Now, while studying geography in class, we have a lot of information: maps, diagrams, photographs. Back in the 19th century, knowledge about natural areas was very scarce. Dokuchaev worked on them for a long time, but he was never able to systematize the collected data, and his work was continued by L. S. Berg, a well-known geographer in the USSR.
Parameters of characteristics of natural zones
Any biological complex has similar characteristics. This applies to flora and fauna, soil, weather conditions winter and summer. The student’s task is to be able to systematize information and provide characteristics of natural zones in Russia using a table.
L. S. Berg not only gave detailed description natural zones throughout Eurasia, but also identified differences on other continents. His textbook “Nature of the USSR” became the basis for the knowledge that we have now.
Rice. 1. Natural areas Russia
Table “Natural zones of Russia” (8th grade)
|
Zone name |
Geographical position |
Climate |
The soil |
Plants |
Animals |
|
Arctic desert |
Northern Islands Arctic Ocean, north of the Taimyr Peninsula |
Cold arctic air masses predominate. Summer is short and cold. |
Permafrost |
Mosses, lichens, polar poppy |
Polar bear, walrus, seal |
|
From the coast of the Arctic Ocean to the Arctic Circle. The widest strip of tundra in Siberia |
Long winter (9 months), high precipitation due to low evaporation, short summer. |
Tundra-gley, peat |
Mosses, lichens, berry bushes |
Reindeer, arctic fox, white hare |
|
|
Forest-tundra |
Extent throughout Russia in a narrow strip from the tundra to the taiga |
Subarctic, gradual warming. Wed. January temperatures from -10° to -40°, in summer +13°-+19° |
Peat and sphagnum bogs predominate. The soils are peat-gley and with a transition of nagle-podzolic |
Low-growing spruce, fir, cedar, dwarf birch |
Brown bear, elk, white hare. Birds: capercaillie, hazel grouse, nutcracker |
|
Length from Baltic Sea to the coast Pacific Ocean. Occupies all of Siberia |
Warm summer 4-5 months and Cold winter. January temperatures are from -10° to -50°. In summer +16° |
Podzolic |
This is a forest area. Representatives: larch, fir, spruce, cedar, pine |
Brown bear, elk, squirrel, wolf, sable, lynx. Birds: capercaillie, hazel grouse |
|
|
Mixed forests |
European part of Russia and Western Siberia |
Temperate climate zone, humus layer predominates |
Podzolic |
Lots of herbaceous vegetation. Trees include both coniferous and deciduous |
Elk, hare, beaver, wild boar, fox, raccoon. |
|
Broadleaf forests |
Russian Plain and the south of the Far East |
Moderate in the European part and monsoonal in Far East. |
Gray podzolic, brown forest soils, in the European part - chernozems. |
Oaks, maples, lindens, aspens. Due to overuse by people. Almost all forests have been cut down |
Hare, wild boar, muskrat, fox |
|
Forest-steppe |
A narrow transition strip from forests to steppes |
Temperate continental. |
Chernozems |
Deciduous trees and a variety of grasses |
Hare, squirrel, beavers, mice |
|
Northern Black Sea coast, southern Western Siberia |
Arid, high evaporation, low humidity. Winters frosty summer roast |
Chernozems |
Herbs and grains: feather grass, tumbleweed, wheat |
Mice, gophers, snakes. Birds: steppe eagle |
|
|
Deserts and semi-deserts |
Areas near the Caspian Sea |
Arid climate with cold winters |
Gray-brown soil, dominated by solonchaks and solonetzes |
Drought-resistant plants. There is valuable feed for sheep and camels |
Snakes, turtle, jerboa, scorpion |
|
Subtropics |
Southern Black Sea coast |
Warm maritime climate throughout the year |
Brown mountain forest soils, yellow soils and humus-carbonate soils |
Boxwood, rhododendron, laurel |
Mouflon, turtle, snakes, red deer |
Rice. 2. Taiga
Formation of natural areas in mountainous areas occurs at a level of more than 2000 m. In the Caucasus and the Urals, this height corresponds to alpine meadows, in northern regions Siberian mountains - mountain tundra.
Arctic air prevails here all year round, the annual radiation balance is less than 400 mJ/m2, and average July temperatures are 4-2°C. The relative humidity is very high - 85%. Precipitation amounts to 400-200 mm, almost all of which falls in solid form, which contributes to the formation of ice sheets and glaciers. However, in some places the supply of moisture in the air is small and therefore, when the temperature rises and strong winds, a large lack of moisture occurs and strong evaporation of snow occurs.
The soil-forming process in the Arctic occurs in a thin active layer and is at the initial stage of development. In the valleys of rivers and streams and on sea terraces, two types of soils are formed - typical polar desert soils on polygonal drained plains and polar desert solonchak soils on saline coastal areas. They are characterized by a low humus content (up to 1.5%), weakly expressed genetic horizons and very low power. In the Arctic deserts there are almost no swamps, few lakes, and salt spots form on the soil surface in dry weather with strong winds.
