animals.

An OASIS located near a natural reservoir, an island of vegetation in the desert. Oases can vary greatly in size and character, from small ponds fringed with date palms to entire cities with agricultural activities and industry. The traditional form of farming, which combines many forms of farming, is oasis farming. Oases are formed thanks to underground rivers or reservoirs in which water is able to reach the surface of the earth due to sufficient self-pressure or with the help of sources organized by man. Some oases, such as those located in the Touath region (central Algeria), are fed by occasional short-term downpours. An impermeable subsoil of rock and stone also helps retain water in water pockets, underground faults or volcanic dikes. In turn, vegetation appears near the oases thanks to migrating birds, which leave seeds after visiting the reservoir.

INTERESTING FACTS In Death Valley, the driest and hottest place on globe, lives over 15 species of birds, 40 species of mammals, 44 species of reptiles, 12 species of amphibians, 13 species of fish and 545 species of plants. The Sahara is the second largest desert on earth, after Antarctica, and the hottest desert in the world, with an area of ​​9,000 square meters. km; In the mythology of the ancient Egyptians and Libyans, there was a deity - the personification of the Libyan Desert - Ha, as well as the archaic deity-ruler of the Libyan Desert - Ash. Later they were replaced and supplanted by another god of the desert - Set. Gecko lizards do not have eyelids, so they are forced to periodically wet a special transparent membrane over their eyes with their tongue. And the web-footed geckos, which live in the deserts of Namibia, use this feature for the reverse process. Almost every morning, fog falls on the dunes here, after which liquid condenses in front of the lizard’s eyes. The gecko then licks it off to quench its thirst. In one day, the wind can blow away a million tons of dust from the Sahara. If it were loaded into railway cars, the length of the train would be 400 km. The air temperature at this time rises to 48 -50 degrees. , accompanied by a sharp drop in humidity. There are dunes that reach a height of up to 180 meters. In one part of the Atacama Desert there has been no rain for 400 years. The Sahara became a desert relatively recently - about 2,700 years ago as a result of very slow climate evolution. And 6,000 years ago - around the same time when the ancient Egyptian state arose - trees grew in the Sahara and there were many lakes.

Semi-deserts – the territory of Eurasia. These are the territories of Kazakhstan, Mongolia and China. In the USA and Argentina in the south.

Semi-deserts are characterized by high temperatures for the summer months. Precipitation amount ≈ 100 – 250mm. And evaporation rate ≈ 1500mm. This causes an arid climate and rapid drying of soils. Biomass 100 c/ha. Most of them relate to root systems (90%).

Brown semi-desert soils. They have a weak differentiated profile. A, ABt(lessivage),Bca, BSA(gypsum),BCs, C. Lessivage in the arid zone (when it is dry and hot). Movement of the sludge fraction from top to bottom. This lessivage is not modern (it is a residual phenomenon). “Soils are a mirror of the landscape, as well as its history.” This is the cause of the last glacial glaciation. During the period when there was more precipitation, lessivage occurred.

Humus content – ​​1%. Humus reserves – 60 – 65 t/ha. Carbonates from the surface. Gypsum at a depth of 50 cm. Chlorides are present in the upper part. At a depth of 70 – 80 cm. Absorption capacity ≈ 10 – 15 mg/eq. Ph ≈ 7.5 – 8, therefore high-silk. Soils are little used in agriculture because... lack of N and no fertilizers. Herd-pasture animal husbandry. And the introduction of N pollutes the environment (water) and products. Nitrogen fertilizers (NO3) enter the body and are converted into NO2. And NO2 turns into nitrosamines.

The soil cover is mosaic. The zonal type is brown semi-desert, brown semi-desert solonetzic, solonchak, solonetz.

Deserts. Located in Asia, Mongolia, China, northern and South America. The vegetation does not form a continuous cover and is represented by xerophytes (plants adapted to life in dry places - camel thorn, sand acacia). Desert landscapes are characterized by low rainfall< 100 мм (т.к. не ежегодные). К < 1 (К < 0,1). Биомасса 40 ц/га. Основная масса под землёй.

Gray-brown desert - formed on loamy soils. They have a thin soil profile. A(k) – melozem cemented with salts into a crust (2 – 5 cm), A(E) – up to 10cm, Bca, Bsacs, C.

These soils are characterized by the content of gypsum and salt on the surface. Poor humus content. Humus reserves – 4 c/ha. Ph ≈ 8 – 8.5. Absorption capacity< 10 мг/экв.

Takyr- soils of flat clayey depressions in the deserts of the subtropical zone. The surface hard horizon (pink or pale gray) is broken up by individual cracks. Contains 0.2-0.5% humus. Distributed in Wed. Asia, Kazakhstan, Mongolia, Western Asia, North. America, Australia, etc.

There are not many salt marshes in deserts.

25. Conditions of soil formation and soils of extra-permafrost provinces of the taiga zone.

	East-European province (Up to the Urals).		Western-Sib. province (to the Yenisei).
Northern taiga	Extra-permafrost taiga.
	1) Gley-podzolic soils.		1) Gley-podzolic.
	2) Podzolic illuvial-umus.		2) Illuvial-humus.
	3) Swamp-podzolic.		3) Swamp-podzolic.
	4) Swamp		4) Swamp
Middle taiga	1) Podzolic on clays.		1) Podzolic.
	2) Podzols on sand.		2) Podzols.
Southern taiga
		1) Soddy-podzolic.		1) Soddy-podzolic.
		2) Podburs.		2) Podburs.

The soils of taiga-forest areas are affected by the presence of rock-sedimentary rocks (marls). Soddy-carbonate soils will form on them. In the eastern part of Eurasia - permafrost-taiga fawn. Soil formation is influenced by Precambrian rocks. When these rocks are weathered, quaternary deposits of light mechanical composition are formed. Podzols are common. Well expressed Ao, Aov. In the north, fulvic acids predominate in the humus composition.

Precipitation. Humidification coefficient > 1. Flushing type dominates water regime, may be frozen stagnant. Permafrost has a tremendous impact on soil formation - it is a water-resistant soil. At small quantity precipitation → stagnation, sub-permafrost gleying occurs. Permafrost type of water regime. For soils in permafrost regions, there are no clearly defined soil horizons. Cryoturbation processes. In the taiga zone, where the leaching type of water regime is favorable conditions for soil formation, where non-leaching conditions are conditions for the development of gleyization.

Soils of the northern taiga.

In the eastern European province and the Western Siberian province, on soils of heavy mechanical composition (loamy moraine) under taiga-coniferous forests, the following are formed:

1. gley-podzolic, which have a profile: Ao, A1(g), A2(g), B(g), C(g).

In gley-podzolic soils, almost all horizons show signs of gleyization. The humus content (A1) is about 2-3% and its sharp decrease with depth. Acidity at the level of 4-5% - acidic soils. Absorption capacity at the level of 15-20 mg/eq. Low content of mobile (digestible) N, P, K. They have a low level of fertility, cold soils. Typical for the northern Taiga in the Western Siberian province and the Eastern European province.