What is a desert in a nutshell. natural area desert

Today we will continue our acquaintance with the natural zones of our planet. The theme of our tour will be places where camels slowly walk, and the wind and the scorching sun are the undivided masters. Let's talk about deserts.

Here, among the sands and heat, there is its own flora and fauna, people live and work. What are the distinguishing features of this zone?

Where are the deserts

Deserts are areas with a continental climate and sparse vegetation. Such places can be found on all continents except Europe. They extend through the temperate zone of the Northern Hemisphere and through the subtropics and tropics of both hemispheres.

The largest deserts are the Sahara, Victoria, Karakum, Atacama, Nazca, and the Gobi desert.

Russian deserts are located in the east of Kalmykia and in the south of the Astrakhan region.

Climate features

The main features of the climate of this zone are high daytime temperatures and extremely dry air. During the day, the content of water vapor in the atmosphere is 5–20%, which is several times lower than the norm. The driest are the deserts of South America. The main reason - almost complete absence of rain. In some places, they fall no more than once every few months or even several years. Sometimes abundant rain streams fall on the dry, heated ground, but evaporate instantly, without having time to saturate the soil.

Often these places are "dry rain" From the resulting rain clouds, ordinary raindrops fall out, but colliding with heated air, they evaporate without reaching the ground. Snowfall is rare here. Only in some cases the snow cover reaches a thickness of more than 10 cm.

In this natural area, the daytime temperature can rise to +50°C, while at night it can drop to 0°C. In the northern regions, the thermometer can drop to minus 40 °C. For these reasons, the desert climate is considered continental.

Often, residents and tourists become witnesses of amazing optical phenomena - mirages. At the same time, tired travelers see in the distance oases with life-giving moisture, wells with drinking water .... But all this is an optical illusion caused by the refraction of the sun's rays in the heated layers of the atmosphere. As they approach these objects, they move away from the observer. To get rid of these optical illusions, you can make a fire. The smoke creeping along the ground quickly dispels this haunting vision.

Relief features

Most of the surface of the deserts is covered with sand and the wild wind becomes the "culprit" of sandstorms. At the same time, they rise above the surface of the earth huge masses of sand. The sandy curtain erases the horizon line, outshines the bright sunlight. Hot air mixed with dust makes breathing difficult.

After 2-3 days, the sand settles. And before the eyes of others, a renewed surface of the desert appears. In some places, rocky areas are exposed, or vice versa, new dunes appear against the background of frozen sandy waves. In the relief of the deserts there are small hills, alternating with plains, ancient river valleys and depressions from once existing lakes.

Deserts tend to light soil color thanks to the lime accumulated in it. The reddish color of the soil has surface areas containing an excess amount of iron oxides. Fertile soil layer - humus is almost absent. In addition to sandy deserts, there are zones with stony, clayey and saline soils.

Vegetable world

In most deserts precipitation falls in spring and winter. Moist soil is literally transformed. In a few days, it blooms with a wide variety of colors. The duration of flowering depends on the abundance of precipitation and on the soil of the area. Local residents and tourists come to admire the bright beautiful flower carpet.

The heat and lack of moisture soon return the desert to its normal state, where only the most resilient plants can grow.

Tree trunks are most often strongly curved. The most common plant in this area is saxaul bushes. They grow in groups, forming small groves. However, do not look for shadows under their crowns. Instead of the usual foliage, the branches are covered with small scales.

How does this shrub survive in such arid soils? Nature has provided them with mighty roots that go into the ground to a depth of 15 meters. And another desert plant - camel-thorn its roots can get moisture from a depth of up to 30 meters. The thorns or very small leaves of desert plants allow them to expend moisture very economically when evaporating.

Among the various cacti growing in the desert, there is Echinocactus Gruzoni. The juice of this one and a half meter plant perfectly quenches thirst.

In the South African desert there is a very amazing flower - fenestraria. Only a few of its leaves are visible on the surface of the earth, but its roots are like a tiny laboratory. It is in it that the development of nutrients occurs, thanks to which this plant even blooms underground.

One can only wonder at the adaptability of plants to the extreme conditions of the desert.

Animal world

In the heat of the day, the desert really seems devoid of all life. Only occasionally there is a nimble lizard, but some bug is in a hurry about its business. But with the onset of night coolness, the desert comes to life. Small and large enough animals crawl out of their shelters to replenish food supplies.

How do animals escape the heat? Some burrow into the sand. Already at a depth of 30 cm the temperature is 40°C lower than on the ground. This is exactly how the kangaroo jumper behaves, which manages not to get out of its underground shelter for several days. In its minks stocks of grains are stored, which absorb moisture from the air. They also satisfy his hunger and thirst.

