The natural complexes of the Earth are very diverse. These are hot and icy deserts, evergreen forests, endless steppes, bizarre mountains. This diversity is the unique beauty of our planet.
You already know how natural complexes, “continents”, “oceans” were formed. But the nature of each continent, like each ocean, is not the same. Various natural zones are formed on their territory.
Theme: Nature of the Earth
Lesson: Natural areas of the Earth
Why are natural areas formed,
On the patterns of placement of natural zones,
Features of the natural zones of the continents.
Thus, the annual precipitation of 200 mm in the cold subarctic zone is excessive moisture, which leads to the formation of swamps (see Fig. 1).
And in hot tropical zones - sharply insufficient: deserts are formed (see Fig. 2).
Due to differences in the amount of solar heat and moisture within geographic zones, natural zones are formed.
In the placement of natural zones on the earth's surface, a clear pattern is visible, which can be clearly seen on the map of natural zones. They stretch in a latitudinal direction, replacing each other from north to south.
Due to the heterogeneity of the relief of the earth's surface and moistening conditions in different parts of the continents, natural zones do not form continuous bands parallel to the equator. More often they are replaced in the direction from the coasts of the oceans to the interior of the continents. In the mountains, natural zones replace each other from the foot to the peaks. This is where altitudinal zonality comes into play.
Natural zones are also formed in the World Ocean: from the equator to the poles, the properties of surface waters, the composition of vegetation and wildlife change.
Rice. 3. Natural areas of the world ()
In the same natural zones on different continents, flora and fauna have similar features.
However, in addition to climate, other factors also influence the features of the distribution of plants and animals: the geological history of the continents, relief, and people.
The unification and separation of the continents, the change in their relief and climate in the geological past have led to the fact that in similar natural conditions, but on different continents, different species of animals and plants live.
So, for example, antelopes, buffaloes, zebras, African ostriches are characteristic of the African savannas, and several species of deer and a flightless rhea bird similar to an ostrich are common in the South American savannahs.
On each continent there are endemics - both plants and animals, peculiar only to this continent. For example, kangaroos are found only in Australia, and polar bears are found only in the Arctic deserts.
Geofocus
The sun heats the spherical surface of the Earth differently: the areas above which it stands high receive the most heat.
Above the poles, the Sun's rays only glide over the Earth. The climate depends on this: hot at the equator, harsh and cold at the poles. The main features of the distribution of vegetation and fauna are also connected with this.
Moist evergreen forests are located in narrow bands and patches along the equator. "Green Hell" - this is what many travelers of past centuries called these places, who had to be here. High multi-tiered forests stand like a solid wall, under the dense crowns of which darkness constantly reigns, monstrous humidity, constant high temperature, there is no change of seasons, downpours regularly fall in an almost continuous stream of water. The forests of the equator are also called permanently rainy. The traveler Alexander Humboldt called them "hylaea" (from the Greek hyle - forest). Most likely, this is what the humid forests of the Carboniferous period looked like with giant ferns and horsetails.
The rainforests of South America are called "selva" (see Fig. 4).
Rice. 4. Selva
Savannahs are a sea of grasses with occasional islands of trees with umbrella crowns (see Fig. 5). Vast expanses of these amazing natural communities are found in Africa, although there are savannahs in South America, Australia, and India. A distinctive feature of the savannas is the alternation of dry and wet seasons, which take about half a year, replacing each other. The fact is that for the subtropical and tropical latitudes, where the savannahs are located, the change of two different air masses is characteristic - humid equatorial and dry tropical. Monsoon winds, bringing seasonal rains, significantly affect the climate of the savannahs. Since these landscapes are located between the very humid natural zones of the equatorial forests and the very dry zones of the deserts, they are constantly influenced by both. But moisture is not present in the savannas long enough for multi-tiered forests to grow there, and dry "winter periods" of 2-3 months do not allow the savannah to turn into a harsh desert.
