Geographical zoning and vertical zonation. Geographical zoning and vertical zonality of the geographical envelope

As a result of studying the material in this chapter, the student should:

• know definition of the law of geographical zoning; titles and placement geographical zones Russia;
• be able to characterize each geographical zone on the territory of Russia; explain the specifics of the configuration of geographical zones of Russia;
• own the idea of ​​zonality as a natural and cultural phenomenon.

Geographical zoning as a natural and cultural phenomenon

Medieval travelers, crossing large spaces and observing landscapes, already noted the natural, not random nature of changes in nature and culture in space. Thus, the famous Arab geographer Al-Idrisi compiled a map of the Earth, where he showed seven climatic latitudinal zones in the form of stripes - from the equatorial strip to the northern snowy desert zone.

Naturalists second half of the 19th century V. tried to explain the phenomenon of geographic zoning from a systemic perspective.

Firstly, they found out that the main reason for the occurrence of this phenomenon is the spherical shape of the Earth, which is associated with the uneven supply of heat at different geographical latitudes. Based on field research carried out mainly on the Russian Plain, the outstanding Russian scientist V.V. Dokuchaev (he has the honor of discovering the law of geographic zonation) showed that not only climate, but also other elements of nature (natural waters, soils, vegetation, animals) world) are distributed over the earth's surface in a certain pattern. The scientist noted that “thanks to the known position of our planet relative to the Sun, thanks to the rotation of the Earth, its spherical shape, climate, vegetation and animals are distributed over the earth’s surface in the direction from north to south, in a strictly defined order, with a regularity that allows for division globe into zones - polar, temperate, subtropical, equatorial, etc.” .

Secondly, scientists explained why geographic zones do not always have a latitudinal extension: if there were no oceans on the Earth and its entire surface was flat, then the zones would encircle the entire Earth in the form of parallel stripes. But the presence, on the one hand, of oceans, and on the other, of irregularities (mountains, hills) distorts the ideal picture. Geographical zoning is better expressed on the plains in the form of certain stripes, belts or zones It is no coincidence that the landscapes of watershed plains and lowlands are called zonal. TO azonal include those landscapes that differ sharply from typical zonal landscapes. Let us recall, for example, the landscapes of the Nile River Valley, which are completely different from the zonal landscapes of the surrounding tropical deserts. The most common azonal landscapes are landscapes of river valleys and mountain landscapes.

However, the most important discovery made by V.V. Dokuchaev is that geographical zonation represents natural and cultural phenomenon. It affects not only nature, but also culture and human activity. According to Dokuchaev, a person is zoned in all manifestations of his life:“in customs, religion (especially in non-Christian religions), in beauty, even sexual activity, in clothing, in all everyday situations; zonal - livestock... cultivated vegetation, buildings, food and drink. Anyone... who had to travel from Arkhangelsk to Tiflis could easily see how much the buildings, dress, morals, customs of the population and their beauty change depending on the climate, animals, plants, soil characteristic of a particular area.”

Under geographical area V.V. Dokuchaev understood a system in which nature (climate, water, vegetation, fauna) and man and his activities are interconnected, “tuned” to each other.

It is obvious that the relationship between human communities and surrounding landscapes was closer before the industrial revolution, when technical capabilities people were more modest, they lived closer to nature, and there were significantly fewer people. Nevertheless, every people, even the most “technical”, retains the memory of the “mother” (well-defined zonal or azonal) landscape, forest or wall, of the images of the Motherland associated with this landscape, not only visual, but also cultural and linguistic . Language preserves the memory of the developed landscapes and contains their characteristics.

Many physical-geographical phenomena in the geographic envelope are distributed in the form of strips extended along parallels, or at some angle to them. This property of geographical phenomena is called zonality (the law of geographical zonality). Ideas about natural zonality arose among ancient Greek scientists. So, in the 5th century. BC. Herodotus and Eudonix noted five zones of the Earth: tropical, two temperate and two polar. A great contribution to the doctrine of natural zonation was made by the German geographer Humboldt, who established the climatic and plant zones of the Earth (“Geography of Plants”, 1836). In Russia, ideas about geographic zoning were expressed in 1899 by Dokuchaev in the book “The Doctrine of Natural Zones. Horizontal and vertical soil zones." Professor Grigoriev has conducted research on the causes and factors of zoning. He came to the conclusion about the important role of the relationship between the radiation balance and the amount of annual precipitation (1966).

Currently, it is believed that natural zonation is represented by

component zoning;

landscape zoning.

All components geographic envelope are subject to the World Law of Zoning. Zoning is noted for climatic indicators, plant groups and soil types. It also manifests itself in hydrological and geochemical phenomena, as a derivative of climatic and soil and plant conditions.

