Natural desert area. Desert Natural Area Southern Desert Place Dominate

In the Northern and Southern Hemispheres, between latitudes 15 and 30, there is a zone of tropical deserts. Some deserts are located inside continents, while others stretch along the western coasts of continents. These are very hot and dry regions of the globe with sparse flora and fauna. There are no permanent rivers here, and vast areas are occupied only by blowing sands, piles of stones and clay surfaces cracked by the heat.

Tropical deserts

Tropical or trade wind deserts, as they are also called, include the deserts of Arabia, Syria, Iraq, Afghanistan and Pakistan; the exceptionally distinctive Atacama Desert in Chile; Thar Desert in northwestern India; the vast deserts of Australia; Kalahari in South Africa; and finally, the greatest desert in the world - the Sahara in North Africa.

Tropical Asian deserts

The tropical Asian deserts, together with the Sahara, form a continuous arid belt stretching 7,200 km from the Atlantic coast of Africa to the east, with an axis approximately coinciding with the Tropic of the North; in some areas within this belt it almost never rains. The patterns of general atmospheric circulation lead to the fact that downward movements of air masses predominate in these places, which explains the exceptional aridity of the climate. Unlike the deserts of America, the Asian deserts and the Sahara have long been inhabited by people who have adapted to these conditions, but the population density here is very low.

The most beautiful deserts in the world

Atacama, Chile

Supposedly the oldest and driest desert in the world (only 3–15 mm of precipitation per year) consists of salt lakes, sand and hardened lava. The composition of its soil is as close as possible to that of Mars. By the way, “A Space Odyssey” was filmed here. In autumn, when the rains fall, the desert is covered with flowers.

Great Sandy Desert, Australia

In the Uluru-Kata Tjuta Nature Reserve, home to the wild dog dingo, stands the 8.6 km² red rock of Uluru, sacred to the Anangu Aboriginal people. The climb takes about an hour, and it is better to do it at dawn or at night to admire the stars.

Gobi, Mongolia

The largest and coldest (up to –40 °C) desert in Asia is famous for its fossils: it was here that paleontologists found dinosaur eggs. Park Gurvansaikhan is famous for the Hongoryn-Els sand massif stretching for 180 km, which means “singing sands”.

Namib, Namibia

Tall sand dunes come close to the ocean, where the cold Benguela Current creates fog, creating obstacles for shipping. To the south of the Kunene River is the Skeleton Coast - a cemetery for lost ships, which is increasingly covered with sand every year.

The desert may seem like a lifeless area only at first glance. In fact, it is inhabited by unusual representatives of the animal and plant world, who have managed to adapt to difficult climatic conditions. The desert natural zone is very vast and occupies 20% of the world's landmass.

Description of the Desert natural area

The desert is a vast flat area with a monotonous landscape, poor soil, flora and fauna. Such land areas are found on all continents, with the exception of Europe. The main feature of the desert is drought.

The relief features of the Desert natural complex include:

• plains;
• plateaus;
• arteries of dry rivers and lakes.

This type of natural zone extends over most of Australia, a relatively small part of South America, and is located in the subtropical and tropical zones of the Northern Hemisphere. On the territory of Russia, deserts are located in the south of the Astrakhan region in the eastern regions of Kalmykia.

💡

The largest desert in the world is the Sahara, which is located in ten countries of the African continent. Life here is found only in rare oases, and on an area of ​​over 9,000 thousand square meters. There is only one river flowing km, communication with which is not accessible to everyone. It is characteristic that the Sahara consists of several deserts, similar in their climatic conditions.

Rice. 1. The Sahara Desert is the largest in the world.

Desert types

Depending on the type of surface, deserts are divided into 4 classes:

TOP 1 articlewho are reading along with this

• Sand and sand-crushed stone . The territory of such deserts is distinguished by a variety of landscapes: from sand dunes without a single hint of vegetation, to plains covered with small bushes and grass.

Even the word “desert” itself evokes associations of emptiness and lack of life, but for the people who live on these lands, it seems beautiful and unique. The natural zone of the desert is a territory very difficult, but life. There are sandy, clayey, rocky, saline and snowy (yes, in the Arctic and Antarctica there is an Arctic desert) deserts. The most famous is the Sahara, it is also the largest in area. In total, deserts occupy 11% of the land, and if you count with Antarctica - more than 20%.

See the geographical location of the desert natural zone on the map of natural zones.

Deserts are located in the temperate zone of the Northern Hemisphere and the subtropical and tropical zones of the Northern and Southern Hemispheres (they are characterized by special moisture conditions - the amount of precipitation per year becomes less than 200 mm, and the moisture coefficient is 0-0.15). Most deserts were formed on geological platforms, occupying the most ancient land areas. Like other landscapes of the Earth, deserts arose naturally, thanks to the peculiar distribution of heat and moisture over the earth's surface. In simple terms, deserts are located in places that receive very little or no moisture. The reasons for this are the mountains that close the deserts from the oceans and seas or the proximity of the desert to the equator.

The main feature of semi-desert and desert lands is drought. Dry, arid zones include lands where the life of people, plants and animals is completely dependent on it. Arid lands make up almost a third of the entire land mass of the planet.

The relief of the desert zone is very diverse - complex highlands, small hills and island mountains, strata plains, ancient river valleys and closed lake depressions. The most common are aeolian landforms, which were formed under the influence of wind.

Sometimes the territory of deserts is crossed by rivers (Okavango - a river flowing into the desert, Yellow River, Syr Darya, Nile, Amu Darya, etc.), there are many drying up watercourses, lakes and rivers (Chad, Lop Nor, Air).

Soils are poorly developed - water-soluble salts predominate over organic substances.
Groundwater is often mineralized.

Features of the climate.

The climate in the deserts is continental: winters are cold and summers are very hot.

Rain falls once a month or only once in several years, in the form of heavy downpours. Small rains simply do not reach the surface of the earth, evaporating under the influence of high temperatures. The driest regions of the world are the deserts of South America.

