What are the features of the placement of natural zones on the continents. Natural areas of the world. Temperate monsoon forests

What does the formation depend on? natural areas? What natural areas stand out on our planet? You can answer these and some other questions by reading this article.

Natural zoning: the formation of natural zones in the territory

The so-called our planet is the largest natural complex. It is very heterogeneous, both in the vertical section (which is expressed in the vertical zonality), and in the horizontal (latitudinal), which is expressed in the presence of various natural zones on Earth. The formation of natural zones depends on several factors. And in this article we will talk specifically about latitudinal inhomogeneity. geographic envelope.

This is a component of the geographic envelope, which differs in a certain set natural components with its own characteristics. These components include the following:

• climatic conditions;
• the nature of the relief;
• hydrological grid of the territory;
• soil structure;
• organic world.

It should be noted that the formation of natural zones depends on the first component. However, natural zones usually get their names from the nature of their vegetation. After all, flora is the most striking component of any landscape. In other words, vegetation acts as a kind of indicator that reflects the deep (those that are hidden from our eyes) processes of the formation of a natural complex.

It should be noted that the natural zone is the highest level in the hierarchy of physical and geographical zoning of the planet.

Natural zoning factors

Let us list all the factors of the formation of natural zones on Earth. So, the formation of natural zones depends on the following factors:

1. Climatic features of the territory (this group of factors should include the temperature regime, the nature of humidification, as well as the properties of the air masses prevailing over the territory).
2. The general nature of the relief (this criterion, as a rule, affects only the configuration, the boundaries of a particular natural zone).

The formation of natural zones can also be influenced by the proximity to the ocean, or the presence of powerful ocean currents off the coast. However, all of these factors are secondary. The main root cause natural zoning is that different parts (belts) of our planet receive unequal amounts of solar heat and moisture.

Natural areas of the world

What natural zones do geographers distinguish on the body of our planet today? Let's list them from the poles to the equator:

• Arctic (and Antarctic) deserts.
• Tundra and forest-tundra.
• Taiga.
• Broad-leaved forest zone.
• Forest-steppe.
• Steppe (or prairie).
• Semi-desert and desert zone.
• Savannah zone.
• Zone of tropical rainforests.
• Wet zone (gilea).
• Zone of rain (monsoon) forests.

If we look at the map of the natural zoning of the planet, we will see that all natural zones are located on it in the form of sub-latitudinal belts. That is, these zones tend to stretch from west to east. Sometimes this sub-latitudinal direction can be violated. The reason for this, as we have already said, is the features of the relief of a particular territory.

It is also worth noting that there are simply no clear boundaries between natural zones (as shown on the map). So, practically each of the zones smoothly "flows" into the neighboring one. At the same time, border "zones" can very often form at the junction. For example, these are semi-desert or forest-steppe zones.

Conclusion

So, we found out that the formation of natural zones depends on many factors. The main ones are the ratio of heat and moisture in a particular area, the properties of the prevailing air masses, the nature of the relief, and so on. The set of these factors is the same for any territory: mainland, country or small region.

Geographers distinguish over a dozen large natural zones on the surface of our planet, which are elongated in the form of belts and replace each other from the equator to the polar latitudes.

The warmth of the sun, clean air and water are the main criteria for life on Earth. Numerous climatic zones have led to the division of the territory of all continents and water areas into certain natural zones. Some of them, even separated by huge distances, are very similar, others are unique.

Natural areas of the world: what is it?

This definition should be understood as very large in area natural complexes (in other words, parts of the geographic belt of the Earth), which have similar, homogeneous climatic conditions. The main characteristic of natural zones is the flora and fauna that inhabits this territory. They are formed as a result of uneven distribution of moisture and heat on the planet.

Table "Natural zones of the world"

This characteristic of the natural zones of the world is only for informational purposes, because you can talk a lot and for a long time about each of them, all the information will not fit into the framework of one table.

Natural zones of the temperate climatic zone

1. Taiga. It surpasses all other natural zones in the world in terms of land area (27% of the territory of all forests on the planet). It is characterized by very low winter temperatures. Deciduous trees they can not stand, therefore the taiga is conifers dense forests(mainly pine, spruce, fir, larch). Highly large territories taigas in Canada and Russia are occupied by permafrost.

2. Mixed forests. Typical to a greater extent for the Northern Hemisphere of the Earth. It is a kind of border between taiga and deciduous forest. They are more resistant to cold and long winters. Species of trees: oak, maple, poplar, linden, as well as rowan, alder, birch, pine, spruce. As the table "Natural zones of the world" shows, soils in the zone mixed forests gray, not very fertile, but still suitable for growing plants.