The zonality of physical-geographical phenomena is based on the pattern of solar radiation, the arrival of which decreases from the equator to the poles. However, this distribution of solar radiation is superimposed on the atmospheric transparency factor, which is azonal, since it is not related to the shape of the Earth. Air temperature depends on solar radiation, the distribution of which is influenced by another azonal factor - the properties of the earth's surface - its heat capacity and thermal conductivity. This factor leads to an even greater violation of zoning. The distribution of heat on the Earth's surface is also greatly influenced by ocean and air currents, which form heat transfer systems.

The distribution of precipitation on our planet is even more complex. They are, on the one hand, zonal in nature, and on the other hand, they are associated with the position of the territory in the western or eastern part of the continents and the height of the earth's surface.

The combined effect of heat and moisture is the main factor that determines most physical and geographical phenomena. Since the distribution of moisture and heat remains oriented in latitude, all climate-related phenomena are oriented in latitude. As a result, a latitudinal structure is formed on Earth, called geographic zonality.

The clarity is manifested in the distribution of the main climatic characteristics: solar radiation, temperature and atmospheric pressure, which leads to the formation of a system of 13 climate zones. Plant groups on Earth also form elongated stripes, but in a more complex configuration than climatic zones. These are called vegetation zones. Soil cover is closely related to vegetation, climate and relief, which allowed V.V. Dokuchaev to identify genetic types of soils.

In the 50s of the 20th century, geographers Grigoriev and Budyko developed Dokuchaev’s law of zonation and formulated the periodic law of geographic zonation. This law establishes the repetition of similar geographical zones within zones - depending on the ratio of heat and moisture. Thus, forest zones are found in the equatorial, subequatorial, tropical and temperate zones. Steppes and deserts are also found in different geographical zones. The presence of similar zones in different zones is explained by the repetition of the same ratios of heat and moisture.

Thus, a zone is a large part of a geographical zone, which is characterized by the same indicators of radiation balance, annual precipitation and evaporation. At the beginning of the last century, Vysotsky proposed a humidification coefficient equal to the ratio of precipitation to evaporation. Later Budyko for justification periodic law introduced an indicator - the radiation dryness index, which is the ratio of the incoming amount solar energy to the heat consumption for evaporation of atmospheric precipitation. It has been established that there is a close connection between geographic zones and the amount of solar heat input and the radiation dryness index.

Geographic zones are internally heterogeneous, which is primarily associated with azonal atmospheric circulation and moisture transfer. Taking this into account, sectors are identified. As a rule, there are three of them: two oceanic (western and eastern) and one continental. Sectority is a geographic zonality, which is expressed in a change in the main natural indicators along longitude, that is, from the oceans inland to the continents.

Landscape zoning is determined by the fact that the geographic envelope, in the process of its development, acquired a “mosaic” structure and consists of many natural complexes of unequal size and complexity. According to the definition of F.N. Milkova PTC is a self-regulated system of interconnected components, functioning under the influence of one or several components that act as a leading factor.

Vertical zonality

Altitudinal zone - part of vertical zoning natural phenomena and processes related only to mountains. Due to the natural decrease in air temperatures with height, the ratio of heat and moisture, runoff conditions, relief formation, soil and vegetation cover and associated animals change.

Climbing a high mountain is accompanied by a change in several belts of vegetation, as when moving from the equator to the poles. Unlike natural areas, there are few animals here, but many birds of prey (the largest bird of prey is the condor. It soars over the Andes at an altitude of up to 7 thousand m). Each type of environment has its own community of animals and plants, even within the same natural zone, but on different continents ( natural complex). Simultaneously with zonal ones, azonal factors also operate, associated with the internal energy of the Earth (relief, height, continental configuration).

In any place on the globe, zonal and azonal factors operate simultaneously. The set of altitudinal zones in the mountains depends on the geographical position of the mountains themselves, which determines the nature of the lower zone, and the height of the mountains, which determines the nature upper tier. The sequence of altitudinal zones coincides with the sequence of changes in natural zones on the plains. But in the mountains, belts change faster; there are zones that are characteristic only of mountains - subalpine and alpine meadows.

The altitudinal zonation of mountain systems is diverse. It is closely related to latitudinal zones. With altitude, climate, soil and vegetation cover, hydrological and geomorphological processes are transformed, the factor of slope exposure, etc. sharply increases. With changes in the components of nature, natural complexes change - high-altitude natural zones are formed. The phenomenon of changing natural-territorial complexes with altitude is called altitudinal zonality, or vertical altitudinal zonality.