The vegetation cover is extremely sparse and spotty, characterized by a poor species composition and extremely low productivity. Low-organized plants dominate: lichens, mosses, algae. The annual growth of mosses and lichens does not exceed 1-2 mm. Plants are extremely selective in their distribution. More or less closed groups of plants exist only in places sheltered from cold winds, on fine earth, where the thickness of the active layer is greater.
The main background of the Arctic deserts is formed by crustose lichens. Hypnum mosses are common; sphagnum mosses appear only in the south of the zone in very limited quantities. Higher plants include saxifrage, arctic poppy, semolina, chickweed, arctic pike, bluegrass and some others. The grasses grow luxuriantly, forming hemispherical cushions up to 10 cm in diameter on a fertilized substrate near the nesting areas of gulls and lemming burrows. Ice buttercup and polar willow grow near patches of snow, reaching only 3-5 cm in height. The fauna, like the flora, is poor in species; there are lemmings, arctic foxes, reindeer, polar bear, and the most common birds are the ptarmigan and the snowy owl. On the rocky shores there are numerous bird colonies - massive nesting grounds for seabirds (guillemots, little auks, white gulls, fulmars, eiders, etc.). Southern Shores Franz Josef Land and the western shores of Novaya Zemlya are a continuous bird market.
In order to find out what natural zones are, let us remember that they are formed on the basis geographical zones: equatorial, subequatorial, tropical, subtropical, temperate, subarctic and arctic. If you wonder how many of them there are, then in geography it is customary to count nine categories. Let's consider natural areas and their features.
Equatorial and tropical forests
Characterized by heat and big amount tropical showers. Here is the most high humidity on the ground. The top layer of soil is very fertile, which makes it possible to grow fruit and vegetable crops all year round and harvest several times.
Largest a tropical forest in the world is located in the Amazon River Valley. Many places in this impenetrable thicket have still not been explored by people. Equatorial forests are rich in different types flora and fauna. Here you can meet the smallest birds - hummingbirds, bloodthirsty alligators and apes.
Rice. 1. Equatorial forests
Equatorial deserts and semi-deserts
These areas are characterized by a very arid climate with scorching sun most of the year. The flora and fauna are very scarce; living organisms have to adapt to the harsh conditions of the desert. There are practically no minerals in the soils, and moisture is so far away that the roots of plants (cacti) have to go hundreds of meters deep.
The largest desert on Earth is the Sahara Desert in Africa.
Rice. 2. Desert
Savannas and woodlands
Already from the name it is obvious that this is an area of rare trees. The vegetation here is predominantly herbaceous, characterized by low shrubs and rare trees. There is very little rainfall per year and it is hot for most of the year.
Hard-leaved forests and shrubs
This zone is typical for Mediterranean countries. A variety of plants and many trees, mostly conifers, are found here. The characteristic fauna can now only be found in zoos. Urbanization and technological progress have led to the fact that forests have practically disappeared in Europe, and with them the ancient fragile natural world. The soils here are red-brown.
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Steppes and forest-steppes
The most fertile lands, chernozems, are formed in this zone. The climate is mild, with moderate winters and an arid climate. The forest-steppe has a rich flora and fauna; the steppes are inhabited mainly by rodents, predators, large birds.
Broadleaf and mixed forests
Most of Russia is just a forest zone. Temperate climate, warm summers and cold winters allow a large number of animals to survive here. The flora is represented by hundreds of species of bushes and trees.
Taiga
The Taiga zone is located in northern countries such as Canada, Sweden, Norway, Finland and Russia. Winter here is getting colder and there is less summer. The entire area is covered evergreen forests, consisting of coniferous trees: spruce, pine, larch. Representatives of the fauna are mainly predators.
Tundra and forest-tundra
The climate zone in which it is located is subarctic. You can find it in two countries: Russia and Canada. In the forest-tundra there are still low-growing trees and shrubs, in the tundra there are only mosses and lichens. The soil is peaty and swamps predominate. Due to the fact that it is winter here most of the year, the earth does not warm up. Among the animals there are hares, arctic foxes, and reindeer.
Natural areas of the Earth
Complex Scientific research nature allowed V.V. Dokuchaev in 1898 to formulate the law of geographical zoning, according to which climate, water, soil, relief, vegetation and fauna in a certain territory are closely interconnected and must be studied as a whole. He proposed dividing the Earth's surface into zones that are naturally repeated in the Northern and Southern Hemispheres.
Different geographical (natural) zones Earth are characterized by a certain combination of heat and moisture, soils, flora and fauna and, as a consequence, the characteristics of the economic activities of their population. These are zones of forests, steppes, deserts, tundra, savanna, as well as transitional zones of forest-tundra, semi-deserts, forest-tundra. Natural areas are traditionally named according to the predominant type of vegetation, reflecting the most important features of the landscape.
A regular change in vegetation is an indicator of a general increase in heat. In the tundra the average temperature is warm month in the year - July - does not exceed + 10°C, in the taiga it fluctuates within + 10... + 18°C in the deciduous and mixed forests+ 18...+20°С, in the steppe and forest-steppe +22...+24°С, in semi-deserts and deserts - above +30°С.