More deserts receive the bulk of their rainfall in spring and winter, and only a few deserts receive maximum rainfall in the summer in the form of showers (the great deserts of Australia and the Gobi).

The air temperature in this natural area can fluctuate greatly - during the day it rises to +50°C, and at night it drops to 0°C.
In the northern deserts, the temperature in winter drops to -40 °C.

One of the most important features is the dryness of the air - during the day the humidity is 5-20%, and at night within 20-60%.

Winds are of great importance in deserts. Each of them has its own name, but they are all hot, dry, carrying dust and sand.

The sandy desert is especially dangerous during a hurricane: the sand turns into black clouds and obscures the sun, the wind carries the sand over long distances, destroying absolutely everything in its path.
Another feature of deserts are mirages created by the sun's rays, which, when refracted, create very amazing pictures on the horizon.

Desert geographic features

Most of the world's deserts were formed on geological platforms and occupy the oldest land areas. Deserts in Asia, Africa and Australia are usually located at altitudes from 200-600 m above sea level, in Central Africa and North America - at an altitude of 1 thousand m above sea level.

Deserts are one of the landscapes of the Earth that arose as naturally as all others, thanks primarily to the peculiar distribution of heat and moisture over the earth’s surface and the associated development of organic life and the formation of biogeocenotic systems. A desert is a specific geographical phenomenon, a landscape that lives its own special life, has its own patterns, and, during development or degradation, has its own inherent features and forms of change.

Speaking about the desert as a planetary and naturally occurring phenomenon, this concept should not mean something monotonous and of the same type. Most deserts are surrounded by mountains or, more commonly, bordered by mountains. In some places, deserts are located next to young high mountain systems, in others - with ancient, heavily destroyed mountains. The first include the Karakum and Kyzylkum, the deserts of Central Asia - Alashan and Ordos, the South American deserts; the second should include the Northern Sahara.

Mountains and deserts are areas of formation of liquid runoff, which comes to the plain in the form of transit rivers and small, “blind” mouths. Underground and sub-channel flow, which feeds their groundwater, is also of great importance for deserts. Mountains are areas from which destruction products are removed, for which deserts serve as a place of accumulation. Rivers supply a mass of loose material to the plain. Here it is sorted, ground into even smaller particles and lines the surface of deserts. As a result of centuries-old work of rivers, the plains are covered with a multi-meter layer of alluvial sediments. The rivers of the sewage areas carry a huge mass of blown and debris material into the World Ocean. Therefore, the deserts of drainage areas are characterized by an insignificant distribution of ancient alluvial and lacustrine sediments (Sahara, etc.). On the contrary, drainage-free regions (Turanian Lowland, Iranian Plateau, etc.) are distinguished by thick thicknesses of sediments.

Surface deposits of deserts are peculiar. They owe this to the geological structure of the territory and natural processes. According to MP Petrov (1973), the surface deposits of deserts are everywhere of the same type. This is “rocky and gravelly eluvium on Tertiary and Cretaceous conglomerates, sandstones and marls that make up the structural plains; pebbly, sandy or loamy-clayey proluvial sediments of piedmont plains; sandy strata of ancient deltas and lake depressions and, finally, aeolian sands” (Petrov, 1973). Deserts are characterized by some similar natural processes that are prerequisites for morphogenesis: erosion, water accumulation, blowing and aeolian accumulation of sand masses. It should be noted that similarities between deserts are found in a large number of features. The differences are less noticeable and are limited to a few examples, quite sharply.

The differences are most associated with the geographical location of deserts in different thermal zones of the Earth: tropical, subtropical, temperate. The first two zones contain the deserts of North and South America, the Near and Middle East, India, and Australia. Among them are continental and oceanic deserts. In the latter, the climate is moderated by the proximity of the ocean, which is why the differences between heat and water balances, precipitation and evaporation are not similar to the corresponding values ​​that characterize continental deserts. However, for oceanic deserts, the ocean currents washing the continents - warm and cold - are of great importance. The warm current saturates the air masses coming from the ocean with moisture, and they bring precipitation to the coast. The cold current, on the contrary, intercepts the moisture of air masses, and they arrive on the mainland dry, increasing the aridity of the coasts. Oceanic deserts are located off the western coasts of Africa and South America.

Continental deserts are located in the temperate zone of Asia and North America. They lie inside the continents (deserts of Central Asia) and are distinguished by arid and extra-arid conditions, a sharp discrepancy between the thermal regime and precipitation, high evaporation, and contrasts in summer and winter temperatures. The differences in the nature of deserts are also influenced by their altitude.

Mountain deserts, like those located in intermountain depressions, are usually characterized by increased climate aridity. The variety of similarities and differences between deserts is primarily due to their location at different latitudes of both hemispheres, in the hot and temperate zones of the Earth. In this regard, the Sahara may have more similarities with the Australian desert and more differences with the Karakum and Kyzylkum in Central Asia. Equally, deserts formed in the mountains may have a number of natural anomalies among themselves, but there are even more differences with the deserts of the plains.

Differences occur in average and extreme temperatures during the same season of the year, in the timing of precipitation (for example, the eastern hemisphere of Central Asia receives more precipitation in the summer from monsoon winds, and the deserts of Central Asia and Kazakhstan - in the spring). Dry riverbeds are a prerequisite for the nature of deserts, but the factors of their occurrence are different. The sparseness of the cover largely determines the low humus content in desert soils. This is also facilitated by dry air in the summer, which prevents active microbiological activity (in winter, fairly low temperatures slow down these processes).

Patterns of desert formation

The “mechanism” of the formation and development of deserts is subject, first of all, to the uneven distribution of heat and moisture on Earth, the zonality of the geographical envelope of our planet. The zonal distribution of temperatures and atmospheric pressure determines the specifics of the winds and the general circulation of the atmosphere. Above the equator, where the greatest heating of land and water occurs, ascending air movements dominate.

