The geographic envelope is not tripled in the same way everywhere, it has a "mosaic" structure and consists of separate natural complexes (landscapes). Natural complex - it is a part of the earth's surface with relatively homogeneous natural conditions: climate, topography, soils, waters, flora and fauna.
Each natural complex consists of components between which there are close, historically established relationships, while a change in one of the components sooner or later leads to a change in others.
The largest, planetary natural complex is the geographic shell; it is subdivided into natural complexes of a smaller rank. The division of the geographic shell into natural complexes is due to two reasons: on the one hand, differences in the structure of the earth's crust and the heterogeneity of the earth's surface, and on the other hand, the unequal amount of solar heat received by its various parts. In accordance with this, zonal and azonal natural complexes are distinguished.
The largest azonal natural complexes are continents and oceans. Smaller - mountainous and flat areas within the continents (West Siberian Plain, Caucasus, Andes, Amazonian lowland). The latter are subdivided into even smaller natural complexes (Northern, Central, Southern Andes). Natural complexes of the lowest rank include individual hills, river valleys, their slopes, etc.
The largest of the zonal natural complexes - geographic zones. They coincide with climatic zones and have the same names (equatorial, tropical, etc.). In turn, geographical zones consist of natural zones, which are distinguished by the ratio of heat and moisture.
natural area called a large land area with similar natural components - soils, vegetation, wildlife, which are formed depending on the combination of heat and moisture.
The main component of the natural zone is the climate, because all other components depend on it. Vegetation has a great influence on the formation of soils and wildlife and is itself dependent on soils. Natural zones are named according to the nature of the vegetation, since it most obviously reflects other features of nature.
The climate naturally changes as you move from the equator to the poles. Soil, vegetation and wildlife are determined by climate. This means that these components should change latitudinally, following climate change. The regular change of natural zones when moving from the equator to the poles is called latitudinal zonation. Moist equatorial forests are located near the equator, and icy Arctic deserts are located near the poles. Between them are other types of forests, savannas, deserts, tundra. Forest zones, as a rule, are located in areas where the ratio of heat and moisture is balanced (equatorial and most of the temperate zone, the eastern coasts of the continents in the tropical and subtropical zone). Treeless zones are formed where there is a lack of heat (tundra) or moisture (steppes, deserts). These are the continental regions of the tropical and temperate zones, as well as the subarctic climatic zone.
The climate changes not only latitudinally, but also due to changes in altitude. As you climb up the mountains, the temperature drops. Up to a height of 2000-3000 m, the amount of precipitation increases. A change in the ratio of heat and moisture causes a change in the soil and vegetation cover. Thus, unequal natural zones are located in the mountains at different heights. This pattern is called altitudinal zonation.
The change of altitudinal belts in the mountains occurs approximately in the same sequence as on the plains, when moving from the equator to the poles. At the foot of the mountains there is a natural zone in which they are located. The number of altitudinal belts is determined by the height of the mountains and their geographical position. The higher the mountains, and the closer they are to the equator, the more diverse the set of altitudinal zones. The most complete vertical zonality is expressed in the Northern Andes. Moist equatorial forests grow in the foothills, then there is a belt of mountain forests, and even higher - thickets of bamboos and tree-like ferns. With an increase in altitude and a decrease in average annual temperatures, coniferous forests appear, which are replaced by mountain meadows, often turning, in turn, into stony placers covered with moss and lichens. The tops of the mountains are crowned with snow and glaciers.
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Under latitudinal zonality(geographical, landscape) understand the regular change in the physical and geographical processes of natural components, as well as the NTC from the equator to the poles. The main reason for zoning is the uneven distribution of the short-wave radiation of the Sun over latitude, due to the sphericity of the Earth. Therefore, two conditions are sufficient for latitudinal zonality:
Uneven distribution of solar radiation
The sphericity of the earth
The latitudinal distribution of solar radiation is not always subject to mathematical calculations. For each of the latitudes, there are also calculations that clearly show a decrease in the number towards the poles. The distribution of solar energy depends on astronomical quantities:
Distance to the sun. The earth is well positioned in relation to the sun.
