Natural area where. Natural areas of land. Arctic desert zone or ice zone

• Remember what a natural area is.
• What are the patterns in the placement of natural zones of the Earth?
• What natural areas are located in Eurasia?
• What sources of geographic information can be used to characterize a natural area?

Natural zoning- one of the main geographic patterns.

The largest German naturalist Alexander Humboldt analyzed climate and vegetation changes and found that there is a very close relationship between them, that climatic zones are at the same time vegetation zones. Subsequently, it became clear that climate change causes the zonal distribution of not only plant communities, but also animal communities, as well as soils, characteristic features surface and ground runoff, water regime of rivers, exogenous processes of relief formation, etc.

At the end of the 19th century, the great Russian scientist Vasily Vasilyevich Dokuchaev proved that zoning is a universal law of nature. It manifests itself to a greater or lesser extent in all natural components, both on the plains and in the mountains. Since all components of nature are in close interaction with each other, the consequence of the law of zoning is the existence of large zonal natural-territorial complexes (PTK), or natural (natural-historical - according to V.V. Dokuchaev) zones (Fig. 67).

Rice. 67. natural areas peace

Each of them is characterized by a certain ratio of heat and moisture, which play a leading role in the formation of the soil and vegetation cover.

Natural areas of our Motherland. 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.

Almost all zones of our country stretch for thousands of kilometers from west to east, and yet they retain significant common features throughout their entire length, due to the prevailing climatic conditions, the degree of moisture, soil types, and the nature of the vegetation cover. The similarity can also be traced in surface waters and modern relief-forming processes.

According to Figure 67, 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?

A great contribution to the study of the natural zones of our country was made by Academician Lev Semenovich Berg. He gave a description of all the natural zones of Russia and showed that each zone consists of a regular combination of landscapes. Natural areas are also called landscape or geographical. Natural zones are natural laboratories in which scientists study the nature of a given territory, explore the possibilities of developing each zone, predict possible consequences influence of human activity. Therefore, in each natural zone created biosphere reserves and protected areas.

Rice. 68. Potential productivity of natural areas (shown by dotted line)

In a number of natural zones of our country, for example, in the steppe and forest-steppe, the original virgin vegetation was almost not preserved due to agricultural economic activity of people. But in nature, everything is interconnected, therefore, along with vegetation, soils, relief, and water regimes have changed a lot, and, of course, animal world.

Such modern natural zones as tundra and forest suffered less. But we are talking about those territories of these natural zones that are not yet sufficiently developed by man. And these are, first of all, parts of the Siberian taiga and the Siberian tundra.

Arctic desert zone located on the islands of the Arctic Ocean and in the extreme north of the Taimyr Peninsula. A significant part of the surface here is covered with glaciers; winters are long and harsh, summers are short and cold. average temperature of the warmest month is close to zero (less than -1-4°C). In such conditions, the snow does not have time to melt everywhere in summer. Glaciers are forming. Large areas are occupied by stone placers. Soils are almost undeveloped.

Rice. 69. The relationship of the components of nature within the natural zone

Vegetation on a snow- and ice-free surface does not form a closed cover. These are cold deserts. The plants are dominated by mosses and lichens. Flowering plants are represented by a small number of species and are rare. Among the animals, those that are fed by the sea predominate: birds and polar bears. Noisy bird colonies are located on the rocky shores in summer.

Tundra zone occupies the coast of the seas of the Arctic Ocean from the western border of the country to the Bering Strait. The tundra in some places reaches the Arctic Circle. The zone reaches its greatest extension from north to south in Western and Central Siberia. This zone occupies almost 1/6 of the territory of Russia.

Rice. 70. The relationship of the components of nature in the tundra zone

Compared to the Arctic deserts, summers are warmer in the tundra, but winters are long and cold. The average July temperature in the tundra zone is +5...+10°C. The southern boundary of the zone almost coincides with the +10°С July isotherm. There is little precipitation, only 200-300 mm per year. But with a lack of heat, evaporation is small, so humidification is excessive (humidification coefficient exceeds 1.5).

In the tundra, permafrost is almost universally distributed, which thaws in summer by only a few tens of centimeters. In places of deeper permafrost thawing, shallow basins filled with water arose. Without seeping into the frozen ground, moisture remains on the surface. The tundra is literally dotted with shallow and small lakes. Great and river flow. The rivers are full of water in the summer.

Rice. 71. A typical inhabitant of the Arctic deserts is a polar bear

The soils of the zone are thin, tundra-gley. Tundra vegetation of mosses, lichens and shrubs dominates here.

In the treelessness of the tundra, not only cold and permafrost are to blame, but also strong winds. The blizzard, falling down from the feet of both a person and a deer, sweeps up snowdrifts in some places, while in others it blows off the already small snow cover from the soil, burns kidneys with ice crystals and grinds trunks, and dehydrates plant tissues. This is why dwarf trees and shrubs knelt here, crawled along the ground, pressed against it, hiding under a cloak of snow.

"Forest" knee-deep, even ankle-deep. The "trees" are slightly larger than a mushroom... The age of one juniper elfin tree, the trunk of which was only 8 cm in diameter, turned out to be 544 years. It grew even before the discovery of America by Columbus!

The total stock of plant matter in the tundra is much greater than in the Arctic deserts. The animal world is also richer here.

In the tundra there are plants that overwinter in green. 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.

The tundra is heterogeneous throughout its space. 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.

It has become customary to regard the nature of this zone as poor. But connoisseurs of the tundra do not exaggerate when they enthusiastically talk about its beauty and richness and strongly disagree to consider the tundra the "backyard" of the Earth. In addition, the bowels of the tundra are just as generous as in more southern latitudes.

AT short months in summer, the tundra is full of bright colors, blueberries turn blue, lingonberries, cranberries glow with red lights, cloudberries - orange berries. There are in the tundra and edible mushrooms. Huge herds of reindeer graze in the tundra. In summer, they eat here not only lichens, but also the foliage of tundra shrubs. In winter, they extract their favorite “reindeer moss” from under a thin snow cover - moss lichen.

Rice. 72. Typical inhabitants of the tundra

The tundra zone with scarce reserves of heat, the spread of permafrost, moss-lichen and shrub communities are reindeer breeding areas. Here and there vegetables are also grown, but only in greenhouses.

This is where fox is mined. There are many fish in the tundra lakes.

Determine on the map which of the largest mineral deposits in our country are located in the tundra zone.

Forest-tundra zone stretched in a narrow strip along the southern border of the tundra zone.

The average July temperature is +10...+14°C, the annual precipitation is 300-400 mm. Much more precipitation falls than can evaporate, so the forest tundra is one of the most swampy natural zones. The rivers are fed by melted snow waters. High water on the rivers occurs at the beginning of summer, when the snow melts.

The forest tundra is a transitional zone from the tundra to the taiga. It is characterized by a combination of tundra and forest communities of plants and animals, as well as soils. Along the river valleys stretch strips of fairly tall forest. On the interfluves there are small islands of light forests - undersized sparse forests with lichen cover. They alternate with shrub tundra.

In winter, reindeer migrate to the forest-tundra for their winter pastures. Places in open field grow potatoes, cabbage, turnips, radishes, lettuce, green onions. Together with the northern and middle taiga, the forest-tundra is included in the zone of focal agriculture.

Questions and tasks

1. What components of nature form a natural zone?
2. What determines the change of natural zones?
3. On the example of our country, justify the pattern of changing natural zones.
4. Think about how the flora and fauna of the Arctic deserts are adapted to their habitat.
5. Indicate the features of the tundra zone of our country and explain them.
6. Think about the reason for the strong vulnerability of the nature of the tundra zone.

Zoning - change in natural components and the natural complex as a whole from the equator to the poles. The basis of zoning is the different supply of heat, light, precipitation, which, in turn, are already reflected in all other components, and above all, soils, flora and fauna.

Zoning is characteristic of both land and the oceans.

The largest zonal divisions of the geographical shell - geographic zones. Belts differ from each other primarily in temperature conditions.

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

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

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

Within natural zones, transitional areas are distinguished. They are formed as a result of gradual changes in climatic conditions. Such transitional zones include, for example, forest-tundra, forest-steppes and semi-deserts.

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

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

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

natural areas

natural areas- large subdivisions of the geographical envelope, which have a certain combination of temperature conditions and moisture regime. They are classified mainly according to the prevailing type of vegetation and regularly change in the plains from north to south, and in the mountains - from the foot to the peaks. The natural zones of Russia are shown in fig. one.

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

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

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

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

polar desert

The very north of our country - the islands of the Arctic Ocean - are located in the natural zone polar (arctic) deserts. This area is also called ice zone. The southern boundary roughly coincides with the 75th parallel. The natural zone is characterized by the dominance of arctic air masses. The total solar radiation is 57-67 kcal/cm2 per year. Snow cover lasts 280-300 days a year.

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

In summer, even round-the-clock lighting is not able to provide enough heat to this area. The air temperature rarely rises above 0 °C, and the average July temperature is +5 °C. For several days there may be drizzling precipitation, but there are practically no thunderstorms and showers. But there are frequent fogs.