3. Broad-leaved forests. They are not adapted to harsh winters, they are deciduous. They occupy most of Western Europe, the south of the Far East, the north of China and Japan. Suitable for them is a maritime climate or temperate continental with hot summers and enough warm winter... As the table "Natural zones of the world" shows, the temperature in them does not drop below -8 ° C, even in the cold season. The soil is fertile, rich in humus. Are characteristic the following types trees: ash, chestnut, oak, hornbeam, beech, maple, elm. Forests are very rich in mammals (ungulates, rodents, predators), birds, including commercial birds.

4. Temperate deserts and semi-deserts. Their main distinctive feature- almost complete absence of vegetation and a meager fauna. There are a lot of natural zones of this nature, they are located mainly in the tropics. There are temperate deserts in Eurasia, and they are characterized by sharp temperature changes over the seasons. Animals are mainly represented by reptiles.

Arctic deserts and semi-deserts

They represent huge areas of land covered with snow and ice. The map of natural zones of the world clearly shows that they are located on the territory North America, Antarctica, Greenland and the northern tip of the Eurasian continent. In fact, these are lifeless places, and only along the coast are polar bears, walruses and seals, Arctic foxes and lemmings, penguins (in Antarctica). Where the land is free of ice, lichens and mosses can be seen.

Humid equatorial forests

Their second name is rain forests... They are located mainly in South America as well as in Africa, Australia and the Greater Sunda Islands. The main condition for their formation is constant and very high humidity (more than 2000 mm of precipitation per year) and a hot climate (20 ° C and above). They are very rich in vegetation, the forest consists of several tiers and is an impenetrable, dense jungle, which has become home to more than 2/3 of all types of creatures living on our planet. These rainforests surpass all other natural areas in the world. Trees remain evergreen, changing foliage gradually and partially. Surprisingly, the soil wet forests contain little humus.

Natural zones of the equatorial and subtropical climatic zone

1. Variable-humid forests, they differ from rain forests in that precipitation occurs there only during the rainy season, and during the period of drought that follows it, the trees are forced to shed their foliage. The flora and fauna are also very diverse and rich in species.

2. Savannas and woodlands. They appear where moisture, as a rule, is no longer sufficient for the growth of variably moist forests. Their development takes place in the interior of the continent, where tropical and equatorial air masses dominate, and the rainy season lasts less than six months. They occupy a significant part of the territory of subequatorial Africa, the interior regions of South America, partly Hindustan and Australia. More detailed information about the location is reflected in the map of natural zones of the world (photo).

Stiff-leaved forests

This climatic zone is considered the most suitable for human habitation. Stiff-leaved and evergreen forests are located along the sea and ocean coasts. Precipitation is not so abundant, but the leaves retain moisture due to the dense leathery shell (oaks, eucalyptus), which prevents them from falling off. In some trees and plants, they are modernized into thorns.

Steppe and forest-steppe

They are characterized by an almost complete absence of woody vegetation, due to the scarce level of precipitation. But the soils are the most fertile (chernozems), and therefore are actively used by humans for agriculture. The steppes occupy large areas in North America and Eurasia. The predominant number of inhabitants is reptiles, rodents and birds. Plants have adapted to the lack of moisture and most often have time to complete their life cycle for a short spring period, when the steppe is covered with a thick carpet of greenery.

Tundra and forest-tundra

In this zone, the breath of the Arctic and Antarctic begins to be felt, the climate becomes more severe, and even conifers cannot withstand it. Moisture is in excess, but there is no heat, which leads to swamping of very large areas. In the tundra, there are no trees at all, the flora is mainly represented by mosses and lichens. It is believed to be the most volatile and fragile ecosystem. Due to the active development of gas and oil fields, it is on the verge of an environmental disaster.

All natural zones of the world are very interesting, be it a seemingly absolutely lifeless desert, endless Arctic ice or thousand-year-old rain forests with boiling life inside.

The spherical surface of our planet is the reason for the uneven distribution of the flow of sunlight over the surface of the Earth. As a result, natural zones of the continents were formed, differing from each other in soil composition, climatic conditions, flora and fauna.

What are the mainland natural areas

A natural zone is an area characterized by a certain ratio of moisture and heat. Since the sun heats the planet unevenly, the climate cannot remain the same in all parts of the Earth: it is especially hot at the equator, and incredibly harsh and cold at the poles.

The distribution of the Earth's surface into natural complexes is based on thermal zones:

• belts of eternal cold (around the poles);
• cold;
• moderate;
• the hot zone at the equator is common to the two hemispheres.