Most animal organisms remain active at temperatures from 0 to +30°C. However, temperatures from + 10°C and above are considered the best for growth and development. Obviously, such a thermal regime is typical for equatorial, subequatorial, tropical, subtropical, as well as temperate climatic zones Earth. The intensity of vegetation development in natural areas also depends on the amount of precipitation. Compare, for example, their number in the forest and desert zones (see atlas map).
So, natural areas- these are natural complexes that occupy large areas and characterized by the dominance of one zonal type of landscape. They are formed mainly under the influence of climate - the distribution of heat and moisture, their ratio. Each natural zone has its own type of soil, vegetation and animal life.
The appearance of a natural area is determined by the type vegetation cover. But the nature of vegetation depends on climatic conditions - thermal regime, moisture, light, soil, etc.
As a rule, natural zones are extended in the form of wide stripes from west to east. There are no clear boundaries between them; they gradually transform into one another. The latitudinal location of natural zones is disrupted by the unequal distribution of land and ocean, relief, distance from the ocean.
General characteristics of the main natural zones of the Earth
Let us characterize the main natural zones of the Earth, starting from the equator and moving towards the poles.
There are forests on all continents of the Earth, except Antarctica. Forest areas have both common features, and special ones, characteristic only of taiga, mixed and broad-leaved forests or tropical forests.
The general features of the forest zone include: warm or hot summers, a fairly large amount of precipitation (from 600 to 1000 or more mm per year), large deep rivers, and the predominance of woody vegetation. Equatorial forests, occupying 6% of the land, receive the greatest amount of heat and moisture. They rightfully hold first place among the forest zones of the Earth in terms of the diversity of plants and animals. 4/5 of all plant species grow here and 1/2 of all land animal species live here.
The climate of the equatorial forests is hot and humid. Average annual temperatures+24... + 28°С. The annual precipitation is more than 1000 mm. It is in the equatorial forest that you can find the largest number of ancient animal species, such as amphibians: frogs, newts, salamanders, toads or marsupials: possums in America, possums in Australia, tenrecs in Africa, lemurs in Madagascar, lorises in Asia; Ancient animals include such inhabitants of equatorial forests as armadillos, anteaters, and lizards.
IN equatorial forests The richest vegetation is located in several tiers. The treetops are home to many species of birds: hummingbirds, hornbills, birds of paradise, crowned pigeons, numerous species parrots: cockatoos, macaws, Amazons, Grays. These birds have tenacious legs and strong beaks: they not only fly, but also climb trees very well. Animals that live in treetops also have prehensile paws and tails: sloths, monkeys, howler monkeys, flying foxes, tree kangaroos. The largest animal that lives in the treetops is the gorilla. Such forests are home to many beautiful butterflies and other insects: termites, ants, etc. There are various types of snakes. Anaconda is the largest snake in the world, reaching a length of 10 m or more. The high-water rivers of the equatorial forests are rich in fish.
The largest areas of equatorial forests occupy in South America, in the Amazon River basin, and in Africa - in the Congo River basin. The Amazon is the deepest river on Earth. Every second it carries 220 thousand m3 of water into the Atlantic Ocean. The Congo is the second most water-rich river in the world. Equatorial forests are also common on the islands of the Malaysian archipelago and Oceania, in the southeastern regions of Asia, and in northeastern Australia (see map in the atlas).
Valuable tree species: mahogany, black, yellow - the wealth of equatorial forests. Harvesting valuable timber threatens the conservation of the Earth's unique forests. Space images showed that in a number of areas of the Amazon the destruction the forest is coming at a catastrophic pace, many times faster than their recovery. At the same time, many species are disappearing unique plants and animals.
Variably wet monsoon forests
Variably humid monsoon forests can also be found on all continents of the Earth except Antarctica. If in the equatorial forests it is summer all the time, then three seasons are clearly defined here: dry cool (November-February) - winter monsoon; dry hot (March-May) - transitional season; humid hot (June-October) - summer monsoon. Most hot month- May, when the sun is almost at its zenith, the rivers dry up, the trees shed their leaves, and the grass turns yellow.
The summer monsoon arrives at the end of May with hurricane winds, thunderstorms, and torrential rains. Nature comes to life. Due to the alternation of dry and wet seasons, monsoon forests are called variable-wet.
India's monsoon forests are located in the tropical climatic zone. They grow here valuable species trees, characterized by the strength and durability of wood: teak, sal, sandalwood, satin and ironwood. Teak wood is not afraid of fire and water, it is widely used for the construction of ships. Sal also has a durable and strong wood. Sandalwood and satin trees are used in the manufacture of varnishes and paints.
Animal world The Indian jungle is rich and diverse: elephants, bulls, rhinoceroses, monkeys. Lots of birds and reptiles.
Monsoon forests in tropical and subtropical regions are also characteristic of Southeast Asia, Central and South America, and the northern and northeastern regions of Australia (see map in the atlas).
Temperate monsoon forests
Monsoon forests temperate zone distributed only in Eurasia. Ussuri taiga- a special place in the Far East. This is a real thicket: multi-tiered, dense forests, intertwined with vines and wild grapes. Cedar, walnut, linden, ash, and oak grow here. The lush vegetation is the result of abundant seasonal rainfall and a fairly mild climate. Here you can meet Ussuri tiger- the largest representative of its species.