Rice. 1. Natural areas of Russia

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

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

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

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

In summer, numerous colonies of birds nest on the rocky islands: gulls, guillemots, guillemots, auks, etc.

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

steppes

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

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

Natural plant communities are predominantly represented by perennial, drought- and frost-resistant herbs with a strong root system. First of all, these are cereals: feather grass, fescue, wheatgrass, snake, thin-legged, bluegrass. In addition to cereals, there are numerous representatives of herbs: astragalus, sage, cloves - and bulbous perennials, such as tulips.

The composition and structure of plant communities change significantly both in the latitudinal and in the meridional direction.

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

Steppe landscapes are fundamentally different from forest ones, which determines the uniqueness of the animal world of this natural zone. Typical animals of this zone are rodents (the most numerous group) and ungulates.

Ungulates are adapted to long-term movements across the vast expanses of the steppes. Due to the thinness of the snow cover, plant food is also available in winter. An important role in nutrition is played by bulbs, tubers, rhizomes. For many animals, plants are also the main source of moisture. Typical representatives of ungulates in the steppes are tours, antelopes, tarpans. However, most of these species were exterminated or driven south as a result of human economic activity. In some areas, saigas, which were widely distributed in the past, have been preserved.

Of the rodents, the most common are ground squirrel, vole, jerboa, etc.

The polecat, badger, weasel, and fox also live in the steppe.

Of the birds, the bustard, little bustard, gray partridge, steppe eagle, buzzard, kestrel are typical for the steppes. However, these birds are now rare.

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

The wealth of the steppes is fertile soils. The thickness of the humus layer of chernozems is more than 1 m. It is not surprising that this natural zone is almost completely developed by man and natural steppe landscapes are preserved only in reserves. In addition to the high natural fertility of chernozems, maintaining Agriculture climate conditions favorable for horticulture, the cultivation of heat-loving cereals (wheat, corn) and industrial (sugar beet, sunflower) crops also contribute. Due to insufficient precipitation and frequent droughts, irrigation systems have been built in the steppe zone.

The steppes are a zone of developed animal husbandry. Cattle, horses, poultry are bred here. Conditions for the development of animal husbandry are favorable due to the presence of natural pastures, fodder grain, waste from the processing of sunflowers and sugar beets, etc.

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

Semi-deserts and deserts

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

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

The rivers located in the zone of semi-deserts and deserts are fed almost exclusively by the spring melting of snow. A significant part of them flows into lakes or is lost in the sands.

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

Plants in semi-deserts are usually low, drought-resistant. The semi-deserts of the south of the country are characterized by such plant species as tree-like and gnarled saltwort, camel's thorn, and juzgun. On the hills, feather grass and fescue dominate.

Steppe grasses alternate with patches of wormwood and romance of yarrow.

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

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

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

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

A special area in the zone of semi-deserts and deserts of Russia are the Volga delta and the Akhtuba floodplain. It can be called a green oasis among the semi-desert. This area stands out for its thickets of reed-reeds (it reaches a height of 4-5 m), shrubs and shrubs (including blackberries), intertwined with climbing plants (hops, bindweed). In the backwaters of the Volga delta there are a lot of algae, white water lilies (including the Caspian rose and water chestnut preserved from the pre-glacial period). Among these plants there are many birds, among which herons, pelicans and even flamingos stand out.

The traditional occupation of the population in the zone of semi-deserts and deserts is cattle breeding: they breed sheep, camels, and cattle. As a result of overgrazing, the area of ​​unfixed windblown sands is increasing. One of the measures to combat the onset of the desert is phytomelioration - a set of measures for the cultivation and maintenance of natural vegetation. To fix the dunes, plant species such as giant grate, Siberian wheatgrass, and saxaul can be used.

Tundra

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

The tundra receives more heat than the polar desert zone. The total solar radiation is 70-80 kcal/cm2 per year. However, the climate here continues to be characterized by low air temperatures, short summers, and severe winters. The average air temperature in January reaches -36 °С (in Siberia). Winter lasts 8-9 months. At this time of the year, southerly winds blowing from the mainland dominate here. Summer is characterized by an abundance of sunlight, unstable weather: strong northerly winds often blow, bringing cooling and precipitation (especially in the second half of summer there are often severe drizzling rains). The sum of active temperatures is only 400-500 °C. The average annual rainfall reaches 400 mm. Snow cover lasts 200-270 days a year.

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

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

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

northern tundra distributed mainly on the mainland coast. Their important difference from the arctic ones is the presence of a closed vegetation cover. Mosses and lichens cover 90% of the soil surface. Green mosses and bushy lichens predominate, moss is often found. species composition flowering plants are also becoming more diverse. There are saxifrages, ozhiki, highlander viviparous. Of the shrubs - lingonberries, blueberries, ledum, crowberry, as well as dwarf birch (dwarf birch), willows.

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

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

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

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

Animals and birds permanently living in the tundra have also adapted well to the harsh natural conditions. They are saved by thick fur or fluffy plumage. In winter, animals are white or light gray in color, and in summer they are grayish-brown. It helps to disguise.

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

The tundra has a relatively low population density. The indigenous peoples here are the Saami, Nenets, Yakuts, Chukchi, etc. They are mainly engaged in reindeer herding. The extraction of minerals is actively carried out: apatites, nephelines, non-ferrous metal ores, gold, etc.

Railway communication in the tundra is poorly developed, and permafrost is an obstacle to the construction of roads.

forest tundra

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

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

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

In the forest-tundra of the European part of Russia, spruce predominates, and pine is less common. In the Asian part, larch is common. Trees grow slowly, their height usually does not exceed 7-8 m. Due to strong winds, a flag-shaped crown shape is common.

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

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

Subtropics

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

The value of total solar radiation reaches 130 kcal/cm2 per year. Summer is long, winter is warm (average January temperature is 0 °C). The sum of active temperatures is 3500-4000 °C. Under these conditions, many plants can develop all year round. In the foothills and on the mountain slopes, 1000 mm or more of precipitation falls annually. In the flat areas, snow cover is practically not formed.

Fertile red earth and yellow earth soils are widespread.

Subtropical vegetation is rich and varied. The flora is represented by evergreen hard-leaved trees and shrubs, among which we will name boxwood, laurel, laurel cherry. Widespread forests of oak, beech, hornbeam, maple. Thickets of trees intertwine liana, ivy, wild grapes. There are bamboo, palm trees, cypress, eucalyptus.

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

The abundance of heat and moisture makes it possible to grow such subtropical crops here as tea, tangerines, and lemons. Significant areas are occupied by vineyards and tobacco plantations.

Favorable climatic conditions, proximity to the sea and mountains make this area a major recreational area of ​​our country. Numerous camp sites, rest houses, sanatoriums are located here.

In the tropical zone there are moist forests, savannahs and light forests, deserts.

Largely open tropical rainforests(South Florida, Central America, Madagascar, Eastern Australia). They are used, as a rule, for plantations (see map of the atlas).

The subequatorial belt is represented by forests and savannahs.

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

At the equator, an abundance of precipitation and high temperatures led to the presence of a zone here evergreen moist forests (Amazon and Congo basin, on the islands of Southeast Asia). The natural area of ​​evergreen moist forests holds the world record for the diversity of animal and plant species.

The same natural areas are found on different continents, however, they have their own characteristics. First of all, we are talking about plants and animals that have adapted to the existence in these natural areas.

The natural zone of the subtropics is widely represented on the coast mediterranean sea, south coast Crimea, in the southeast of the USA and in other regions of the Earth.

Western Hindustan, Eastern Australia, the Paraná basin in South America and South Africa are areas of distribution of more arid tropical savannas and woodlands. The most extensive natural zone of the tropical belt - desert(Sahara, Arabian desert, deserts of Central Australia, California, as well as the Kalahari, Namib, Atacama). Huge expanses of pebbly, sandy, rocky and saline surfaces are devoid of vegetation here. The animal world is small.

natural area - a territory with close conditions of temperature and moisture, which determine generally homogeneous soils, vegetation and wildlife. On the plains, the zones extend in a latitudinal direction, regularly replacing each other from the poles to the equator. Often, significant distortions in the pattern of the zone are introduced by the relief and the ratio of land and sea.

Arctic and Antarctic deserts . These are cold deserts with very low air temperatures in the Arctic and Antarctica. In this zone, snow and ice persists almost all year round. In the warmest month - August - in the Arctic, the air temperature is close to 0°C. Ice-free spaces are bound by permafrost. Very intense frosty weathering. There is little precipitation - from 100 to 400 mm per year in the form of snow. In this zone, the polar night lasts up to 150 days. Summer is short and cold. Only 20 days, rarely 50 days a year the air temperature exceeds 0°C. The soils are thin, underdeveloped, stony, and placers of coarsely broken material are common. Less than half of the Arctic and Antarctic deserts are covered with sparse vegetation. It is devoid of trees and shrubs. Scale lichens, mosses, various algae, and only a few flowering plants are common here. The animal world is richer than the plant world. These are polar bears, arctic foxes, polar owls, deer, seals, walruses. Of the birds, there are penguins, eiders and many other birds that nest on rocky shores and form “bird colonies” in summer. In the zone of icy deserts, fishing for marine animals is carried out, among birds of particular interest is the eider, whose fluff is lined with nests. Eider down is harvested from abandoned nests to produce clothes worn by polar sailors and airmen. There are Antarctic oases in the icy desert of Antarctica. These are ice-free areas of the coastal strip of the mainland, with an area from several tens to hundreds of square meters. kilometers. organic world oases is very poor, there are lakes.