Rice. 1. Thermal zones of the Earth.

Changes in the composition of soil, flora and fauna of natural zones are also connected with this. Names natural complexes with a similar set of characteristics come from the predominant vegetation cover. Frozen arctic deserts give way to treeless tundras, which give way to taiga and forests. Forests gradually thin out and turn into endless steppes, and then into deserts. At and near the equator, there are alternating humid and rainfall equatorial forests.

Most of the natural zones are located in Eurasia, and least of all in Antarctica. Natural complexes that are similar to each other, in which the flora, fauna, soil and climate are largely the same, are located in North America and Eurasia.

Rice. 2. Natural zones of Eurasia are very diverse.

Features of the natural zones of the continents

A characteristic feature of natural complexes is their regular change, which depends on the following factors:

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• Latitudinal zoning. The zones smoothly pass from one to another in the latitudinal direction, that is, from the poles towards the equator.
• Meridional zoning ... The change of zones occurs from the oceans inland.
• Altitudinal zonality ... Pronounced zoning when climbing from the foot of the mountain to its top.

Latitudinal zoning on Earth is observed only on flat areas and in areas of a temperate continental climate, as well as on those land areas where the amount atmospheric precipitation changes from north to south. There are very few territories corresponding to these conditions, and therefore latitudinal zoning in its pure form observed quite rarely.

The meridional zoning is most pronounced on the territory of Eurasia, since this continent is the largest on the planet. In the temperate zone on the west coast, there is a relatively even distribution of moisture, while the monsoon circulation reigns on the east coast, as a result of which rainy seasons are replaced by dry seasons.

When moving inland, western forests are replaced by forest-steppe zones, steppes and deserts. As we move to the East, a forest zone reappears, but of a different type. The flora and fauna of natural zones change with climate change.

There are continents on Earth in which endemics are found - a certain type of animals or plants that live only on this continent. For example, the largest predator in nature is polar bear- in natural conditions, it lives only in the snowy deserts of the Arctic, and kangaroos can be found only in Australia. Moreover, there are many species that are similar to each other. For example, many representatives of the animal world of the South American and African savannas have many similarities and only minor differences.

1. What is the difference between soil and rock? What are the prevailing soils in your area?
2. What natural complexes are called natural zones?

Soil map. Soils are one of the components of the natural zone. The location of the main soil types on the earth's surface and on each continent is shown on a thematic map (see the soil map of the world in the atlas).

In order to understand well the features of the distribution of soils on the earth's surface, it is important to know their dependence on other components of nature. Soil formation depends on many reasons: rocks, relief, fauna, but mainly from climate and vegetation. Where there is little rainfall and sparse vegetation, the soil layer is thin and contains little humus. On the contrary, in places with a sufficient amount of heat, precipitation and rich, especially herbaceous, vegetation, more powerful and fertile soil.

Depending on the parent rock, the amount of humus and other reasons, the color of the soil is different. Many soils are usually named according to their color, for example, chestnut, brown, red-brown, etc. On the school soil map, only the prevailing soils of a particular territory are indicated in different colors.

Using the soil map of the world, determine which soils are dominant:

1. v equatorial belt all continents;
2. in the subequatorial belts;
3. in tropical zones;
4. in the subtropical zone;
5. in the Antarctic belt.

Features of the location of natural areas. The composition of natural zones and their location are directly dependent on climatic conditions. On the territory of the southern continents there are all natural zones of low latitudes and the Antarctic belt. Zones are poorly represented temperate zone... As a rule, natural areas correspond climatic regions(see the map on the flyleaf and atlas). In the distribution of zones, latitudinal zoning is clearly expressed. This is due to the predominance of plains on the continents. Altitudinal zonality is also clearly manifested. It is especially pronounced in South America.

Equatorial forests are rich valuable breeds trees. The largest tracts of these forests are found in South America and Africa. Parent rocks of soils, as in other places of low latitudes of the Earth, are rich in iron compounds, and therefore are red in color. The soils formed on these rocks also acquire a reddish tint. They are called red-yellow ferralite (from the Latin "ferrum" - iron). Organic matter entering the soil in large quantities decomposes to the end, and does not accumulate in it. These nutrients are quickly absorbed by the plant. The abundance of moisture leads to continuous leaching of the soil to a great depth, causing waterlogging in some places.

The hot climate and abundant rainfall contribute to the development of dense evergreen woody vegetation. Trees grow in several tiers. Light-loving trees stretch towards the sun, forming the upper tier 35-50 m high. The trunks of the trees rise like columns and only spread a dense crown above. Under these giants, trees of lesser height and less demanding light grow in several tiers.