The formation of types of altitudinal zonation of mountain systems is determined by the following factors:

• > Geographical location of the mountain system. The number of mountain altitudinal belts in each mountain system and their altitudinal position are mainly determined by the latitude of the place and the position of the territory in relation to the seas and oceans. As you move from north to south, the altitudinal position of natural belts in the mountains and their composition gradually increase.
• > Absolute height of the mountain system. The higher the mountains rise and the closer they are to the equator, the greater the number of altitude zones they have. Therefore, each mountain system develops its own set of altitude zones.
• > Relief. The relief of mountain systems (orographic pattern, degree of dissection and evenness) determines the distribution of snow cover, moisture conditions, preservation or removal of weathering products, affects the development of soil and vegetation cover and thereby determines the diversity of natural complexes in the mountains. For example, the development of leveling surfaces contributes to an increase in the areas of altitudinal belts and the formation of more homogeneous natural complexes.
• > Climate. This is one of the most important factors shaping altitudinal zonation. As you rise into the mountains, temperature, humidity, solar radiation, wind direction and strength, and weather types change. Climate determines the nature and distribution of soils, vegetation, fauna, etc., and, consequently, the diversity of natural complexes.

Slope exposure. It plays a significant role in the distribution of heat, moisture, wind activity, and, consequently, weathering processes and the distribution of soil and vegetation cover. On the northern slopes of each mountain system, altitude zones are usually located lower than on the southern slopes.

The position, changes in boundaries and natural appearance of altitudinal zones are also influenced by human economic activity.

Already in the Neogene on the plains of Russia there were latitudinal zones almost similar to modern ones, but due to the warmer climate of the zone arctic deserts and tundra were absent. In Neogene-Quaternary times, significant changes in natural zones occur. This was caused by active and differentiated neotectonic movements, climate cooling and the appearance of glaciers on the plains and mountains. Therefore, natural zones shifted to the south, the composition of their flora (increased deciduous boreal and cold-resistant flora of modern coniferous forests) and fauna changed, the youngest zones were formed - tundra and arctic desert, and in the mountains - alpine, mountain-tundra and nival-glacial belts

During the warmer Mikulino interglacial period (between the Moscow and Valdai glaciations), natural zones shifted to the north, and altitudinal zones occupied more high levels. At this time, the structure of modern natural zones and altitudinal zones is formed. But due to climate change in the late Pleistocene and Holocene, the boundaries of zones and belts shifted several times. This is confirmed by numerous relict botanical and soil finds, as well as spore-pollen analyzes of Quaternary deposits.

In the mountains, as you go up, the amount and composition of solar radiation changes, the amount of precipitation decreases and Atmosphere pressure. Change climatic conditions leads to changes in the same direction in geomorphological processes, vegetation composition, soil characteristics and the nature of the animal world. This makes it possible to identify vertical belts in mountain systems.

Vertical belts are similar to horizontal zones in the sense that they change when moving upward in approximately the same order (starting from the latitudinal zone in which the Mountain country), in which latitudinal zones change when moving from the equator to the poles. But vertical belts are not exact copies of similar latitudinal zones, since they are influenced by local conditions (relief ruggedness, differences in slope exposures, mountain heights, history of area development, etc.).

Despite some similarities in vertical zonation in different mountain systems, the latter manifests itself differently on different continents and geographical latitudes. The degree of expression of vertical zonation, i.e. the number of vertical belts, their height, continuity of extension, floristic and faunal composition depend on the position of the mountain system, its latitude, the direction of the ridges, the degree of dissection, the history of formation and some other reasons.

Let us demonstrate this using the example of two mountain systems (Verkhoyansk Range and Greater Caucasus).

a) The Verkhoyansk ridge, or rather a whole system of ridges, is several times larger in size than the system of ridges of the Greater Caucasus. Despite this, the Verkhoyansk Range has a less diverse nature, i.e., within its boundaries there is a smaller number of vertical belts than in the Greater Caucasus, and similar belts of these mountain systems differ sharply in the nature of vegetation, soils and wildlife.

The Verkhoyansk Range is located in the temperate zone, in the taiga zone, in the northeast of Siberia. The climate here is very harsh. Near the ridge there is a “pole of cold”; priming all year round frozen; piercing winds blow; the amount of precipitation is insignificant (200--300 mm per year).

The slopes of the ridge from the base to a height of approximately 1 thousand m are covered with taiga, in the northern part sparse, consisting of Dahurian larch (Larix dahurica). The latter is adapted to living in the harshest conditions, on frozen ground. Podzolic soils are developed under the taiga. The taiga belt is replaced by a belt of subalpine bushes (at podzolic soils), the most common of which is dwarf cedar (Pinus pumila) - a creeping species of cedar pine. Above 1000-1500 m, the alpine belt begins, i.e. mountain lichen-crushed stone tundra with reindeer moss (Cladonia), partridge grass ( Dryas punctata), cinquefoil (Potentilla nivea), etc. Such is the sparse vegetation of the Verkhoyansk Range.

b) The Greater Caucasus is located on the border of temperate and subtropical climate zones. This alone suggests a variety of natural conditions in the Greater Caucasus in the form of a significant number of vertical belts and their differences on the northern and southern slopes. In addition, the vertical zonation is complicated here by the increase in dryness from west to east. All these factors greatly diversify the vertical zonation in the Greater Caucasus and lead to its differences on the northern and southern slopes, as well as in the west and east.