Tundra. This space lies within parts of the Arctic and subarctic belts in the Northern Hemisphere, while in the Southern Hemisphere tundra is common only on some islands. This is a territory with a predominance of moss-lichen vegetation, as well as low-growing perennial grasses, shrubs and low-growing shrubs. Trunks of shrubs and grass roots are hidden in moss and lichen turf.

The climate of the tundra is severe, the average July temperature only in the south of the natural zone does not exceed +11°C, the snow cover lasts 7-9 months. Precipitation is 200-400 mm, and in some places up to 750 mm. main reason treeless tundra - low air temperatures combined with high relative humidity, strong winds, widespread permafrost. In the tundra there are also unfavorable conditions for the germination of seeds of woody plants on a moss-lichen cover. Plants in the tundra are pressed against the surface of the soil, forming densely intertwined shoots in the form of a pillow. In July, the tundra is covered with a carpet of flowering plants. Due to excessive moisture and permafrost, there are many swamps in the tundra. On the warmed banks of rivers and lakes, you can find poppies, dandelions, polar forget-me-nots, and pink flowers of mytnik. According to the prevailing vegetation in the tundra, 3 zones are distinguished: arctic tundra , characterized by sparse vegetation due to the severity of the climate (in July + 6 ° C); moss-lichen tundra , characterized by richer vegetation (in addition to mosses and lichens, sedge, bluegrass, creeping willow are found here), and shrub tundra , located in the south of the tundra zone and characterized by richer vegetation, which consists of thickets of willow and alder shrubs, which in some places rise to the height of a person. In areas of this subzone, bush is an important source of fuel. The soil of the tundra zone is predominantly tundra-gley, characterized by gleying (see "Soils"). She is infertile. Frozen soils with a thin active layer are ubiquitous. The fauna of the tundra is represented by reindeer, lemming, arctic fox, ptarmigan, and in summer - many migratory birds. Shrub tundra gradually turns into forest tundra.

forest tundra . This is a transitional zone between the tundra and the forest zone. temperate zone. It is distributed in the Northern Hemisphere in North America and Eurasia. The climate is less severe than in the tundra: the average July temperature here is +10-14°C. The annual rainfall is 300-400 mm. Precipitation in the forest tundra falls more than evaporates, so the forest tundra is characterized by excessive moisture, it is one of the most swampy natural zones. The snow cover lasts for more than six months. High water on the rivers of the forest-tundra usually occurs in summer, since the rivers of this zone are fed by melt water, and snow melts in the forest-tundra in summer. The woody vegetation that appears in this zone grows along the river valleys, as rivers have a warming effect on the climate of this zone. Islands of forests consist of birch, spruce, larch. The trees are stunted, sometimes bent to the ground. The forest area increases in the forest-tundra when moving south along it. In the interfluves, there are stunted and sparse forests. Thus, the forest-tundra is an alternation of treeless shrublands and light forests. Soils are tundra (peat-bog) or forest. The fauna of the forest-tundra is similar to the fauna of the tundra. Arctic foxes, white partridges, snowy owls and a wide variety of migratory waterfowl also live here. The main winter reindeer pastures and hunting grounds are located in the forest-tundra.

temperate forests . This natural zone is located in the temperate climate zone and includes subzones taiga, mixed and deciduous forests, monsoon forests temperate zone. Differences in climatic features contribute to the formation of vegetation characteristic of each subzone.

Taiga (Turk.). This zone of coniferous forests is located in the north North America and northern Eurasia. The climate of the subzone is from maritime to sharply continental with relatively warm summers (from 10°С to 20°С), and the lower the winter temperatures, the more continental the climate is (from -10°С in northern Europe to -50°С in northeastern Europe). Siberia). Permafrost is widespread in many regions of Siberia. The subzone is characterized by excessive moisture and, as a result, swampiness of interfluve spaces. There are two types of taiga: light coniferous and topicsconiferous. Light coniferous taiga - these are the least demanding pine and larch forests in terms of soil and climatic conditions, the sparse crown of which transmits the sun's rays to the ground. Pines, having a branched root system, have acquired the ability to use nutrients from infertile soils, which is used to fix soils. This feature allows these plants to grow in areas with permafrost. The shrub layer of the light coniferous taiga consists of alder, dwarf birches, polar birches, polar willows, and berry bushes. This type of taiga is common in Eastern Siberia. dark coniferous taiga - These are conifers, consisting of numerous species of spruce, fir, cedar. This taiga, unlike the light coniferous one, has no undergrowth, since its trees are tightly closed, and it is rather gloomy in these forests. The lower tier is made up of shrubs (lingonberries, blueberries, blueberries) and dense ferns. This type of taiga is common in the European part of Russia and Western Siberia.

The soils of the taiga zone are podzolic. They contain little humus, but when fertilized they can provide a high yield. In the taiga Far East- acidic soils.

The fauna of the taiga zone is rich. Numerous predators are found here, which are valuable game animals: otter, marten, sable, mink, weasel. Of the large ones - wolves, bears, lynxes, wolverines. In North America, bison and elk deer used to be found in the taiga zone. Now they live only in reserves. The taiga is also rich in rodents, of which the most typical are beavers, muskrats, squirrels, hares, and chipmunks. The world of birds is very diverse.

Mixed temperate forests . These are forests with various tree species: coniferous-broad-leaved, small-leaved-pine. This zone is located in the north of North America (on the border of the USA and Canada), and in Eurasia it forms a narrow strip between the taiga and the zone of deciduous forests. The zone of mixed forests is also found in Kamchatka and the Far East. In the Southern Hemisphere, this forest zone occupies small areas in southern South America and New Zealand.

The climate of the zone of mixed forests is maritime or transitional to continental (toward the center of the mainland), summers are warm, winters are moderately cold (in a maritime climate with positive temperatures, and in a more continental climate up to -10 ° C). Moisture here is sufficient. The annual amplitude of temperature fluctuations, as well as the annual amount of precipitation, vary from oceanic regions to the center of the continent.

The diversity of vegetation in the zone of mixed forests of the European part of Russia and the Far East is explained by differences in climate. For example, on the Russian Plain, where precipitation falls all year round due to westerly winds coming from the Atlantic, European spruce, oak, elm, fir, and beech are common - coniferous-broad-leaved forests.

The soils in the zone of mixed forests are gray forest and sod-podzolic, and in the Far East they are brown forest.

The animal world is similar to the animal world of the taiga and the zone of deciduous forests. Elk, sable, bear live here.

Mixed forests have long been subjected to heavy cutting and losses. They are best preserved in North America and the Far East, and in Europe they are cut down for agricultural land - field and pasture land.

Temperate broadleaf forests . They occupy the east of North America, Central Europe, and also form a high-altitude zone in the Carpathians, Crimea and the Caucasus. In addition, individual foci of broad-leaved forests are found in the Russian Far East, Chile, New Zealand, and central Japan.

The climate is favorable for the growth of deciduous trees with a wide leaf plate. Here, temperate continental air masses bring precipitation from the oceans (from 400 to 600 mm) mainly in the warm season. The average temperature in January is -8°-0°С, and in July +20-24°С.

Beech, hornbeam, elm, maple, linden, ash grow in the forests. In the zone of deciduous forests of North America, there are species that are absent on other continents. These are American oak species. Trees with a powerful spreading crown predominate here, often entwined with climbing plants: grapes or ivy. To the south there are magnolias. For European broad-leaved forests, oak and beech are most typical.

The fauna of this natural zone is close to the taiga, but there are such animals as black bears, wolves, minks, raccoons, which are not typical for the taiga. Many animals of the broad-leaved forests of Eurasia are under protection, as the number of individuals is sharply reduced. These include such animals as the bison, the Ussuri tiger.

Soils under deciduous forests are gray forest or brown forest. This zone has been heavily developed by man, forests have been cleared over large areas, and the land has been plowed up. In its true form, the zone of broad-leaved forests has been preserved only in areas inconvenient for arable farming and in reserves.

forest-steppe . This natural zone is located within the temperate climate zone and represents a transition from forest to steppe, with alternating forest and steppe landscapes. It is distributed in the Northern Hemisphere: in Eurasia from the Danubian lowland to Altai, further in Mongolia and the Far East; in North America, this zone is located in the north of the Great Plains and in the west of the Central Plains.

The forest-steppes are naturally distributed within the continents between the forest zones, which choose the most humid areas here, and the steppe zone.

The climate of the forest-steppes is temperate continental: winters are snowy and cold (from -5°С to -20°С), summers are warm (+18°С to +25°С). In different longitudinal zones, the forest-steppe differs in precipitation (from 400 mm to 1000 mm). Humidification is slightly lower than sufficient, evaporation is very high.