An area of ​​calms and weak variable winds forms here. Warm air rising above the equator, cooling somewhat, loses a large amount of moisture, which falls in the form of tropical showers. Then, in the upper atmosphere, the air flows north and south, towards the tropics. These air currents are called anti-trade winds. Under the influence of the rotation of the earth in the northern hemisphere, the antitrade winds bend to the right, in the southern hemisphere - to the left.

Approximately above latitudes of 30-40° C (near the subtropics), their deviation angle is about 90° C, and they begin to move along parallels. At these latitudes, air masses descend to the heated surface, where they heat up even more, and move away from the critical saturation point. Due to the fact that in the tropics there is high atmospheric pressure all year round, and at the equator, on the contrary, it is low, a constant movement of air masses (trade winds) occurs at the surface of the earth from the subtropics to the equator. Under the influence of the same deflecting influence of the Earth, trade winds move from northeast to southwest in the northern hemisphere, and from southeast to northwest in the southern hemisphere.

Trade winds cover only the lower layer of the troposphere - 1.5-2.5 km. The trade winds that dominate in equatorial-tropical latitudes determine the stable stratification of the atmosphere and prevent vertical movements and the associated development of clouds and precipitation. Therefore, cloudiness in these belts is very insignificant, and the influx of solar radiation is the greatest. As a result, the air here is extremely dry (relative humidity in the summer months averages about 30%) and extremely high summer temperatures. The average air temperature on continents in the tropical zone in summer exceeds 30-35° C; here the highest air temperature on the globe occurs - plus 58 ° C. The average annual amplitude of air temperature is about 20 ° C, and the daily temperature can reach 50 ° C; the soil surface sometimes exceeds 80 ° C.

Precipitation occurs very rarely, in the form of showers. In subtropical latitudes (between 30 and 45° C northern and southern latitudes), the amount of total radiation decreases, and cyclonic activity contributes to moistening and precipitation, confined mainly to the cold period of the year. However, sedentary depressions of thermal origin develop on the continents, causing severe aridity. Here, the average temperature in the summer months is 30° C or more, and the maximum can reach 50° C. In subtropical latitudes, intermountain depressions are the driest, where the annual precipitation does not exceed 100-200 mm.

In the temperate zone, conditions for the formation of deserts occur in inland regions such as Central Asia, where precipitation falls less than 200 mm. Due to the fact that Central Asia is fenced off from cyclones and monsoons by mountain uplifts, a pressure depression forms here in the summer. The air is very dry, high temperature (up to 40° C or more) and very dusty. Rarely penetrating here with cyclones, air masses from the oceans and the Arctic quickly warm up and dry out.

Thus, the nature of the general circulation of the atmosphere is determined by planetary features, and local geographical conditions create a unique climatic situation that forms a desert zone to the north and south of the equator, between 15 and 45 ° C latitude. Added to this is the influence of cold currents of tropical latitudes (Peruvian, Bengal, Western Australian, Canary and Californian). By creating a temperature inversion, cool, moisture-laden maritime air masses and easterly persistent wind pressure highs lead to the formation of coastal cool and foggy deserts with even less rainfall.

If land covered the entire surface of the planet and there were no oceans or high mountain rises, the desert belt would be continuous and its boundaries would exactly coincide with a certain parallel. But since land occupies less than 1/3 of the area of ​​the globe, the distribution of deserts and their size depend on the configuration, size and structure of the surface of the continents. So, for example, the Asian deserts spread far to the north - up to 48 ° N.L. In the southern hemisphere, due to the vast water spaces of the oceans, the total area of ​​the deserts of the continents is very limited, and their distribution is more localized. Thus, the emergence, development and geographical distribution of deserts on the globe are determined by the following factors: high values ​​of radiation and radiation, a small amount of precipitation or their complete absence. The latter, in turn, is determined by the latitude of the area, the conditions of the general circulation of the atmosphere, the features of the orographic structure of the land, and the continental or oceanic position of the area.

Aridity of the territory

In terms of the degree of aridity - aridity, many territories are not the same. This gave grounds to divide arid lands into extra-arid, arid and semi-arid, or extremely arid, arid and semi-arid. At the same time, areas where the probability of permanent droughts is 75-100% are classified as extra-arid, 50-75% as arid and 20-40% as semi-arid. The latter include shrouds, pampas, pushtas, prairies, where organic life takes place in a natural environment in which, except for individual years, drought is not a determining condition for development. Rare droughts with a probability of 10-15% are also characteristic of the steppe zone. Consequently, not all land areas where droughts occur, but only those where organic life is largely under their influence for a long time, belong to the arid zone.

According to M.P. Petrov (1975), deserts include territories with an extremely arid climate. Precipitation falls less than 250 mm per year, evaporation exceeds precipitation many times, agriculture is impossible without artificial irrigation, the movement of water-soluble salts predominates and their concentration on the surface, there is little organic matter in the soil.

The desert is characterized by high summer temperatures, low annual precipitation - usually from 100 to 200 mm, lack of surface runoff, often the predominance of sandy substrate and the large role of aeolian processes, groundwater salinity and migration of water-soluble salts in the soil, uneven amount of precipitation, which determines the structure , yield and feeding capacity of desert plants. One of the features of the distribution of deserts is the island, local nature of their geographical location. On no continent do desert lands form a continuous strip, like the Arctic, tundra, taiga or tropical zones. This is due to the presence within the desert zone of large mountain structures with their greatest peaks and significant expanses of water. In this respect, deserts do not completely obey the law of zonation.

In the northern hemisphere, the desert areas of the African continent lie between 15° C and 30° N latitude, where the world's largest desert, the Sahara, is located. In the southern hemisphere, they are located between 6 and 33° S, covering the Kalahari, Namib and Karoo deserts, as well as the desert areas of Somalia and Ethiopia. In North America, deserts are confined to the southwestern part of the continent between 22 and 24° N, where the Sonoran, Mojave, Gila, and other deserts are located.