Rivers monsoon forests have rain power and spill during the summer monsoon rains. The largest of them are the Ganges, Indus, and Amur.
Monsoon forests have been heavily cut down. According to experts, in Eurasia only 5% of the former remains forest areas. Monsoon forests suffered not so much from forestry, but also from agriculture. It is known that the largest agricultural civilizations appeared on fertile soils in the valleys of the Ganges, Irrawaddy, Indus rivers and their tributaries. The development of agriculture required new territories - forests were cut down. Agriculture has adapted for centuries to alternating wet and dry seasons. The main agricultural season is the wet monsoon period. The most important crops are planted here - rice, jute, sugar cane. In the dry, cool season, barley, legumes, and potatoes are planted. During the dry hot season, farming is possible only with artificial irrigation. The monsoon is capricious, its delay leads to severe droughts and destruction of crops. Therefore, artificial irrigation is necessary.
Temperate forests
Temperate forests occupy significant areas in Eurasia and North America(see map in the atlas).
In the northern regions it is taiga, to the south - mixed and broadleaf forests . In the forest zone of the temperate zone, the seasons of the year are clearly defined. Average temperatures in January are negative throughout, in some places down to - 40°C, in July + 10... + 20°C; the amount of precipitation is 300-1000 mm per year. The vegetation of plants stops in winter, and there is snow cover for several months.
Spruce, fir, pine, and larch grow both in the taiga of North America and in the taiga of Eurasia. The animal world also has a lot in common. The bear is the owner of the taiga. True, in the Siberian taiga it is called a brown bear, and in the Canadian taiga it is called a grizzly bear. Can be found bobcat, elk, wolf, as well as marten, ermine, wolverine, and sable. Flow through the taiga zone largest rivers Siberia - Ob, Irtysh, Yenisei, Lena, which in terms of flow are second only to the rivers of the equatorial forest zone.
To the south, the climate becomes milder: mixed and broad-leaved forests grow here, consisting of species such as birch, oak, maple, linden, among which there are also conifers. Characteristic of the forests of North America are: white oak, sugar maple, yellow birch. Noble deer, elk, wild boar, hare; Among the predators, the wolf and the fox are representatives of the animal world of this zone known to us.
If the northern taiga is considered by geographers to be a zone slightly modified by humans, then mixed and broad-leaved forests have been cut down almost everywhere. Their place was taken by agricultural areas, for example, the “corn belt” in the United States; many cities and transport routes are concentrated in this zone. In Europe and North America natural landscapes These forests are preserved only in mountainous regions.
Savannah
Savannah - natural area low latitudes in the subequatorial, tropical and subtropical zones of the Northern and Southern Hemispheres. Occupies about 40% of the territory of Africa (sub-Saharan Africa), distributed in South and Central America, Southeast Asia, Australia (see map in the atlas). The savanna is dominated by herbaceous vegetation with separate standing trees or groups of trees (acacia, eucalyptus, baobab) and bushes.
The fauna of African savannas is surprisingly diverse. To adapt to the conditions of endless dry spaces, nature endowed animals with unique properties. For example, the giraffe is considered the tallest animal on Earth. His height exceeds 5 m, he has long tongue(about 50 cm). The giraffe needs all this in order to reach the high branches of the acacia trees. The crowns of acacias begin at a height of 5 m, and giraffes have practically no competitors, calmly eating tree branches. Typical savannah animals are zebras, elephants, and ostriches.
Steppes
Steppes are found on all continents of the Earth, except Antarctica (in the temperate and subtropical zones of the Northern and Southern Hemispheres). They differ in abundance solar heat, low precipitation (up to 400 mm per year), as well as warm or hot summers. The main vegetation of the steppes is grass. Steppes are called differently. In South America, the tropical steppes are called pampa, which in the Indian language means “a large area without forest.” Animals characteristic of the pampa are the llama, the armadillo, and the viscacha, a rodent similar to a rabbit.
In North America, steppes are called prairies. They are located in both temperate and subtropical climate zones. "Kings" of the American prairies for a long time there were bison. TO end of the 19th century centuries they were almost completely exterminated. Currently, through the efforts of the state and the public, the number of bison is being restored. Another resident of the prairies is the coyote - the steppe wolf. Along the banks of rivers in bushes you can find spotted big cat- jaguar. Peccaries are a small boar-like animal also typical of the prairies.
The steppes of Eurasia are located in the temperate zone. They are very different from the American prairies and African savannas. It has a drier, sharply continental climate. In winter it is very cold (average temperature - 20°C), and in summer it is very hot (average temperature + 25°C), strong winds. In summer, the vegetation of the steppes is sparse, but in spring the steppe is transformed: it blooms with many varieties of lilies, poppies, and tulips.
The flowering time does not last long, about 10 days. Then drought sets in, the steppe dries out, the colors fade, and by autumn everything turns yellow-gray.