In the forests, which are interspersed with steppe ones, broad-leaved (oak) and small-leaved tree species (birch) are more common, less often - conifers. The soils of the forest-steppe are mainly gray forest soils, which alternate with chernozems. The nature of the forest-steppe zone has been greatly changed by human economic activity. In Europe and North America, the plowing of the zone reaches 80%. Since this zone has fertile soils, wheat, corn, sunflower, sugar beet and other cultures. The fauna of the forest-steppe zone includes species characteristic of the forest and steppe zones.

The West Siberian forest-steppe is specific with numerous birch groves-pegs (singular number - pegs). Sometimes they have an admixture of aspen. The area of ​​individual pegs reaches 20-30 ha. Numerous pegs, alternating with areas of steppes, create a characteristic landscape of Southwestern Siberia.

steppes . This is a landscape with a grassy type of vegetation, located in the temperate and partly in the subtropical zone. In Eurasia, the steppe zone extends latitudinally from the Black Sea to Transbaikalia; in North America, the Cordillera distribute air currents in such a way that the zone of insufficient moisture, and with it the steppe zone, is located from north to south along the eastern outskirts of this mountainous country. In the Southern Hemisphere, the steppe zone is located within the subtropical climate, in Australia and Argentina. Atmospheric precipitation (from 250 mm to 450 mm per year) falls here irregularly and is insufficient for tree growth. The winter is cold, the average temperature is below 0°С, in some places up to -30°, with little snow. Summer is moderately hot - +20°С, +24°С, drought is not uncommon. Inland waters in the steppe are poorly developed, river flow is small, and rivers often dry up.

The undisturbed vegetation of the steppe is a dense grass cover, but the undisturbed steppes all over the world have remained only in reserves: all the steppes are plowed up. Depending on the nature of the vegetation in the steppe zone, three subzones are distinguished. They differ from each other in the prevailing vegetation. it meadow steppes (bluegrass, bonfire, timothy grass), cereals and southern wormwood-cereal .

The soils of the steppe zone - chernozems - have a significant humus horizon, due to which they are very fertile. This is one of the reasons for the strong tillage of the zone.

The fauna of the steppes is rich and varied, but it has changed a lot under the influence of man. Back in the 19th century, wild horses, aurochs, bison, and roe deer disappeared. Deer are pushed back into the forests, saigas - into the virgin steppes and semi-deserts. Now the main representatives of the animal world of the steppes are rodents. These are ground squirrels, jerboas, hamsters, voles. Occasionally there are bustards, little bustards, larks and others.

The steppes and partly the forest-steppes of the temperate and subtropical zones of North America are called prairies . At present, they are almost completely plowed up. Part of the American prairie is dry steppe and semi-desert.

The subtropical steppe on the plains of South America, located mainly in Argentina and Uruguay, is called pampa . AT eastern regions, where the precipitation brought from the Atlantic Ocean falls, there is sufficient moisture, and aridity increases to the west. Most of the pampas have been plowed up, but in the west there are still dry steppes with thorny bushes used as pastures for livestock.

Semi-deserts and temperate deserts . In the south, the steppes pass into semi-deserts, and then into deserts. Semi-deserts and deserts are formed in a dry climate, where there is a long and hot warm period (+20-25°С, sometimes up to 50°С), strong evaporation, which is 5-7 times higher than the amount of annual precipitation (up to 300 mm in year). Weak surface runoff, poor development inland waters, many drying channels, vegetation is not closed, sandy soils heat up during the day, but quickly cool down on a cool night, which contributes to physical weathering. The winds dry up the land very strongly here. The deserts of the temperate zone differ from the deserts of other geographical zones in more cold winter(-7°C-15°C). Deserts and semi-deserts of the temperate zone are common in Eurasia from the Caspian lowland to the northern bend of the Huang He, and in North America - in the foothills and basins of the Cordilleras. In the Southern Hemisphere, deserts and semi-deserts of the temperate zone are found only in Argentina, where they are found in broken areas in the interior and foothills. Of the plants here there are steppe feather grass, fescue, wormwood and saltwort, camel thorn, agave, aloe. Of the animals - saigas, turtles, many reptiles. The soils here are light chestnut and brown desert, often saline. Under conditions of sharp fluctuations in temperature during the day, with little moisture, a dark crust forms on the surface of the desert - desert tan. It is sometimes called protective, as it protects rocks from rapid weathering and destruction.

The main use of semi-deserts is grazing (camels, fine-fleeced sheep). Farming of drought-resistant crops is possible only in oases. An oasis (from the Greek name of several inhabited places in the Libyan Desert) is a place of growth of tree, shrub and herbaceous vegetation in deserts and semi-deserts, in conditions of more abundant surface and soil moisture compared to neighboring areas and areas. The sizes of oases are different: from ten to tens of thousands of kilometers. Oases - centers of population concentration, areas of intensive agriculture on irrigated lands (Nile Valley, Fergana Valley in Central Asia).

Deserts and semi-deserts of the subtropical and tropical zones . These are natural zones located in both hemispheres, on all continents along tropical zones of high atmospheric pressure. Most often, the semi-deserts of the subtropical belt are located in the transitional part from deserts to mountain steppes in the form of an altitudinal belt in the inland parts of the Cordilleras and the Andes of America, in western Asia, Australia, and especially widely in Africa. The climate of deserts and semi-deserts of these climatic zones is hot: the average temperature in summer rises to +35°С, and in the coldest months of winter it does not fall below +10°С. Precipitation is 50-200 mm, in semi-deserts up to 300 mm. Precipitation sometimes falls in the form of short showers, and in some areas precipitation may not fall for several years in a row. With a lack of moisture, the weathering crust is very thin.

Groundwater is very deep and may be partially saline. In such conditions, only plants that can tolerate overheating and dehydration can live. They have a deeply branched root system, small leaves or spines that reduce evaporation from the leaf surface. In some plants, the leaves are pubescent or covered with a wax coating, which protects them from sunlight. In the semi-deserts of the subtropical zone, cereals are common, cacti appear. In the tropical zone, the number of cacti increases, agaves, sand acacias grow, various lichens are common on stones. A characteristic plant for the Namib Desert, located in the tropical belt of South Africa, is the amazing velwigia plant, which has a short trunk, from the top of which two leathery leaves extend. The age of velwigia can reach 150 years. The soils are rubbly serozems, gray-brown, they are not very fertile, since the layer of humus is thin. The fauna of deserts and semi-deserts is rich in reptiles, spiders, scorpions. There are camels, antelopes, rodents are quite widespread. Agriculture in semi-deserts and deserts of the subtropical and tropical zones is also possible only in oases.

hardwood forests . This natural zone is located within the subtropical zone of the Mediterranean type. They mainly grow in southern Europe, northern Africa, southwest and southeast Australia. Separate fragments of these forests are found in California, in Chile (south of the Atacama Desert). Hardwood forests grow in a mild temperate warm climate with hot (+25°C) and dry summers and cool and rainy winters. The average amount of precipitation is 400-600 mm per year with rare and short-lived snow cover. The rivers are mainly rain-fed, and the flood occurs during the winter months. In rainy winter conditions, grasses grow rapidly.

The animal world is strongly exterminated, but herbivorous and leaf-eating forms, many birds of prey and reptiles are characteristic. In the forests of Australia, you can meet the koala bear, which lives in trees and leads a nocturnal sedentary lifestyle.

The territory of hardwood forests is well developed and largely changed by human economic activity. Large areas of forests have been cut down here, and oilseed plantations, orchards and pastures have taken their place. Many tree species have solid wood, which is used as a building material, and oils, paints, medicines (eucalyptus) are made from leaves. Large harvests of olives, citrus fruits, grapes are taken from the plantations of this zone.

Monsoon forests of the subtropical zone . This natural area is located in the eastern parts of the continents (China, southeastern United States, eastern Australia, southern Brazil). It is located in the most humid conditions compared to other zones of the subtropical belt. The climate is characterized by dry winters and wet summers. Annual rainfall is greater than evaporation. The maximum amount of precipitation falls in the summer due to the influence of the monsoons, which bring moisture from the ocean. On the territory of monsoon forests, internal waters are quite rich, fresh groundwater is shallow.

Here, on red soils and yellow soils, high-stemmed mixed forests grow, among which there are evergreen and deciduous, shedding foliage in the dry season. The species composition of plants may vary depending on the soil conditions. Subtropical species of pines, magnolias, camphor laurel, and camellias grow in the forests. On the flooded coasts of Florida in the United States and on the Mississippi lowlands, swamp cypress forests are common.

The monsoon forest zone of the subtropical belt has long been mastered by man. Field and pasture lands are located on the site of the reduced forests; rice, tea, citrus fruits, wheat, corn and industrial crops are grown here.