Large areas of the Great Basin and the Chihuahuan Desert are quite close in nature to the conditions of the arid steppe. In South America, deserts, located between 5 and 30° S, form an elongated strip (more than 3 thousand km) along the western, Pacific coast of the continent. Here, from north to south, stretch the deserts of Sechura, Pampa del Tamarugal, Atacama, and behind the Patagonian mountain ranges. The deserts of Asia are located between 15 and 48-50 ° N and include such large deserts as Rub al-Khali, Greater Nefud, Al-Hasa on the Arabian Peninsula, Dasht-Kevir, Dasht-Lut, Dashti-Margo, Registan , Haran in Iran and Afghanistan; Karakum in Turkmenistan, Kyzylkum in Uzbekistan, Muyunkum in Kazakhstan; Thar in India and Thal in Pakistan; Gobi in Mongolia and China; Taklamakan, Alashan, Beishan, Tsaidasi in China. Deserts in Australia occupy a vast area between 20 and 34° N latitude. and are represented by the Great Victoria, Simpson, Gibson and Great Sandy deserts.

According to Meigl, the total area of ​​arid territories is 48,810 thousand square meters. km, that is, they occupy 33.6% of the earth's land, of which extra-arid accounts for 4%, arid - 15 and semi-arid - 14.6%. The area of ​​typical deserts, excluding semi-deserts, is about 28 million square meters. km, that is, about 19% of the earth's land area.

According to Shants (1958), the area of ​​arid territories, classified according to the nature of vegetation cover, is 46,749 thousand square meters. km, that is, about 32% of the earth's land area. At the same time, the share of typical deserts (extra-arid and arid) falls on about 40 million square meters. km, and the share of semi-arid lands is only 7044 thousand square meters. km per year, arid (21.4 million sq. km) - with precipitation from 50 to 150 mm and semi-arid (21.0 million sq. km) - with precipitation from 150 to 200 mm.

In 1977, UNESCO compiled a unified new picture on a scale of 1: 25,000,000 in order to clarify and establish the boundaries of the world's arid regions. Four bioclimatic zones are highlighted on the map.

Extra-arid zone. Precipitation less than 100 mm; deprived of vegetation cover, excluding ephemeral plants and shrubs along the beds of watercourses. Agriculture and animal husbandry (except in oases) is impossible. This zone is a pronounced desert with possible droughts for one or several years in a row.

Arid zone. Precipitation 100-200 mm. Sparse, sparse vegetation, represented by perennial and annual succulents. Rain-fed agriculture is impossible. Nomadic cattle breeding zone.

Semi-arid zone. Precipitation 200-400 mm. Shrub communities with intermittent herbaceous cover. Area of ​​cultivation of rain-fed agricultural crops (“dry” farming) and livestock raising.

Zone of insufficient moisture (subhumid). Precipitation 400-800 mm. Includes some tropical savannas, Mediterranean communities such as maquis and chaparral, and black soil steppes. Zone of traditional rain-fed farming. To conduct highly productive agriculture, irrigation is necessary.

According to this map, the area of ​​arid territories is about 48 million square meters. km, which is equal to 1/3 of the entire land surface, where moisture is the decisive factor determining the biological productivity of arid lands and the living conditions of the population.

Desert classification

In arid territories, despite their apparent monotony, there is not at least 10-20 square meters. km of area within which the natural conditions would be exactly the same. Even if the topography is the same, the soils are different; if the soil is the same type, then the water regime is not the same; if there is a single water regime, then different vegetation, etc.

Due to the fact that the natural conditions of vast desert territories depend on a whole complex of interrelated factors, the classification of desert types and their zoning is a complex matter. There is not yet a unified and satisfactory from all points of view classification of desert territories, compiled taking into account all their geographical diversity.

There are many works in Soviet and foreign literature devoted to the classification of desert types. Unfortunately, in almost all of them there is no uniform approach to solving this issue. Some of them base their classification on climatic indicators, others on soil, others on floristic composition, others on lithoedaphic conditions (i.e. the nature of the soil and conditions for vegetation growing on them), etc. Rarely do any researchers base their classification on from a complex of characteristics of desert nature. Meanwhile, based on a generalization of the components of nature, it is possible to correctly identify the ecological features of the region and quite reasonably evaluate its specific natural conditions and natural resources from an economic point of view.

M.P. Petrov in his book “Deserts of the Globe” (1973) proposes ten lithoedaphic types for the deserts of the world on a multi-stage classification:

* sandy on loose sediments of ancient alluvial plains;

* sand-pebble and pebble on gypsum tertiary and lilac structural plateaus and piedmont plains;

* crushed stones, gypsum on tertiary plateaus;

* gravelly on foothill plains;

* rocky in low mountains and small hills;

* loamy on low-carbonate cover loams;

* loess on piedmont plains;

* clayey ones in low mountains, composed of salt-bearing marls and clays of various ages;

* solonchaks in saline depressions and along sea coasts.

Various classifications of types of arid territories of the globe and individual continents are also available in foreign literature. Most of them are compiled on the basis of climate indicators. There are relatively few classifications for other elements of the natural environment (relief, vegetation, wildlife, soils, etc.).

Desertification and nature conservation

In recent years, alarming signals have been heard from different parts of the globe about the increasing advance of desert into territories inhabited by humans. For example, according to the UN, in North America alone, the desert annually robs people of about 100 thousand hectares of usable land. The most likely causes of this rather dangerous phenomenon are considered to be unfavorable weather conditions, destruction of vegetation, irrational environmental management, mechanization of agriculture, and transport without compensation for damage caused to nature. In connection with the intensification of desertification processes, some scientists talk about the possibility of an aggravation of the food crisis.

According to UNESCO, over the past 50 years, an area of ​​just under half of South America has been turned into barren deserts. This happened as a result of excessive grazing of pastures, predatory deforestation, unsystematic farming, construction of roads and other engineering structures. The rapid growth of population and technology also leads to intensifying desertification processes in some areas of the world.

