Speaking of deserts, the imagination draws endless, uninhabited areas of sandy or rocky wasteland without any signs of life. Traveling by plane and looking at the vast, forested territory of Russia, with riverbeds and pits of lakes, it is difficult to imagine a place where there are such places. However, this is not the case: there are deserts and semi-deserts in Russia. They are amazing, beautiful in their own way and not lifeless at all.
Deserts of Russia: geography and natural features
The semi-deserts and deserts of Russia occupy a small area in the southeast of the European part of the country, to the west and east of the lower Volga and up to the foothills of the Caucasian ridge. There is a border to the South of Volgograd separating the steppe and desert zones, starting from the left bank of the Volga, further northeast to Kazakhstan, then south to the foothills of the Caucasus and to the Terek valley.
The once significant area of deserts and semi-deserts of the modern Caspian lowland was the seabed, which left its mark on the landscape - a surface flat as a table, many kilometers long, stretches to the very horizon. During the melting of snows or rains, water settles in small lakes on the desert surface, creating the impression of a "patchiness" of the earth.
Soils and flora are different here, there are alkaline, clayey and sandy areas. Semi-deserts have a more benign climate and living conditions; they are used as pastures for grazing. 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 caverns... Underground rock salt deposits move under the pressure of rocks and are forced to the surface of the earth, forming hillocks and hills and revitalizing the desert landscape.
Climatic characteristics
Deserts and semi-deserts are characterized by a climate with a sharp daily temperature drop and a small amount of 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 for 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 drops cannot but affect the formation of the flora and fauna of the semi-deserts of Russia.
Flora and fauna
Life flourishes from April to June. Lack of sufficient moisture and sudden temperature changes make it possible for 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 scarce the vegetation.
In winter, a strong wind is added to the frost, which blows snow from the plains and exposes the ground. Such areas look black, they are called "Black Lands". But they got their name not only for this reason. In semi-deserts, black wormwood grows: a plant with small leaves and dark branches. A certain area of the desert lands is set aside for the reserve, which is also called "Black Lands".
What grows in semi-deserts?
The following crops grow in deserts and semi-deserts:
- Ephemeroids: Short-lived plants wilt quickly but leave tubers and bulbs in the soil.
- Ephemeral plants: with a short life cycle of two to three months.
Perennial grasses, cacti, ephedra, camel thorn, kendyr, sand acacia and even tulips grow here. TO short-cycle plants life can be attributed to the bulbous bluegrass. It covers the earth with a carpet, turning the desert into an oasis of life for a short time.
In sandy soils, cereals and other plants with deep and strong roots feel good: hairline, saxaul, elimus. Sandy soils absorb water well and retain it, preventing it from evaporating.
Desert and semi-desert animals
Despite the harsh climate and poor flora, the fauna of the semi-deserts is diverse. It is not easy to adapt to the sizzling heat, lack of constant 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, know how to store moisture for a long time. It is difficult to hide among the sands and sparse vegetation: the ability to run quickly and make long jumps helps to escape from predators. Birds are capable of long distance flights.
Representatives of the fauna of deserts and semi-deserts:
- Mammals: sandstone hares, jerboas, eared hedgehogs, corsacs, ground squirrels, gazelles, antelopes, fennecs, camels.
- Reptiles: snakes, turtles, monitor lizards, lizards.
- Insects: spiders, locusts, beetles.
- Birds: bullfinches, larks, partridges, jays, sparrows.
Depending on the geographical latitude of the area, the corresponding climatic zones are formed in the deserts and semi-deserts of Russia different ecosystems... The flora and fauna of these zones is also different.
Desert problems and their development
The ecological crisis is as follows:
Man is responsible for land desertification. Cutting down trees, draining springs, changing river channels, plowing up land, long-term use of pastures, illiterate irrigation methods, indefatigable extraction of natural resources 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 to us many more of their secrets.
Temperate semi-deserts- a natural zone of the temperate zone, with features transitional from steppes to deserts. A sharply continental climate is characteristic, the evaporation rate is 3-4 times higher than the amount of precipitation. The annual amount of precipitation ranges from 150-250 mm.
In semi-deserts, brown semi-desert-steppe soils are formed, as well as light chestnut soils poor in humus. Along with them, salt licks are very widespread.
In the semi-deserts, sparse wormwood-grass vegetation grows, which is torn.
The fauna of semi-deserts does not differ in originality; it includes types of steppe and desert zones. Rodents play an exclusive role in the animal kingdom.