Equatorial forests are evergreen. There are many vines in the forest (climbing plants, sometimes with a woody stem). Lianas densely twine around tree trunks, climb high on them and hang from there in garlands, making the thicket in places impassable. Sunlight barely penetrates through the dense foliage. In such a forest it is gloomy even during the day. Therefore, shrubs and grass cover are poorly developed.

The fauna of the equatorial forests is rich and varied. His characteristic feature is that many animals live in trees. The world of monkeys, birds, insects, ants, etc. is rich here.

Savannah. The zone of equatorial forests on the continents is gradually changing variable wet forests and then savannas. This natural zone is characterized by a change of dry and wet seasons, a predominance of grassy cover with individual trees or groups of trees and shrubs of the hot zone. Savannah can be called a tropical forest-steppe. Its formation, as you might guess, is due to the appearance of the dry season. There is not enough moisture for the forest.

The process of soil formation in savannas occurs under conditions of seasonal precipitation. During the rainy season, the decay of organic matter and soil leaching are observed. In the dry (winter) period, due to a lack of moisture, the vital activity of microorganisms slows down and the plant litter of a rich herbaceous cover does not decompose completely. Therefore, humus accumulates in the soil. Red-brown soils prevail here. The general appearance of the savannah changes dramatically with the seasons. During the dry season, the grasses burn out, many trees shed their foliage and the savannas become yellow in color. The heat dries up everything. But as soon as the first rains fall, nature comes to life, succulent grasses grow with amazing speed, trees are covered with foliage.

Animals, like plants, adapt to the dry season. Some of them, such as invertebrates and amphibians, take refuge in shelters during drought and hibernate. Many animals migrate to places with bodies of water. The savannah zone covers a large area on all three continents. Each continent is distinguished by a significant uniqueness of flora and fauna.

Tropical deserts are also widespread on the southern continents. (Why?) The zone is distinguished by sparse vegetation, and in some places it is devoid of it, by large daily and significant annual temperature ranges. There is very little humus in the soil of deserts; desert tropical soils are formed here. Desert plants have a highly developed root system that allows them to collect water from great depths and from large areas (for example, a camel thorn). Many plants have very small leaves to reduce evaporation, often replaced by thorns. Some plants appear only after rains and grow unusually quickly, flower and bear fruit, and then dry up. Animals also adapt to desert climates.

1. What are the features geographic location southern continents?
2. Name common features relief of the southern continents. How are they explained?
3. In what climatic zones is located most of southern continents, in which - smaller?
4. What are the features of the rivers of the southern continents? Using the example of any river, show the dependence of rivers on topography and climate.
5. What natural areas cover a large area and why?
6. On which continents is the most pronounced latitudinal zoning, on which is the altitudinal zonation? Why?
7. Using the text of the tutorial, climate maps Africa, Australia and South America, identify the main features of each natural area.

Zoning - change in natural components and the natural complex as a whole from the equator to the poles. Zoning is based on the different influx of heat, light, atmospheric precipitation to the Earth, which, in turn, are already reflected in all other components, and above all - soils, vegetation and fauna.

Zoning is typical for both land and the World Ocean.

The largest zonal subdivisions of the geographic envelope are geographic zones. The belts differ from each other primarily in temperature conditions.

The following geographical zones are distinguished: equatorial, subequatorial, tropical, subtropical, temperate, subpolar, polar (Antarctic and Arctic).

Inside the belts on land, natural zones are distinguished, each of which is characterized not only by the same type of temperature conditions and moisture, which leads to a commonality of vegetation, soils and fauna.

You are already familiar with the zone of arctic deserts, tundra, forest zone of the temperate climatic zone, steppes, deserts, humid and dry subtropics, savannahs, humid evergreen equatorial forests.

Transitional areas are distinguished within natural zones. They are formed as a result of a gradual change in climatic conditions. Such transitional zones include, for example, forest-tundra, forest-steppe and semi-desert.

Zoning can be not only latitudinal, but also vertical. Vertical zoning is a natural change in height and depth of natural complexes. For mountains, the main reason for this zoning is the change in temperature and moisture content with height, and for the depths of the ocean, heat and sunlight.

The change of natural zones depending on the height above sea level in mountainous areas is called, as you already know, high-altitude zonation.

It differs from horizontal zoning in the length of the belts and the presence of a belt of alpine and subalpine meadows. The number of belts usually increases in high mountains and closer to the equator.