There are many different factors leading to desertification in arid regions of the globe. However, among them there are common ones that play a special role in intensifying desertification processes. These include:

extermination of vegetation cover and destruction of soil cover during industrial and irrigation construction;

degradation of vegetation cover due to overgrazing;

destruction of trees and shrubs as a result of fuel procurement;

deflation and soil erosion due to intensive rainfed agriculture;

secondary salinization and waterlogging of soils under irrigated farming conditions;

destruction of the landscape in mining areas due to industrial waste, discharge of waste and drainage water.

Among the natural processes leading to desertification, the most dangerous are:

climatic – an increase in aridity, a decrease in moisture reserves caused by changes in macro- and microclimate;

hydrogeological – precipitation becomes irregular, groundwater recharge becomes episodic;

morphodynamic – geomorphological processes become more active (erosion, deflation, etc.);

soil – drying out of soils and their salinization;

phytogenic – degradation of soil cover;

zoogenic - reduction in the population and number of animals.

The fight against desertification processes is carried out in the following directions:

early identification of desertification processes in order to prevent and eliminate them, focusing on the formation of conditions for rational environmental management;

creation of protective forest strips along the edges of oases, field boundaries and along canals;

creation of forests and green “umbrellas” from local species - psamophytes in the depths of deserts to protect livestock from strong winds, scorching rays of the sun and strengthen the food supply;

restoration of vegetation cover in areas of open-pit mining, along the construction of an irrigation network, roads, pipelines and all places where it has been destroyed;

consolidation and afforestation of moving sands in order to protect irrigated lands, canals, settlements, railways and highways, oil and gas pipelines, and industrial enterprises from sand drifts and blowing out.

The main lever for successfully solving this global problem is international cooperation in the field of nature conservation and combating desertification. The life of the Earth and life on Earth largely depends on how timely and urgently the tasks of monitoring and managing natural processes are solved.

The problem of combating adverse events observed in the arid zone has existed for a long time. It is generally accepted that of the 45 identified causes of desertification, 87% are due to irrational human use of water, land, vegetation, wildlife and energy, and only 13% are due to natural processes.

Nature conservation is a very broad concept. It includes not only measures to protect specific areas of the desert or individual species of animals and plants. In modern conditions, this concept also includes measures to develop rational methods of environmental management, restoration of ecosystems destroyed by humans, forecasting physical and geographical processes during the development of new territories, and the creation of controlled natural systems.

firstly, because its flora and fauna are unique. Preserving the desert intact means leaving its indigenous inhabitants outside of economic progress, and the national economy without many, including unique, types of raw materials and fuel.

Secondly, because the desert itself is wealth, in addition to what is hidden in its depths or in the fertility of irrigated land.

Rich in various natural resources, the desert is very attractive, especially in early spring, when its short-lived plants bloom, and late autumn, when cold rains and wind fall almost everywhere in our country, and there are warm sunny days in the desert. The desert is attractive not only for geologists and archaeologists, but also for tourists. It is also healing, its dry air, long warm period, medicinal mud and hot mineral springs make it possible to treat kidney diseases, rheumatism, nervous and many other diseases.

» Planet Earth » Desert - natural area

Since ancient times, people have been moving around the desert on hardy and strong camels, which are sometimes called ships of the desert.

A desert is a vast area where it is very hot and dry. During the day, the air temperature here rises to +45-50 degrees.

There is no water in the desert. There are no rivers flowing there and no lakes to be found. Due to the lack of moisture in desert areas, little grows and few people live. For most of the year, the only plants you can see there are cacti and camel thorns. And only for a short period of rain, lasting 1-2 months, green cover appears in some places.

Cactus is one of the few plants that have adapted to life in the desert.

As for animals, in this climatic zone you can meet camels, snakes, lizards, jerboas, various beetles.

In the desert, although rare, they are found oases- islands with tree, shrub or herbaceous vegetation. Oases arise where there are springs that are fed by groundwater.

Scorpio feels at home in the desert

Sometimes strong winds blow in the deserts, the speed of which can reach 80-100 kilometers per hour.

They raise sand and dust, creating peculiar hills - the so-called dunes. The dunes are mobile, and the wind drives them along the ground, since there are almost no plants in the desert whose root system could hold the sands in place. The height of the dunes can reach 100 meters, and the length can be even several kilometers.

A dune is a kind of dune, only the dunes along the edges are, as it were, attached to the ground by plants, but the dunes are not, they are free like the wind

The largest desert in the world is the sandy-rocky Sahara, located in North Africa. She is called the queen of the deserts.

The greatest danger in the desert is sandstorm. A dark cloud of sand and dust rises to a height of several kilometers, covering the entire sky and the sun. The storm can rage for several hours or drag on for a couple of days.

Large areas to the north and south of the savannahs are occupied by zones of tropical semi-deserts and deserts. It experiences only irregular, sporadic rainfall, once every few years in some areas. The zone is characterized by extreme dry air, large daily temperature ranges, and dust and sand storms. The surface of deserts is covered with rocks or sands, salt marshes in place of dried salt lakes, or clay where there once were seas.

The vegetation here is very sparse and specific. The leaves are either replaced by spines or are very small, the roots spread both widely and far into the soil. Some plants can live in saline soils, others have a short development cycle (they live only after rains). In search of scarce food and water, desert animals can travel long distances (ungulates, such as antelopes) or go without water for a long time (some reptiles, camels); some of them are nocturnal. The soils are poor in organic matter, but rich in mineral salts. With irrigation, this, on the one hand, makes it possible to grow many crops, but on the other hand, it creates the problem of secondary salinization of soils and groundwater. As a result, agricultural land turns into barren salt marshes.

A common feature of the climates of all African deserts is poor moisture throughout the year with sufficient heat. In most of the Sahara, annual precipitation does not exceed 50-100 mm. Rains are irregular, although there is a season of 1-2 months when they usually fall in the form of short showers. In the south of the Sahara, the probable rainy season is in summer, and in the north - in winter. In its center there may be no precipitation for several years. Poor hydration is accompanied by high temperatures. Their daily amplitude is characteristic - frosts can occur in the morning on desert hills and in the subtropics.