Close "canine relatives" of jackals and coyotes from the heat saves rapid breathing and protruding tongue.

Saliva evaporating from the tongue cools these curious animals well. African foxes, hedgehogs radiate excess heat with large ears.

Long legs ostriches and camels help to escape from the hot sand, because they are high enough above the ground, and there the temperature is lower.

In general, the camel is more adapted to life in the desert than other animals. Thanks to his wide, callused feet, he can walk on hot sand without getting burned or falling through. And its thick and dense coat prevents the evaporation of moisture. Fat accumulated in the humps, if necessary, is processed into water. Although without water, he may well live for more than two weeks. And in food, these giants are not picky - they chew a camel thorn for themselves, and even branches of saxaul or acacia are already a luxury in a camel diet.

Desert insects "thought of" reflecting the scorching sun's rays the surface of your body.

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Unbearable heat during the day, very cold at night. Around only dried earth, sands or cracked stones. Not a single green tree nearby. Instead of trees, dry trunks or "rocking" bushes. How does the desert live? Or rather, how do plants and animals survive in these harsh desert conditions?

In nature, there are areas where there is no or almost no vegetation, as well as very few animals. Such natural areas are called deserts. They are found on all continents of the globe and occupy about 11% of the land surface (about 16.5 million sq. km).

A prerequisite for the formation of a desert on the surface of the earth is the uneven distribution of heat and moisture. Deserts form where there is little rainfall and dry winds prevail. Many are located near or already surrounded by mountains, which prevent precipitation.

The desert is characterized by:

• - Dryness. The amount of precipitation per year is approximately 100-200 mm, and somewhere they do not happen for decades. Often, even these small precipitations, evaporating, do not have time to reach the surface of the earth. And those precious drops that have fallen into the soil will replenish groundwater supplies;
• - Winds arising from excessive heating and associated air currents that reach 15 - 20 m/s or more;
• - The temperature, which depends on where the desert is located.

Desert climate

The climate in Putin is influenced by geographical location. There can be either warm or dry climate. When the air is dry, it practically does not protect the surface from solar radiation. During the day, the air warms up to + 50 ° C, and quickly cools down at night. During the day, the sun's rays, not lingering in the air, quickly reach the surface and heat it up. Due to the lack of water, there is no heat transfer, which is why it is so hot during the day. And at night it is cold for the same reason - the lack of moisture. There is no water in the soil, so there are no clouds to hold heat. If the daily temperature fluctuations of the desert of the tropical zone are 30-40 ° C, then the temperate zone is 20 ° C. The latter are characterized by hot summers and cold winters (up to -50 ° C with light snow cover).

Desert flora and fauna

Few plants and animals can live in such difficult climatic conditions. They are characterized by:

• - Long roots to get moisture in the deep layers of the soil;
• - Small hard leaves, and in some they are replaced by needles. All for less evaporation of moisture.

Desert dwellers change depending on the location of the desert. Wormwood, saxaul, saltwort, grate, juzgun are characteristic of the temperate desert; succulents (cacti) are added to the subtropical and tropical deserts of Africa and Arabia. A lot of light, poor soil, lack of a lot of water - all that cacti need. Cacti have adapted perfectly: thorns do not allow excessive waste of moisture, a developed root system collects morning dew and night soil moisture.

The deserts of North America and Australia are much richer and more diverse (dwarf acacia, eucalyptus, quinoa, prutnyak, etc.). In oases, large river valleys of the temperate zone of Asia, trees grow: jida, willow, elm, turanga poplar; in subtropical and tropical - evergreen palm, oleander. And this small list is very valuable in the desert. Plants serve as food for camels, for heating on cold nights.

The animal world is not whimsical to food, water, and the color is close to the color of the earth's surface. Many are characterized by night life, during the day they sleep.

The most famous and widespread is the camel, the only one that can eat camel thorn and go without water for a long time. All thanks to its hump, which contains a supply of nutrients.

Reptiles also live: lizard, agama, monitor lizard. The length of the latter can reach one and a half meters. A variety of insects, arachnids, mammals (jerboas, gerbils) make up the desert fauna.

What is the secret to scorpion survival in deserts?

Scorpions are representatives of the arachnid species. And this is surprising, since they do not look like spiders at all. Scorpions prefer dry and hot deserts, but even some of their species have adapted to tropical rainforests. These arachnids also live in Russia. For example, the yellow scorpion can be found in the forests of Dagestan and Chechnya. In the Lower Volga region, the motley scorpion lives in wastelands and dried-up desert areas, and the Italian and Crimean scorpions are found on the Black Sea coasts.

