Natural land areas. Natural area What natural areas exist on earth
All year round, the arctic air prevails here, the radiation balance for the year is less than 400 mJ / m 2, the average July temperatures are 4-2 ° С. The relative humidity is very high - 85%. Precipitation falls 400-200 mm, and almost all of them fall in solid form, which contributes to the emergence of ice sheets and glaciers. However, in some places, the supply of moisture in the air is small, and therefore, with an increase in temperature and strong winds, a large lack of moisture is formed and strong evaporation of snow occurs.
The soil-forming process in the Arctic takes place in a thin active layer and is at the initial stage of development. In the valleys of rivers and streams and on sea terraces, two types of soils are formed - typical polar desert soils on polygonal drained plains and polar desert solonchaks in saline coastal areas. They are characterized by a low humus content (up to 1.5%), weakly expressed genetic horizons and a very low thickness. In the arctic deserts, there are almost no swamps, few lakes, salt spots form on the soil surface in dry weather with strong winds.
The vegetation cover is extremely sparse and patchy; it is characterized by a poor species composition and extremely low productivity. Low-organized plants dominate: lichens, mosses, algae. The annual growth of mosses and lichens does not exceed 1–2 mm. Plants are extremely selective in their distribution. More or less closed groupings of plants exist only in places sheltered from cold winds, on fine earth, where the thickness of the active layer is greater.
The main background of the Arctic deserts is formed by crustose lichens. Hypnum mosses are common, sphagnum mosses appear only in the south of the zone in very limited quantities. Higher plants are characterized by saxifrage, polar poppy, crumbs, stellate, Arctic pike, bluegrass and some others. Cereals thrive, forming hemispherical cushions up to 10 cm in diameter on a fertilized substrate near nesting gulls and burrowing lemmings. At the spots of snow, an ice buttercup and a polar willow grow, reaching only 3-5 cm in height. Fauna, like flora, is poor in species; there are lemming, arctic fox, reindeer, polar bear, and ptarmigan and snowy owl are ubiquitous among birds. On the rocky shores there are numerous bird colonies - massive nesting sites of seabirds (guillemots, luriks, ivory gulls, fulmars, eiders, etc.). The southern shores of Franz Josef Land, the western shores of Novaya Zemlya are a continuous bird colony.
The geographic envelope is not equally tripled 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, relief, 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 envelope, it is subdivided into natural complexes of a smaller rank. The division of the geographic envelope 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 areas. In accordance with this, zonal and azonal natural complexes are distinguished.
The largest azonal natural complexes are continents and oceans. Smaller are 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 are geographic zones. They coincide with climatic zones and have the same names (equatorial, tropical, etc.). In turn, the geographic zones consist of natural zones, which are released by the ratio of heat and moisture.
Natural area is a large area of land with similar natural components - soils, vegetation, fauna, which are formed depending on the combination of heat and moisture.
The main component of the natural area is the climate, since 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 vegetation, since it most obviously reflects other features of nature.
The climate changes naturally as it moves from the equator to the poles. Soil, vegetation and fauna are determined by the climate. This means that these components should change latitudinal, following the climate change. The natural change in natural zones when moving from the equator to the poles is called latitudinal zoning. In the equator region there are humid equatorial forests, at the poles - icy arctic deserts. Between them are other types of forests, savannahs, 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 zones). Treeless zones are formed where there is a lack of heat (tundra) or moisture (steppe, desert). These are continental regions of the tropical and temperate zones, as well as the subarctic climatic zone.
The climate changes not only latitudinal, but also due to changes in altitude. With the rise in the mountains, the temperature decreases. The amount of precipitation increases to an altitude of 2000-3000 m. A change in the ratio of heat and moisture causes a change in the soil - vegetation cover. Thus, different natural zones are located in the mountains at different heights. This pattern is called high-altitude zonation.
The change of altitude zones in the mountains occurs in approximately 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 zones is determined by the height of the mountains and their geographic location. The higher the mountains, and the closer they are to the equator, the more diverse the set of altitudinal zones. The vertical zonation is most fully expressed in the Northern Andes. In the foothills, humid equatorial forests grow, then there is a belt of mountain forests, and even higher - thickets of bamboos and tree 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 rocky placers covered with moss and lichens. The peaks of the mountains are crowned with snow and glaciers.