When climbing the mountains from the Rioni lowland, we will encounter the following vertical belts:

• 1. Belt of relict Colchis forests, developed mainly on podzolic-yellow soils. The basis of the forest here is made up of broad-leaved species: Hartwis oak (Quercus hartwissiana), Georgian oak (Quercus iberica), noble chestnut (Castanea satwa), oriental beech (Fagus orientalis), hornbeam (Carpinus caucasica). Evergreen shrubs are developed in the undergrowth: Pontic rhododendron ( Rhododendron ponticum), laurel (Laurus nobiles), etc.
• 2. From a height of 600 m to a height of about 1200 m stretches a belt of beech forests (dark and humid), consisting mainly of oriental beech, joined by other broad-leaved species. In this belt, mountain forest brown soils are developed.
• 3. Even higher stretches a belt of coniferous and coniferous-deciduous forests, consisting of Caucasian spruce (Picea orientalis), Caucasian fir. (Abies nordmanniana) and eastern beech; Under them, mountain-podzolic and mountain-forest brown soils are developed.
• 4. From an altitude of about 2000 m, the subalpine belt begins - tall grass meadows and thickets of Caucasian rhododendron (Rhododendron caucasicum) on mountain meadow soils. The alpine belt stretches even higher, where alpine meadows developed on mountain-meadow soils alternate with almost bare rocks and screes. And finally, the last is the nival belt - the area of ​​​​distribution of eternal snow and glaciers.

The northern slope of the Western Caucasus differs from the southern slope in the absence of a belt of Colchis forests, which is replaced here by a belt of oak forests, consisting mainly of oak (Quercus petraca). The remaining vertical belts are somewhat different from the above in their floristic composition.

A completely different character of vertical zonality is observed in the Eastern Caucasus. At the foot of the slope there are deserts and semi-deserts of the Kura Lowland on grey-earth, brown and chestnut soils; deserts and semi-deserts in the extreme east rise into the mountains to a height of 800 m. Their main representative is Hansen's wormwood (Artemisia Hanseniana). Above is a belt of steppes, on mountain chernozems and dark chestnut soils, which gradually tapers out as you move west.

Higher up (at an average altitude of 500-1200 m) there is a belt of oak forests with an admixture of other broad-leaved species (Georgian oak, Caucasian hornbeam) on brown soils. Where forests have been cut down, upland xerophytic vegetation (shrub), consisting mainly of pine trees (Paliurus spina), is widely developed.

At an altitude of 1200-2000 m there is a belt of beech and beech-hornbeam forests, which at the upper border of the forest give way to thickets of eastern oak (Quercus macranthera). There are no coniferous forests in the Eastern Caucasus. Brown forest soils.

At an altitude of 2000-2500 m, subalpine meadows are developed, which differ from those of the Western Caucasus in their strong steppe and low grass stand (high-mountain steppes). Higher up they turn into alpine meadows. The soils are mountain meadow. And finally, on maximum altitudes a nival belt has been developed, which has a slight distribution in the Eastern Caucasus.

The northern slope of the Eastern Caucasus (including Dagestan) is distinguished by the absence of deserts at the foot, the greater xerophytic nature of high-mountain meadows (high-mountain steppes on mountain meadow-steppe soils) and the greater development of mountain xerophytic vegetation.

We all know that the shape of the Earth is spherical. This structure is reflected in the distribution of solar radiation over its surface, which naturally decreases from the equator to the poles. This phenomenon is associated with the thermal regime of the Earth's surface, the consistent distribution of landscapes, and the patterns of the spatial state of the components of nature. This well-known global pattern is called geographic zonation.

The root cause of the formation of geographic zonality is considered to be the uneven distribution of solar radiation over the earth's surface and the unequal receipt of thermal energy per unit area. The existence of geographic zonality on the Earth's surface is not only the result of the uneven distribution of solar radiation, but also the intrinsic properties of the geographic shell. Evidence of this is the boundaries of geographical zones, which are not located at the same latitude, but change depending on one or another feature of the geographical envelope.
IN late XIX century, the famous Russian soil scientist V.V. Dokuchaev, having determined the unity and inextricable connection of the components of the geographical shell, noted that these components naturally change from south to north and create natural (geographical) zones.