Vegetation and flora of the desert

Biogeographically, the Sahara and some areas of the Somali Peninsula, on the one hand, and the deserts of southern Africa, on the other, are in many ways unique and different. The arid territories of the south and southwest of the continent are distinguished by the special antiquity of many representatives of the plant world; here are the centers of species diversity of some families (Namib Desert, desert and semi-desert regions of the Kalahari and Karoo).

The vegetation of the Sahara varies not only in latitude (subtropical and tropical parts), but also to an even greater extent depending on the substrate (soil). Rocky (gravelly) deserts - gammads - have sparse vegetation cover, however, a rich set of species. Here are squat tree and shrub forms with a powerful root system that penetrates into rock cracks and deep into the ground. Pebble deserts - serirs - and shifting dune sands - ergs, as well as crusty salt marshes are almost devoid of plants. In clayey, moderately saline areas, halophytic species of different families (solyankas) grow with a predominance of gonoceae, or quinoaceae. The still, lumpy sands are distinguished by relatively rich vegetation and flora. Psammophilous trees, shrubs and herbs live here. In the dry beds of episodic watercourses - wadis - groundwater often lies shallow. Therefore, it is here that there is often rich, of course compared to other desert areas, vegetation with tree and shrub groups, including date palms, oleanders, camel thorn, and zilla. Along the southern and northern periphery of the Sahara, vegetation often consists of low, rare subshrubs and turf grasses. The arid regions of the Somali Peninsula, in contrast to the Sahara, are characterized by peculiar stem succulents (euphorbias, etc.) and thickets of thorny bushes. Deserts are also characterized by such a biological group of plants as ephemera. After rains (sometimes even once every few years), they quickly cover the soil with their shoots, bloom and bear fruit. The seeds are then stored in the soil until re-moistened. In desert and semi-desert areas, where short-term rains occur constantly during the wet period (1-2 months), a significant part of the plants belong to ephemeroids. Unlike ephemerals, they survive long-term drought not in the form of seeds, but in the form of bulbs, rhizomes, etc. Among different plant families, some forms close to ephemerals, called Jericho roses, are unique. During drought, their short branches are bent towards the center and tightly clenched, as if into a fist. When moistened, they quickly open, and the fruits hidden inside release mature seeds, which immediately germinate. An example of the rose of Jericho is odontospermum.

Typical of the desert shrubs of the Sahara are retam and Saharan gorse, in which the leaves are almost undeveloped, and photosynthesis is carried out by green shoots. The leaves of ephedras that form thickets along the wadi are also underdeveloped. Bushes of camel thorn, zilla, juzgun, or kandym, parfolia, and saltpeter are more common here. All of these plant genera are also characteristic of the deserts and semi-deserts of Eurasia, and the latter two also live on other continents. In the southern parts of the Sahara, acacia trees are characteristic, as in the Sahelian regions.

Interesting are the nomadic lichens that roll over the surface and are capable of absorbing dew. An example is lecanora edible, or manna. Lumps of manna swollen with moisture can be eaten, although this dish cannot be said to have any special taste.

Among the herbaceous plants of sandy deserts, the spiny aristida is characteristic, which is related to our Central Asian gray and tall grass aristida species from savannas. Northern semi-deserts are often formed by tall feather grass alpha-alpha.

Among the desert, near permanent water sources and along river valleys, there are oases, the vast majority of which are densely populated and used for irrigated agriculture. The number one plant of African (and Arabian) oases is the date palm. This tree requires high temperatures to ripen the fruit, but can tolerate light night frosts that occur in subtropical and mountainous areas during winter. Thickets of reeds are typical for oases; along the outskirts there are thickets of tamarix, camel thorns, various types of quinoa and other goosefoot. On irrigated lands, cotton, rice, millet and other grains are cultivated, citrus plantations are planted, etc. In small oases, the date palm is often the only cultivated species, providing food and raw materials necessary for humans.

The arid regions of the south of the continent are extremely distinctive in flora with many endemic forms. The vegetation cover is often dominated by succulents. Particularly characteristic are the species of Euphorbiaceae and Crassulaceae; endemic species of Aloe from Liliaceae are typical. The various sunflowers, which are called crystal grass, ice grass, pebble grass, and window plant, are very original. Their fleshy vegetative organs (often resembling pebbles) can be almost completely immersed in the soil. A transparent greenish “window” peeks out at the surface - a part of the leaf surface saturated with aquifer cells. After the rains, the sunflowers are covered with large and bright flowers. Most of them (more than 300 of the 400 known species) live only in the Karoo and Kalahari regions. However, there are species of this genus that also grow in savannas in southern and eastern Africa. The most surprising plant of the African deserts for botanists is Welwitschia. Its specific Latin name is; This is how it is translated - “amazing” or “wonderful”. Velvichia grows only in the Namib Desert. It belongs to the type of gymnosperms (this includes conifers), but all its closest relatives have long since died out in past geological eras. Velvichia has a lignified trunk half a meter high, more than 1-1.5 m thick. At the top, the trunk bifurcates into blades, from each of them a long leaf extends up to 3 m. The end of the leaf dies over time, and its base grows all the time. The age of individual specimens can exceed 150 years.

Animal population and fauna of the desert

The fauna of African deserts is a natural continuation and transition from the groupings of the driest areas of short-grass savannas and thorny forests. In many ways (especially in the southern Sahara, Somalia, Kalahari, Karoo and Namib deserts) the animal population and fauna of the deserts are largely a depleted version of the wetter border regions. This is especially emphasized by the fact that in the recent past this commonality was even stronger, and the boundaries between dry savannas and shrubby deserts were more gradual and smooth. As a result of centuries-old use of peripheral areas for grazing, the boundaries have become sharper, new areas of loose sand have appeared within the zone, and the desert itself is gradually expanding to the south.