Earth mass affects the nature of the zoning. The mass of the earth holds the atmosphere with the help of the core, in which there is a lot of metal, and the atmosphere redistributes the radiant energy. The moon is devoid of atmosphere.
The inclination of the earth's axis to the plane of the ecliptic (66.5 o). This angle determines the uneven distribution of solar energy over the seasons, which complicates the zonal distribution of heat and moisture and sharpens zonal contrasts. If the earth's axis were perpendicular to the plane of the ecliptic, then each parallel would receive almost the same amount of solar heat throughout the year, and seasonal phenomena would not appear.
Earth's daily rotation causes the deviation of moving bodies, including air masses in the northern hemisphere - to the right, and in the southern hemisphere - to the left (Coriolis force).
The heterogeneous structure of the Earth the presence of continents, large and small islands, oceans, water areas, a variety of rocks (by strength - rocks and loose rocks), a variety of land relief, covering the territory with glaciers, all this causes disturbances in the distribution of solar energy.
Consequently, the mechanism of geographic zonality is very complex and manifests itself ambiguously in different parts of the geographic envelope, in its various components and constituent parts, as well as in various processes occurring within the geographic envelope.
The first result of the zonal distribution of radiant energy is the ZONALITY of the RADIATION BALANCE on the Earth's surface. The maximum of total radiation falls on the 20-30th latitudes in both hemispheres, because the atmosphere here is transparent, the radiant energy entering the Earth's surface and converted into thermal energy is spent on evaporation and heat transfer to the atmosphere. Another important regularity that depends on the uneven distribution of heat is the AIR MASS ZONALITY, ATMOSPHERIC CIRCULATION AND MOISTURE CYCLE.
Air masses:
Equatorial (warm and humid)
Tropical (warm and dry)
Moderate (dry and wet, cool)
Antarctic, arctic (cold, dry)
Air masses heat up differently, therefore, they have different densities and there is a violation of thermodynamic equilibrium in the troposphere and, as a result, the circulation of air masses. If the Earth did not rotate around its axis, then the circulation of air masses would be primitive, i.e. in the northern hemisphere, air masses would have a direction from north to south, and in the southern hemisphere, from south to north. But as a result of the Coriolis force, circulation zones are formed, which correspond to the zonal types of air masses:
equatorial zone- low pressure, ascending air currents, calm prevails.
tropical zone- high pressure, the predominance of the eastern rhumb of air masses, which change in the northern hemisphere to the northeast, and in the south - to the southeast.
temperate zone– low pressure, western air transport.
polar zone- low pressure, easterly winds.
Transition zones: subarctic, subtropical, subequatorial. In which in summer the circulation shifts in accordance with the hemisphere to the pole, and in winter to the equator. In landscape science, 7 circulation zones are distinguished.
Atmospheric circulation is a mechanism for the redistribution of heat and moisture. If this regularity did not exist, then on the globe there would be sharp boundaries between all zonal, temperature differences. The zonal distribution of solar heat is reflected by the distribution of the planet's thermal zones:
Hot– average annual temperature >20 o
2 moderate
2 cold when the temperature of the warmest month< +10 о.
Inside the cold belt, areas of eternal frost (ice zones) are distinguished when the temperature of the warmest month is below 0.
Zonal circulation of the atmosphere is associated with moisture and moisture circulation. Moisture circulation and humidification have their own zonal specifics when maxima are distinguished in the distribution of precipitation (usually there are 3 of them) - one at the equator, 2 in temperate latitudes. 4 minima - 2 in the polar latitudes, 2 in the tropics. The amount of precipitation does not determine the conditions for the moisture supply of landscapes (in the steppes up to 500 mm, but moisture is insufficient, and in the tundra 300-350 mm, moisture is excessive). Therefore, the moisture content is affected by the moisture coefficient.