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They often drop to -50 ° С, there are strong winds, many days with a blizzard and; 85% of the territory of the zone is covered. The sparse vegetation cover consists of mosses, lichens, algae and rare flowering plants. The polar desert soils are very thin. Usually on top they have a layer of peat (1-3 cm). Significant evaporation over a long polar day (about 150 days) and dry air lead to the formation of saline varieties of polar desert soils.
The fauna in the Arctic zone is poor, since the productivity of the plant mass is very low. Arctic foxes and polar bears live on the islands. There are especially many polar bears. On the rocky shores of the islands there are “bird colonies” - colonies of seabirds. Thousands of auks, gulls, guillemots, guillemots, kittiwakes, puffins and other birds nest on the coastal rocks.
The tundra zone occupies about 8-10% of the entire territory of the country. In short and cool summers with an average July temperature from + 4 ° С in the north to + 11 ° С in the south. Winter is long, harsh with strong and. The winds are cold throughout the year. In summer they blow from the Arctic Ocean, in winter - from the cooled mainland. There is very little rainfall - 200-300 mm per year. Despite this, the soils in the tundra are overwetted everywhere, which is facilitated by the impermeable permafrost and weak evaporation at low temperatures. Typical tundra and podzolized soils are thin, low in humus, relatively high in acidity, and are usually swampy.
The vegetation cover is formed by mosses, lichens, shrubs and shrubs. All plants have characteristic shapes and properties that reflect their adaptability to harsh climates. Pelvic and cushion forms of plants dominate, which help to use surface heat and shelter from strong winds. Due to the fact that the summer is very short and the growing season is limited, most of the plants are perennials and even evergreens. These include lingonberries and cranberries. All of them begin to vegetate immediately as soon as the snow melts. In the north of the zone there are arctic tundras dominated by moss-lichen groups and. Among the herbaceous species are sedge, cotton grass, polar poppy. In the middle part of the zone there is a typical tundra with moss, lichen and shrub groups. In the eastern part of the country, sedge-cushy tussock tundras dominate. Bushy lichen - lichen (“reindeer moss”) is used to feed the reindeer. Yagel grows very slowly, at a rate of 3-5 mm per year. Therefore, the restoration of pastures takes a very long time - within 15-20 years. For this reason, only nomadic animal husbandry is possible in the tundra, in which numerous herds of deer are constantly moving in search of food. There are many berry plants among the plants: cloudberries, lingonberries, blueberries, blueberries. There are thickets of bushy willow. In the south of the zone, where there is more warmth and weaker winds, shrub tundras dominate. Among the shrubs, the most common is dwarf birch, various types of willows. In shelters along the tundra, thickets of bushy alder enter the tundra from the south. There are a lot of berry plants - blueberries, blueberries, lingonberries, heather shrubs and mushrooms grow.
The fauna of the tundra is very poor in terms of species, but abundant in the number of individuals. Reindeer (wild and domestic), lemmings, arctic foxes and wolves, tundra partridge and snowy owl live in the tundra throughout the year. In summer, many birds arrive. The abundance of food in the form of midges and mosquitoes attracts a huge number of geese, ducks, swans, waders and loons to the tundra for breeding chicks.
Farming in the tundra is impossible due to the low temperature of the soils and their lack of nutrients. But in the tundra, numerous herds of deer graze, forage for furs, and gather eider down.
Forest-tundra is a transitional zone between tundra and forest. The forest-tundra is much warmer than the tundra. In some places, about 20 days a year, the average daily temperature is above + 15 ° С, and the average July temperature is up to + 14 ° С. Annual precipitation reaches 400 mm, which is much higher than evaporation. As a result, the forest-tundra has excessive moisture.
In the forest-tundra, there are forest and tundra plant groups nearby. The forests are made up of curved low-growing birches, spruces and larch trees. Trees in forests are far apart from each other, since their root system is located in the upper layers of the soil above permafrost. The most productive reindeer pastures are located in the forest-tundra, since lichen grows here much faster than in the tundra. In addition, deer can hide in forests from strong winds and use forest vegetation as food. Both tundra and forest animals live here - elk, brown bear, squirrel, white hare, wood grouse and hazel grouse. Hunting gives a lot of furs, of which the skins of the Arctic fox are the most valuable.