The steppes contain the most fertile soils The lands are therefore almost completely plowed. The treeless spaces of the temperate steppes are characterized by strong winds. Wind soil erosion occurs here very intensively - frequent dust storms. To preserve soil fertility, forest belts are planted and organic fertilizers, light agricultural machinery.
Deserts
Deserts occupy vast areas - up to 10% of the Earth's land area. They are located on all continents and in different climatic zones: temperate, subtropical, tropical and even polar.
The desert climates of the tropical and temperate zones have common features. Firstly, an abundance of solar heat, secondly, a large amplitude of temperatures between winter and summer, day and night, and thirdly, a small amount of precipitation (up to 150 mm per year). However, the latter feature is also characteristic of polar deserts.
In the deserts of the tropical zone, the average summer temperature is +30°C, winter + 10°C. Greatest tropical desert The lands are located in Africa: Sahara, Kalahari, Namib.
Plants and animals of deserts adapt to dry and hot climates. For example, a giant cactus can store up to 3000 liters of water and “not drink” for up to two years; and the Welwitschia plant, found in the Namib Desert, is capable of absorbing water from the air. The camel is an indispensable helper for humans in the desert. It can be without food and water for a long time, storing it in its humps.
The largest desert in Asia, the Rub al-Khali, located on the Arabian Peninsula, is also located in the tropical zone. Desert regions of North and South America and Australia are located in tropical and subtropical climate zones.
The temperate deserts of Eurasia are also characterized by low precipitation and a large temperature range, both annual and daily. However, they are characterized by lower winter temperatures and a pronounced flowering period in the spring. Such deserts are located in Central Asia east of the Caspian Sea. The fauna here is represented by various species of snakes, rodents, scorpions, turtles, and lizards. Typical plant- saxaul.
Polar deserts
Polar deserts are located in the polar regions of the Earth. The absolute minimum temperature recorded in Antarctica is 89.2 °C.
On average, winter temperatures are -30 °C, summer temperatures are 0 °C. Just like in the deserts of the tropical and temperate zones, the polar desert receives little precipitation, mainly in the form of snow. The polar night lasts almost half a year here, and the polar day lasts almost half a year. Antarctica is considered the highest continent on Earth, given the thickness of its ice shell at 4 km.
Indigenous inhabitants of the polar deserts of Antarctica - emperor penguins. They cannot fly, but they swim perfectly. They can dive greater depth and swim vast distances, escaping from their enemies - the seals.
The northern polar region of the Earth - the Arctic - got its name from the ancient Greek arcticos - northern. The southern, as if opposite, polar region is Antarctica (anti - against). The Arctic occupies the island of Greenland, the islands of the Canadian Arctic Archipelago, as well as the islands and waters of the Arctic Ocean. This area is covered with snow and ice all year round. The polar bear is rightfully considered the owner of these places.
Tundra
Tundra is a treeless natural area with vegetation of mosses, lichens and creeping shrubs. The tundra is widespread in the subarctic climate zone only in North America and Eurasia, which are characterized by harsh climatic conditions (little solar heat, low temperatures, short cold summers, low rainfall).
The moss lichen was called " reindeer moss", because it is the main food reindeer. Arctic foxes and lemmings - small rodents - also live in the tundra. Among the sparse vegetation there are berry bushes: blueberries, lingonberries, blueberries, as well as dwarf trees: birch, willow.
Permafrost in the soil is characteristic of the tundra, as well as Siberian taiga phenomenon. As soon as you start digging a hole, at a depth of about 1 m you will encounter a frozen layer of earth several tens of meters thick. This phenomenon must be taken into account during construction, industrial and agricultural development of the territory.
Everything grows very slowly in the tundra. This is precisely why the need for careful attention to its nature is connected. For example, pastures overrun by deer are restored only after 15-20 years.
Altitudinal zone
Unlike flat areas, climatic zones and natural zones in the mountains change according to the law of vertical zonation, i.e. from bottom to top. This is due to the fact that the air temperature decreases with altitude. Consider, as an example, the greatest mountain system world - the Himalayas. Almost all natural zones of the Earth are represented here: tropical forest grows at the foot, at an altitude of 1500 m it is replaced by broad-leaved forests, which in turn turn into mixed forests at an altitude of 2000 m. Further, as you rise into the mountains, they begin to predominate coniferous forests from Himalayan pine, fir and juniper. In winter, there is snow here for a long time and frosts persist.
Above 3500 m, shrubs and alpine meadows begin; they are called “alpine”. In summer, the meadows are covered with a carpet of brightly blooming herbs - poppies, primroses, gentians. Gradually the grasses become shorter. From approximately 4500 m altitude there is eternal snow and ice. The climatic conditions here are very harsh. They live in the mountains rare species animals: Mountain goat, chamois, argali, snow leopard.
Latitudinal zonation in the ocean
The world's oceans occupy more than 2/3 of the planet's surface. Physical properties And chemical composition Ocean waters are relatively constant and create an environment favorable for life. It is especially important for the life of plants and animals that oxygen and oxygen coming from the air dissolve in water. carbon dioxide. Photosynthesis of algae occurs mainly in the upper layer of water (up to 100 m).