The natural zone of the taiga is located in the north of Eurasia and North America (see Fig. 6). On the North American continent, it stretches from west to east for more than 5 thousand km, and in Eurasia, originating in the Scandinavian Peninsula, it spread to the shores of the Pacific Ocean. The Eurasian taiga is the largest continuous forest zone on Earth. It occupies more than 60% of the territory of the Russian Federation. The taiga contains huge reserves of wood and supplies a large amount of oxygen to the atmosphere. In the north, the taiga smoothly turns into the forest-tundra, gradually the taiga forests are replaced by light forests, and then by separate groups of trees. The furthest taiga forests enter the forest-tundra along river valleys, which are most protected from strong northern winds. In the south, the taiga also smoothly turns into coniferous-deciduous and broad-leaved forests. For many centuries, humans have interfered with natural landscapes in these areas, so now they are a complex natural-anthropogenic complex.
Under the influence of human activity, the geographical envelope is changing. Swamps are being drained, deserts are being irrigated, forests are disappearing, and so on. Thus, the appearance of natural areas is changing.
Homework
Read § 9. Answer the questions:
What determines the moisture content of an area? How do different moisture conditions affect natural complexes?
Are there natural areas in the ocean?
Bibliography
MainI
1. Geography. Earth and people. Grade 7: Textbook for general education. uch. / A.P. Kuznetsov, L.E. Savelyeva, V.P. Dronov, "Spheres" series. - M.: Education, 2011.
2. Geography. Earth and people. Grade 7: atlas, series "Spheres".
Additional
1. N.A. Maksimov. Behind the pages of a geography textbook. - M.: Enlightenment.
Literature for preparing for the GIA and the Unified State Examination
1. Tests. Geography. Grades 6-10: Teaching aid / A. A. Letyagin. - M .: LLC "Agency" KRPA "Olimp": Astrel, AST, 2007. - 284 p.
2. Study guide for geography. Tests and practical tasks in geography / I. A. Rodionova. - M.: Moscow Lyceum, 1996. - 48 p.
3. Geography. Answers on questions. Oral exam, theory and practice / V. P. Bondarev. - M.: Publishing house "Exam", 2009. - 160 p.
4. Thematic tests to prepare for the final certification and the exam. Geography. - M.: Balass, ed. House of RAO, 2011. - 160 p.
1. Russian Geographical Society ().
3. Study guide for geography ().
4. Geographical directory ().
5. Geological and geographical formation ().
Depending on the ratio of heat and moisture, natural systems (complexes), which form latitudinal divisions - natural areas(Fig. 187). Within the natural zone, all components are closely interconnected with each other, ensuring its integrity and originality.
Creator of the doctrine of natural zones V. V. Dokuchaev proved that zoning is inherent not only in individual components, but in all of nature as a whole. Each natural zone is a complex of interconnected components - a geographical system. Thus, zonality is a universal law of nature.
When moving from north to south, we observe a consistent change in natural zones: Arctic deserts , tundra , forest-tundra , taiga , mixed and wide-quantity forests , forest-steppe , steppes , semi-deserts , desert , subtro peaks. They tend to run in bands from west to east, although other directions are also found.
In the mountains, the ratio of heat and moisture changes with height, which leads to a change in soil, flora and fauna. Observed altitudinal zoning (zonation).
| Rice. 187. Natural areas of Russia |
Within the natural zone, similarities can be traced not only in climate, soil and vegetation cover and wildlife, but also in surface and ground waters, modern processes of relief formation, and the overall stability of the landscape to anthropogenic impact.
Living conditions for the population in natural areas differ in varying degrees of favorableness. Because of this, natural areas are developed unequally. The economic development of the landscapes of the more southern zones was more intensive and generally more uniform, while the forest-tundra and tundra located to the north are distinguished by the focal nature of development (for example, in mining areas).
The natural conditions of different natural zones influenced the direction of their economic development. This especially affected the types and methods of farming, crafts, and recreation. In the agricultural steppe regions, the main breadbasket, crops of cereals (wheat, barley), as well as sugar beet, corn, and sunflower are of great importance. Centuries-old traditions of a certain craft provide high quality products.
Natural areas are distinguished by a different set of grain, technical and fruit crops. For example, in the forest zone, crafts associated with woodworking have long been developed.