The forest zone occupies more than half of the territory of Russia. But the forested area is only 45% of the country's area. In most of the zone, winters are harsh and cold. January temperature even in the south is below 0 ° С. But the summer is warm, and even hot in places. The average July temperature in the north of the zone is + 15 ° С, and in the south - + 20 ° С.
Summer is cool in the taiga subzone. The average July temperature is not higher than + 18 ° С. The amount of precipitation (300-900 mm) is slightly higher than evaporation. The snow cover is stable and lasts all winter. The ratio of heat and moisture is such that it is universally conducive to tree growth.
In the forest-steppe zone, summer becomes hot. The average July temperature rises to + 19 ... + 21 ° С. In the north of the zone, the amount of precipitation (560 mm per year) is approximately equal to evaporation. In the south, the evaporation rate is slightly higher than the amount of precipitation. Droughts are common here. The climate of the zone is unstable - wet years alternate with dry ones. In general, the forest-steppe has a warm and relatively dry climate.
Throughout the entire zone, small forests alternate with forb steppes. On the East European Plain, oak forests with an admixture of maple, ash, linden and elm prevail in the forest-steppe. In the West Siberian Plain, birch and aspen dominate the forests. In Eastern Siberia, there are pine-larch forests with an admixture of birch and aspen. Under deciduous forests, the same soil-forming processes take place as in the subzone of deciduous forests. Therefore, gray forest soils are widespread here. Chernozem soils were formed under areas of forb steppes.
The forests of the zone are inhabited by common forest species of animals and birds. And in open steppe areas there are ground squirrels and brown hares (often), marmots, hamsters, bustards (rarely). Both in the forests and in the steppe areas of the zone, wolves and foxes are common.
Favorable climatic conditions, high soil fertility have led to the fact that the forest-steppe is intensively developed and populated. Up to 80% of the land in this zone is plowed up. Wheat, corn, sugar beets and sunflowers are grown here. The vast orchards are rich in apples, pears, apricots and plums.
The steppe zone stretches in the south of the European part of Russia from the Black and seas, foothills. In the east, it stretches in a continuous strip to. For steppe areas are found only in intermontane basins in the south of Siberia.
Many live in the steppes - ground squirrels, marmots, hamsters, voles. There is a fox and a wolf. Of the birds, the most common are larks and steppe partridges. Some species of animals have adapted to the plowed area, and their number not only did not decrease, but even increased. These include ground squirrels, which cause great damage to grain crops.
The semi-desert zone is located in the Caspian region. It has a dry, sharply continental climate. In summer, the average July temperatures rise to + 23 ... + 25 ° С, and in January they drop to -10 ... -15 ° С. The annual amount of precipitation does not exceed 250 mm per year. Winter is extremely unstable - there are often strong winds and the temperature can drop to -40 ° C. Frost can suddenly be replaced by thaws, accompanied by ice or (with a further decrease in temperature). At the same time, many sheep die, since they cannot get grass from under the ice crust.
The semidesert is dominated by wormwood-cereal communities. But the vegetation cover is spotty and sparse. There are areas of bare soil between the clumps of plants. The grass stand is dominated by feather grass, fescue, and tyrsa. Many types of dwarf shrubs - white wormwood, prutnyak, biyurgun and others. Wormwood-grass vegetation is used as pastures. Many semi-desert plants are exceptionally rich in nutrients and are readily eaten by sheep, horses and camels. Farming is carried out only with the use of irrigation.
Chestnut soils are zonal in the semi-desert. Compared to them, they are much poorer in humus, have less thickness and are often solonetzic. Salt licks and, rarely, salt marshes are found throughout the zone. The semi-desert is inhabited by animals of the steppes and deserts. The main animals are rodents: ground squirrel, jerboas, voles, mice. A typical animal of the semi-desert is the saiga antelope. There are wolves, steppe polecat, and corsac fox. From birds - steppe eagle, bustard, larks.
The desert zone is located in the Caspian lowland. This is the driest territory in Russia. Summers are long and very hot. The average temperature in July is + 25 ... + 29 ° С. But very often the temperature in summer reaches + 50 ° С. Winter is short, with freezing temperatures. The average January temperature is -4 ... -8 ° С. The snow cover is thin and unstable. The annual amount of precipitation is 150 - 200 mm. Evaporation rate is 10 - 12 times higher than precipitation.