The relief is also subject to zonality, but mainly morphosculptural types of relief, which are formed under the influence of exogenous processes, and they do not appear everywhere in the same way, depending on climatic conditions. Groundwater is also subject to the process of zonality. At the same depth, for example, they are located in the zone of broad-leaved foxes and steppes, they can differ in different degrees of mineralization, which are determined by different ways of feeding groundwater, different degrees of evaporation. Thus, zoning is a universal geographical regularity, which manifests itself in all landscape-forming processes and in the distribution of natural complexes on the earth's surface.
Zoning must be considered in historical terms, because. it has evolved over hundreds of millions of years of geological history. The most ancient are the equatorial landscapes, which have existed since the middle of the Paleozoic. Many landscapes were influenced by the Paleogene-Neogene stages of development, especially in temperate latitudes. Pleistocene glaciation, when periods of glacial and interglacial periods were observed, the boundaries of landscapes shifted. The youngest natural zone yavl. Tundra zone. When considering the patterns of latitudinal zonality, the most important factor is macroclimatic conditions. The most inert factor is the geological structure and relief.
Types and classes of landscapes
The type of landscapes depends on zonal features, the most important of which are the ratios of heat and moisture, which determine the regime of surface and ground waters, the nature and direction of the main natural processes, the composition and structure of phyto- and zoocenoses. The types are tundra, forest, forest-steppe, desert and other landscapes. A.G. Isachenko considers the type of landscapes to be the highest unit of classification, and the class of landscapes is subordinate to the type.
To isolate the genus of landscapes, V.A. Nikolaev puts forward the genetic type of relief as the main criterion, and G.I. Yurenkov - provincial features of landscape types (Eastern European landscapes of mixed forests, Far Eastern landscapes of mixed forests, etc.).
Landscape type is the smallest unit of classification, distinguished either by the genetic features of the territory (A.G. Isachenko, N.L. Beruchashvili, G.I. Yurenkov), or by the structure of dominant tracts (V.A. Nikolaev).
Along with the listed basic units of landscape classification, there are intermediate ones - subclass, subtype, subgenus, subspecies, etc. For example, in the class of plains there may be subclasses of elevated and lowland landscapes; in the forest type - subtypes of northern taiga, middle taiga, southern taiga landscapes. The separation of such categories is dictated by the collected and elaborated material, the degree of its detail and reliability, and the scale of the map. Like the main ones, intermediate units occupy a strictly defined place in the taxonomic system and obey all the rules of classification.
Any classification presupposes some formalization, ordering and generalization of concepts. To the greatest extent, generalization is inherent in the highest units of classification (departments, classes, types). Their differentiation is made according to the most important, essential features, against which the diversity of subordinates only emphasizes the complexity of the internal structure of large PTK. The minimum degree of generalization is characteristic of landscape types as relatively homogeneous sections.
The first classification of Belarusian landscapes was published by V.A. Dementiev and G.I. Martsinkevich in 1968. The main principle of classification was genetic. Its main drawback is the lack of a clear system of classification units.
The modern classification of landscapes of the Republic of Belarus has been developed in relation to a map at a scale of 1:600 OOO (authors N.K. Klitsunova, G.I. Martsinkevich, L.V. Loginova, G.T. Kharanicheva, scientific editor A.G. Isachenko), published in 1984. It takes into account the experience of researchers, embodied in the creation of landscape maps of Kazakhstan, Ukraine, Lithuania, the Non-Chernozem center of Russia. The highest classification unit is the class of landscapes. The territory of Belarus is entirely located within the East European platform with a flat relief and a clearly defined structure of latitudinal zones, therefore its landscapes belong to the class of flat ones. The next unit - the type of landscapes - is singled out taking into account bioclimatic factors. The position of the territory of Belarus in temperate latitudes with favorable conditions for the growth of forests predetermined that its NTC belongs to the temperate continental forest type of landscapes. At the same time, the length of the territory from north to south for more than 500 km is due to changes in the hydrothermal regime in this direction. On this basis, two subtypes of landscapes are distinguished: subtaiga (mixed-forest) and woodland (broad-leaved-forest). The first subtype covers the northern and central, the second - the southern parts of the republic. The border between them runs along the northern outskirts of the Belarusian Polissya.