The deserts of the temperate zone occupy the flat areas of Eurasia from the Caspian Sea in the west to Central China in the east, the largest of them are the Karakum and Kyzylkum deserts in Central Asia. In North America, these are the arid regions of the Great Basin, in South America, Patagonia.
The desert climate is characterized by extreme aridity and continentality, with sharp contrasts between very hot summers and cold winters. The amount of precipitation ranges from 75 to 150 mm per year.
The soil cover is dominated by brown and gray-brown desert soils, often saline. Takyrs are characteristic - specific formations of clay deserts, which are a cracked dry clay surface.
The vegetation cover is sparse, and it is dominated by perennial shrubs and ephemerals (annual herbaceous plants that fade during a short rainy period). Of the semi-shrubs, the leading role belongs to various types of wormwood and hodgepodge. In some places, there are "forests" of saxaul - a small leafless tree, the roots of which go down to a depth of 20 m. At the height of summer, temperate deserts differ little from tropical deserts, but they have a short but stormy period of flowering - early spring. It happens that the desert is covered with a real flowering carpet.
The fauna is mainly represented by reptiles (snakes, lizards). Many desert animals can be without food or water for a long time, for example, a domesticated camel. Among birds, various larks, plovers, beauty bustard, desert warbler, etc. are widespread.
Deserts of the subtropical and tropical zones
Subtropical and tropical deserts are located in the northwest of India, Pakistan, Iran, Asia Minor. They cover the Arabian Peninsula and all of northern Africa, the western coast of South America for almost 3,500 km and the central part of Australia.
The climate in the deserts is sharply continental. Summers are very dry and hot, during the day the air temperature in the shade rises above 40 ° C. At night, the heat subsides, the temperature often drops to 0 ° C. There is no more than 180 mm of precipitation per year. Chile's Atacama Desert receives less than 10 mm of rainfall per year.
The soil cover is mainly represented by brown desert soils, but in vast territories there are no soils at all. In places of shallow groundwater, salt marshes are formed. Large areas are occupied by rocky deserts. Clay deserts, usually located in depressions in the relief, are almost devoid of vegetation. They are easily flooded during the period of short-term rains and look like lakes, although the depth of these "lakes" is only a few millimeters. The clay layer does not absorb water - it quickly evaporates in the sun, the dry surface of the earth cracks, and takyrs are formed. Clay areas give way to spaces of mobile sand with forms of aeolian relief - dunes, "crescent" or "crescent" shape, reaching a height of 12 m, and dunes.
Desert plants usually have a well-developed root system. Mostly thorny shrubs, cacti and some herbs grow here. Other plants - ephemerals - survive drought in the form of seeds, having time to germinate and bloom in a couple of months after a rare rain.
The fauna of deserts is represented by a wide variety of reptiles (snakes, lizards, turtles), birds (eagles, crows, sparrows, owls, etc.) and mammals (cheetah, kulan, camel, etc.).
Human life in deserts is possible only in oases.
An acute lack of moisture and alkalinity of soils determine the characteristics of the vegetation cover of semi-deserts - its torn, discontinuous nature, the predominance of drought-resistant turf grasses and semi-shrubs, a significant development of ephemerals and ephemeroids, sometimes lichens. In terms of the composition and structure of the herbage, these are wormwood-grass steppes. Of the grasses, fescue, tyrsa, Lessing feather grass (Stipa lessingiana), and Sarepta feather grass (Stipa sareptana) are the most typical (According to T.B. occurs only “in special conditions of existence”), crested wheatgrass (Agropyrum cristatum), Siberian wheatgrass (A. sibiricum), desert wheatgrass (A. desertorum); from shrubs - white wormwood (Artemisia lercheana), black wormwood (A. pauciflora), twig (Kochia prostrata), chamomile (Pyrethrum achilleifolium). A typical ephemeroid of semideserts is viviparous bluegrass (Poa bulbosa), tulips (Tulipa) are found.
Like soils, the vegetation cover of semi-deserts is extremely variegated (complex). In the Caspian semi-desert, the plant complex is most often three-membered: fescue-chamomile groups on light chestnut soils alternate with wormwood and wormwood-saltwort associations on solonetzes and grass-meadow steppe along depressions and estuaries. Compared with the cereal steppes in semi-deserts, the total stock of plant mass is sharply reduced - to 5-12.5 t / ha. For most of the year, from April to November, the wormwood-grass steppes are used as pastures. In warm winters in the south of the zone, grazing is possible all year round. "Spills" and estuaries are used for hay making.