Zoogeographically, the Sahara is very different from the deserts of South Africa. The deserts of Somalia also stand somewhat apart, in many respects, however, similar to the Sahara. There is historical evidence that in the past, in terms of large vertebrate fauna, they were closer to the south of the Sahara than they are now. Therefore, they can be considered together under the name of the northern regions, contrasting the southern regions already lying in the other hemisphere.

Among insects, for example, we can name the migratory locust, the sacred scarab, the Egyptian cockroach. In each order of invertebrates, one can find species whose ranges include the Sahara and the deserts of Central Asia. Among vertebrates of the same kind, a variety of reptiles (long-legged skink, spotted foot-and-mouth disease, western boa constrictor, zeringe, etc.), birds (desert and little larks, desert sparrow, desert bullfinch), mammals (red-tailed gerbil, steppe and dune cats , jackal, striped hyena, caracal). In autumn and spring, some migratory birds nesting in temperate latitudes cross the Sahara, which also gives the desert (but more often oases) a shade of temperate latitudes at this time. At the same time, there are also specific groups of animals of the Sahara-Arabian distribution, many of them are related to species of savannas and woodlands. It must be borne in mind that there are large areas in the interior, and the upland areas are extremely poor. Overgrown sands are more evenly populated by animals and are richer in life. A very characteristic feature of the desert animal population is activity in the morning, evening and night hours. During the day, everything is hidden from the scorching rays of the sun either in the thickness of the sand, under stones and in cracks in the soil, or away from the hot surface of the soil on the branches of bushes and desert trees. When the heat subsides, a variety of darkling beetles appear on the exposed surface of the ground, from small ones the size of a ladybug to giants 3-4 cm long. Adesmia, which have very long legs, attract attention. Especially many species (70) of these darkling beetles live in arid landscapes throughout Africa, but there are several in the south of Central Asia. Even in the most “lifeless” areas, insects reveal themselves at night when they flock to the light of a lantern. Usually these are small single-colored or variegated moths (there are many moths among them; caterpillars of desert species often develop on the roots of plants - the same applies to cutworms, small beetles, leafhoppers, and dipterans.

Among locusts, characteristic forms are those that stay on the surface of the earth, and not on plants. Darkling beetles, some cockroaches, and scarabs feed mainly on dead plant debris and excrement of herbivorous animals. Adjacent to this group are termites, usually inconspicuous, since in deserts they make nests very deep (10-15 m) underground and do not appear in dry air.

Locusts, some caterpillars, beetles, and borers eat the green parts of plants. Their larvae, as well as the caterpillars of many butterflies, gnaw on roots. Small leafhoppers and bugs suck the juices of living plants. In some places, harvester ants are very numerous, feeding on plant seeds. Ants of this genus are also common in arid regions of our country. There are also a number of omnivorous and predatory ants adapted to desert conditions (pale coloration, highly raised body and fast running, storing sweet syrup in “living barrels” - working individuals with swollen abdomens). Among the invertebrate predators there are various spiders, scorpions, and centipedes. Very characteristic are large hairy arachnids from a special order of salpugs, which are often called phalanges. Contrary to popular belief, salpugs do not have poisonous glands and are generally not dangerous to humans.

Amphibians require water, or at least moist conditions, for their larvae (tadpoles) to develop. Therefore, there is no place for them in the desert. However, the green toad penetrates river valleys and peripheral oases, adult individuals of which are active at night and withstand significant moisture losses.

But reptiles in the desert are diverse and numerous, ranking first among vertebrates in terms of biomass. Among the agamidae are the spiny tails, which make long and deep burrows. They are active even in the middle of the day, when the stony soil heats up to +57°C. Unlike most lizards, spinytails eat fruits, fresh leaves and shoots of plants in significant quantities. They are often found on the outskirts of oases in the strip of saltworts. The Egyptian spiketail, or dabb, reaches a length of 75 cm, and is heavily hunted by the locals, as dabb meat is very tasty. Of the other lizards in the Sahara, the pharmacy skink, which is readily eaten by local residents, and related species, which are often called sand fish, are also common. Skinks live in sandy deserts and can not only quickly burrow, but also move in the thickness of the soil. The wedge-shaped chalcid is similar in lifestyle to them. The comb-toed lizards from the family of real lizards living there are similar to our reticulated foot-and-mouth lizards from Central Asia in that they also have a brush on their fingers, which facilitates movement on the sand. Characteristic of the desert are boas of the genus Eryx, sand snakes. Poisonous reptiles are represented by Avicenna's viper, horned viper, efa, Egyptian cobra, or Gaia, viper. Efa and viper are also found in our deserts.

Birds in deserts are few and inferior to reptiles in terms of biomass and even more so in terms of numbers. Some species, however, have adapted to the conditions of this zone. In the most arid areas, desert larks and desert sparrows are found. Desert bullfinches are found near rock outcrops. Also characteristic are wheatears, some species of bustards, deserts with rare bushes called cerca - a very family of warblers, the range of which covers the peninsula, the south of Central Asia and Pakistan.

Tater species penetrate the Sahara from the south, and the red-tailed gerbil appears in subtropical latitudes. But the most characteristic and abundant are small, jerboa-like pygmy gerbils. The jerboas themselves are also common here. Pygmy gerbils and jerboas hide in burrows for a day, plugging them with an earth plug. The small fat-tailed gerbil is interesting for its ability to accumulate fat reserves in its thick tail. Rodents of a special family of comb-toed, endemic to Africa, also settle here. Among comb-toed animals, gundi is the most common. A number of species of desert gazelles (they are close to our goitered gazelle) can do without water for a long time. In the center of the Sahara, for example, the sand gazelle lives. For the southern outskirts of this area, the saber-horned antelope is known, which also lives in dry savannahs. The typical Saharan addax species is similar to it. Both of these relatively large antelopes are now exterminated, and their former vast range has shrunk.

Of the predatory animals in the desert and semi-desert, a striped hyena, a jackal, a honey badger, several types of cats (caracal, steppe and dune cats) can live. Of these, only the caracal and the sand cat do not need watering places. The prey of these predators is rodents, birds and other small animals.