The Khokhloma craft (Nizhny Novgorod region) enjoys well-deserved fame in Russia and abroad - the manufacture and artistic processing of wooden dishes. Its uniqueness lies in the fact that the technique of painting wood in gold color goes without the cost of precious metal. She uses the techniques of icon painting of the 12th-13th centuries, which came here with the schismatics. The art of Khokhloma is a fusion of the traditions of folk crafts and ancient painting.
Zoning was reflected in the way of life of people, household and economic buildings, costume, customs, and spiritual heritage. So, in the zone of taiga and coniferous-deciduous forests with long severe winters, warm housing, clothing, food and fodder for livestock were needed for a long period. Large houses were built with spacious yards, barns, cellars, storerooms. The wooden structures of the huts, which are distinguished by high hygienic qualities, kept warm and protected from dampness. material from the site
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| Rice. 191. Russian hut |
Human activity has significantly changed the original natural appearance of natural areas. It is significant that the nature has changed not only in the long-established zones with a favorable climate, but also in unfavorable for life landscapes of the tundra, forest-tundra, as well as the taiga regions of Siberia and the Far East in Russia. Therefore, today it is more correct to speak not about natural, but about natural and economic zones. Natural economic zones were formed on the basis of natural natural zones under the influence of human transformative activity.
Natural zones are an expression of the law of geographical zoning. Their formation is determined by differences in the flow of heat and moisture and is manifested in all natural components. Zonal landscapes influence the way of life and occupations of the population living here. Under the influence of economic activity, natural geosystems have undergone significant changes and turned into natural economic zones.
On this page, material on the topics:
Zoning of ecosystems in the Tyumen region abstract
Report on Natural Areas
What is the natural zonality of Russia
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The natural complexes of the Earth are very diverse. These are hot and icy deserts, evergreen forests, endless steppes, bizarre mountains, etc. This diversity is the unique beauty of our planet. You already know how the natural complexes "mainland" and "ocean" were formed. But the nature of each continent, like each ocean, is not the same. In their territories there are various natural zones.
A natural zone is a large natural complex with a common temperature and moisture conditions, soils, vegetation and wildlife. The formation of zones is due to climate, on land - the ratio of heat and moisture. So, if there is a lot of heat and moisture, that is, high temperatures and a lot of precipitation, a zone of equatorial forests is formed. If the temperatures are high, and there is little precipitation, then a zone of deserts of the tropical belt is formed.
Natural areas of land outwardly differ from each other in the nature of vegetation. Of all the components of nature, the vegetation of the zones most clearly expresses all the most important features of their nature, the relationship between the components. If there are changes in individual components, then outwardly this affects primarily the change in vegetation. The names of the natural zones of the land were received according to the nature of the vegetation, for example, zones of deserts, equatorial forests, etc.
There are also natural zones (natural belts) in the World Ocean. They differ in water masses, organic world, etc. The natural zones of the ocean do not have clear external differences, with the exception of the ice cover, and are named according to their geographical location, like climatic zones.
In the placement of natural zones on the earth's surface, scientists have found a clear pattern, which can be clearly seen on the map of natural zones. To understand this regularity, let us trace the change of natural zones on the map from north to south along 20°E. e. In the subarctic zone, where temperatures are low, there is a zone of tundra and forest-tundra, which gives way to taiga to the south. There is enough heat and moisture for the growth of coniferous trees. In the southern half of the temperate zone, the amount of heat and precipitation increases significantly, which contributes to the formation of a zone of mixed and broad-leaved forests. Somewhat to the east, the amount of precipitation decreases, so the steppe zone is located here. On the Mediterranean coast in Europe and Africa, the Mediterranean climate dominates with dry summers. It favors the formation of a zone of hard-leaved evergreen forests and shrubs. Then we get into the tropical zone. Here, in the expanses scorched by the sun, it is hot, the vegetation is sparse and stunted, in some places it is completely absent. This is a tropical desert zone. To the south, it is replaced by savannas - tropical forest-steppes, where there is already a wet season of the year and a lot of heat. But the amount of rainfall is not enough for the growth of the forest. In the equatorial climatic zone there is a lot of heat and moisture, therefore a zone of humid equatorial forests with very rich vegetation is formed. In South Africa, zones, like climatic zones, are repeated.