The warmth of the sun, clean air and water are the main criteria for life on Earth. Numerous climatic zones led to the division of the territory of all continents and water space into certain natural zones. Some of them, even separated by vast distances, are very similar, others are unique.
Natural areas of the world: what is it?
This definition should be understood as very large natural complexes (in other words, parts of the geographic belt of the Earth), which have similar, uniform 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"
natural area | climate zone | Average temperature (winter/summer) |
Antarctic and Arctic deserts | Antarctic, arctic | 24-70°С /0-32°С |
Tundra and forest tundra | Subarctic and Subantarctic | 8-40°С/+8+16°С |
Moderate | 8-48°C /+8+24°C |
|
mixed forests | Moderate | 16-8°С /+16+24°С |
broadleaf forests | Moderate | 8+8°С /+16+24°С |
Steppes and forest-steppes | subtropical and temperate | 16+8 °С /+16+24°С |
temperate deserts and semi-deserts | Moderate | 8-24 °С /+20+24 °С |
hardwood forests | Subtropical | 8+16 °С/ +20+24 °С |
Tropical deserts and semi-deserts | Tropical | 8+16 °С/ +20+32 °С |
Savannahs and woodlands | 20+24°C and above |
|
Variable rainforests | subequatorial, tropical | 20+24°C and above |
Permanently wet forests | Equatorial | above +24°C |
This characteristic of the natural areas of the world is only introductory, because you can talk about each of them for a very long time, all the information will not fit in the framework of one table.
Natural zones of the temperate climate zone
1. Taiga. Surpasses all other natural zones of the world in terms of the area occupied on land (27% of the territory of all forests on the planet). It is characterized by very low winter temperatures. Deciduous trees do not withstand them, so the taiga is dense coniferous forests (mainly pine, spruce, fir, larch). Very large areas of the taiga in Canada and Russia are occupied by permafrost.
2. Mixed forests. Characteristic to a greater extent for the Northern Hemisphere of the Earth. It is a kind of border between the taiga and the broad-leaved forest. They are more resistant to cold and long winters. Tree species: oak, maple, poplar, linden, as well as mountain ash, alder, birch, pine, spruce. As the table "Natural areas of the world" shows, the soils in the zone of mixed forests are gray, not very fertile, but still suitable for growing plants.
3. Broad-leaved forests. They are not adapted to harsh winters and 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 or temperate continental climate with hot summers and fairly warm winters. As the table "Natural zones of the world" shows, the temperature in them does not fall below -8 ° C even in the cold season. The soil is fertile, rich in humus. The following types of trees are characteristic: ash, chestnut, oak, hornbeam, beech, maple, elm. The forests are very rich in mammals (ungulates, rodents, predators), birds, including commercial ones.
4. Temperate deserts and semi-deserts. Their main distinguishing feature is the almost complete absence of vegetation and sparse wildlife. There are a lot of natural areas of this nature, they are located mainly in the tropics. There are temperate deserts in Eurasia, and they are characterized by sharp temperature changes during the seasons. Animals are represented mainly by reptiles.
Arctic deserts and semi-deserts
They are 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 of North America, Antarctica, Greenland and the northern tip of the Eurasian continent. In fact, these are lifeless places, and polar bears, walruses and seals, arctic foxes and lemmings, penguins (in Antarctica) live only along the coast. Where the land is free of ice, lichens and mosses can be seen.