Natural areas

Natural areas- large subdivisions of the geographic envelope with a certain combination temperature conditions and humidification regime. They are classified mainly by the prevailing type of vegetation and regularly change in the plains from north to south, and in the mountains - from the foothills to the peaks. Natural zones of Russia are shown in Fig. 1.

The latitudinal distribution of natural zones on the plains is explained by the supply of unequal amounts of solar heat and moisture to the earth surface at different latitudes.

The resources of flora and fauna of natural zones are biological resources territory.

The set of altitudinal belts depends primarily on the latitude at which the mountains are located and what their height is. It should also be noted that, for the most part, the boundaries between the altitudinal zones are not clear-cut.

Let us consider in more detail the features of the placement of natural zones using the example of the territory of our country.

Polar desert

The very north of our country is the Northern Islands Arctic Ocean- located in a natural area polar (arctic) deserts. This zone is also called ice zone. The southern border roughly coincides with the 75th parallel. The natural zone is characterized by the dominance of the Arctic air masses. The total solar radiation is 57-67 kcal / cm 2 per year. Snow cover lasts 280-300 days a year.

In winter, the polar night dominates here, which at a latitude of 75 ° N. NS. lasts 98 days.

In summer, even round-the-clock lighting is not able to provide this area with enough warmth. The air temperature rarely rises above 0 ° С, and average temperature July is +5 ° С. Drizzling precipitation can last for several days, but there are practically no thunderstorms and showers. But fogs are frequent.

Rice. 1. Natural zones of Russia

A significant part of the territory is characterized by modern glaciation. There is no continuous vegetation cover. Near-glacial areas of land on which vegetation develops are small. On the placers of pebbles, fragments of basalt and boulders, mosses and crusty lichens "settle". Occasionally there are poppies and saxifrage, which begin to bloom when the snow has barely had time to melt.

The fauna of the Arctic desert is represented mainly by Marine life... These are the harp seal, walrus, ringed seal, sea hare, beluga whale, porpoise, killer whale.

The species of baleen whales are diverse in the northern seas. Blue and bowhead whales, sei whales, fin whales, humpback whales are rare and endangered species and are listed in the Red Book. Inner side long horny plates that replace whale teeth, split into hairs. This allows the animals to filter a large volume of water, harvesting plankton, which is the basis of their diet.

The polar bear is also a typical representative of the animal world of the polar desert. "Maternity hospitals" for polar bears are located in Franz Josef Land, Novaya Zemlya, about. Wrangel.

In summer, numerous bird colonies nest on the rocky islands: gulls, guillemots, guillemots, auk, etc.

There is practically no permanent population in the polar desert zone. The weather stations operating here monitor the weather and the movement of ice in the ocean. On the islands they hunt Arctic foxes in winter and game birds in summer. Fishing is carried out in the waters of the Arctic Ocean.

Steppe

Steppes extend to the south of the forest-steppe zone. They are distinguished by the absence of forest vegetation. The steppes stretch in a narrow continuous strip in the south of Russia from the western borders to Altai. Further to the east, the steppe areas have focal distribution.

The climate of the steppes is moderately continental, but drier than in the zone of forests and forest-steppe. The amount of annual total solar radiation reaches 120 kcal / cm 2. The average January temperature at the start is -2 ° С, and in the east -20 ° С and below. Summer in the steppe is sunny and hot. The average July temperature is 22-23 ° C. The sum of active temperatures is 3500 ° C. Annual precipitation is 250-400 mm. Showers are frequent in summer. The moisture coefficient is less than one (from 0.6 in the north of the zone to 0.3 in the southern steppes). A stable snow cover lasts up to 150 days a year. Thaws often occur in the west of the zone, so the snow cover there is thin and very unstable. The dominant steppe soils are chernozems.

Natural plant communities are represented mainly by perennial, drought and frost-resistant grasses with a powerful root system. These are, first of all, cereals: feather grass, fescue, wheat grass, serpentine, thin-legged, bluegrass. In addition to cereals, there are numerous representatives of forbs: astragalus, sage, carnation - and bulbous perennials, such as tulips.

Composition and structure plant communities change significantly in both latitudinal and meridional directions.

In the European steppes, narrow-leaved grasses form the basis: feather grass, fescue, bluegrass, fescue, thin-legged, etc. There are many brightly blooming forbs. In summer, feather grass sways like waves in the sea, here and there you can see lilac irises. In the more arid southern regions, in addition to cereals, wormwood, breast milk, and cinquefoil are common. There are many tulips in the spring. In the Asian part of the country, tansy and cereals predominate.