"Spills" is one of the remarkable types of semi-desert terrain, best expressed in the north of the Caspian lowland. These are delta-type estuaries, “mouths” of closed rivers. In spring, for a short time, floods turn into shallow lakes, in summer they are covered with dense meadow vegetation, interrupted by patches of salt marshes, reed-reed thickets, less often lakes. Such are the Kamysh-Samarsky, Chizhinsky, Dyurinsky and others. A significant part of them are covered with beautiful wheatgrass meadows. The huge forage resources of spills can be judged by the fact that their area in high-water years in only one former West Kazakhstan region reaches 500 thousand hectares.
In the fauna of semi-deserts, rodents play an exclusive role. Small and yellow (sandy) ground squirrels (Citellus pygmaeus, C. fulvus) are distinguished among them by their abundance and impact on the landscape. The small gopher finds optimal conditions for its existence. The formation of hummock microrelief is associated with the emissions of ground squirrels, which enhances the complexity of the soil and vegetation cover. The yellow gopher, not found east of Sary-Su, is of commercial importance. The steppe lemongrass and various types of jerboas, especially the hentai (Scirtopoda telum), are very characteristic of the semideserts; many voles, mice, mole voles (Ellobius talpinus). The saiga antelope (Saiga tatarica) is still common in semi-deserts, the number of which in the USSR, including semi-deserts, reaches 1.9 million heads (as of 1974). With an organized fishery, tens of thousands of saigas can be hunted annually without prejudice to their main livestock.
Common predators include the wolf, the steppe polecat, and the corsac fox. The composition of birds is diverse: steppe eagle, jack bustard, or wobbly (Otis undulata), belladonna crane (Anthropoides virgo), black and white-winged larks (Melanocrypha yeltoniensis, M. leucoptera). The Italian locust (Calliptamus italicus), a dangerous crop pest, is very abundant in the semi-desert. "In" locust years "the locust surpasses all other insect species of dry and desert steppes in weight and serves as the most important food for a huge number of animals, from predatory beetles, lizards and snakes to small and large birds and many mammals" (Formozov). The total stock of zoo mass in semi-deserts is very small - on average 20-30 kg / ha, decreasing to several kilograms per hectare in the arid eastern regions of the zone.
Literature.
1. Milkov F.N. Natural zones of the USSR / F.N. Milkov. - M.: Mysl, 1977 .-- 296 p.
Speaking about the desert, first of all, we imagine the sandy expanses, where there is no water, no animals, no plants. But this landscape is not ubiquitous, and the nature in the desert is very diverse. Deserts are home to some species of birds, mammals, herbivores, insects and reptiles. This means that they have something to eat in the desert.
Despite the hot and dry climate, strong winds and sandstorms, lack of precipitation, representatives of the animal world are able to survive in such conditions. Several species of flora have also adapted to these conditions.
What are the living conditions of plants in deserts?
The local flora has adaptations thanks to which it survives:
- thorns;
- powerful root system;
- fleshy leaves;
- small height.
These adaptations allow plants to gain a foothold in the soil. Long roots reach underground waters, and leaves retain moisture for a long time. Since shrubs and trees grow at a certain distance from each other, they can absorb moisture to the maximum in their radius. Only under such conditions does flora exist in the desert.
What types of flora grow in deserts?
The flora of the desert is very unusual. Various types of cacti are most common in this natural area. They come in a variety of sizes and shapes, but overall they are massive and spiny. Some species live for about a hundred years. Aloe is also found here, with thorns and fleshy leaves.
Baobabs also grow in deserts. These are trees that have massive trunks and long roots, therefore they are powered by underground water sources. Spherical tumbleweed bushes are quite common in deserts. The jojoba tree also grows here, from the fruits of which valuable oil is obtained.
In the desert, there are numerous small plants that bloom when it rains. During this period, the desert dresses up in colorful flowers. Among small plants camel thorns and.
Among other plants in the deserts grow lithops and elm, creosote bush and comb, cereus, stapelia. Wormwood, sedge, bluegrass and other herbaceous plants, trees and shrubs grow in the oases.
All desert plants have adapted to the harsh climatic conditions. But, despite the thorns, thorns, small size, the flora of the deserts is magnificent and amazing. When the rain falls, the plants even bloom. Those who have seen the blooming desert with their own eyes will never forget this magnificent miracle of nature.
Desert Plants Informative Video
How plants adapted to life in the desert
A variety of plants in the desert is possible because they have special adaptations and differ significantly from the vegetation of forests and steppes. If the plants of these natural zones have powerful stems and branches, then desert plants have very thin stems, in which moisture accumulates. Leaves and branches transform into thorns and shoots. Some plants have scales instead of leaves, for example, y. Despite the fact that the plants of the desert are small in size, they have a long and powerful root system that allows them to take root in sandy soil. On average, the length of the roots reaches 5-10 meters, and in some species even more. This allows the roots to reach the groundwater that plants feed on. So that every shrub, tree or perennial plant gets enough moisture, they grow on a specific plant apart from each other.