In Antarctica, there is a zone of the Antarctic desert, characterized by exceptional severity: very low temperatures and strong winds.
So, you, apparently, were convinced that the alternation of natural zones on the plains is explained by a change in climatic conditions - geographical latitude. However, scientists have long noted that natural conditions change not only when moving from north to south, but also from west to east. To confirm this idea, let us follow the map of the change of zones in Eurasia from west to east along the 45th parallel - in the temperate zone.
On the coast of the Atlantic Ocean, where sea air masses coming from the ocean dominate, there is a zone of broad-leaved forests, beech, oak, linden, etc. grow. When moving east, the forest zone is replaced by a zone of forest-steppes and steppes. The reason is the decrease in rainfall. Even farther to the east, precipitation becomes less and the steppes turn into deserts and semi-deserts, which further to the east are again replaced by steppes, and near the Pacific Ocean - by a zone of mixed forests. These coniferous-deciduous forests amaze with their richness and diversity of plant and animal species.
What explains the alternation of zones at the same latitude? Yes, all the same reasons - a change in the ratio of heat and moisture, which is determined by the proximity or remoteness of the direction of the prevailing winds. There are changes at the same latitudes and in the ocean. They depend on the interaction of the ocean with land, the movement of air masses, currents.
The location of natural zones is closely related to climatic zones. Like climatic zones, they naturally replace each other from the equator to the poles due to a decrease in solar heat entering the Earth's surface and uneven moistening. Such a change in natural zones - large natural complexes is called latitudinal zonality. Zoning is manifested in all natural complexes, regardless of their size, as well as in all components of the geographical envelope. Zoning is the main geographical pattern.
The change of natural zones, as you know, occurs not only on the plains, but also in the mountains - from the foot to their peaks. With altitude, temperature and pressure decrease, up to a certain height, the amount of precipitation increases, and lighting conditions change. In connection with the change in climatic conditions, there is also a change in natural zones. The zones replacing one another, as it were, encircle mountains at different heights, which is why they are called high-altitude belts. The change of altitudinal belts in the mountains occurs much faster than the change of zones on the plains. It is enough to climb 1 km to be convinced of this.
The first (lower) altitudinal belt of mountains always corresponds to the natural zone in which the mountain is located. So, if the mountain is located in the taiga zone, then when climbing to its top you will find the following altitudinal belts: taiga, mountain tundra, eternal snow. If you have to climb into the Andes near the equator, then you will start your journey from the belt (zone) of equatorial forests. The pattern is as follows: the higher the mountains and the closer they are to the equator, the more altitudinal zones and the more diverse they are. In contrast to zonality on the plains, the alternation of natural zones in the mountains is called altitudinal zonality or altitudinal zonality.
The law of geographical zonality also manifests itself in mountainous areas. Some of them we have already considered. Also, the change of day and night, seasonal changes depend on the geographical latitude. If the mountain is near the pole, then there is a polar day and a polar night, a long winter and a short cold summer. In the mountains at the equator, day is always equal to night, there are no seasonal changes.
1. Natural complexes are very diverse. Which of them are called natural areas?
The natural complex of land, as well as the complex of the geographic envelope as a whole, is a heterogeneous formation and includes natural complexes of lower ranks, which differ in the quality of the natural components that make up the complex. Such lower ranks are natural areas. Having studied the map of natural zones, you will be able to independently name these natural zones and trace the patterns of their placement.
2. Highlight the main features of the concept of "natural zone".
Each natural zone differs from others in the quality of its constituent soils, flora and fauna. And the quality of these components, in turn, depends on the characteristics of the climate, the totality of the received light, heat and moisture.
3. What are the features of the placement of natural zones on the continents and in the ocean?
The boundaries of natural zones on land are most clearly traced by the nature of the vegetation. It is no coincidence that vegetation is taken as the basis for the name of natural land areas.
Natural zones are also distinguished in the World Ocean, but the boundaries of these zones are less clear, and the division into zones in the ocean is based on the qualitative characteristics of water masses (salinity, temperature, transparency, etc.).