Moist equatorial forests
Their second name is rainforests. 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 a 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 that has become home to more than 2/3 of all types of creatures that now live on our planet. These rainforests are superior to all other natural areas of the world. Trees remain evergreen, changing foliage gradually and partially. Surprisingly, the soils of moist forests contain little humus.
Natural zones of the equatorial and subtropical climatic zone
1. Variably humid forests, they differ from rainforests in that precipitation falls there only during the rainy season, and during the period of drought that follows it, the trees are forced to shed their leaves. The animal and plant world is also very diverse and rich in species.
2. Savannas and woodlands. They appear where moisture, as a rule, is no longer enough for the growth of variable-humid forests. Their development occurs in the depths of the mainland, 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 of South America, partly Hindustan and Australia. More detailed information about the location is reflected in the map of natural areas of the world (photo).
hardwood forests
This climate zone is considered the most suitable for human habitation. Hardwood and evergreen forests are located along sea and ocean coasts. Precipitation is not so abundant, but the leaves retain moisture due to a dense leathery shell (oaks, eucalyptus), which prevents them from falling off. In some trees and plants, they are modernized into thorns.
Steppes and forest-steppes
They are characterized by the almost complete absence of woody vegetation, this is due to the meager level of precipitation. But the soils are the most fertile (chernozems), and therefore are actively used by man for agriculture. Steppes occupy large areas in North America and Eurasia. The predominant number of inhabitants are reptiles, rodents and birds. Plants have adapted to the lack of moisture and most often manage to complete their life cycle in 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 coniferous trees cannot withstand it. Moisture is in excess, but there is no heat, which leads to swamping of very large areas. There are no trees at all in the tundra, the flora is mainly represented by mosses and lichens. It is believed that this is the most unstable and fragile ecosystem. Due to the active development of gas and oil fields, it is on the verge of an ecological disaster.
All natural areas of the world are very interesting, whether it is a desert that seems completely lifeless at first glance, boundless Arctic ice or thousand-year-old rainforests with boiling life inside.
Physiographic zones - natural land zones, large subdivisions of the geographic (landscape) shell of the Earth, regularly and in a certain order replacing each other depending on climatic factors, mainly on the ratio of heat and moisture. In this regard, the change of zones and belts occurs from the equator to the poles and from the oceans to the interior of the continents. They are usually elongated in the sublatitudinal direction and do not have sharply defined boundaries. Each zone has typical features of its constituent natural components and processes (climatic, hydrological, geochemical, geomorphological, soil nature, vegetation cover and wildlife), its own type of interrelations that have historically developed between them and the dominant type of their combinations - zonal natural territorial complexes. Many physiographic zones are traditionally named according to the most striking indicator - the type of vegetation, which reflects the most important features of most natural components and processes (forest zones, steppe zones, savannah zones, etc.). The name of these zones is often assigned to individual components: tundra vegetation, tundra-gley soils, semi-desert and desert vegetation, desert soils, etc. Within the zones, which usually occupy vast strips, narrower divisions are distinguished - physiographic subzones. For example, the savannah zone as a whole is distinguished by the seasonal rhythm of the development of all natural components, due to the seasonal influx of precipitation. Depending on the number of the latter and the duration of the rainy period, subzones of moist tall grass, typical dry and desert savannas are distinguished within the zone; in the steppe zone - dry and typical steppes; in the zone of temperate forests - taiga subzones (often considered an independent zone), mixed and broad-leaved forests, etc.