The scientist was also the first to notice that the formation of geographical zones is not only influenced by direct solar radiation, but also depends on the distribution of heat and moisture on the earth’s surface, especially on the comparative ratio of the latter two factors. This means that although natural zones are strips of landscapes successively located from the equator to the poles, their boundaries are not lines of parallels. Depending on the structure of the Earth’s surface, the distribution of moisture, the proximity of sea coasts and for other reasons, the signs of zones sometimes appear inconsistently, intermittently, sometimes appear, sometimes disappear temporarily (for example, deserts and semi-deserts, deciduous forests, etc.), and sometimes landscapes are formed not according to the zonal principle, but according to azonal factors.

Geographical zoning has a huge impact on human economic activity and on its relationship with the environment. For example, from the equator to the poles, a person spends more and more labor to ensure his life (construction, transport, production of clothing, food, etc.), his life support becomes more and more expensive.

Geographical zoning speeds up or slows down the progress of similar natural processes and phenomena. For example, woody plants in the humid tropics and in the taiga grow at different rates; or take the productivity of 1 km2 of tundra pastures, which allows one to obtain only 800-900 kg of meat per year, while the productivity of African savannas reaches 27-30 tons. Thus, one cannot ignore zonality in the use of animal resources.

The geographic envelope is a natural complex on a global scale. It is divided into natural-territorial complexes of a lower rank (continent, ocean, country, region, etc.). Natural-territorial complexes at the local level are “tract” and “facies”. The main properties of a natural complex are the unity of its components, the continuous exchange of substances between these components and the directed flows of energy inherent in this complex.

According to the law of materialist dialectics: without knowing the whole, it is impossible to know its parts. Therefore, without knowing the patterns of development of the global system - the geographical envelope, it is impossible to fully know the properties of natural complexes of the lowest rank, and based on the study of only one of these latter it is impossible to identify general patterns development of nature. Identified patterns for one of the components natural environment or based on local territorial studies cannot be extended to all components or ranks of natural-territorial complexes. Environmental problems are multifaceted, diverse, and different in nature. Modern environmental problems are taking on a global scale, so their resolution must be comprehensive, taking into account the conditions of all components of the natural environment and the complexity of the problems.

This is one of the main laws of the geographical shell of the Earth. It manifests itself in a certain change in natural complexes of geographical zones and all components from the poles to the equator. Zoning is based on the different supply of heat and light to the earth's surface, depending on geographic latitude. Climatic factors affect all other components and, above all, soils, vegetation, and fauna.

The largest zonal latitudinal physical-geographical division of the geographic envelope is the geographic belt. It is characterized by common (temperature) conditions. The next level of division of the earth's surface is a geographical zone. It is distinguished within the belt not only by the common thermal conditions, but also by moisture, which leads to common vegetation, soils and other biological components of the landscape. Within the zone, transitional subzones are distinguished, which are characterized by mutual penetration of landscapes. They are formed due to gradual changes in climatic conditions. For example, in the northern taiga, tundra areas (forest-tundra) are found in forest communities. Subzones within zones are distinguished by the predominance of landscapes of one type or another. Thus, in the steppe zone, two subzones are distinguished: the northern steppe on chernozems and. southern steppe on dark chestnut soils.

Let's briefly get acquainted with the geographical zones of the globe in the direction from north to south.

Ice zone, or arctic desert zone. Ice and snow persist almost all year round. In the warmest month, August, the air temperature is close to 0°C. Glacier-free areas are bound by permafrost. Intense frost weathering. Placers of coarse clastic material are common. Soils are underdeveloped, rocky, low power. Vegetation covers no more than half of the surface. Mosses, lichens, algae and a few species of flowering plants (poppy, buttercup, saxifrage, etc.) grow. Animals include lemmings, arctic fox, and polar bear. In Greenland, northern Canada and Taimyr - musk ox. Bird colonies nest on rocky coastlines.

Tundra zone of the Earth's subarctic belt. Summer is cold with frosts. The temperature of the warmest month (July) in the south of the zone is +10°, +12°C, in the north +5°C. There are almost no warm days with an average daily temperature above + 15°C. There is little precipitation - 200-400 mm per year, but due to low evaporation there is excessive moisture. Permafrost is almost ubiquitous; high wind speeds. The rivers are full of water in summer. The soils are thin and there are many swamps. The treeless spaces of the tundra are covered with mosses, lichens, grasses, shrubs and low-growing creeping shrubs.

The tundra is home to reindeer, lemmings, arctic foxes, and ptarmigan; in summer there are many migratory birds - geese, ducks, waders, etc. In the tundra zone, moss-lichen, shrub and other subzones are distinguished.