4. What is latitudinal zonality and altitudinal zonality?
The regularity with which natural zones are located on the surface of the Earth is called latitudinal zonality. The change in the quality of the components that make up the natural zone occurs depending on their geographical location, especially on the geographical latitude, on which the amount of heat and moisture received depends.
In the mountains, in contrast to the flat territories, natural zones change with height. The change in natural zones from the foot of mountains to their peaks is similar to the change in natural zones from the equator to the poles. The pattern of changes in natural zones with height in the mountains is called altitudinal zonation or altitudinal zonality.
5. Which mountains have the largest number of altitudinal zones, which have the least? Why?material from the site
The number of natural zones in the mountains depends on the geographical position of the mountains in relation to the equator and on their height. On the southern slopes of the Himalayas, almost all natural zones are replaced: from humid equatorial zones at the foot to arctic deserts at the peaks. In mountains located at higher latitudes, the number of natural zones will be less. Thus, one can trace the relationship that exists between the number of natural zones in the mountains and the geographical position of the mountains in relation to the equator. The reason for this regularity is in the amount of heat and moisture received.
Zoning - change in natural components and the natural complex as a whole from the equator to the poles. The basis of zonality is the different supply of heat, light, and precipitation to the Earth, which, in turn, is already reflected in all other components, and above all, soils, vegetation, and wildlife.
Zoning is characteristic of both land and the oceans.
The largest zonal divisions of the geographical shell - geographic zones. 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).
Within 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 wildlife.
You are already familiar with the arctic desert zone, tundra, temperate forest zone, steppes, deserts, wet and dry subtropics, savannahs, humid equatorial evergreen forests.
Within natural zones, transitional areas are distinguished. They are formed as a result of gradual changes in climatic conditions. Such transitional zones include, for example, forest-tundra, forest-steppes and semi-deserts.
Zoning is not only latitudinal, but also vertical. Vertical zonality is a regular change in natural complexes in height and depth. For mountains, the main cause of this zonality is the change in temperature and amount of moisture 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, altitudinal zonation.
It differs from horizontal zonality in the length of belts and the presence of a belt of alpine and subalpine meadows. The number of belts usually increases in high mountains and as we approach the equator.
natural areas
natural areas- large subdivisions of the geographical envelope, which have a certain combination of temperature conditions and moisture regime. They are classified mainly according to the prevailing type of vegetation and regularly change in the plains from north to south, and in the mountains - from the foot to the peaks. The natural zones of Russia are shown in fig. one.
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's surface at different latitudes.
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.
Let us consider in more detail the features of the placement of natural zones on the example of the territory of our country.
polar desert
The very north of our country - the islands of the Arctic Ocean - are located in the natural zone polar (arctic) deserts. This area is also called ice zone. The southern boundary roughly coincides with the 75th parallel. The natural zone is characterized by the dominance of arctic air masses. The total solar radiation is 57-67 kcal/cm2 per year. Snow cover lasts 280-300 days a year.
In winter, the polar night dominates here, which at a latitude of 75 ° N. sh. lasts 98 days.
In summer, even round-the-clock lighting is not able to provide enough heat to this area. The air temperature rarely rises above 0 °C, and the average July temperature is +5 °C. For several days there may be drizzling precipitation, but there are practically no thunderstorms and showers. But there are frequent fogs.
Rice. 1. Natural areas of Russia
A significant part of the territory is characterized by modern glaciation. There is no continuous vegetation cover. The near-glacial areas of land on which vegetation develops are small areas. On placers of pebbles, fragments of basalt and boulders, mosses and scale lichens “settle”. Occasionally there are poppies and saxifrages that begin to bloom when the snow barely has 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, white whale, porpoise, killer whale.
Species of baleen whales are diverse in the northern seas. Blue and bowhead whales, sei whale, fin whale, humpback whale are rare and endangered species and are listed in the Red Book. The inner side of the long horny plates that replace the teeth of whales is split into hairs. This allows the animals to filter large volumes of water, harvesting the plankton that forms the basis of their diet.