Forests of the tropical and subequatorial belts . They are located along the east of Central America, in the Caribbean, on the island of Madagascar, in southeast Asia, and in northeast Australia. Two seasons are distinctly expressed here: dry and wet. The existence of forests in the dry and hot tropical zone is possible only thanks to the precipitation that the monsoons bring in summer from the oceans. In the subequatorial belt, precipitation comes in summer, when equatorial air masses dominate here. Depending on the degree of moisture, among the forests of the tropical and subequatorial belts, there are permanently wet and seasonally wet(or variable-moist) forests. Seasonally wet forests are characterized by a relatively poor species composition of tree species, especially in Australia, where these forests consist of eucalyptus, ficus, and laurel. Often in seasonally wet forests there are areas where teak and sal grow. There are very few in the forests of this group of palm trees. According to its species diversity of flora and fauna permanently wet forests close to equatorial. There are many palms, evergreen oaks, tree ferns. Many vines and epiphytes from orchids and ferns. Soils located under the forests are mostly lateritic. During the dry season (winter) most deciduous trees do not shed all their leaves, but some species remain completely bare.

Savannah . This natural zone is located mainly within the subequatorial climate, although it is also within the tropical and subtropical zones. In the climate of this zone, the change of the wet and dry seasons is clearly expressed at consistently high temperatures (from + 15°С to + 32°С). As you move away from the equator, the period of the wet season decreases from 8-9 months to 2-3, and precipitation - from 2000 to 250 mm per year.

The savannas are characterized by the predominance of grassy cover, among which high (up to 5 m) grasses dominate. Shrubs and single trees rarely grow among them. The grass cover near the borders with the equatorial belt is very dense and high, and sparse near the borders with semi-deserts. A similar pattern can be traced in trees: their frequency increases towards the equator. Among the savannah trees you can find a variety of palm trees, umbrella acacias, tree-like cacti, eucalyptus, water-storing baobabs.

Savannah soils depend on the length of the rainy season. Closer to the equatorial forests, where the rainy season lasts up to 9 months, there are red ferralitic soils. Closer to the border of savannahs and semi-deserts, red-brown soils are located, and even closer to the border, where it rains for 2-3 months, unproductive soils with a thin layer of humus are formed.

The fauna of the savannas is very rich and diverse, as the high grass cover provides animals with food. Elephants, giraffes, hippos, zebras live here, which in turn attract lions, hyenas and other predators. The world of birds of this zone is also rich. Sunbirds live here, ostriches - the largest birds on Earth, a secretary bird that hunts for small animals and reptiles. Many in the savanna and termites.

Savannahs are widespread in Africa, where they occupy 40% of the mainland, in South America, Australia and India.

Tall-grass savannahs in South America, on the left bank of the Orinoco River, with a dense, mainly grassy grass cover, with individual specimens or groups of trees, are called llanos (from the Spanish plural "plains"). The savannas of the Brazilian Plateau, where the region of intensive animal husbandry is located, are called campos .

Today, savannahs play a very important role in the economic life of man. Significant areas of this zone have been plowed up; cereals, cotton, peanuts, jute, and sugar cane are grown here. Animal husbandry is developed in drier places. Breeds of many trees are used on the farm, as their wood does not rot in water. Human activity often leads to desertification of the savannas.

Moist equatorial forests . This natural zone is located in an equatorial and partly subequatorial climate. These forests are common in the Amazon, the Congo, the Malay Peninsula and the Sunda Islands, as well as other smaller islands.

The climate here is hot and humid. All year round the temperature is +24-28°С. The seasons are not expressed here. Moist equatorial forests are located within a low pressure area, where, as a result of intense heating, ascending air currents are formed and a lot of precipitation (up to 1500 mm per year.) Falls throughout the year.

On the coasts, where the wind from the ocean influences, precipitation is even more (up to 10,000 mm). Precipitation falls evenly throughout the year. Such climatic conditions contribute to the development of lush evergreen vegetation, although, strictly speaking, trees change their leaves: some of them are shed every six months, others after a completely arbitrary period, and others change leaves in parts. Flowering periods also vary, and even more erratically. The most frequent cycles are ten and fourteen months. Other plants may bloom once every ten years. But at the same time, plants of the same species bloom at the same time so that they have time to pollinate each other. Plants in this zone have little branching.

Trees of humid equatorial forests have disc-shaped roots, large leathery leaves, the shiny surface of which saves them from excessive evaporation and the scorching rays of the sun, from the impact of rain jets during heavy showers. Many leaves end in a graceful thorn. This is a tiny drain. In plants of the lower tier, the leaves, on the contrary, are thin and delicate. The upper tier of equatorial forests is formed by ficuses and palms. In South America, ceiba grows in the upper tier, reaching a height of 80 m. Bananas and tree ferns grow in the lower tiers. Large plants are entwined with vines. There are many orchids on the trees of the equatorial forests, epiphytes are found, sometimes flowers form directly on the trunks. For example, the flowers of the cocoa tree. In the forest of the equatorial zone, it is so hot and humid that favorable conditions are created for the development of moss and algae, which adhere to the crown and hang from the branches. They are epiphytes. The flowers of trees in the crown cannot be pollinated by the wind, because the air there is practically still. Consequently, they are pollinated by insects and small birds, which are lured by a brightly colored corolla or a sweet scent. The fruits of plants are also brightly colored. This allows them to solve the problem of transporting seeds. The ripe fruits of many trees are eaten by birds, animals, the seeds are not digested and, together with the droppings, are far from the parent plant.

There are many host plants in the equatorial forests. First of all, these are vines. They begin their life on the ground in the form of a small bush, and then, tightly wrapping themselves around the stem of a giant tree, they climb up. The roots are in the soil, so the plant is not fed by a giant tree, but sometimes the use of these trees for support by vines can lead to oppression and death. "Robbers" are some ficuses. Their seeds germinate on the bark of a tree, the roots tightly wrap around the trunk and branches of this host tree, which begins to die. Its trunk is rotting, but the roots of the ficus have become thick and dense and are already able to support themselves.

The equatorial forests are home to many valuable plants, such as the oil palm, from which palm oil is obtained. The wood of many trees is used to make furniture and is exported in large quantities. This group includes ebony, the wood of which is black or dark green. Many plants of the equatorial forests give valuable fruits, seeds, juice, bark, which are used in technology and medicine.

The equatorial forests of South America are called selva . Selva is located in the periodically flooded area of ​​the Amazon River Basin. Sometimes, when describing humid equatorial forests, the name is used hylaea , sometimes these forests are called jungle , although, strictly speaking, the jungle is called the forest thickets of South and Southeast Asia, located within the subequatorial and tropical climate.

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 areas is animal and vegetable world who inhabit this area. 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 they can not withstand, 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- almost complete absence of vegetation and poor 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 rain forests. They are located mainly in South America, as well as in Africa, Australia and the Greater Sunda Islands. The main condition for their formation is 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 have time to make their life cycle for a short spring period, when the steppe is covered with a dense 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 the natural areas of the world are very interesting, whether it is a seemingly completely lifeless desert, endless arctic ice or millennia-old rainforests teeming with life.

Natural conditions in different parts of the globe are not the same, but naturally change from the poles to the equator. The main reason for this is the spherical shape of the Earth. Indeed, if the Earth were flat, like a blackboard, its surface, oriented (directed) strictly across the sun's rays, would be heated everywhere equally, both at the poles and at the equator.

But our planet has the shape of a ball, which is why the sun's rays fall on its surface at different angles, and therefore heat it differently. Above the equator, the sun “looks” at the earth’s surface almost “point-blank” during the day, and twice a year, at noon, its hot rays fall here at a right angle (the sun in such cases is at its zenith, i.e. directly overhead) . At the poles, the sun's rays fall obliquely, at an acute angle, the sun moves low above the horizon for a long time, and then does not appear at all in the sky for several months. As a result, the equator and even temperate latitudes receive much more heat than the regions near the poles.

Therefore, in both hemispheres of the Earth, several thermal zones are distinguished: equatorial, two tropical, two temperate and two cold. Solar heat is the driving force of natural processes and phenomena that we observe around us in the surface shell of the Earth. Now scientists call this shell the biosphere, that is, the sphere of life.

And since solar heat is unevenly distributed on Earth, then in the biosphere, in the nature around us, large differences are clearly expressed from one thermal zone to another. Accordingly, geographic zones are already distinguished. Their boundaries coincide with the boundaries of thermal zones.

But in each of the geographical zones, the natural conditions are different. After all, the width of these belts in places is more than 4 thousand km. km! The closer to the equator one or another part of the geographic zone, the more heat it receives and the more it differs from other parts remote from the equator. Such differences are especially pronounced in climate, soils, vegetation and wildlife. Therefore, within the geographical zones, geographical, or natural, zones are clearly expressed, that is, areas more or less homogeneous in terms of natural conditions. They stretch most often in a strip along the parallels. So, in temperate zones, zones are distinguished: forest, forest-steppe, steppe, semi-desert and desert.

The distribution of natural zones around the globe and their boundaries are determined not only by the amount of solar heat. Of great importance is the amount of moisture, which is also unevenly distributed on land. This leads to large differences in natural conditions even at the same latitude. In Africa, there is a lot of heat everywhere near the equator, but on the west coast, where there is also a lot of moisture, dense tropical forests grow, and on the east, where it is not enough, there are savannahs, sometimes quite dry.

In addition, the position of geographic land areas is influenced by mountain ranges that change the direction of the zones along the parallels. The mountains have their own high-altitude zones, as it gets colder with the rise. At high altitudes, the earth's surface gives off a lot of heat to the surrounding space, "supplied" to it by the sun. This happens because the air above is rarefied, and although here it transmits more sunlight than at the foot of the mountains, the loss of heat from the earth's surface increases with height to an even greater extent.