Temperate forest zone with a predominance of coniferous and summer-green deciduous forests. Cold snowy winters and warm summers, excessive moisture; the soil is podzolic and marshy. Meadows and swamps are widely developed. IN modern science The forest zone of the northern hemisphere is divided into three independent zones: taiga, mixed forests and deciduous forest zone.

The taiga zone is formed by both pure coniferous and mixed species. In the dark coniferous taiga, spruce and fir predominate, in the light coniferous taiga - larch, pine, and cedar. They are mixed with narrow-leaved trees, usually birch. The soils are podzolic. Cool and warm summers, harsh, long winters with snow cover. Average July temperatures in the north are +12°, in the south of the zone -20°C. January from - 10°C in western Eurasia to -50°C in Eastern Siberia. Precipitation is 300-600 mm, but this is higher than the evaporation value (except for the south of Yakutia). There is a lot of swampiness. The composition of the forests is uniform: dark coniferous spruce forests predominate on the western and eastern edges of the zone. In areas with a sharply continental climate (Siberia) there are light larch forests.

The mixed forest zone is coniferous-deciduous forests on soddy-podzolic soils. The climate is warmer and less continental than in the taiga. Winter with snow cover, but without severe frosts. Precipitation 500-700 mm. On Far East The climate is monsoon with annual precipitation up to 1000 mm. The forests of Asia and North America are richer in vegetation than in Europe.

The broad-leaved forest zone is located in the south of the temperate zone along the humid (precipitation 600-1500 mm per year) edges of the continents with their maritime or temperate continental climate. This zone is especially widely represented in Western Europe, where several types of oak, hornbeam, and chestnut grow. The soils are brown forest, gray forest and soddy-podzolic. In the Russian Federation, such forests grow in their pure form only in the very southwest, in the Carpathians.

Steppe zones are common in temperate and subtropical zones of both hemispheres. Currently heavily plowed. The temperate zone is characterized by a continental climate; precipitation - 240-450 mm. Average July temperatures are 21-23°C. Winter is cold with thin snow cover and strong winds. Predominantly cereal vegetation on chernozem and chestnut soils.

Transitional strips between zones are forest-tundra, forest-steppe and semi-desert. Their territory is dominated, as in the main zones, by its own zonal type of landscape, which is characterized by alternating areas, for example: forest and steppe vegetation - in the forest-steppe zone; open forest with typical tundra in the lowlands - for the forest-tundra subzone. Other components of nature—soil, fauna, etc.—alternate in the same way. Significant differences are also noticeable throughout these zones. For example, the Eastern European forest-steppe is oak, the Western Siberian is birch, the Daurian-Mongolian is birch-pine-larch. Forest-steppe is also widespread in Western Europe (Hungary) and North America.

In temperate, subtropical and tropical zones there are desert geographical zones. They are characterized by aridity and continental climate, sparse vegetation and soil salinity. Annual precipitation is less than 200 mm, and in ultra-arid areas it is less than 50 mm. In the formation of the relief of desert zones, the leading role belongs to weathering and wind activity (aeolian landforms).

Desert vegetation is drought-resistant subshrubs (wormwood, saxaul) with long roots that allow them to collect moisture from large areas and lush flowering ephemerals in early spring. Ephemera are plants that develop (bloom and bear fruit) in the spring, i.e., in the wettest time of the year. Usually it lasts no more than 5-7 weeks.

Subshrubs are able to tolerate overheating and dehydration, even with water losses of up to 20-60%. Their leaves are small, narrow, sometimes turning into spines; Some plants have pubescent leaves or are covered with a waxy coating, others have succulent stems or leaves (cacti, agaves, aloe). All this helps plants tolerate drought well. Among animals, rodents and reptiles predominate everywhere.

In subtropical zones, the temperature of the coldest month is at least -4°C. Humidification varies by season: winter is the wettest. In the western sector of the continents there is a zone of evergreen hard-leaved forests and shrubs of the Mediterranean type. They grow in the northern and southern hemispheres between approximately 30 and 40° latitude. In the inland parts of the northern hemisphere there are deserts, and in the eastern sectors of the continents with a monsoon climate and heavy summer rainfall there are deciduous forests (beech, oak) with an admixture of evergreen species, under which yellow soils and red soils are formed.

Tropical zones are located approximately between 20 and 30° N. and Yu. w. Their main features: arid conditions, high temperatures air on land, anticyclones with dominance of trade winds, low clouds and light precipitation. Semi-deserts and deserts predominate, they are replaced in the more humid eastern edges of the continents by savannas, dry forests and woodlands, and in more favorable conditions and tropical rainforests. The most pronounced savannah zone is a tropical type of vegetation, combining grassy grass cover with single trees and shrubs. The plants are adapted to withstand prolonged drought: the leaves are hard, heavily pubescent or in the form of thorns, the tree bark is thick.