The polar bear is also a typical representative of the animal world of the polar desert. The "maternity hospitals" of polar bears are located on Franz Josef Land, Novaya Zemlya, about. Wrangel.
In summer, numerous colonies of birds nest on the rocky islands: gulls, guillemots, guillemots, auks, etc.
There is practically no permanent population in the polar desert zone. The meteorological stations operating here monitor the weather and the movement of ice in the ocean. On the islands, foxes are hunted in winter and game birds in summer. Fishing is carried out in the waters of the Arctic Ocean.
steppes
Steppes extend 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 a patchy distribution.
The climate of the steppes is temperate continental, but drier than in the zone of forests and forest-steppes. The amount of annual total solar radiation reaches 120 kcal/cm 2 . The average January temperature in the west is -2 °С, and in the east -20 °С and lower. Summer in the steppe is sunny and hot. The average temperature in July is 22-23 °С. The sum of active temperatures is 3500 °C. Precipitation falls 250-400 mm per year. Showers are frequent in summer. The moisture coefficient is less than unity (from 0.6 in the north of the zone to 0.3 in the southern steppes). Steady snow cover lasts up to 150 days a year. In the west of the zone, thaws often occur, so the snow cover there is thin and very unstable. The predominant soils of the steppes are chernozems.
Natural plant communities are represented mainly by perennial, drought- and frost-resistant herbs with a strong root system. First of all, these are cereals: feather grass, fescue, wheatgrass, snake, thin-legged, bluegrass. In addition to cereals, there are numerous representatives of herbs: astragalus, sage, cloves - and bulbous perennials, such as tulips.
The composition and structure of plant communities change significantly both in the latitudinal and in the meridional direction.
In the European steppes, narrow-leaved grasses form the basis: feather grass, fescue, bluegrass, fescue, thin-legged, etc. There are many brightly flowering herbs. In summer, like waves in the sea, feather grass sways, here and there you can see lilac irises. In the drier southern regions, in addition to cereals, wormwood, thorax, and cinquefoil are common. Lots of tulips in spring. In the Asian part of the country, tansy and cereals predominate.
Steppe landscapes are fundamentally different from forest ones, which determines the uniqueness of the animal world of this natural zone. Typical animals of this zone are rodents (the most numerous group) and ungulates.
Ungulates are adapted to long-term movements across the vast expanses of the steppes. Due to the thinness of the snow cover, plant food is also available in winter. An important role in nutrition is played by bulbs, tubers, rhizomes. For many animals, plants are also the main source of moisture. Typical representatives of ungulates in the steppes are tours, antelopes, tarpans. However, most of these species were exterminated or driven south as a result of human economic activity. In some areas, saigas, which were widely distributed in the past, have been preserved.
Of the rodents, the most common are ground squirrel, vole, jerboa, etc.
The polecat, badger, weasel, and fox also live in the steppe.
Of the birds, the bustard, little bustard, gray partridge, steppe eagle, buzzard, kestrel are typical for the steppes. However, 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, muzzle.
The wealth 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, climate conditions favorable for horticulture, the cultivation of heat-loving grains (wheat, corn) and industrial (sugar beet, sunflower) crops also contribute to agriculture. Due to insufficient precipitation and frequent droughts, irrigation systems have been built in the steppe zone.
The steppes are a zone of developed animal husbandry. Cattle, horses, poultry are bred here. Conditions for the development of animal husbandry are favorable due to the presence of natural pastures, fodder grain, waste from the processing of sunflowers and sugar beets, etc.
Various branches of industry are developed in the steppe zone: metallurgy, mechanical engineering, food, chemical, textile.
Semi-deserts and deserts
Semi-deserts and deserts are located in the southeast of the Russian Plain and in the Caspian lowland.
The total solar radiation here reaches 160 kcal/cm 2 . The climate is characterized by high air temperatures in summer (+22 - +24 °С) and low in winter (-25-30 °С). Because of this, there is a large annual temperature amplitude. The sum of active temperatures is 3600 °C and more. In the zone of semi-deserts and deserts, a small amount of precipitation falls: an average of up to 200 mm per year. In this case, the moisture coefficient is 0.1-0.2.