The vegetation cover of deserts is closely related to the nature of the soil. Plants with powerful rhizomes and adventitious roots are widespread on the sands, which strengthen the plant in loose soil and help find moisture. Solyanka, saltwort, sarsazan are confined to the salt marshes. In the northern part of the desert, wormwood and saltwort prevail. In the north, sandy soils are widespread and gray-brown soils are often found. They are carbonate, solonetzic and contain little humus. Takyrs are ubiquitous. These are clay soils in depressions - with impassable mud in the spring and a hard cracked crust - in dry. Takyrs are practically devoid of vegetation.
Saigas and dune cat live in. A large number of rodents - jerboas and gerbils, many lizards. Numerous insects are diverse - scorpions, tarantulas, mosquitoes, locusts.
The abundance of sunlight and heat, a long growing season allows growing high yields of the most valuable crops - grapes, melons and gourds - on irrigated lands. Numerous canals have been built for irrigation, and. Thanks to irrigation, agricultural farms and new oases arose in the scorched desert. The vast desert pastures are used for grazing sheep and camels.
The subtropical zone occupies small areas covered by mountains from the north. the coast of the Caucasus near Novorossiysk are dry subtropics with hot dry summers, with an average July temperature of + 24 ° С. Winters are relatively warm and humid. Average temperatures of the coldest month - February - are close to + 4 ° С. Frosty periods are rare and short-lived. The annual amount of precipitation reaches 600-700 mm with a maximum in winter. The best time of the year is autumn, when there are warm sunny days during September and October.
In the past, dry subtropics were covered with forests of downy oak, arboreal juniper, and Pitsunda pine, strawberry and sandalwood groves. Shrub thickets of shibliak and maquis are widespread. Shiblyak - undersized thickets of deciduous plants of a fluffy oak, thorny shrubs hold the tree, sumach, wild rose. Makvis - thickets of evergreen shrubs and low trees: myrtle, wild olive, strawberry tree, tree heather, rosemary, stone oak. The soils of dry subtropics are brown forest and brown.
At present, the natural vegetation cover is practically reduced. Most of the territory is occupied by vineyards, gardens, parks of numerous sanatoriums and rest houses.
"" Photo: Aziz J.Hayat Belt zoning
The Sun heats the spherical surface of the Earth unevenly: the areas above which it stands high receive the most heat. The farther from the equator, the greater the angle the rays reach the earth's surface and, therefore, less thermal energy per unit area. 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 flora and fauna are also related to this. According to the features of heat distribution, seven heat zones are distinguished. In each hemisphere there are zones of eternal frost (around the poles), cold, moderate. The hot belt at the equator is one for both hemispheres. Heat zones are the basis for dividing the earth's surface into geographic zones: areas that are similar in the prevailing types of landscapes - natural-territorial complexes that have a common climate, soils, vegetation and fauna.
At the equator and near it there is a belt of humid equatorial and subequatorial forests (from Latin sub - under), to the north and south of it, replacing each other, there are belts of tropics and subtropics with forests, deserts and savannas, a temperate belt with steppes, forest-steppe and forests, then the treeless areas of the tundra stretch, and, finally, the polar deserts are located at the poles.
But the land surface of the Earth in different places receives not only different amounts of solar energy, but also has many additional dissimilar conditions - for example, remoteness from the oceans, uneven relief (mountain systems or plains) and, finally, unequal height above sea level. Each of these conditions strongly affects the natural features of the Earth.
Hot belt. Near the equator, there are practically no seasons; it is humid and hot here all year round. Moving away from the equator, in the subequatorial zones, the year is divided into drier and more humid seasons. Savannas, woodlands and mixed evergreen deciduous tropical forests are located here.
Near the tropics, the climate becomes drier; deserts and semi-deserts are located here. The most famous of them are the Sahara, Namib and Kalahari in Africa, the Arabian Desert and Thar in Eurasia, Atacama in South America, Victoria in Australia.
There are two temperate zones on Earth (in the Northern and Southern Hemispheres). Here there is a clear change of seasons, which are very different from each other. In the Northern Hemisphere, coniferous forests adjoin the northern border of the belt - taiga, alternating to the south with mixed and deciduous forests, and then forest-steppe and steppes. In the interior regions of the continents, where the influence of the seas and oceans is almost not felt, there may even be deserts (for example, the Gobi desert in Mongolia, the Karakum in Central Asia).