The trees are low-growing, with gnarled trunks and an umbrella-shaped crown; some trees store moisture in their trunks (baobab, bottle tree, etc.). Animals include large herbivores - elephants, rhinoceroses, giraffes, zebras, antelopes, etc.

Studying the contents of the paragraph provides the opportunity to:

Ø to form an idea of ​​the geographical shell as a natural body;

Ø deepen knowledge about the essence of the periodic law of geographic zoning;

Ø deepen understanding of the peculiarities of the natural conditions of individual geographical zones of the Earth.

Features of the geographical shell. The geographic shell was formed simultaneously with the development of the Earth, therefore its history is part of the general history of the development of the Earth. ( What is the geographic envelope? What components of the geographic envelope have you already studied in your geography and biology course?)

All components of the geographical envelope are in contact, interpenetration and interaction . There is a continuous exchange of matter and energy between them. Life is concentrated in the geographical shell.

In its development, the geographic envelope went through three stages. The beginning of the first - inorganic - can be considered the appearance of the atmosphere. At the second stage, a biosphere was formed in the geographic shell, transforming all the processes that had previously taken place in it. At the third – modern – stage, human society appeared in the geographical shell. Man began to actively transform the geographical envelope.

Due to the fact that the geographical envelope of the Earth represents the environment for human life and activity, and the human impact on nature increases every year, its composition includes: sociosphere With technosphere And anthroposphere.

The sociosphere (from the Latin societas - society) is a part of the geographical envelope, including humanity with its inherent production and production relations, as well as the part of the natural environment developed by man.

Technosphere (from the Greek technе - art, skill) is a set of artificial objects within the geographical envelope of the Earth, created by man from the substance of the surrounding nature. The increasing anthropogenic pressure on the biosphere, which has caused the inclusion of elements of the technosphere and other means and products of human activity in the biosphere, contributes to the transition of the biosphere to a qualitatively new state.

The anthroposphere (from the Greek anthropos - man) embraces humanity as a collection of organisms. The life of any organism in all forms of its manifestation is possible only with constant interaction with the outside world and the continuous flow of energy into the body from the outside. All types of living beings ultimately use the same energy - the energy of the Sun, but the forms of manifestation and use of this energy are different.

Geographical zoning is expressed in the natural change of geographical zones from the equator to the poles and the distribution of geographical zones within these zones. The largest latitude-zonal unit of the geographic envelope is the geographic belt, which is distinguished by its characteristics radiation balance And general atmospheric circulation. Within the belt, the climate is relatively homogeneous, which is reflected in other components of nature (soils, vegetation, fauna, etc.) ( Remember what geographical zones are distinguished on Earth? What is their total number?).

The shape and area of ​​the belts depend on many factors, the main of which are: the proximity of oceans and seas, relief, and sea currents. In geographical zones there are geographical (natural) zones. Their release is associated, first of all, with the uneven distribution of heat and moisture on the Earth's surface. ( Why?) They are often elongated in the latitudinal direction (Africa), but under the influence of the configuration of the continents and orographic factors they can have a meridional direction (North America).

V.V. Dokuchaev and L.S. Berg made a great contribution to the development of the doctrine of geographic zoning. V.V. Dokuchaev based his doctrine of natural zones on the proposition that each natural zone (tundra, taiga, steppe, desert and other zones) represents a natural complex in which the components of living and inanimate nature are interconnected and interdependent. This served as the basis for the classification of natural zones developed by L. S. Berg.

A further development of the law of geographical zonation was periodic law of geographical zonation, which was formulated in 1956 by famous geographers A.A. Grigoriev and M.I. Budyko. The essence of the periodic law is that geographic zones at different latitudes have a number of properties that are periodically repeated (for example, the zone of forest-steppe and savannas, deciduous forests of the temperate zone and forests of the humid subtropics, etc.) According to this law, the differentiation of the geographical envelope is based lie: the amount of absorbed solar energy (the annual value of the radiation balance of the earth’s surface); amount of incoming moisture (annual precipitation); the ratio of the radiation balance to the amount of heat required to evaporate the annual amount of precipitation (radiation dryness index). The value of the dryness index in different zones ranges from 0 to 4-5. The periodicity is also manifested in the fact that the dryness index value, close to unity, is repeated three times between the pole and the equator (Fig....).

These conditions are characterized by the highest biological productivity of landscapes (with the exception of equatorial forests (hylea).

Thus, geographic zonality is expressed in the natural change of geographic zones from the equator to the poles and the distribution of geographic zones within these zones. The very list of names of geographical zones emphasizes their symmetrical position in relation to the equator. The share of the area of ​​each geographical zone in relation to total area the globe is clearly shown in the figure (Fig...).