Natural zones, if they are formed in more or less similar geological and geomorphological (azonal) conditions, are repeated in general terms on different continents with a similar geographical position (latitude, position in relation to the oceans, etc.). Therefore, there are types of zones that are typological units of the territorial classification of the geographical shell (for example, tropical western oceanic deserts). At the same time, the local features of a particular territory (relief, composition of rocks, paleogeographic development, etc.) give individual features to each zone, in connection with which specific natural zones are considered as regional units (for example, the Atacama desert, the Himalaya highland, the desert Namib, West Siberian Plain). In the physical and geographical atlas of the world for 1964, the allocation of 13 geographical zones was adopted, based on the climatic classification of B. P. Alisov: the equatorial belt and two (for both hemispheres) subequatorial, tropical, subtropical, temperate, subpolar and polar (supporters of the thermal factor, as the main one in the formation of zoning, are limited to the allocation of only five or even three belts). Inside the belts, it is possible to distinguish sub-belts, or stripes.
Each belt and each of its large longitude segments - the sector (oceanic, continental and transitional between them) has its own zonal systems - its own set, a certain sequence and stretch of horizontal zones and subzones on the plains, its own set (spectrum) of altitudinal zones in the mountains. So, the forest-tundra zone is inherent only in the subpolar (subarctic) belt, the taiga subzone is in the temperate zone, the "Mediterranean" subzone is in the western oceanic sector of the subtropical belt, the monsoon mixed forest subzone is in its eastern oceanic sector, forest-steppe zones exist only in transitional sectors. . The forest-tundra spectrum of altitudinal zones is typical only for the temperate zone, and the hylainoparamos spectrum is characteristic only for the equatorial zone. Depending on the position in a particular sector or on a particular morphostructural basis within zones and subzones, smaller taxonomic units can be distinguished - typological: western oceanic dark coniferous taiga, continental light coniferous taiga, etc., or regional: Western - Siberian taiga, Central Yakut taiga, West Siberian forest-steppe, etc.
Since natural zones are determined mainly by the ratio of heat and moisture, this ratio can be expressed quantitatively (for the first time, the physical and quantitative basis of zoning was formulated in 1956 by A. A. Grigoriev and M. I. Budyko). For this purpose, various hydrothermal indicators are used (most often moisture indicators). The use of these indicators helps, first of all, the development of theoretical issues of zoning, the identification of general patterns, and the objective refinement of the characteristics of zones and their boundaries. For example, with values of the Budyko radiation index of dryness less than 1 (excessive moisture), humid zones of forests, forest-tundra and tundra dominate, with values more than 1 (insufficient moisture) - dry zones of steppes, semi-deserts and deserts, with values close to 1 (optimal moisture ), - zones and subzones of forest-steppes, deciduous and light forests and humid savannahs. The definition and further refinement of quantitative indicators are also of great practical importance, for example, for the application of various agricultural activities in various sectors, zones, subzones. At the same time, it is very important to take into account not just the similarity of the final indicators, but also from which values in these conditions they are made up. So, establishing the "periodic law of zoning", A. A. Grigoriev noted the periodic repetition of the same values of the radiation index of dryness in zones of different belts (for example, in the tundra, subtropical hemihylae and equatorial forest swamps). However, while the index is common, both the annual radiation balance and the annual amount of precipitation in these zones are sharply different, just as all natural processes and complexes as a whole are different.
Along with zonal factors, the formation and structure of zonal systems are also strongly influenced by a number of azonal factors (in addition to the primary distribution of land and oceans, which largely determines circulation, currents, and moisture transport). First of all, there is a polar asymmetry of the landscape envelope of the Earth, which is expressed not only in the greater oceanicity of the Southern Hemisphere, but also in the presence, for example, of the subtropical hemigil subzone peculiar only to it and, on the contrary, in the absence of many zones and subzones of the Northern Hemisphere (tundra, forest tundra, taiga, deciduous forests, etc.). In addition, the configuration and size of the land area in any latitudes play a significant role (for example, the wide distribution of tropical deserts in North Africa and Arabia or Australia and their limited territory in the tropical belts of North America or South Africa, which occupy a smaller area). The nature of the large features of the relief also greatly influences. The high meridional ridges of the Cordillera and the Andes enhance continentality and determine the presence of corresponding semi-desert and desert zones on the inner plateaus of the subtropical and tropical belts. The Himalayas contribute to the immediate proximity of the high-mountainous deserts of Tibet and the humid-forest zonal spectrum of the southern slopes, and the Patagonian Andes are even the primary reason for the presence of a semi-desert zone in the east of the temperate zone. But usually the influence of regional factors only strengthens or weakens the general zonal patterns.