Steppe landscapes are fundamentally different from forest landscapes, which determines the originality of the fauna of this natural zone. Typical animals of this zone are rodents (the largest group) and ungulates.

Ungulates are adapted to long-term movements across the endless expanses of the steppes. Due to the thinness of the snow cover, plant food is available in winter as well. Bulbs, tubers, rhizomes play an important role in nutrition. For many animals, plants are also the main source of moisture. Typical representatives ungulates in the steppes are rounds, antelopes, tarpans. However, most of these species result in economic activity people were exterminated or driven south. Saigas, which were widespread in the past, have survived in some areas.

Of the rodents, the most common are the gopher, vole, jerboa, etc.

Ferret, badger, weasel, fox also live in the steppe.

Of the birds, the bustard, little bustard, partridge, steppe eagle, buzzard, and kestrel are typical of the steppes. However, even these birds are now rare.

There are much more reptiles than in the forest zone. Among them, we single out the steppe viper, snake, common snake, nimble lizard, shitomordnik.

The richness of the steppes is fertile soils. The thickness of the humus layer of chernozems is more than 1 m. It is not surprising that this natural zone is almost completely developed by man and natural steppe landscapes are preserved only in reserves. In addition to the high natural fertility of chernozems, Agriculture climatic conditions favorable for gardening, the cultivation of thermophilic cereals (wheat, corn) and industrial (sugar beets, sunflowers) crops also contribute. In connection with the insufficient amount of atmospheric precipitation and frequent droughts, irrigation systems have been built in the steppe zone.

The steppe is a zone of developed animal husbandry. Here they breed a large cattle, horses, bird. Conditions for the development of animal husbandry are favorable due to the presence of natural pastures, feed grains, waste from the processing of sunflowers and sugar beets, etc.

Various industries are developed in the steppe zone: metallurgy, mechanical engineering, food, chemical, textile.

Semi-deserts and deserts

In the southeast of the Russian Plain and on Caspian lowland there are semi-deserts and deserts.

The total solar radiation here reaches 160 kcal / cm 2. The climate is characterized by high air temperatures in summer (+22 - + 24 ° C) and low in winter (-25-30 ° C). Because of this, there is a large annual temperature range. The sum of active temperatures is 3600 ° C and more. In the zone of semi-deserts and deserts, a small amount of atmospheric precipitation falls: per year, on average, up to 200 mm. In this case, the moisture coefficient is 0.1-0.2.

The rivers located in the semi-desert and desert zones are fed almost exclusively by the spring melting of snow. Most of them flow into lakes or are lost in the sands.

Typical soils of the semi-desert and desert zone are chestnut. The amount of humus in them decreases in the directions from north to south and from west to east (this is primarily due to a gradual increase in the sparseness of vegetation in these directions), therefore, in the north and west, the soils are dark chestnut, and in the south - light chestnut ( the humus content in them is 2-3%). In the depressions of the relief, the soils are saline. There are salt marshes and solonetzes - soils, from the upper layers of which, due to leaching, a significant part of the readily soluble salts is carried away to the lower horizons.

Plants in semi-deserts are usually low, drought-resistant. The semi-deserts of the south of the country are characterized by such plant species as treelike and gnarled hodgepodge, camel thorn, and juzgun. Feather grasses and fescue are dominant on the uplands.

Steppe grasses alternate with spots of wormwood and romantic yarrow.

The deserts of the southern part of the Caspian lowland are the kingdom of semi-shrub polynyas.

For life in conditions of lack of moisture and salinization of the soil, plants have developed a number of adaptations. Solyanka, for example, has hairs and scales that protect them from excessive evaporation and overheating. Others, such as tamariks, kermek, "acquired" special salt-removing glands to remove salts. In many species, the evaporating surface of the leaves has decreased, and their pubescence has occurred.

The growing season for many desert plants is short. They manage to complete the entire development cycle for a favorable time of the year - spring.

The fauna of semi-deserts and deserts is poor in comparison with the forest zone. The most common reptiles are lizards, snakes, and turtles. There are many rodents - gerbils, jerboas and poisonous arachnids - scorpions, tarantulas, karakurt. Birds - bustard, little bustard, lark - can be seen not only in the steppes, but also in semi-deserts. Of the most large mammals note the camel, the saiga; there are korsak, wolf.