Along with zonality, azonality or regionality is distinguished. Azonality means the spread of any geographical phenomenon without connection with the zonal characteristics of a given territory. The main reasons for azonality are the geological structure, tectonic features, the nature of the relief, etc. In the presence of these factors, large areas of the geographical envelope acquire individual unique features, which complicates its structure and disrupts the zonation scheme. Azonality is most often and clearly manifested in the mountains and foothills.

Features of the Earth's geographic zones. Equatorial belt occupies 6% of the total land area of ​​the Earth. It is represented by equatorial forests ( Using the map, determine the boundaries of the equatorial belt)

A feature of the equatorial belt is the extremely high intensity of all natural processes (geomorphological, biochemical and others), as a result of which a powerful weathering crust is formed. The reason for the high intensity of the processes is, first of all, the constantly hot and humid climate.

Subequatorial belts occupy about 11% of the total land area. ( Using a map, determine the location of the subequatorial belts). Most of the area of ​​the subequatorial belts, like the equatorial belt, falls on the World Ocean. Here the belts are clearly expressed and can be identified by trade wind currents. Belts of both hemispheres in the Pacific and Atlantic Oceans shifted to the north compared to their position on land.

An essential feature of the subequatorial belts is variable atmospheric circulation, when there is a seasonal change from equatorial air to tropical air, and vice versa, which determines the presence of dry and wet (rainy) seasons.

In the subequatorial belts, two natural zones are distinguished: savanna(savannas and woodlands), which is the main area, and the zone variable-humid forests- narrow, transitional from gils to savannas.

The eastern margins of the continents within these belts are under the influence of monsoons and trade winds.

Tropical zones. In total, they occupy 35% of the Earth's total land area. (Locate them on the map). These latitudes are dominated by dry and hot air both on continents and oceans. By natural features within tropical zones there are zones: forests, savannas And woodlands, semi-deserts and deserts (Using the atlas, determine the boundaries of the natural zones of the tropical zones).

Subtropical zones occupy an area equal to 15% of the total land area (Determine their location on the map and compare their distribution along longitude in the northern and southern hemispheres). The peculiarity of the nature of these belts is determined by their geographical location and is expressed in the predominance here tropical(summer) and moderate(in winter) air masses. In the western oceanic regions of these zones (see map) the nature is Mediterranean with dry summers and wet winters. The eastern coastal territories (see map) have a monsoon climate with high summer humidity. Inland areas have an arid climate. In general, natural zones are distinguished in subtropical zones: forests, forest-steppes, steppes, semi-deserts and deserts.

The natural conditions of the subtropical zones are favorable for human life, so these territories have long been developed and populated. Here the forests have been heavily cleared, and in their place are fields, plantations of cotton, tea, citrus fruits, etc.

Temperate zones characterized by the asymmetry of their location in the Northern and Southern Hemispheres (Use the map to determine the location of the belts in the northern and southern hemispheres). The large extent of the territory from east to west and from north to south causes a wide variety of natural conditions. According to natural features, the temperate zone is divided into moderately warm, dry, and moderately cold, damp. The first identifies natural zones: semi-deserts and deserts, steppes, forest-steppes; in the second: the zone of taiga (coniferous forests), broad-leaved forests, small-leaved and mixed forests. ( Using the atlas, determine the boundaries of the natural zones of the temperate zone of the northern hemisphere)

Subarctic belt located on the northern edges of Eurasia and North America. Its southern border is determined largely by the influence of sea currents. In Europe, under the influence of a warm current, the belt occupies a narrow strip of land and is located north of the Arctic Circle, while in the northeastern part of Eurasia, where there is no effect of this current, it expands and reaches 60° N. w. In North America (Hudson Bay region), under the influence of cold currents, its boundary drops to 50° N. sh., i.e. to the latitude of Kyiv. The southern boundary of the belt approximately corresponds to the 10°C isotherm of the warmest month of the year. This is the limit of the northern distribution of forests. Permafrost is widespread, which in some places begins at a depth of 30 cm. Natural zones: tundra, forest-tundra and woodlands.

Subantarctic belt almost entirely located in oceanic spaces. Only a few islands represent land. The largest of them are Falkland, Kerguelen, South Georgia and others. The islands have oceanic tundra conditions, high humidity, strong winds, poor moss-lichen vegetation. On some islands, tundra can be traced up to 50° S. w.

Arctic And Antarctic belts (Define them geographical position) although they are located in territories with different underlying surfaces - the first is on oceanic expanses, the second is on the continent of Antarctica, but they have common features more than different: low temperatures winter and summer ( Determine the temperature of the warmest month), strong winds, lack or little vegetation, etc. The Arctic tundra zone, Arctic and Antarctic deserts are distinguished.

Questions and tasks