Marine organisms live mainly in the surface layer of water illuminated by the Sun. These are the smallest plant and animal organisms - plankton (bacteria, algae, small animals), various fish and marine mammals(dolphins, whales, seals, etc.), squid, sea snakes and turtles.
There is life on the seabed too. These are bottom algae, corals, crustaceans, and mollusks. They are called benthos (from the Greek benthos - deep). The biomass of the World Ocean is 1000 times less than the biomass of the Earth's land.
Distribution of life in world ocean uneven and depends on the quantity solar energy, arriving at its surface. Polar waters are poor in plankton due to low temperatures and the long polar night. The largest amount of plankton develops in the waters of the temperate zone in summer. The abundance of plankton attracts fish here. The temperate zones of the Earth are the most fishy areas of the World Ocean. In the tropical zone, the amount of plankton decreases again due to the high salinity of the water and high temperatures.
Formation of natural areas
From today's topic, we learned how diverse the natural complexes of our planet are. The natural zones of the Earth are replete with evergreen forests, endless steppes, various mountain ranges, hot and icy deserts.
Each corner of our planet is distinguished by its uniqueness, varied climate, relief, flora and fauna, and therefore different natural zones are formed on the territories of each continent.
Let's try to figure out what natural areas are, how they were formed, and what was the impetus for their formation.
Natural zones include those complexes that have similar soils, vegetation, fauna and similarities temperature regime. Natural zones received their names based on the type of vegetation, and are called such as taiga zone or deciduous forests, etc.
Natural areas are diverse due to the uneven redistribution of solar energy on the Earth's surface. This is the main reason for the heterogeneity of the geographical envelope.
After all, if we consider one of the climatic zones, we will notice that those parts of the belt that are located closer to the ocean are more humidified than its continental parts. And this reason lies not so much in the amount of precipitation, but rather in the ratio of heat and moisture. Because of this, on some continents we observe more humid climate, and on the other - arid.
And with the help of the redistribution of solar heat, we see how the same amount of moisture in some climate zones leads to excess moisture, and in others to a lack of moisture.
For example, in a hot tropical zone, a lack of moisture can cause drought and the formation of desert areas, while in the subtropics, excess moisture contributes to the formation of swamps.
So you learned that due to the difference in the amount of solar heat and moisture, different natural zones were formed.
Patterns of natural zones location
Natural zones of the Earth have clear patterns of their location, extending in the latitudinal direction and changing from north to south. Most often, a change in natural zones is observed in the direction from the coast making its way inland.
IN mountainous areas exists altitudinal zone, which changes one zone to another, starting from the foot and moving towards the mountain peaks.
In the World Ocean, zones change from the equator to the poles. Here, changes in natural areas are reflected in the surface composition of waters, as well as differences in vegetation and fauna.
Features of the natural zones of the continents
Since planet Earth has a spherical surface, the Sun heats it unevenly. Those areas of the surface above which the Sun is high receive the most heat. And where Sun rays only glide over the Earth - a more severe climate prevails.
And although on various continents Vegetation and animals have similar characteristics, but are influenced by climate, topography, geology and humans. Therefore, historically, due to changes in relief and climate, different species of plants and animals live on different continents.
There are continents where endemics are found, where only a certain type of living beings and plants live, which are peculiar to these continents. For example, polar bears can only be found in nature in the Arctic, and kangaroos can only be found in Australia. But in African and South American shrouds there are similar species, although they have certain differences.
But human activity contributes to changes that occur in the geographical environment, and under such influence natural areas also change.
Questions and tasks to prepare for the exam
1. Create an interaction plan natural ingredients in the natural complex and explain it.
2. How do the concepts “ natural complex", "geographical envelope", "biosphere", "natural zone"? Show with a diagram.
3. Name the zonal type of soil for tundra, taiga, mixed and deciduous forest zones.
4. Where soil cover Is it more difficult to recover: in the steppes of Southern Russia or in the tundra? Why?
5. What is the reason for the difference in the thickness of the fertile soil layer in different natural zones? What does soil fertility depend on?
6. What types of plants and animals are characteristic of the tundra and why?
7. What organisms live on the surface of the waters of the World Ocean?
8. Which of the following animals can be found in African savannah: rhinoceros, lion, giraffe, tiger, tapir, baboon, llama, hedgehog, zebra, hyena?
9. In what forests is it impossible to determine its age from the cut of a cut tree?
10. What measures, in your opinion, will help preserve the human habitat?
Maksakovsky V.P., Petrova N.N., Physical and economic geography of the world. - M.: Iris-press, 2010. - 368 pp.: ill.
Natural area - a territory with similar conditions of temperature and moisture, which determine generally homogeneous soils, vegetation and fauna. On the plains, the zones extend in the latitudinal direction, naturally 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 relationship between land and sea.