The deserts of the southern continent differ in many ways from the northern regions. As in the plant world, among the animals there are many ancient isolated groups. In the Namib Desert lives the only species of a special genus of golden moles - eremitalpa. In the succulent Karoo desert, Cape rats are common among rodents of the mouse family. Only in the southern region is the short-eared gerbil very common in the Kalahari and the desert highlands. The south of the mainland and Madagascar are characterized by a special family of lizards - the belt-tailed lizards, the species of which are characterized by numerous spiny scales and bony plates on the head and back. The small belt-tail, which lives in South-West Africa, curls up in a ring when threatened, holding the end of its tail with its teeth. On the outside, hard spiny coverings remain, the ventral side turns out to be invulnerable. Some spinytails are able to absorb dew with their skin (the same ability is found in the Australian moth, also a desert lizard). Among the snakes for the southern region, we point out the shield cobra, which can easily burrow into the sand. In the Namib and Kalahari deserts there also lives a dwarf viper, barely reaching 30 cm, which is a relative of the large Gabon vipers. In the south, land turtles are especially diverse; here is the center of their species differentiation.

Natural desert zone: characteristics, description and climate

January 13, 2015

The word “desert” alone evokes corresponding associations in us. This space, which is almost completely devoid of flora, has a very specific fauna, and is also located in a zone of very strong winds and monsoons. The desert zone is about 20% of the entire landmass of our planet. And among them there are not only sandy ones, but also snowy ones, tropical ones and many others. Well, let's get to know this natural landscape more closely.

What is a desert

This term corresponds to flat terrain, the type of which is homogeneous. The flora here is almost completely absent, and the fauna has very specific characteristics. The desert relief zone is a vast area, most of which is located in the tropical and subtropical zones of the Northern Hemisphere. The desert landscape also occupies a small part of South America and most of Australia. Among its features, in addition to plains and plateaus, are also arteries of dry rivers, or closed reservoirs where lakes could previously have been. Also, the desert zone is a place where there is very little rainfall. On average, this is up to 200 mm per year, and in particularly dry and hot areas – up to 50 mm. There are also desert regions where precipitation does not fall for ten years.

Animals and plants

The natural desert zone is characterized by completely sparse vegetation. Sometimes the distances that lie between the bushes reach kilometers in length. The main representatives of the flora in such a natural zone are thorny plants, only a few of which have the green foliage familiar to us. The animals that live on such lands are the simplest mammals or reptiles and reptiles that accidentally wandered here. If we are talking about an icy desert, then only animals that can tolerate low temperatures live here.

Climate indicators

To begin with, we note that in terms of its geological structure, the desert zone is no different from, say, flat terrain in Europe or Russia. And such severe weather conditions that can be traced here were formed due to trade winds - winds that are characteristic of tropical latitudes. They literally disperse clouds over the area, preventing them from irrigating the ground with precipitation. So, in the climatic sense, the desert zone is a region with very sharp temperature changes. During the day, due to the scorching sun, it can be as much as 50 degrees Celsius, and at night the thermometer drops to +5. In deserts that lie in more northern zones (temperate and arctic), daily temperature fluctuations have the same indicator - 30-40 degrees.

However, here during the day the air heats up to zero, and at night it cools down to -50.

Semi-desert and desert zone: differences and similarities

In temperate and subtropical latitudes, any desert is always surrounded by semi-desert. This is a natural area in which there are no forests, tall trees or conifers. All that is available here is flat terrain or plateau, which is covered with grasses and shrubs that are unpretentious to weather conditions. A characteristic feature of a semi-desert is not aridity, but, unlike a desert, increased evaporation. The amount of precipitation that falls on such a belt is sufficient for the full existence of any animals here. In the eastern hemisphere, semi-deserts are often called steppes. These are vast, flat areas where you can often find very beautiful plants and stunning landscapes. On the western continents this territory is called savanna. Its climatic features are somewhat different from the steppe; strong winds always blow here, and there are much fewer plants.

The most famous hot deserts on Earth

The tropical desert zone literally divides our planet into two parts - North and South. Most of them are in the Eastern Hemisphere, and very few of them are in the west. Now we will look at the most famous and beautiful such zones on Earth. The Sahara is the greatest desert on the planet, which occupies all of North Africa and much of the Middle East. Local residents divide it into many “sub-deserts”, among which Belaya is popular. It is located in Egypt and is famous for its white sands and extensive limestone deposits. Along with her, there is also Black in this country. Here the sands are mixed with stones of a characteristic color. The vast red expanses of sand are the destiny of Australia. Among them, the landscape called Simpson deserves respect, where you can find the highest dunes on the continent.

Arctic desert

The natural zone, which is located at the northernmost latitudes of our planet, is called the Arctic desert. It includes all the islands that are located in the Arctic Ocean, the extreme coasts of Greenland, Russia and Alaska. Throughout the year, most of this natural area is covered with glaciers, so there are practically no plants here. Only in the area that comes to the surface in summer do lichens and mosses grow. Coastal algae can be found on the islands. Among the animals found here are the following individuals: arctic wolf, deer, arctic foxes, polar bears - the kings of this region. Near the ocean waters we see pinniped mammals - seals, walruses, fur seals. The most common birds here are, perhaps, the only source of noise in the Arctic desert.

Arctic climate

The ice zone of deserts is a place where the polar night and polar day occur, which are comparable to the concepts of winter and summer. The cold season here lasts about 100 days, and sometimes more. The air temperature does not rise above 20 degrees, and in particularly harsh times it can reach -60. In summer, the sky is always overcast, it rains with snow and constant evaporation occurs, due to which the air humidity increases. The temperature on summer days is around 0. As in sandy deserts, winds constantly blow in the Arctic, which form storms and terrible snowstorms.

Conclusion

There are also a number of deserts on our planet that differ from sandy and snowy ones. These are the salt expanses, Acatama in Chile, where a lot of flowers grow in the arid climate. Deserts can be found in Nevada, USA, where they overlap with red canyons, forming incredibly beautiful landscapes.