Since the respiratory system of these arachnids is poorly adapted to a dry and hot climate, this feature makes the insect hide from the heat in various crevices, cracks, under stones, burrow into sand or soil. There they find at least some moisture. That is why scorpions are nocturnal animals: during the day they sleep, waiting out the heat, and at night they do good. Desert scorpions can do almost without water, feeding on various insects, and large individuals can eat a lizard or a small rodent. Cases have been recorded when a scorpion survives after starvation from 0.5 to 1.5 years. In the desert, scorpions mainly extract moisture from food, but sometimes suck it out of wet sand.

For any animal and plant of the desert, the main difficulty is the lack of moisture, the lack of water. It is this feature that gives the world such bizarre forms of life. Someone adapted not to drink, limited to moisture obtained from food. Someone often changes their place of stay in search of water. Someone moves in the dry season closer to the water. For some, metabolic water is formed in the process of metabolism. One way or another, desert animals have found a way to survive in the harsh desert climate.

In addition, watch the BBC documentary from the "Forces of Nature" series, the film explains in detail the features of desert branding

The desert and its inhabitants

Deserts belong to the arid zone. In summer, the desert is extremely hot, with very little rainfall. Because of this, there is little moisture. The air temperature in the shade is 40-45 0 C, and the sand is heated to 70 0 FROM.

Usually the desert is covered with sand. Its surface is dunes - sandy waves that slowly move

Among the red-hot dunes, there are very rare "paradise", shady palm trees and some clean cool water - "Oases".

Among the animals of the desert there are mammals, reptiles and birds. All of them are adapted to live in its climate.

Camel 1. Thick wool (protects from overheating, maintaining body temperature). 2 The store of fat in the humps (helps to do without water for a long time)

3. Rough digestive system (camel eats thorns).

5. 4. Narrow foot (helps to move easily on the sand and not get burned). 5. Large nostrils (contribute to air cooling). 6. Filters in the nose (protect from sand).

6 . Jerboa .

Has a long tail. Fleeing from the heat leads a twilight lifestyle

7. dancing lizard Webbed lizard.

This little lizard often dances to keep the temperature down. During intense heat hides in the sand

8. African pygmy viper

What is a desert without snakes. This small viper (25 cm) hides from the sun in the sand. Only the eyes are visible. She can wait so many days until her victim approaches her.

9. Birds also live in deserts: desert sparrows, larks, nightjars, and predators are also found.

10. Vulture-lamb. This bird has learned to break skeletons. She rises to a height and throws bones on flat stones to break them. And then it eats the bone marrow, which contains a lot of water.

11. Plants live in any ecosystem. Desert dwellers: saxaul, camel thorn, seline. They adapted to life in the desert

They acquired long roots, the leaves were turned into thorns or covered with wax, they store water in thick stems. Here is such an amazing living world in the desert. All its inhabitants for millions of years have learned to survive in its climate and extract water for themselves.

Thanks for attention

Secondary general education multidisciplinary school No. 44 named after. V. Kudzoeva

"The Desert and Its Inhabitants"

2015

And semi-deserts are specific natural zones, the main distinguishing feature of which is drought, as well as poor flora and fauna. Such a zone can form in all climatic zones - the main factor is the critically low amount of precipitation. Deserts and semi-deserts are characterized by a climate with a sharp daily temperature difference and a small amount of precipitation: no more than 150 mm per year (in spring). The climate is hot and dry, it evaporates without having time to soak into. Temperature fluctuations are characteristic not only for the change of day and night. The temperature difference between winter and summer is also very large. The general background of weather conditions can be defined as extremely severe.

Deserts and semi-deserts are waterless, dry regions of the planet, where no more than 15 cm of precipitation falls per year. The most important factor in their formation is the wind. However, not all deserts experience hot weather; on the contrary, some of them are considered the coldest regions of the Earth. Representatives of flora and fauna have adapted to the harsh conditions of these areas in different ways.

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

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

Deserts and semi-deserts are found in:

• The tropical belt is a large part of such territories - Africa, South America, the Arabian Peninsula of Eurasia.
• Subtropical and temperate zones - in South and North America, Central Asia, where a low percentage of precipitation is complemented by topographical features.

There is also a special type of desert - the Arctic and Antarctic, the formation of which is associated with a very low temperature.

There are many reasons for the formation of deserts. 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 main snow mass falls on the coast; snow practically does not reach the interior regions. Precipitation levels generally vary greatly, for one snowfall, for example, an annual norm can fall. Such snow drifts form over hundreds of years.

natural area desert

Climate features, desert classification

This natural zone occupies about 25% of the planet's land mass. In total there are 51 deserts, of which 2 are icy. Almost all deserts were formed on the most ancient geological platforms.