Polar belts. The lack of heat leads to the fact that there are practically no forests in these zones, the soil is swampy, and in some places there is permafrost. At the poles, where the climate is the most severe, continental ice appears (as in Antarctica) or sea ice (as in the Arctic). Vegetation is absent or is represented by mosses and lichens.
Vertical zonation is also related to the amount of heat, but it only depends on the height above sea level. Climbing the mountains changes the climate, soil type, flora and fauna. It is interesting that even in hot countries one can find landscapes of the tundra and even the icy desert. But in order to see this, you have to climb high in the mountains. Thus, in the tropical and equatorial zones of the Andes of South America and in the Himalayas, landscapes consistently change from wet rain forests to alpine meadows and zones of eternal glaciers and snows. It cannot be said that the altitudinal zonation completely repeats the latitudinal geographic zones, because in the mountains and on the plains many conditions do not repeat. The most diverse range of altitudinal belts is at the equator, for example, on the highest peaks of Africa, the mountains of Kilimanjaro, Kenya, the peak of Marguerite, in South America on the slopes of the Andes.
Natural areas
Among the natural zones there are those confined to a certain belt. For example, the Arctic and Antarctic ice desert zone and the tundra zone are located in the Arctic and Antarctic zones; the forest-tundra zone corresponds to the subarctic and subantarctic belts, and the taiga, mixed and broad-leaved forests - to the temperate zone. And such natural zones as prairies, forest-steppe and steppes and semi-deserts are widespread both in the temperate and in the tropical and subtropical zones, having, of course, their own characteristics in them.
Natural zones, their climatic features, soils, vegetation and fauna of each continent are described in chapter 10 and in the table "Continents (reference information)". Here we will dwell only on the general features of natural zones as the largest natural-territorial complexes.
Arctic and Antarctic Desert Zone
Air temperatures are constantly very low, there is little rainfall. On rare ice-free land areas - stony deserts (in Antarctica they are called oases), sparse vegetation is represented by lichens and mosses, flowering plants are rare (only two species have been found in Antarctica), soils are practically absent.
Tundra zone
The tundra zone is widespread in the Arctic and subarctic belts, forms a strip 300-500 km wide, stretching along the northern coasts of Eurasia and North America and the islands of the Arctic Ocean. In the Southern Hemisphere, areas of tundra vegetation are found on some islands near Antarctica.
The climate is harsh with strong winds, the snow cover lasts up to 7-9 months, the long polar night gives way to short and humid summers (summer temperatures do not exceed 10 ° c). There is a little bit of precipitation of 200-400 mm, mostly in solid form, but they do not have time to evaporate, and the tundra is characterized by excessive moisture, an abundance of lakes and swamps, which is also facilitated by the ubiquitous permafrost. The main distinguishing feature of the tundra is its treelessness, the predominance of a sparse moss-lichen, in places grassy, cover; in the southern parts with shrubs and shrubs of dwarf and creeping forms. The soils are tundra-gley.
Zone of forest tundra and woodlands
Zone of forest-tundra and woodlands. This transitional zone, which is characterized by alternation of treeless tundra areas and forests (light forests), combines the features of the bordering zones. Tundra natural complexes are characteristic of watersheds, light forests are taken to the north along river valleys. To the south, the area occupied by forests increases.
In the Southern Hemisphere (subantarctic belt), the place of forest-tundra on islands (for example, South Georgia) is occupied by oceanic meadows. For more information on the tundra zone, see the characteristics of the tundra.
Forest zone
The forest zone in the Northern Hemisphere includes subzones of taiga, mixed and deciduous forests and a subzone of temperate forests; in the Southern Hemisphere, only the subzone of mixed and deciduous forests is represented. Some scientists consider these subzones to be independent zones.
In the taiga subzone of the Northern Hemisphere, the climate varies from maritime to sharply continental. Summers are warm (10-20 ° c, the severity of winter increases with distance from the ocean (in Eastern Siberia up to -50 ° c), and the amount of precipitation decreases (from 600 to 200 mm). The amount of precipitation exceeds evaporation, and watersheds are often swampy, rivers Dark coniferous (from spruce and fir) and light coniferous (from larch in Siberia, where permafrost soils are widespread) forests with an admixture of small-leaved species (birch, aspen) and pine, in the east of Eurasia - cedar prevail. taiga.