The delta of the Volga and the Akhtubinskaya floodplain are a special area in the zone of semi-deserts and deserts of Russia. It can be called a green oasis in the middle of a semi-desert. This territory is distinguished by its thickets of reed-reeds (it reaches 4-5 m in height), shrubs and shrubs (including blackberries), intertwined with climbing plants (hops, bindweed). In the creeks of the Volga delta, there are many algae, white water lilies (including the Caspian rose and water walnut preserved from the preglacial period). There are many birds among these plants, among which herons, pelicans and even flamingos stand out.

The traditional occupation of the population in the semi-desert and desert zone is cattle breeding: sheep, camels, and cattle are raised. As a result of overgrazing, the area of ​​unsecured scattered sand increases. One of the measures to combat the advance of the desert - phytomelioration - a set of measures for the cultivation and maintenance of natural vegetation. For fixing the dunes, such plant species as giant spikelet, Siberian wheatgrass, saxaul can be used.

Tundra

The vast expanses of the Arctic Ocean coastline from the Kola Peninsula to the Chukchi Peninsula are occupied tundra. The southern border of its distribution is practically owls
e falls by the July isotherm of 10 ° C. Furthest north southern border tundra moved to Siberia - north of 72 ° N latitude. In the Far East, the influence of cold seas has led to the fact that the border of the tundra reaches almost the latitude of St. Petersburg.

The tundra receives more heat than the polar desert zone. The total solar radiation is 70-80 kcal / cm 2 per year. However, the climate here continues to be characterized by low air temperatures, short summers, and severe winters. The average air temperature in January reaches -36 ° С (in Siberia). Winter lasts 8-9 months. At this time of the year, southerly winds blowing from the mainland prevail here. Summer is distinguished by an abundance of sunshine, unstable weather: strong northerly winds often blow, bringing cooling and precipitation (especially in the second half of summer there are often heavy drizzling rains). The sum of active temperatures is only 400-500 ° C. The average annual rainfall reaches 400 mm. Snow cover lasts 200-270 days a year.

The prevailing types of soils in this zone are peat-bog and slightly podzolic. Due to the spread of permafrost, which has a water-resistant property, there are many swamps here.

Since the tundra zone has a significant length from north to south, within its limits climatic conditions change markedly: from severe in the north to more moderate in the south. In accordance with this, the arctic, northern, they are also typical, and southern tundras are distinguished.

Arctic tundra occupy mainly the arctic islands. Of the vegetation, mosses, lichens predominate, flowering plants are found, in comparison with arctic deserts there are more of them. Flowering plants represented by shrubs and perennial grasses. Common willow and creeping willow, dryad (partridge grass). Of the perennial grasses, the most common are the polar poppy, small sedges, some cereals, and saxifrage.

Northern tundra distributed mainly on the mainland coast. Their important difference from the arctic ones is the presence of a closed vegetation cover. Mosses and lichens cover 90% of the soil surface. Green mosses and bushy lichens predominate; lichen is often found. Species composition flowering plants are also becoming more diverse. There are saxifrage, ozhiki, viviparous mountaineer. From shrubs - lingonberry, blueberry, wild rosemary, crowberry, as well as dwarf birch (dwarf birch), willow.

V southern tundra, as in the northern ones, the vegetation cover is continuous, but it can already be divided into tiers. The upper tier is formed by dwarf birch and willows. Medium - grasses and shrubs: crowberry, lingonberry, blueberry, wild rosemary, sedge, cloudberry, cotton grass, cereals. Lower - mosses and lichens.

The harsh climatic conditions of the tundra "forced" many plant species to "acquire" special adaptations. So, plants with creeping and creeping shoots and leaves collected in a rosette better "use" the warmer ground air layer. Short stature helps to survive harsh winter... Although due to strong winds the thickness of the snow cover in the tundra is small, it is enough to take cover and survive.

Some adaptations "serve" plants and in summer time... For example, cranberries, dwarf birch, and crowberry “struggle” to retain moisture by “reducing” the size of the leaves as much as possible, thereby reducing the evaporating surface. In dryad and polar willow, the underside of the leaf is covered with dense pubescence, which impedes the movement of air and thereby reduces evaporation.

Almost all plants in the tundra are perennial. For some species, the so-called viviparity is characteristic, when, instead of fruits and seeds, the plant has bulbs and nodules, which quickly take root, which provides a "gain" in time.

The animals and birds that constantly inhabit the tundra have also adapted well to the harsh natural conditions... They are saved by thick fur or fluffy plumage. In winter, animals are white or light gray in color, and in summer they are grayish brown. This helps to camouflage.

Typical animals of the tundra are arctic fox, lemming, white hare, reindeer, white polar and tundra partridges, snowy owl... In summer, the abundance of food (fish, berries, insects) attracts birds such as waders, ducks, geese, etc. to this natural area.