Arctic and Antarctic deserts . These are cold deserts with very low air temperatures in the Arctic and Antarctica. In this area, snow and ice persist almost all year round. In the warmest month - August - in the Arctic the air temperature is close to 0°C. Ice-free areas are bound by permafrost. Very intense frost 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, rocky, and there are widespread scatterings of coarsely broken material. Less than half of the Arctic and Antarctic deserts are covered with sparse vegetation. It is devoid of trees and bushes. Crucible lichens, mosses, various algae, and only some flowering plants are common here. The animal world is richer than the plant world. These are polar bears, arctic foxes, polar owls, deer, seals, and walruses. Among the birds, there are penguins, eiders and many other birds that nest on rocky shores and form “bird colonies” in the summer. In the zone icy deserts Fishing for marine animals is carried out; among birds, eiders are of particular interest, with their nests lined with down. Eider down is collected from abandoned nests to produce clothing worn by polar sailors and pilots. In the icy desert of Antarctica there are Antarctic oases. These are areas of the continental coastal strip free from ice cover, with an area of several tens to hundreds of square meters. kilometers. The organic world of oases is very poor; there are lakes.
Tundra. This is an area that lies within parts of the Arctic and subarctic zones in the Northern Hemisphere; in the Southern Hemisphere, the tundra is distributed only on some islands. This is an area with a predominance of moss-lichen vegetation, as well as low-growing perennial grasses, shrubs and low bushes. The trunks of shrubs and the roots of grasses are hidden in the moss and lichen turf.
The climate of the tundra is harsh, the average July temperature only in the south of the natural zone does not exceed +11°C, snow cover lasts 7-9 months. Precipitation amounts to 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. The tundra also creates unfavorable conditions for the germination of seeds of woody plants on the moss-lichen cover. Plants in the tundra are pressed to 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 excess 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 myrtle flowers. Based on the predominant 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, and 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 bushes, which in some places rise to the height of a person. In areas of this subzone, shrubs are 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 widespread. The fauna of the tundra is represented by reindeer, lemmings, arctic foxes, ptarmigan, and in summer - many migratory birds. Shrub tundra gradually turns into forest-tundra.
Forest-tundra . This transition zone between the tundra and the temperate forest 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 precipitation is 300-400 mm. There is more precipitation in the forest-tundra than evaporates, so the forest-tundra is characterized by excessive moisture; it is one of the most swampy natural zones. Snow cover lasts more than six months. Floods on the rivers of the forest-tundra usually occur in the summer, since the rivers of this zone are fed by melt water, and the snow melts in the forest-tundra in the summer. Woody vegetation that appears in this zone grows along river valleys, since rivers have a warming effect on the climate of this zone. The forest islands consist of birch, spruce, and larch. The trees are stunted and in some places bent to the ground. The area of forests increases in the forest-tundra as you move along it to the south. In the interfluves there are low-growing and sparse forests. Thus, the forest-tundra consists of an alternation of treeless shrub areas and open forests. Tundra (peat-swamp) or forest soils. The fauna of the forest-tundra is similar to the fauna of the tundra. It is also home to Arctic foxes, ptarmigan, snowy owls and a wide variety of migratory waterfowl. The forest-tundra contains the main winter pastures for reindeer and hunting grounds.
Temperate forests . This natural zone is located in a 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 coniferous forests located in northern North America and northern Eurasia. The climate of the subzone ranges from maritime to sharply continental with relatively warm summers (from 10°C to 20°C), and the lower the winter temperatures, the more continental the climate is (from -10°C in northern Europe to -50°C in northeastern Europe). Siberia). Permafrost is widespread in many areas of Siberia. The subzone is characterized by excessive moisture and, as a consequence, swampy interfluve spaces. There are two types of taiga: light coniferous And thoseconiferous. Light coniferous taiga - These are the least demanding pine and larch forests in terms of soil and climatic conditions, the sparse crown of which allows the sun's rays to reach the ground. Pines, having an extensive root system, have acquired the ability to use nutrients from infertile soils, which is used to stabilize 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, and cedar. This taiga, unlike the light-coniferous taiga, has no undergrowth, since its trees are tightly closed, and it is quite gloomy in these forests. The lower tier consists 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 of the Far East there are acidic soils.
The fauna of the taiga zone is rich. There are numerous predators here that are valuable game animals: otter, marten, sable, mink, weasel. Large ones include wolves, bears, lynxes, and wolverines. In North America, bison and wapiti deer used to be found in the taiga zone. Now they live only in nature reserves. The taiga is also rich in rodents, the most typical of which are beavers, muskrats, squirrels, hares, and chipmunks. The world of birds is very diverse.
Temperate mixed forests . These are forests with different tree species: coniferous-broad-leaved, small-leaved and 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 broad-leaved forests. The mixed forest zone 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 mixed forest zone is maritime or transitional to continental (towards the center of the continent), summers are warm, winters are moderately cold (in maritime climates with positive temperatures, and in more continental climate up to -10°С). There is sufficient moisture here. The annual amplitude of temperature fluctuations, as well as annual quantity precipitation varies from oceanic regions to the center of the continent.
The diversity of vegetation in the mixed forest zone 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 thanks to the westerly winds coming from the Atlantic, European spruce, oak, elm, fir, and beech are common - coniferous-deciduous forests.
The soils in the mixed forest zone are gray forest and soddy-podzolic, while in the Far East they are brown forest.
The fauna is similar to the fauna of the taiga and the deciduous forest zone. Elk, sable, and bear live here.