The subzone of mixed and deciduous forests (sometimes two separate subzones are distinguished) is distributed mainly in the oceanic and transitional zones of the continents. It occupies small areas in the Southern Hemisphere, winter is much warmer here and snow cover is not formed everywhere. Coniferous-broad-leaved forests on sod-podzolic soils are replaced in the inner parts of the continents by coniferous-small-leaved and small-leaved forests, and to the south (in North America) or west (in Europe) by broad-leaved forests of oak, maple, linden, ash, beech and hornbeam on gray forest soils.
Forest-steppe
The forest-steppe is a transitional natural zone of the Northern Hemisphere, with an alternation of forest and steppe natural complexes. By the nature of natural vegetation, forest-steppe with deciduous and coniferous-small-leaved forests and prairies are distinguished.
Prairies are a subzone of the forest-steppe (sometimes considered as a subzone of the steppe) with abundant moisture, stretching along the eastern coasts of the Rocky Mountains in the USA and Canada with tall grasses on chernozem-like soils. Natural vegetation is practically not preserved here. Similar landscapes are characteristic of the subtropics of the eastern regions of South America and East Asia.
Steppe
This natural zone is widespread in the northern temperate or both subtropical geographic zones and is a treeless area with herbaceous vegetation. The growth of woody vegetation here, in contrast to the tundra, is prevented not by low temperatures, but by a lack of moisture. Trees can grow only along river valleys (the so-called gallery forests), in large erosional forms, for example, gullies that collect water from the surrounding interfluvial spaces. Now most of the zone is plowed up; irrigated agriculture and pasture cattle breeding are developing in the subtropical zone. Soil erosion is highly developed on arable land. Natural vegetation is represented by drought and frost-resistant herbaceous plants dominated by turf grasses (feather grass, fescue, fine-legged). Fertile soils - chernozems, dark chestnut and chestnut in the temperate zone; brown, gray-brown, saline in places in the subtropical).
The subtropical steppe in South America (Argentina, Uruguay) is called the pampa (i.e. plain, steppe in the Quechua language). See vegetation and animals of the steppe.
Deserts and semi-deserts
These natural zones are distributed in six geographic zones - temperate, subtropical and tropical on both sides of the equator, where precipitation falls so little (10-30 times less evaporation) that the existence of living organisms is extremely difficult. Therefore, the herbaceous cover is sparse, the soils are poorly developed. Under such conditions, the rocks that make up the territory acquire great importance, and depending on them, clay deserts (takyrs in Asia), stony (hamadas of the Sahara, Central Asia, Australia), sandy (Thar desert in India and Pakistan, North American deserts ). In the temperate zone, deserts are formed in areas with a sharply continental climate, subtropical and tropical deserts owe their existence to constant baric maximums of 20-30 ° latitudes. Rare areas of increased moisture (high level of groundwater, outflows of sources, irrigation from nearby rivers, lakes, wells, etc.) - centers of population concentration, growth of woody, shrub and herbaceous vegetation are called oases. Sometimes such oases occupy vast areas (for example, the Nile Valley stretches over tens of thousands of hectares). For more, see: Natural Desert Zone.
Savannah
Savannah is a natural zone, distributed mainly in the subequatorial belts, but also found in tropical and even subtropical zones. The main feature of the savannah climate is a clear change between dry and rainy periods. The duration of the rainy period decreases when moving from the equatorial regions (here it can last 8-9 months) to tropical deserts (here the rainy season is 2-3 months). Savannah is characterized by a dense and high grassy cover, trees standing alone or in small groups (acacia, baobab, eucalyptus) and the so-called gallery forests along the rivers. The soils of typical tropical savannahs are red earths. In the deserted savannas, the grass cover is sparse and the soils are red-brown. Tall grass savannas in South America, on the left bank of the river. Orinoco, called llanos (from the Spanish "plain"). See also: Savanna vegetation and animals.
Forest subtropics
Forest subtropics. The monsoon subtropical subzone is characteristic of the eastern margins of the continents, where seasonally changing air circulation forms at the contact between the ocean and the continent, and there is a dry winter and humid summer with abundant monsoon rains, often with typhoons.
Heat zones and natural zones
Evergreen and deciduous (shedding foliage in winter due to lack of moisture) with a wide variety of tree species grow here on red earth and yellow earth soils.