Altitude zones occupy smaller spaces than plains (latitudinal) zones, and seem to repeat them: mountain glaciers - the polar zone, mountain tundra - tundra, mountain forests - forest zone etc. The lower part of the mountains usually merges with the latitudinal zone within which they are located. So, for example, taiga approaches the foothills of the Northern and Middle Urals, at the feet of some mountains of Central Asia, which lie in the desert zone, a desert spreads, and in the Himalayas the lower part of the mountains is covered with tropical jungle, etc. The largest number of high-altitude zones (from glaciers on the tops of the mountains to the tropical forests at the foot) is observed in the high mountains located near the equator. Altitude zones, although similar to the plains, but the similarity is very relative.

Indeed, the amount of precipitation in the mountains usually increases with height, while in the direction from the equator to the poles it generally decreases. In mountains with height there is no such change in the length of day and night as when moving from the equator to the poles. In addition, climatic conditions become more complicated in the mountains: the steepness of the slopes and their exposure (northern or southern, western or eastern slopes) play a significant role here, special wind systems arise, etc. All this leads to the fact that both soils and the vegetation and fauna of each altitudinal zone acquire special features that distinguish it from the corresponding flat zone.

Differences in natural zones on land are most clearly reflected by vegetation. Therefore, most of the zones are named after the type of vegetation that prevails in them. These are the zones of temperate forests, forest-steppes, steppes, tropical rainforests, etc.

Geographical zones can also be traced in the oceans, but they are less pronounced than on land, and only in the upper layers of water - up to a depth of 200-300 m. Geographical zones in the oceans generally coincide with thermal zones, but not completely, since water is very mobile, sea currents constantly mix it up, and in some places transfer it from one zone to another.

In the oceans, as well as on land, seven main geographical zones are distinguished: equatorial, two tropical, two temperate and two cold. They differ from one another in temperature and salinity of water, the nature of currents, vegetation and wildlife.

So, the waters of cold zones have a low temperature. In them, somewhat less than in the waters of other zones, there are dissolved salts and more oxygen. The vast expanses of the seas are covered powerful ice, and the flora and fauna are poor in species composition. In temperate zones, the surface layers of water heat up in summer and cool down in winter. Ice in these zones appears only in places, and even then only in winter. The organic world is rich and varied. Tropical and equatorial waters are always warm. Their life is abundant. What are geographic land areas? Let's get acquainted With the most important of them.

Ice is a natural zone adjacent to the poles of the globe. In the northern hemisphere, the ice zone includes the northern outskirts of the Taimyr Peninsula, as well as numerous islands of the Arctic - areas lying around the North Pole, under the constellation Ursa Major ("arktos" in Greek - bear). These are the northern islands of the Canadian Arctic Archipelago, Grenland of the day, Svalbard, Franz Josef Land, etc.

In the southern polar region - Antarctica (from the Greek word "anti" - against, that is, against the Arctic) - there is an ice-covered continent of Antarctica, which is part of the ice zone of the southern hemisphere.

The harsh nature of the ice zone. Snow and ice do not melt here completely even in summer. And although the sun shines for several months without interruption, around the clock, it does not warm the earth, which has cooled down during the long winter, as it does not rise high above the horizon. In addition, the sun is often covered with thick clouds and fogs, and the white surface of snow and ice reflects its rays. On the polar night, severe frosts rage.

In 1961, Soviet researchers of Antarctica had to work at frosts of 88.3°. At the same time, hurricane winds were still blowing - up to 70 m/sec. In motors due to such low temperatures gasoline did not catch fire, and metal and rubber became brittle, like glass.

Summer is coming, the sun is rising over the Arctic desert, now it will not hide behind the horizon for a long time. Still, clear, sunny weather is rare. The sky is overcast with low clouds, it rains for several days in a row, and even snow. There are very few plants here: the conditions are too harsh. Ice fields covered with snow are spread everywhere, and bare rocks and stony placers darken on the islands and the coast. Even where ice and snow do not interfere with plants, strong winds destroy them. Only in places, in the lowlands protected from ice breathing, do small “oases” manage to form in a short summer. But here, too, the plants do not stretch upwards, but press against the ground: it is easier for them to stand against the wind. As soon as the snow melts, the first flowers appear. They develop very quickly, because the sun shines around the clock.

In the most favorable conditions In the icy desert of the Arctic there are patches of arctic meadows and marshes. On the island of Svalbard, polar poppies turn yellow. More than thirty species of flowering plants are found in the flora of Franz Josef Land. Even in the icy expanses of the central part of Greenland, red-brown or green fields formed by microorganisms can be seen from an airplane.

Noisy in summer in the Arctic. Migratory birds return to their nesting grounds: little auks, guillemots, guillemots, various gulls... There are not so many species, but each is represented by many thousands of birds. They nest on ledges of coastal cliffs in huge colonies, making a terrible noise. That is why these colonies are called "bird colonies". How to explain the desire of birds to settle in such huge numbers in small areas? The fact is that steep cliffs with ledges, small platforms are very convenient for nesting, and nearby there is an abundance of fish that birds feed on. In addition, together it is easier to drive away the predator.

Other birds also fly to the Arctic: geese, terns, eiders. In spring, the eider grows a long fluff on its abdomen, with which it covers its nest. This fluff is unusually warm and light and therefore highly valued. People collect it on eider nesting sites and even arrange artificial nests for it in the form of a half-open box.

In Greenland and on the islands of the Canadian Arctic archipelago, an animal has survived, whose ancestors lived back in the days of mammoths and long-haired rhinos. This is a wild musk ox, or musk ox. It really resembles both a ram and a bull at the same time. Its massive body is covered with long hair.

The nature of the Antarctic is even poorer than the Arctic. The average height of Antarctica is 2200 m above sea level, but earth's surface is much lower here, because it is hidden under a thick layer of ice, its average thickness is more than 1500 m, and the largest is 5000 m. Sparse vegetation is found here only on the coast of the mainland. These are mainly mosses and lichens. Only three species of flowering plants are known here. Not rich in species and the Antarctic fauna. There are no such large animals as the polar bear. Seals live off the coast of Antarctica, and petrels and albatrosses fly over the oceans washing it. Albatross wingspan up to 4 m. These birds spend most of their lives above the water, catching fish.

The most remarkable animals of Antarctica are penguins. These birds have lost the ability to fly, their wings have turned into swimming flippers. Penguins are excellent swimmers and divers. And on land they are clumsy, waddling, while resembling fat funny little men in black tailcoats and white shirts. Penguins nest in numerous colonies. Their only enemy is the sea leopard (one of the species of local seals).

For a long time, the Arctic and especially the Antarctic were almost undeveloped by man. Now, thanks to the achievements of science and technology, we can already talk not only about the study and use of these little-studied areas, not only about the adaptation of man to their harsh natural conditions, but also about the influence of man on the nature of the ice zone.

At high altitudes in the mountains it is as cold as in the ice zone, the same wind-blown stones, only in some places covered with mosses and lichens. But there are no sea spaces nearby, migratory birds do not arrange “bazaars”. There are no many months of polar days and nights here. At high mountains, atmospheric pressure is low, the air is poorer in oxygen, so not all animals can adapt to life in high mountain conditions. A large predator, the snow leopard, tolerates cold and height well. The whitish shade of the fur makes it hardly noticeable against the background of snow and gray stones. In summer, the leopard usually stays on the line of eternal snows, and in winter it descends lower, following its prey - mountain sheep and mountain turkeys (ulars).

The more grass in the steppe, the more large herbivores. And the more predators. In our steppes, the characteristic predator is the wolf (although it is also found in other zones), and in the North American steppes, small wolves are coyotes.

Of the steppe birds, only the bustard and the gray partridge live settled, not flying away to warm countries for the winter. But in the summer, many representatives of the feathered kingdom settle in the steppe: ducks, waders, demoiselle crane, larks.

At a great height above the steppe, raptors soar: eagles, vultures, etc. Open spaces allow them to notice prey from above at a distance of several kilometers. Birds of prey sit down to rest on mounds, telegraph poles and other elevations, from where it is better to see and easier to take off.

The steppes of North America are called prairies. In them, along with plants common to our steppes (feather grass, wheatgrass), there are those that are not in the eastern hemisphere: bison grass, Graam grass, etc. The steppes of South America, pampa, are even more diverse.

Rigid grasses a meter - one and a half high in places completely cover large areas of the pampas. Where the soil is somewhat wetter, bright green creepers appear, and with them - scarlet, pink, white verbena. Yellow and white lilies grow in damp places. The most beautiful pampa plant is the silvery hynerium, whose silky panicles seem to have absorbed the most diverse tones of the azure sky. In this sea of ​​grass, herds of wild cattle roam, herds of horses, Nandu ostriches stride importantly. Near lakes and rivers, where groves of trees and shrubs meet, one can see black squirrels, tiny hummingbirds, noisy parrots.