Of course, the zonal systems have undergone significant changes in the process of paleogeographic development. Belt and sector differences have already been established for the end of the Paleozoic. Later, there were changes in the distribution of land and sea, macroforms of relief, climatic conditions, in connection with which, in the emerging zonal systems, some zones disappeared and were replaced by others, the strike of zones varied. Modern zones are of different ages; due to the huge role that the Pleistocene glaciation played in their formation, the zones of high latitudes are the youngest. In addition, the increased temperature contrast between the poles and the equator in the Pleistocene increased the number of physiographic zones and significantly complicated their system. The impact of man also had a great influence, in particular on the boundaries of the zones.
The map in the appendix clearly shows the distribution of zones by belts and sectors and the differences in the manifestation of zoning in the high and middle latitudes of the Northern and Southern hemispheres. In the belts of high latitudes (polar, subpolar and the northern part of the northern temperate zone - the boreal subbelt, which is absent on land in the Southern Hemisphere), there are relatively small changes in the ratio of heat and moisture and almost universally excessive moisture. Natural differentiation is associated mainly with changes in thermal conditions, that is, with an increase in the radiation balance with decreasing latitude. Consequently, the zones of polar deserts, tundra, forest-tundra and taiga extend sublatitudinally, and sectoral differences are weakly expressed (ice deserts in the Atlantic sector of the Arctic are mainly due to regional features). At the same time, the polar asymmetry of the zonal spectra, caused by contrasts in the distribution of land and oceans in different hemispheres, is most pronounced. In the subboreal subbelts, with an even more increasing heat input, the role of moisture also increases. Its increase is determined by the predominance of westerly winds, and in the east by extratropical monsoons. Moisture indices vary significantly both in latitude and longitude, which is the reason for the diversity of zones and subzones and differences in their strike. The oceanic sectors are occupied by humid forests, the transitional sectors are occupied by forests, forest-steppes and steppes, and the continental sectors are predominantly semi-deserts and deserts. The most striking manifestation of these zonal features is observed in subtropical belts, within which there are still large latitudinal differences in radiation conditions, and moisture comes from both the west (only in winter) and from the east (mainly in summer). In the belts of low latitudes (tropical, subequatorial and equatorial), the asymmetry of the hemispheres is smoothed out, the radiation balance reaches its maximum, and its differences in latitude are weakly expressed. The leading role in changes in the ratio of heat and moisture passes to the latter. In tropical (trade wind) belts, moisture comes only from the east. This explains the presence of relatively humid zones (tropical forests, savannahs and light forests), extending submeridionally in the eastern sectors, semi-deserts and deserts that fill the continental and western sectors. Subequatorial belts receive moisture mainly from the equatorial monsoons, that is, its amount decreases rapidly from the equator to the tropics.
1) Remember what a natural zone is.
A natural complex is a part of the earth's surface with relatively homogeneous natural conditions.
2) What are the patterns in the placement of natural zones of the Earth?
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. 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.
3) What natural zones are located in Eurasia?
Arctic deserts, tundra and forest-tundra, taiga, mixed and broad-leaved forests, forest-steppe and steppe, semi-desert and desert.
4) What sources of geographic information can be used to characterize a natural area?
Observations, geographical maps, meteorological data.
*From the figure, determine how natural areas are located in our country. Why do not all zones extend from the western to the eastern outskirts of the country? What zones are located only in the European part of the country? How can this be explained?