The Mediterranean subzone is typical for the western regions of the continents (Mediterranean, California, Chile, southern Australia and Africa). Precipitation occurs mainly in winter; summer is dry. Evergreen and broadleaf forests on brown and brown soils and stiff-leaved shrubs are well adapted to summer drought, the plants of which have adapted to hot and arid conditions: they have a waxy coating or pubescence on the leaves, thick or dense leathery bark, and secrete aromatic essential oils. See: animals of the subtropics.
Rainforests
More on the topic:
Taiga zone, plants and animals
Savannah
Characteristics of the forest-tundra
Characteristics of the tundra
Equatorial forest
Equatorial humid forests... Equatorial climate. Warm all year round (about 25 ° C), slight fluctuations in temperature throughout the year, high rainfall all year round. Low pressure.
Savannah... Subequatorial climate. It's hot all year round. Precipitation falls unevenly throughout the year; there are dry and wet seasons. The main vegetation is grasses.
Deserts... In tropical deserts, precipitation is very rare. There is very little vegetation. In the deserts of the temperate zone, there is a wet spring (March-April).
Steppe... Continental climate with cold winters with little snow and hot dry summers.
Broadleaved and mixed forests... Favorable climatic conditions - sufficient moisture, many sunny days, frost-free period of about six months or more.
Taiga... There is enough moisture, but the cold period is significant. Summers are warm enough (up to 20 ° C), severe frosts in winter (average temperature –30 ° C).
Tundra... The soil is permafrost. The climate is subarctic.
Natural areas
Strong winds. Long cold winters, polar nights in many parts. In summer, the temperature is about +5 ° C.
Arctic desert... The dominance of ice, the absence of plants, the animal world is rather poor. In winter, the average temperature is -30 ° C and strong winds, in summer it can be slightly above 0, frequent rains and fogs. Polar night and day.
Antarctic desert... In winter, up to –70 ° C, in summer no higher than –20 ° C (on the coast of the Antarctic Peninsula it rises to 10 ° C). Strong winds blowing towards the coast and central regions of Antarctica.
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Natural zones of Russia and their features
Nature is a complex of interconnected components that are in constant interconnection with each other and depend on each other. Changes in one natural chain will necessarily lead to disruptions in the accompanying components. There is a constant exchange of resources and energy between individual members of the natural community. The presence of certain relationships is characteristic for each specific territory. This is how natural areas are formed. They, in turn, affect human economic activity and its characteristics.
Natural areas of Russia are very diverse. This is due to the vast territory, the difference in relief and climatic conditions.
Among the main natural zones of our country, there are steppes, semi-deserts, taiga, forests, forest-steppe, tundra, arctic desert, forest-tundra. Natural areas of Russia have a fairly large area that stretches for thousands of kilometers. Each of them is characterized by a certain climate, soil types, flora and fauna, as well as the degree of moisture in the territory.
The arctic desert zone is characterized by the presence of a large amount of snow and ice all year round. The air temperature here varies within 4-2 degrees. Glaciers are caused by solid precipitation. The soil is poorly developed and at the initial level. The formation of salt spots is observed in dry windy weather. The climatic conditions of this zone also affect the nature of the vegetation. Low mosses and lichens prevail here. Less common are the polar poppy, saxifrage and some other plants. The fauna is also not very rich. Arctic fox, deer, owl, partridge and lemming are practically the only inhabitants of the Arctic desert.
The natural zones of Russia also include the tundra zone. It is a less cold area than arctic deserts. But, nevertheless, it is distinguished by cold and strong winds, which is due to the proximity of the Arctic Ocean. Frost and snowfall is possible all year round. The climate of the tundra zone is humid. The soil is also very poorly developed, which affects the vegetation cover. Basically, low shrubs and trees, mosses and lichens predominate.
Natural zones of Russia are gradually replacing each other. This is followed by the forest-tundra. There is already warmer weather in the summer, but the winter is cold with a lot of snow. The plants are dominated by spruce, birch and larch. During the warm season, the forest-tundra serves as a pasture for deer.
The forest-tundra is replaced by taiga. It is characterized by warmer weather and less severe winters. The relief is characterized by the presence of a large number of water bodies (rivers, lakes and swamps). The soil here is more favorable for the flora, therefore the fauna is numerous here. The taiga is inhabited by sable, hazel grouse, wood grouse, hare, squirrel, bear and many other species.
The semi-desert zone is the smallest in area. Typically hot summers and severe winters with little rainfall are typical for her. It is mainly used for pastures.