So, a wide variety of flora has adapted to life in the desert. Since cacti live for several decades, and some individuals grow for more than 100 years. Various shapes and shades have ephemerals that bloom especially vividly in the rain. In some places you can find original saxaul forests. They can grow in the form of trees or shrubs, which reach an average of 5 meters, but there are also more. Very large shrubs are found in the desert. It can be sandy acacias. They have thin trunks and small leaves with small purple flowers. It has a yellow flowering creosote bush. It is adapted to prolonged drought and harsh climatic conditions, scares away animals, emitting an unpleasant odor. Various succulents grow in the desert, for example, lithops. It is worth emphasizing that any desert in the world can surprise you with the diversity and beauty of its flora.
The driest areas of our planet are semi-deserts and deserts. Temperature fluctuations in deserts during the day can reach 30 degrees or more. Rains are rare here, and the sun is incredible.
Daytime temperatures in the summer are more than 50 degrees, and sometimes even frost is possible at night. It would seem that there is no place for plants, but this is not so - in all deserts there are special forms of vegetation inherent only to it.
Deserts with extreme rates:
The lowest is Simpson (here and further on the map - 1), Australia, - 12 m from sea level.
The highest is Tsaidam (2), Central Asia, from 2600 to 3100 m above sea level.
The driest are Atacama (3), South America, from 10 to 50 mm / year; Nubian (4), North Africa, 25 mm / yr.
The wettest are Tar (5), India, from 150 to 500 mm / year; Namib (6), South Africa, 100 to 500 mm / yr
Highest absolute temperatures in deserts:
In tropical deserts: North Africa - Sahara, + 56 ° С; Libyan Desert, (7), + 58 ° С; Nubian Desert (4), + 53 ° С; Arabian Peninsula - Big Nefud (8), + 54 ° С.
In subtropical and inland deserts: North America - Mojave (9), + 57 ° С, Central Asia - Karakum Desert (10), + 50 ° С, Hindustan Peninsula - Thal (11), + 49 ° С.
The climatic conditions of the deserts have shaped the vegetation that flourishes magnificently in the spring, when, after rains, sandy or clay soils are covered for a short time with a bright carpet of flowering plants. But as soon as a long hot and dry summer sets in, all desert vegetation freezes, annual plants dry out, and perennial grasses continue their life underground. Shrubs and shrubs also shed their leaves at this time.
Where do plants get their water from during the hot dry season? Indeed, in the desert, the amount of evaporated moisture is many times greater than the amount received. It turns out that sands are capable of condensing atmospheric moisture at night, turning it into water and accumulating in the near-surface layer. Due to it, there are desert plants with superficial roots. Another source of water is deep groundwater, to which plants with long roots "reach". But there is still little moisture, and desert plants over the many millennia of their existence have developed special devices for the minimum water consumption. Their leaves have a very small evaporating surface, often disappearing altogether or turning into thorns.
For example, acacia... Translated from Greek "acacia" - thorn.
Acacia spines are very diverse: large and small, thick and thin, long and sharp, like needles, or branched into several thorns that look in different directions. But there are acacias without thorns. In the sandy spring, acacia has fluffy silvery leaves, which soon fall off, and short leaf petioles-thorns remain the only decoration of the plant for the entire period of summer heat.
In the deserts of the temperate zone - Karakum, Kyzylkum, Gobi and some others - there are small trees of white and black saxaul. They often form extensive thickets - a kind of desert forests.
Saxaul is an amazing shrub tree. It occupies vast, almost waterless spaces in the deserts. Black saxaul grows in highly saline soils, while white saxaul, with a more powerful root system, prefers sands. Saxaul is a tree without leaves. In black saxaul, they are replaced by branches diverging in different directions and hanging down with brittle greenish twigs at the ends, and in white saxaul - scales with a film edge.
In the deserts of North and South America, there are many different species cactus, and in South Africa - Molochaev, extremely similar to them. These plants store water in their fleshy stems, protected by sharp needles and thorns.
The peculiarity of these desert plants is that they have adapted not only to store water in the stem, but also to protect it from animals. The most creepy of thorny trees under the general name alluaudia grow in the deserts of southern Madagascar. Similar thorny trees are found in the southwestern deserts of the United States and in Mexico - these are giants cereus.