In some mountains (Tien Shan, Altai, in the mountains of Transbaikalia, in the Greater Khingan, in the Cordillera, etc.) there are places where much resembles a flat steppe. In Central Asia, the mountain steppes almost do not differ from the flat feather grass-fescue steppes.

In ancient times, the steppes occupied vast territories on the plains of North America and Eurasia. Now they are completely open. On fertile steppe soils, wheat, corn, millet, various melons and gourds are grown.

The natural vegetation cover of the steppes is now almost non-existent. The animal world has also changed. The ancestors of our domestic animals have long disappeared here - the wild bull aurochs and wild horses tarpans, some birds have become rare. Now only in a few reserves, in such, for example, as our Askania-Nova, you can see a real virgin steppe.

Subtropical forests and shrubs

Approximately between 30 and 40 ° N. sh. and y.sh. lie the subtropics. Their nature is extremely diverse. Under these latitudes, one can see a lush evergreen forest, and a steppe, and a sultry desert - moisture is so unevenly distributed here - the source of life.

On the western outskirts of the continents there are subtropics, often called Mediterranean, because all the features of their nature are most pronounced on the coasts of the Mediterranean Sea.

Summers in these parts are hot and dry, with rain falling mostly in winter, during which even mild frosts are rare. The vegetation cover of the Mediterranean subtropics is dominated by thickets of evergreen shrubs and low trees. A noble laurel, a strawberry tree that annually sheds its bark, tender myrtle, wild olives, roses, and junipers grow here. In many plants that have adapted to the dry summer, the leaves have turned into thorns. Entwined with the same prickly vines, they become an insurmountable obstacle for travelers.

When it's time to bloom, the bushy thickets (they are called maquis) turn into a sea of ​​​​luxurious flowers - yellow, white, blue and red. A strong aroma spreads in the surrounding air.

One of the most beautiful plants Mediterranean subtropics - Italian pine, or pine. The wide, sprawling crowns of pines seem especially magnificent in the neighborhood with dense, spindle-shaped crowns of cypresses. These beautiful trees grow most often alone. Very few pine groves have survived. Small forests, which can still be found in the Mediterranean subtropics, consist mainly of evergreen oaks - cork and holm. Trees rarely stand here, and grasses and shrubs grow wildly between them. In such a forest there is a lot of light, and in this way it differs greatly from the shady Russian oak forests.

A different picture is presented by the subtropics on the eastern outskirts of the continents. In southeastern China and southern Japan, precipitation is also uneven, but it only rains more in summer (and not in winter, as in the Mediterranean subtropics), i.e., at a time when the vegetation is especially in need of moisture. Therefore, dense moist forests of evergreen oaks, camphor laurel, and magnolias grow here. Numerous creepers entangling tree trunks, thickets of tall bamboos and various shrubs enhance the originality of the subtropical forest.

In the southeastern part of the United States, swampy subtropical forests dominate, consisting of American species of pine, ash, poplar, and maple. Swamp cypress is widespread here - a huge tree reaching 45 m tall and 2 m across. In Russia, the subtropics include the Black Sea coast of the Caucasus, the Lankaran lowland on the Caspian coast. The subtropics are the birthplace of valuable cultivated plants: oranges, tangerines, lemons, grapefruits, persimmons, etc. In addition to citrus fruits, olives, laurel cherries, figs, pomegranates, almonds, date palms and many other fruit trees and shrubs are grown here. See also: .

desert

The deserts occupy the globe vast territories, especially in Asia, Africa and Australia. Their total area is estimated at 15-20 million hectares. km 2 . There are deserts of the temperate zone, subtropical and tropical.

In the temperate zone, all the plains of Asia, from the Caspian Sea in the west to Central China in the east, are almost entirely desert spaces. In North America, some intermountain depressions in the west of the mainland are deserted.

Subtropical and tropical deserts are located in the north-west of India, in Pakistan, Iran, Asia Minor. They cover the Arabian Peninsula and the entire north of Africa, the western coast of South America for almost 3500 km and central Australia. On the outskirts of the desert, they are usually bordered by transitional zones of semi-deserts.

The climate in the deserts is sharply continental. Summer is very dry and hot, during the day the air temperature in the shade rises above 40 ° (in tropical deserts up to 58 °). At night, the heat subsides, the temperature often drops to 0 °. In winter, colds come, even in the Sahara at this time there are frosts. There is little precipitation in the deserts - no more than 180 mm in year. Chile's Atacama Desert gets fewer than 10 mm. In places in the tropical deserts, there is no rain for several years in a row.

In a hot, sultry summer, the meager remains of plants in the soils of the desert, as it were, “burn out”. Hence the light gray or light yellow (sometimes almost white) color of the soils, which are called gray soils. Most often, the soil cover in deserts is very weakly expressed. Stony or clayey areas are replaced here by seas of moving sand. "Sand waves" - dunes - reach 12 m height. Their shape is crescent-shaped or crescent-shaped, one slope (concave) is steep, the other is gentle. Connecting at the ends, the dunes often form whole dune chains. Under the influence of the wind, they move at speeds from tens of centimeters to hundreds of meters per year. Unobstructed winds in the desert sometimes reach terrible strength. Then they raise clouds of sand into the air and rush over the desert like a formidable sandstorm.

Clay deserts are almost devoid of vegetation. These are usually low-lying places. They are easily flooded and during the period of light rains they look like lakes, although the depth of such "lakes" is only a few millimeters. The clay layer does not absorb water - it quickly evaporates in the sun, and the dry surface of the earth cracks. Such areas of the desert are called takyrs. Often in deserts, various salts (common salt, Glauber's salt, etc.) come out directly to the surface, forming barren solonchaks. In the sands, plants feel better than on takyrs, because the sands absorb water better and are less saline. In summer, even small reserves of moisture form in the lower, cooler layers of the sands: this is the condensation of water vapor coming from the atmosphere.

The name "desert" does not mean at all total absence life. Some plants and animals have adapted well to existence in conditions of dry climate and high temperatures.

In the deserts of Central Asia grows saxaul - black and white. Large saxaul sometimes reaches 5 m height. Its leaves-twigs are so small (this helps to retain moisture) that on a hot summer day the trees seem to be bare in winter. But under the black saxaul in the lowlands there is even a weak shadow that saves animals and people from the sun.

In many desert plants, during the hot period, relatively large “spring” leaves are replaced by small “summer” ones. And if larger “summer” leaves are found, then they are either fluffy (near wormwood in Central Asia) or covered with a shiny wax layer. Such leaves reflect the sun's rays and do not overheat. In some plants (sand acacia), the leaves have turned into thorns, which also prevents moisture from evaporating. A small shrub - black wormwood - is usually devoid of leaves and looks very gloomy. And only in spring the black wormwood seems to come to life, covered for a short while with fluffy silvery foliage.

In the deserts of the Western Hemisphere, many different cacti grow. They adapted to the arid climate in their own way: large reserves of water accumulate in the fleshy stems and leaves, sometimes 96% of the total weight of the plant. North American cactus carnegia giant (height up to 15 m) stores in its stems 2-3 thousand. l water. Desert plants tend to have well-developed root systems. It allows them to extract moisture from deep layers of the soil. Some of these plants (desert sedge) can fix sands with a strong root system.

Desert animals also have their own adaptations to the environment. Many desert dwellers are painted in yellow and gray colors, which allows them to hide from enemies or sneak up on prey unnoticed.

All the inhabitants of the desert try to hide from the scorching heat. Pigeons, sparrows and owls manage to nest and rest in the walls of wells. Birds of prey (eagles, crows, falcons) nest on mounds and in the ruins of buildings, choosing the shady side. Many animals hide in burrows where it is not so dry and hot in summer and not too cold in winter. And if the inhabitants of most temperate zones hibernate in winter, then other desert animals fall asleep in summer, thus enduring a lack of moisture.

And the thin-toed gopher generally does without drinking water: he needs enough moisture contained in the plants he eats. The bushy-legged jerboa also does not “know how” to drink: when in captivity they offer water to it, it wets its paws in it and licks them.

Like many inhabitants of the steppes, some desert animals are excellent runners. Huge distances run in search of water and food wild asses kulans. They can reach speeds up to 70 km/h. Cheetahs run even faster - wild cats on long legs with semi-retractable claws.

The dry climate of the deserts is extremely unfavorable for amphibians, but there are a lot of reptiles here: various snakes, lizards (including very large monitor lizards), turtles. Fleeing from the heat and from enemies, many of them quickly burrow into the sand. And the agama lizard, on the contrary, climbs the bushes - away from the hot sand.

The camel is excellently adapted to life in the desert. He can eat grass, which is not digested by other animals, drinks little, is able to drink even salt water. Camels tolerate prolonged hunger well: a supply of fat is deposited in their humps (up to 100 kg and more). On the body and legs of the camel there are calluses that allow him to lie down on hot sand. Leaning on a wide cloven hoof, the camel moves freely on the sands. All these features make it an indispensable assistant to a person in the desert. The camel walks in a harness, under a pack and a saddle, gives warm wool. It was domesticated 4 thousand years ago.

Traces of ancient settlements and irrigation systems are often found under the desert sands. They were destroyed during the wars, and, abandoned by people, once flowering lands became the prey of the desert. But even now, where grazing areas do not change for a long time, or where bushes are cut down too much, the sands, which are no longer held together by plant roots, go on the offensive.