The rivers located in the zone of semi-deserts and deserts are fed almost exclusively by the spring melting of snow. A significant part of them flows into lakes or is lost in the sands.
Typical soils of the semi-desert and desert zone are chestnut. The amount of humus in them decreases in 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 content of humus in them is 2-3%. In depressions of the relief, the soils are saline. There are solonchaks and solonetzes - soils, from the upper layers of which, due to leaching, a significant part of the easily soluble salts has been 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 tree-like and clumsy saltwort, camel's thorn, and juzgun. On the hills, feather grass and fescue dominate.
Steppe grasses alternate with patches of wormwood and romance of 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 salinity of the soil, plants have developed a number of adaptations. Solyanka, for example, have hairs and scales that protect them from excessive evaporation and overheating. Others, such as tamarix, kermek, “acquired” special salt-removing glands to remove salts. In many species, the evaporative 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 in a favorable time of the year - spring.
The fauna of semi-deserts and deserts is poor compared to the forest zone. The most common reptiles are lizards, snakes, turtles. There are many rodents - gerbils, jerboas and poisonous arachnids - scorpions, tarantulas, karakurts. Birds - bustard, little bustard, lark - can be seen not only in the steppes, but also in semi-deserts. Of the largest mammals, we note the camel, saiga; there is a corsac, a wolf.
A special area in the zone of semi-deserts and deserts of Russia are the Volga delta and the Akhtuba floodplain. It can be called a green oasis among the semi-desert. This area stands out for its thickets of reed-reeds (it reaches a height of 4-5 m), shrubs and shrubs (including blackberries), intertwined with climbing plants (hops, bindweed). In the backwaters of the Volga delta there are many algae, white water lilies (including the Caspian rose and water chestnut preserved from the pre-glacial period). Among these plants there are many birds, among which herons, pelicans and even flamingos stand out.
The traditional occupation of the population in the zone of semi-deserts and deserts is cattle breeding: they breed sheep, camels, and cattle. As a result of overgrazing, the area of unfixed windblown sands is increasing. One of the measures to combat the onset of the desert is phytomelioration - a set of measures for the cultivation and maintenance of natural vegetation. To fix the dunes, plant species such as giant grate, Siberian wheatgrass, and saxaul can be used.
Tundra
Huge expanses of the coast of the Arctic Ocean from the Kola Peninsula to the Chukotka are occupied tundra. The southern border of its distribution is practically owls
falls e by the July isotherm of 10 °C. Farthest to the north, the southern border of the tundra moved away in Siberia - north of 72 ° N. In the Far East, the influence of cold seas has led to the fact that the tundra border 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/cm2 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 dominate here. Summer is characterized by an abundance of sunlight, 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 predominant types of soils in this zone are peat-bog and weakly 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, arctic, northern, they are also typical, and southern tundras are distinguished.
arctic tundra occupy mainly the arctic islands. The vegetation is dominated by mosses, lichens, there are flowering plants, in comparison with the Arctic deserts there are more of them. Flowering plants are represented by shrubs and perennial herbs. Polar and creeping willow, dryad (partridge grass) are common. Of the perennial grasses, the most common are the polar poppy, small sedges, some grasses, 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, moss is often found. The species composition of flowering plants is also becoming more diverse. There are saxifrages, ozhiki, highlander viviparous. Of the shrubs - lingonberries, blueberries, ledum, crowberry, as well as dwarf birch (dwarf birch), willows.
AT 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 - herbs 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" a warmer ground layer of air. Short stature helps to survive the harsh winter. Although due to strong winds, the thickness of the snow cover in the tundra is small, it is enough to cover and survive.
Some devices "serve" plants in the summer. For example, cranberries, dwarf birch, crowberry “fight” for moisture retention by “reducing” the size of the leaves as much as possible, thereby reducing the evaporating surface. In the dryad and the 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 live birth is characteristic, when instead of fruits and seeds, bulbs and nodules appear in the plant, which quickly take root, which provides a “gain” in time.
Animals and birds permanently living in 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. It helps to disguise.