The location of natural zones is closely related to climatic zones. Like climatic zones, they replace each other from the equator to the poles due to a decrease in solar heat entering the Earth's surface and uneven moistening. In Russia, from north to south, the following natural zones replace each other - arctic deserts and semi-deserts, tundra and forest-tundra, taiga, mixed and broad-leaved forests, forest-steppes and steppes, variable-humid forests, deserts and semi-deserts. Not all natural zones extend from the western to the eastern borders of the country. This is due to the fact that Russia has a large latitudinal elongation and climatic conditions change with advancement inland. Only in the European part is there a natural zone of mixed and broad-leaved forests. This can be explained by the fact that in inland areas there is not enough moisture to form forests.
Questions in a paragraph
*There are evergreens in the tundra. How do you explain this fact? Name the representatives of the flora and fauna of the tundra known to you. Consider how they adapt to harsh climates.
There are many evergreens in the tundra. Such plants can use sunlight as soon as they are free from under the snow, without wasting time and energy on the formation of new foliage. Flora - mosses, lichens, shrubs - crowberry, bearberry, wild rosemary, dwarf birch, willow. Tundra plants have peculiar forms that help them make the best use of the sun's heat and protect themselves from the wind. Pillows form, for example, stemless resin, saxifrage. They are so dense that from a distance they resemble moss-covered stones. The fauna of the tundra is not rich in species, but quantitatively large enough. What animals live in the tundra permanently? The indigenous inhabitants of the tundra include reindeer, lemmings, arctic foxes, wolves, and birds - a snowy owl and a white partridge. Very rare animals - musk oxen.
* Determine on the map which of the largest mineral deposits of our country are located in the tundra zone.
Large industrial hubs have been created in the area of the cities of Nikel, Vorkuta and Norilsk. Non-ferrous metals are being mined in Norilsk, and oil and gas are actively produced in the north of the Tomsk and Tyumen regions. The Arctic tundra zone contains a large supply of important natural resources such as uranium and oil.
Questions at the end of the paragraph
1. What components of nature form a natural zone?
Communities of plants, communities of animals, soils, characteristic features of surface and ground runoff, water regime of rivers, exogenous processes of relief formation.
2. What determines the change of natural zones?
The change of natural zones occurs as a result of a regular change in the ratio of heat and moisture.
3. On the example of our country, justify the pattern of changing natural zones.
On the territory of Russia, there is a change from north to south of the following natural zones: arctic deserts, tundra, forest-tundra, taiga, mixed and broad-leaved forests, forest-steppes, steppes, semi-deserts.
4. Think about how the flora and fauna of the Arctic deserts are adapted to their habitat.
Plants do not form a dense vegetation cover, are small, flowering plants have a very short growing season. Animals of the Arctic deserts have adapted to get food from the sea, many have thick white wool, birds inhabit the coast.
5. Indicate the features of the tundra zone of our country and explain them.
A feature of the tundra zone of Russia is its wide distribution and the separation of several subzones in it from north to south. From north to south, three subzones are distinguished: arctic tundras are replaced by typical (moss-lichen), and then by shrubs from dwarf birch and polar willows.
6. Think about the reason for the strong vulnerability of the nature of the tundra zone.
Pollutants do not remain in place, air currents carry them over long distances. And the inhabitants of the tundra, especially lichens, are extremely sensitive to their effects. In the tundra, pollutants accumulate rather than being washed away by meltwater. Low temperatures inhibit the destruction of harmful compounds. Dozens of rivers and lakes perish. Streams of fuel oil and diesel fuel from drilling rigs flow into the soil and water bodies all year round. The coast of the Arctic seas and the entire tundra are littered with ownerless barrels and rusty iron. Many settlements are in an unsanitary state. There are practically no environmentally friendly enterprises. Thermal power stations smoke the sky. Smog settles on white snow, dividing it with black, and patches of bare ground appear in places where pollution is especially high. Not a single plant will grow here for many years. Another problem of the tundra is uncontrolled hunting and poaching. Many plant and animal species have become rare.