General signs

The natural zone called “desert” is characterized by:

• flat surface;
• critical volume of precipitation(annual rate - from 50 to 200 mm);
• rare and specific flora;
• peculiar fauna.

Deserts are often found in the temperate zone of the Northern Hemisphere of the Earth, as well as tropical and subtropical. The relief of such an area is very heterogeneous: it combines highlands, insular mountains, small hills and layered plains. Basically, these lands are drainless, but sometimes a river can flow through part of the territory (for example, the Nile, the Syrdarya), and there are also drying lakes, the outlines of which are constantly changing.

Important! Almost all desert areas are surrounded by mountains or are located next to them.

Classification

Deserts are of different types:

• Sandy. Such deserts are characterized by dunes and sandstorms often occur. The largest, the Sahara, is characterized by loose, light soil, which is easily blown by winds.
• Clayey. They have a smooth clay surface. They are found in Kazakhstan, the western part of Betpak-Dala, on the Ustyurt plateau.
• rocky. The surface is represented by stones and rubble, which forms placers. For example, Sonora in North America.
• saline. The soil is dominated by salts, the surface often looks like a salt crust or a bog. Distributed on the coast of the Caspian Sea, in Central Asia.
• arctic- located in the Arctic and Antarctica. They are snowless or snowy.

Climatic conditions

The desert climate is warm and dry. The temperature depends on the geographical location: the maximum +58°C was recorded in the Sahara on September 13, 1922. A distinctive feature of the desert area is a sharp temperature drop of 30-40°C. During the day the average temperature is +45°C, at night - +2-5°C. In winter, in the deserts of Russia, it can be frosty with little snow.

In desert lands it is characterized by low humidity. Strong winds often occur here at a speed of 15-20 m/s or more.

Important! The driest desert is the Atacama. There has been no precipitation on its territory for more than 400 years.

Flora

The desert flora is very sparse, mostly sparse shrubs that can extract moisture deep in the soil. These plants are specially adapted to live in hot and dry habitats. For example, a cactus has a thick, waxy outer layer to keep water from evaporating. Sagebrush and desert grasses need very little water to survive. Plants of deserts and semi-deserts have adapted to protect themselves from animals by growing sharp needles and thorns. Their leaves are replaced by scales and spines or covered with hairs that protect the plants from excessive evaporation. Almost all sand plants have long roots. In sandy deserts, in addition to grassy vegetation, there is also shrubby vegetation: zhuzgun, sand acacia, teresken. Shrub plants are low and slightly leafy. Saxaul also grows in deserts: white - on sandy, and black - on alkaline soils.

Most desert and semi-desert plants bloom in spring, reproducing flowers until the onset of hot summer. During wet winter and spring years, semi-desert and desert plants can produce surprisingly many spring flowers. In the desert canyons, on the rocky mountains, pine trees coexist, junipers and sage grow. They provide shelter from the scorching sun for many small animals.

The least known and underestimated species of desert and semi-desert plants are lichens and cryptogamous plants. Cryptogamous or mystogamous plants - spore fungi, algae, ferns, bryophytes. Cryptogamous plants and lichens need very little water to survive and live in dry, hot climates. These plants are important because they help stop erosion, which is very important for all other plants and animals because it helps keep the soil fertile during high winds and hurricanes. They also add nitrogen to the soil. Nitrogen is an important nutrient for plants. Cryptogamous plants and lichens grow very slowly.

In clay deserts, annual ephemera and perennial ephemeroids grow. In solonchaks - halophytes or saltworts.

One of the most unusual plants that grow in such an area is saxaul. It often moves from place to place under the influence of the wind.

Fauna

The animal world is also not numerous - reptiles, spiders, reptiles or small steppe animals (hare, gerbil) can live here. Of the representatives of the order of mammals, a camel, an antelope, a kulan, a steppe ram, a desert lynx live here.

In order to survive in the desert, animals have a specific sandy coloration, they can run fast, dig holes and live without water for a long time, they are preferably nocturnal.

Of the birds, you can meet a crow, a saxaul jay, a desert chicken.

Important! In sandy deserts, there are sometimes oases - this is a place that is located above the accumulation of groundwater. There is always dense and abundant vegetation, ponds.

Characteristics of the climate, flora and fauna of the semi-desert

Semi-desert is a type of landscape that is an intermediate option between desert and steppe. Most of them are located in the temperate and tropical zones.

General signs

This zone is distinguished by the fact that there is absolutely no forest on it, the flora is rather peculiar, as is the composition of the soil (very mineralized).