Typical animals of the tundra are arctic fox, lemming, white hare, reindeer, white and tundra partridge, snowy owl. In summer, the abundance of food (fish, berries, insects) attracts such birds as waders, ducks, geese, etc. to this natural area.
The tundra has a relatively low population density. The indigenous peoples here are the Saami, Nenets, Yakuts, Chukchi, etc. They are mainly engaged in reindeer herding. The extraction of minerals is actively carried out: apatites, nephelines, non-ferrous metal ores, gold, etc.
Railway communication in the tundra is poorly developed, and permafrost is an obstacle to the construction of roads.
forest tundra
forest tundra- transitional 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 the climate of the tundra. The main difference: the summer here is warmer - the average July temperature is + 11 (+14) ° С - and long, but the winter is colder: the influence of the winds blowing from the mainland affects.
The trees in this zone are stunted and bent to the ground, with a twisted appearance. This is due to the fact that permafrost and waterlogging of the 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 predominates, and pine is less common. In the Asian part, larch is common. Trees grow slowly, their height usually does not exceed 7-8 m. Due to strong winds, a flag-shaped crown shape is common.
The few animals that remain in the forest-tundra to spend the winter are perfectly adapted to local conditions. Lemmings, voles, tundra partridge make long passages in the snow, feed on the leaves and stems of evergreen tundra plants. With an abundance of food, lemmings even bring offspring at this time of the year.
Animals from the forest zone enter the southern regions through small forests and bushes along the rivers: mountain 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 length and area in Russia.
The value of total solar radiation reaches 130 kcal/cm2 per year. Summer is long, winter is warm (average January temperature is 0 °C). The sum of active temperatures is 3500-4000 °C. In these conditions, many plants can develop all year round. In the foothills and on the mountain slopes, 1000 mm or more of precipitation falls annually. In the flat areas, snow cover is practically not formed.
Fertile red earth and yellow earth soils are widespread.
Subtropical vegetation is rich and varied. The flora is represented by evergreen hard-leaved trees and shrubs, among which we will name boxwood, laurel, laurel cherry. Widespread forests of oak, beech, hornbeam, maple. Thickets of trees intertwine liana, ivy, wild grapes. There are bamboo, palm trees, cypress, eucalyptus.
Of the representatives of the animal world, we note the chamois, deer, wild boar, bear, pine and stone marten, Caucasian black grouse.
The abundance of heat and moisture makes it possible to grow such subtropical crops here as tea, tangerines, and lemons. Significant areas are occupied by vineyards and tobacco plantations.
Favorable climatic conditions, proximity to the sea and mountains make this area a major recreational area of our country. Numerous camp sites, rest houses, sanatoriums are located here.
In the tropical zone there are moist forests, savannahs and light forests, deserts.
Largely open tropical rainforests(South Florida, Central America, Madagascar, Eastern Australia). They are used, as a rule, for plantations (see map of the atlas).
The subequatorial belt is represented by forests and savannahs.
Subequatorial moist forests located mainly in the Ganges valley, southern Central Africa, on the northern coast of the Gulf of Guinea, northern South America, in Northern Australia and on the islands of Oceania. In drier areas they are replaced savannas(Southeast Brazil, Central and East Africa, central regions of Northern Australia, Hindustan and Indochina). Characteristic representatives of the animal world of the subequatorial belt are ruminant artiodactyls, predators, rodents, termites.
At the equator, an abundance of precipitation and high temperatures led to the presence of a zone here evergreen rainforests(Amazon and Congo basin, on the islands of Southeast Asia). The natural area of evergreen moist forests holds the world record for the diversity of animal and plant species.
The same natural areas are found on different continents, but they have their own characteristics. First of all, we are talking about plants and animals that have adapted to the existence in these natural areas.
The natural zone of the subtropics is widely represented on the coast of the 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 Paraná basin in South America and South Africa are areas of distribution of more arid tropical savannas and woodlands. The most extensive natural zone of the tropical belt - desert(Sahara, Arabian desert, deserts of Central Australia, California, as well as the Kalahari, Namib, Atacama). Huge expanses of pebbly, sandy, rocky and saline surfaces are devoid of vegetation here. The animal world is small.