Fixing loose sands with plants is one of the surest ways to conquer the desert. In addition, sands can be “forged” with special emulsions, the thin film of which is easily penetrated by young shoots of plants.

If you water the desert with enough moisture, its appearance will change. Then it will be possible to grow rice, cotton, melons, corn, wheat, orchards, vineyards here. Desert oases provide 25-30% of the world's cotton harvest and almost 100% of the world's date harvest. On the irrigated lands in the deserts of Central Asia, you can harvest two crops of various crops a year. More about the desert zone.

Savannah

In the equatorial belts of the northern and southern hemispheres there are tropical steppes - savannahs (from the Spanish "saban" - wild plain). In Africa, in the Brazilian Highlands in South America and in the north of Australia, they occupy vast spaces.

The climate of the savannas is tropical. There are very clearly defined two seasons - dry and wet. In this regard, the whole life of nature is subject to a certain rhythm.

In the dry period, the heat reaches 50 °. At this time, the savanna makes a dull impression: yellowed and withered grass, trees devoid of foliage, red-brown, cracked soil, no visible signs of life.

Savannas are vast expanses covered with grassy vegetation with sparsely scattered acacias, baobabs and shrubs.

But then the rains begin, and the savannah awaits literally before our eyes. The soil greedily absorbs moisture and is covered with tall, taller than human growth, grass. Trees and shrubs growing in groups or alone are green everywhere. The crowns of the trees are umbrella-shaped, especially in acacias.

The largest plant in the African savannas is the baobab. It is not taller than our pine, but its trunk is extremely thick - up to 10 m across. Outwardly, this tree is unattractive, only its large white flowers are beautiful. Baobab fruits are not tasty, but for monkeys they are a real delicacy.

Eucalyptus trees grow in the savannahs of Australia - giant trees height up to 150 m. There are many types of them. In some species of eucalyptus, the leaves can turn to the sun's rays with an edge and therefore give almost no shade, but this reduces the evaporation of moisture. Among the rarely scattered trees there is a scrub - dense thickets of brigolo acacia, desert oak, sandalwood. Between them come across bizarre " bottle trees» with a trunk swollen from the base to the crown.

The fauna of the savannas, especially African ones, is unusually rich and diverse. Large representatives of land animals live here: clumsy hippos live on the shores of lakes and in the water, heavy buffaloes come, among the branches of mimosa you can see beautiful giraffe heads. In the thick of the grass, crouching to the ground, a lion guards its prey. And not always the fast legs of antelopes save these light graceful animals from the formidable lord African savannah. But more often, careless zebras become its victims.

A slight rustle of grass betrays the presence of other inhabitants. These are snakes. There are a lot of them here, and the most terrible of them is the asp. Both man and animals are afraid of him: the bite of an asp is fatal. Only the buffoon eagle fearlessly fights this snake and almost always wins. See also: .

The abundance of heat, and during the wet period and rainfall, fertile, like our black soil, soils make it possible to grow various crops in the savannah zone, cotton, peanuts, sugar cane, bananas, pineapples. Therefore, people have been farming here since time immemorial, and livestock graze on the luxurious pastures of the savannas. In the African savannas lives the largest modern bird - the African ostrich.

Rainforests

Tropical forests grow near the equator, on both sides of it, between the northern and southern tropics. It's very hot and humid here. The annual rainfall reaches 10,000 tons in some places. mm, and in Cherrapunj (India) - 12 thousand. mm. This is 20 times more than in temperate forests. The abundance of heat and moisture is the main reason for the fabulous wealth and diversity of plants and animals in the tropical rainforest.

The weather here is remarkably consistent. Before sunrise, the forest is rather cool and quiet, the sky is cloudless. The sun is rising and the temperature is starting to rise. By noon, the heat sets in, the air becomes suffocating. Two or three hours later, clouds appear in the sky, lightning flashes, deafening peals of thunder shake the air, and a downpour begins. Water flows like a continuous stream. Under its weight, branches of trees break and collapse. Rivers overflow their banks. The rain usually lasts no more than an hour. Before sunset, the sky clears, the wind subsides, and soon the forest plunges into the darkness of the night, which comes quickly, almost without twilight.

Red lateritic soils up to several tens of meters thick form under tropical rainforests. Their color is due to the presence of a large amount of iron oxides. Sometimes yellow-white aluminum oxides are also mixed in - then the soil becomes spotty. During tropical downpours, a significant part of the humus is washed out of the soil, and for the cultivation of cultivated plants (sugarcane, citrus fruits, etc.), it has to be fertilized.

Some trees lose leaves alternately from different branches. Falling leaves usually do not turn yellow, and therefore green color prevails everywhere. In the tropics, there are up to 600 species of various ficuses, some of them are much larger than our oak. In the forest grow tree-like ferns that look like palm trees. There are a lot of palm trees in the tropics. They do not have branches - the leaves are collected at the top of a tall trunk. The fruits of date, coconut, oil and other palms are used by man.

A variety of animals live in the wilds of the rainforest. From gigantic elephants, rhinos, hippos to barely noticeable insects - everyone finds shelter and food here. Representatives of some animal groups in tropical forests are numerous. It is here that most monkeys live, including anthropoids. Of the birds alone

There are more than 150 species of parrots in South America. The Amazon parrot is easy to teach to speak. The parrot does not understand the meaning of the spoken words - it simply imitates the combination of sounds. There are a lot of insects in the rainforest: over 700 species of butterflies are known in Brazil, which is almost five times more than in Europe. Some of them are giants, such as the tizania butterfly: its wingspan is up to 30 cm.

In water-rich tropical forests, along with various reptiles (crocodiles, turtles, lizards, snakes), there are many amphibians. On the island of Kalimantan alone, there are 7 times more amphibian species than in Europe. Tropical reptiles reach enormous sizes: some crocodiles are up to 10 m, and the South American anaconda boa reaches 9 m. There are a lot of different ants in the tropics. The abundance of plant food attracts many herbivorous animals to the tropical forests, which in turn are followed by predators: leopards (panthers), jaguars, tigers, various mustelids, etc. The striped or spotted color of many inhabitants, although it seems very bright and noticeable, in fact, it helps animals hide in the semi-darkness of the lower tiers of the tropical forest, penetrated in some places by the sun's rays.

The nature of the so-called mangrove tropical forests is peculiar. They grow on low-lying sea coasts, protected from the surf, but flooded during high tide hours. Mangrove forests are dense thickets of low (5-10 m) trees and shrubs. They grow on viscous muddy soil. Under such conditions, the plant is supported by branched aerial (stilted) roots, which are immersed in silt. But since the muddy soil here is poisoned with hydrogen sulfide, plants receive oxygen only from the air - with the help of other, special aerial roots. At the same time, fresh water reserves are formed in old leaves, which are necessary for young foliage. The fruits of plants have air cavities and do not sink in water, but can swim in the ocean for a long time until they linger somewhere on the shallows and germinate. Mangrove forests, by fixing silt and sand, interfere with navigation in the mouths of tropical rivers.

The rich nature of tropical forests has long supplied people with their gifts. But even today large areas wild jungle inaccessible, swampy, poorly mastered by man. The rainforest is growing very fast. Abandoned for some reason fields, roads, clearings and clearings immediately overgrow. People all the time have to fight against the jungle advancing on the fields. Raids of predators on villages, monkeys and ungulates on plantations bring a lot of harm.

Many wonderful representatives of the tropical fauna (elephants, rhinos, antelopes) were barbarously exterminated by the European colonialists. Now some states have already taken measures to protect rare tropical animals: hunting is prohibited, reserves have been created.

The appearance of the natural zones of the Earth and their boundaries were not always the same as they are now. Over the long history of our planet, the relief, climate, vegetation, and fauna have repeatedly changed.

In the distant past, the Earth experienced many cold snaps. During the last such period, a significant part of Eurasia and North America was covered with thick ice.

In the southern hemisphere, ice has penetrated into South America and Australia. But then it became warmer again and the ice receded in the northern hemisphere to the north, and in the southern hemisphere to the south, remaining huge caps only in Greenland and Antarctica.

After the end of the last ice age, modern natural zones arose on Earth. But even now they do not remain unchanged, because nature has not stopped in eternal development, it continues to change and renew itself continuously. A significant role in this process is played by a person, his labor activity. Man grows cultivated plants in the place of wild steppes and dense forests, destroys some animals and breeds others, irrigates arid territories and drains swamps, connects rivers and creates artificial seas - he transforms the face of the Earth.

But sometimes human impact on nature leads to undesirable consequences. The plowing of lands is often accompanied by erosion and washout of soils, their scattering and, consequently, the deterioration of the conditions for the existence of plants. Therefore, in the USA, after 2/3 of the forests were destroyed, the area of ​​deserts doubled.

The burning of forests in Africa has caused deserts to invade the savannah, which in turn arises where tropical forests are reduced.

Such changes in geographical areas reduce the natural wealth of our planet. The transformation of nature must be reasonable. We must not impoverish her, but make her even richer and more beautiful.