Important! There are semi-deserts on all continents except Antarctica.

Climatic conditions

They are characterized by a hot and long summer period with a temperature of about 25°C. Evaporation here is five times higher than the level of precipitation. There are few rivers and they often dry up.

In the temperate zone, they run in an unbroken line across Eurasia in an east-west direction. In the subtropical zone, they are often found on the slopes of plateaus, highlands and plateaus (Armenian Highlands, Karru). In the tropics, these are very large areas (Sahel zone).

Flora

The flora of this natural zone is uneven and sparse. It is represented by xerophytic grasses, sunflowers and wormwood, ephemerals grow. On the American continent, cacti and other succulents are most common, in Australia and Africa - xerophytic shrubs and stunted trees (baobab, acacia). Here vegetation is often used to feed livestock.

In the desert-steppe zone, both steppe and desert plants are common. The vegetation cover is mainly made up of fescue, wormwood, chamomile, and hairy feather grass. Often wormwood occupies large areas, creating a dull monotonous picture. In some places, kokhiya, ebelek, teresken, and quinoa grow among the wormwood. Where groundwater comes close to the surface, thickets of brilliant chia come across on saline soils.

The soil, as a rule, is poorly developed, and water-soluble salts predominate in its composition. Among the soil-forming rocks, ancient alluvial and loess-like deposits predominate, which are processed by winds. Gray-brown soil is inherent in elevated flat areas. Deserts are also characterized by solonchaks, that is, soils that contain about 1% of easily soluble salts. In addition to semi-deserts, salt marshes are also found in steppes and deserts. Groundwater, which contains salts, when it reaches the soil surface, is deposited in its upper layer, resulting in soil salinization.

Fauna

The animal world is quite diverse. It is mostly represented by reptiles and rodents. The mouflon, antelope, caracal, jackal, fox and other predators and ungulates also live here. The semi-deserts are home to many birds, spiders, fish and insects.

Protection of natural areas

Part of the desert areas are protected by law and are recognized as nature reserves and national parks. Their list is quite large. From the deserts man guards:

• Etosha;
• Joshua Tree (in Death Valley).

From the semi-deserts are subject to protection:

• Ustyurt Reserve;
• Tiger beam.

Important! The Red Book includes such desert inhabitants as serval, mole rat, caracal, saiga.

Economic activity

The climatic features of these zones are unfavorable for economic life, but throughout history, entire civilizations have developed in the desert zone, for example, Egypt.

Special conditions made it necessary to look for a way to graze livestock, grow crops and develop industry. Taking advantage of the available vegetation, sheep are usually grazed in such areas. Bactrian camels are also bred in Russia. Farming here is possible only with additional irrigation.

The development of technological progress and the limited reserves of natural resources have led to the fact that man has reached the deserts. Scientific research has shown that in many semi-deserts and deserts there are considerable reserves of natural resources, such as gas, precious. The need for them is constantly increasing. Therefore, being equipped with heavy equipment, industrial tools, we are going to destroy previously miraculously untouched territories.

1. The two largest deserts on planet Earth are Antarctica and the Sahara.
2. The height of the highest dunes reaches 180 meters.
3. The driest and hottest area in the world is Death Valley. But, nevertheless, more than 40 species of reptiles, animals and plants live in it.
4. Approximately 46,000 square miles of arable land turns into desert every year. This process is called desertification. According to the UN, the problem threatens the lives of more than 1 billion people.
5. Passing through the Sahara, people often see mirages. To protect travelers, a map of mirages was drawn up for caravaners.

The natural zones 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.

Even the word "desert" itself evokes associations of emptiness and the absence 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 - the 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 position of the natural zone of deserts 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, due to the peculiar distribution of heat and moisture over the earth's surface. In simple terms, deserts are located in places where very little or no moisture gets in. The reasons for this are the mountains that cover the desert 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. Arid, 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 uplands, hillocks and insular mountains, stratified plains, ancient river valleys, and closed lake depressions. The most common are eolian landforms, which were formed under the action of the wind.

Sometimes the territory of the deserts is crossed by rivers (Okavango - a river flowing into the desert, Huang He, Syr Darya, Nile, Amudarya, etc.), there are many drying streams, lakes and rivers (Chad, Lop Nor, Air).

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

Climate features.

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

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

Most deserts receive their main precipitation in spring and winter, and only in some deserts the maximum amount of precipitation falls in summer in the form of showers (in the large 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 it is 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 overshadows the sun, the wind carries the sand over long distances, destroying absolutely everything in its path.
Another feature of the deserts are mirages created by the sun's rays, which, when refracted, create very amazing pictures on the horizon.