The tundra has a fairly low population density. The indigenous peoples here are the Sami, Nenets, Yakuts, Chukchi, etc. They are mainly engaged in reindeer herding. The mining of minerals is actively carried out: apatite, nepheline, non-ferrous metal ore, gold, etc.

The railway communication in the tundra is poorly developed; permafrost is an obstacle to the construction of roads.

Forest tundra

Forest tundra- transition zone from tundra to taiga. It is characterized by the alternation of areas occupied by forest and tundra vegetation.

The climate of the forest-tundra is close to that of the tundra. The main difference: the summer here is warmer - the average July temperature is + 11 (+14) ° С - and longer, but the winter is colder: the influence of the winds blowing from the mainland affects.

The trees in this zone are undersized and bent to the ground, have a curved appearance. This is due to the fact that permafrost and waterlogged soil do not allow plants to have deep roots, and strong winds bend them to the ground.

In the forest-tundra of the European part of Russia, spruce prevails, pine is less common. Larch is widespread in the Asian part. Trees grow slowly, their height usually does not exceed 7-8 m. Due to strong winds, the flag-like shape of the crowns is widespread.

The few animals that spend the winter in the forest-tundra are perfectly adapted to the local conditions. Lemmings, voles, tundra partridge make long passages in the snow, feed on leaves and stems of evergreen tundra plants. With an abundance of food, lemmings even bring offspring at this time of the year.

For small forests and the thickets of bushes along the rivers, animals from the forest zone enter the southern regions: white hare, brown bear, ptarmigan. There are wolf, fox, ermine, weasel. Small insectivorous birds fly in.

Subtropics

This zone, which occupies the Black Sea coast of the Caucasus, is characterized by the smallest extent and area in Russia.

The total solar radiation reaches 130 kcal / cm 2 per year. Summer is long, winter is warm (average January temperature is 0 ° С). The sum of active temperatures is 3500-4000 ° C. Under these conditions, many plants can develop all year round... In the foothills and on mountain slopes, 1000 mm or more of atmospheric precipitation falls per year. On flat areas, snow cover is practically not formed.

Fertile red earth and yellow earth soils are widespread.

The subtropical vegetation is rich and varied. Vegetable world represented by evergreen rigid-leaved trees and shrubs, among which we will name boxwood, laurel, cherry laurel. Oak, beech, hornbeam, maple forests are widespread. Thickets of trees intertwine with liana, ivy, wild grapes. There are bamboo, palms, cypress, eucalyptus.

Among the representatives of the animal world, we note the chamois, deer, wild boar, bear, pine and stone marten, Caucasian black grouse.

The abundance of warmth and moisture allows the cultivation of such subtropical crops as tea, tangerines, lemons. Large areas are occupied by vineyards and tobacco plantations.

Favorable climatic conditions, the proximity of the sea and mountains make this region a large recreational area of ​​our country. There are numerous camp sites, rest houses, sanatoriums.

In the tropical zone there are humid forests, savannas and woodlands, deserts.

Pretty much plowed up tropical rainforest(South Florida, Central America, Madagascar, Eastern Australia). They are usually used for plantations (see atlas map).

The subequatorial belt is represented by forests and savannas.

Subequatorial moist forests located mainly in the Ganges valley, the southern part Central Africa, on the northern coast of the Gulf of Guinea, northern South America, northern Australia and the islands of Oceania. In drier areas, they are replaced savannah(Southeast Brazil, Central and East Africa, central regions of Northern Australia, Hindustan and Indochina). Typical representatives of the fauna of the subequatorial belt are ruminants, artiodactyls, predators, rodents, and termites.

At the equator, the abundance of precipitation and heat caused the presence of a zone here evergreen moist forest(Amazon and Congo basin, on the islands South-East Asia). The natural zone of evergreen humid forests holds the world's record for the diversity of animal and plant species.

The same natural zones are found on different continents, but they have their own characteristics. First of all it comes about plants and animals that have adapted to living in these natural areas.

The natural area of ​​the subtropics is widely represented on the coast Mediterranean Sea, the southern coast of Crimea, in the southeast of the United States and in other regions of the Earth.

Western Hindustan, Eastern Australia, the Parana Basin in South America, and South Africa are zones of more arid tropical savannas and woodlands. The largest natural zone in the tropical zone - desert(Sahara, the Arabian Desert, the deserts of Central Australia, California, as well as the Kalahari, Namib, Atacama). Huge spaces of pebble, sandy, rocky and saline surfaces are devoid of vegetation. The fauna is small n.