The division of the territory into zones also affects human activities. Numerous natural and economic zones of Russia also determine its extensive activities in the economic sphere.
Each zone is subdivided into smaller species.
Natural zones of the world: a brief description. Table "Natural areas of the world"
There are also transition zones, which are characterized by the climatic features of each adjacent region. Therefore, each natural area is inextricably linked with the neighboring one. Violations occurring in a certain area of the country lead to changes not only in the climate, but also in the world of animals and plants in another zone.
The characteristic of the natural zones of Russia implies the peculiarities of each of them, but they do not have clear boundaries and the division is conditional. In addition, human activities can affect the nature and climate of the environment.
Formation of natural zones
The natural zone is a natural complex with uniform temperatures, moisture, similar soils, flora and fauna. The natural zone is called by the type of vegetation. For example, taiga, deciduous forests.
The main reason for the heterogeneity of the geographic envelope is the uneven redistribution of solar heat on the Earth's surface.
In almost every climatic zone of the land, the oceanic parts are more humid than the inland, continental ones. And it depends not only on the amount of precipitation, but also on the ratio of heat and moisture. The warmer it is, the more moisture precipitated with precipitation evaporates. The same amount of moisture can lead to excess moisture in one belt and insufficient moisture in the other.
Rice. 1. Swamp
Thus, the annual amount of precipitation of 200 mm in the cold subarctic belt 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).
Rice. 2. Desert
Due to differences in the amount of solar heat and moisture, natural zones are formed within the geographic zones.
Placement patterns
There is a clear pattern in the placement of natural zones on the earth's surface, which can be clearly traced 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 moisture conditions in different parts of the continents, natural zones do not form continuous stripes 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 foothills to the peaks. Altitudinal zonation is manifested here.
Natural zones are also formed in the World Ocean: from the equator to the poles, the properties of surface waters change, the composition of vegetation and fauna.
Rice. 3. Natural areas of the world
Features of the natural zones of the continents
In the same natural zones on different continents, the flora and fauna have similar features.
However, the features of the distribution of plants and animals, in addition to climate, are influenced by other factors: the geological history of continents, relief, people.
The unification and separation of continents, changes in their relief and climate in the geological past have become the reason that different species of animals and plants live in similar natural conditions, but on different continents.
For example, antelopes, buffaloes, zebras, African ostriches are characteristic of the African savannas, and several species of deer and a flightless bird, the rhea, similar to an ostrich, are common in the South American savannas.
On every continent there are endemics - both plants and animals, characteristic only of 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 unevenly: 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 flora and fauna are also related to this.
Wet evergreen forests are located in narrow stripes and patches along the equator. "Green hell" - this is how many travelers of past centuries called these places, who had to visit here. A solid wall is high multi-tiered forests, under the dense crowns of which dusk constantly reigns, monstrous humidity, constant high temperature, there is no change of seasons, showers regularly fall in an almost continuous stream of water. Equator forests are also called permanent rainforests. Traveler Alexander Humboldt called them "gilea" (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 Figure 4).
Rice. 4. Selva
Savannah is a sea of grasses with rare islets of trees with umbrella crowns (see Fig. 5). Vast expanses of these amazing natural communities are found in Africa, although there are savannas in South America, Australia and India. A distinctive feature of savannas is the alternation of dry and wet seasons, which take about six months, 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 - the humid equatorial and dry tropical. Monsoon winds, bringing seasonal rains, significantly affect the climate of the savannahs. Since these landscapes are located between very humid natural zones of equatorial forests and very dry zones of deserts, they are constantly influenced by both. But moisture is not present long enough in the savannas 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.
Rice. 5. Savannah
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 stretched from west to east for more than 5 thousand km, and in Eurasia, originating on 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 over 60% of the territory of the Russian Federation. 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 taiga forests are replaced by light forests, and then by separate groups of trees. The farthest taiga forests enter the forest-tundra along the river valleys, which are most protected from strong northerly winds. In the south, the taiga also smoothly turns into coniferous-deciduous and broad-leaved forests. On these sites, people intervened in natural landscapes for many centuries, so now they are a complex natural-anthropogenic complex.
Rice. 6. Taiga
Under the influence of human activity, the geographic envelope is changing. Swamps are being drained, deserts are being watered, forests are disappearing, and so on. Thus, the appearance of natural zones changes.
Bibliography
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