Mixed forests have long been subject to severe deforestation and loss. They are best preserved in North America and the Far East, and in Europe they are cut down for agricultural land - field and pasture lands.
Temperate broadleaf forests . They occupy the east of North America, Central Europe, and also form an altitudinal zone in the Carpathians, Crimea and the Caucasus. In addition, isolated pockets 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 blade. Here, moderate continental air masses bring precipitation from the oceans (from 400 to 600 mm) mainly in the warm season. average temperature January -8°-0°С, and July +20-24°С.
Beech, hornbeam, elm, maple, linden, and ash grow in the forests. In the deciduous forest zone of North America, species are found that are not found on other continents. These are American oak species. The predominant species here are trees with a powerful spreading crown, often entwined with climbing plants: grapes or ivy. To the south there are magnolias. For European broad-leaved forests, oak and beech are the most typical.
The fauna of this natural zone is close to the taiga, but there are animals such 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 declining. These include animals such as bison and Ussuri tiger.
The soils under broad-leaved forests are gray forest or brown forest. This zone has been heavily developed by humans, forests have been cleared over large areas, and the lands have been plowed. In its true form, the zone of broad-leaved forests has been preserved only in areas inconvenient for arable farming and in nature 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 widespread in the Northern Hemisphere: in Eurasia from the Danube Lowland to Altai, further in Mongolia and the Far East; in North America, this zone is located in the northern Great Plains and western Central Plains.
Forest-steppes are naturally distributed within continents between forest zones, which here choose the most humidified areas, and the steppe zone.
The climate of the forest-steppes is moderate continental: winters are snowy and cold (from -5°C to -20°C), summers are warm (+18°C to +25°C). In different longitudinal zones, forest-steppe varies in precipitation (from 400 mm to 1000 mm). Humidification is slightly below sufficient, evaporation is very high.
In the forests that alternate steppes, broad-leaved (oak) and small-leaved tree species (birch) are more common, and conifers are less common. 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 plowed area reaches 80%. Since this zone has fertile soils, wheat, corn, sunflowers, sugar beets and other crops. The fauna of the forest-steppe zone includes species characteristic of the forest and steppe zones.
The West Siberian forest-steppe with numerous birch groves-kolok (singular number - kolok) is specific. Sometimes they have an admixture of aspen. The area of individual pegs reaches 20-30 hectares. Numerous forests, alternating with areas of steppes, create the characteristic landscape of Southwestern Siberia.
Steppes . This is a landscape with a herbaceous vegetation type, located in the temperate and partly subtropical zone. In Eurasia, the steppe zone extends in a latitudinal direction from the Black Sea to Transbaikalia; in North America, the Cordillera distributes air flows in such a way that the zone of insufficient moisture and with it the steppe zone are located from north to south along the eastern edge of this mountainous country. IN Southern Hemisphere The steppe zone is located within the subtropical climate of Australia and Argentina. Atmospheric precipitation (from 250 mm to 450 mm per year) falls here irregularly and is insufficient for the growth of trees. Winter is cold, average temperature below 0°C, in some places down to -30°, with little snow. Summer is moderately hot - +20°С, +24°С, drought is common. 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 thick grass cover, but undisturbed steppes throughout the world remain only in nature reserves: all steppes are plowed. Depending on the nature of vegetation in the steppe zone, three subzones are distinguished. They differ from each other in the predominant vegetation. This meadow steppes (bluegrass, bonfire, timothy), cereals and southern wormwood-cereals .
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 highly plowed area.
The fauna of the steppes is rich and diverse, but it has changed greatly under the influence of humans. Back in the 19th century, wild horses, aurochs, bison, and roe deer disappeared. Deer are pushed into forests, saigas - into virgin steppes and semi-deserts. Now the main representatives of the animal world of the steppes are rodents. These are gophers, jerboas, hamsters, voles. Bustards, little bustards, larks and others are occasionally seen.
Steppes and partly forest-steppes of temperate and sub tropical zones North America are called prairies . Currently they are almost completely plowed. Part of the American prairies is dry steppes and semi-deserts.
The subtropical steppe on the plains of South America, located mainly in Argentina and Uruguay, is called pump . In the eastern regions, where precipitation falls from the Atlantic Ocean, there is sufficient moisture, but to the west the aridity increases. Most of the pampa territory is plowed, 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 turn into semi-deserts, and then into deserts. Semi-deserts and deserts are formed in dry climates, where there is a long and hot warm period (+20-25°C, sometimes up to 50°C), strong evaporation, which is 5-7 times higher than the amount annual precipitation(up to 300 mm per year). Weak surface runoff, poor development of inland waters, many dry riverbeds, vegetation is not closed, sandy soils heat up during the day but cool quickly cool night, which promotes physical weathering. The winds dry out the land very strongly here. Temperate deserts differ from deserts of other geographical zones more cold winter(-7°C-15°C). Deserts and semi-deserts of the temperate zone are widespread in Eurasia from the Caspian lowland to the northern bend of the Yellow River, and in North America - in the foothills and basins of the Cordillera. In the Southern Hemisphere, temperate deserts and semi-deserts are found only in Argentina, where they occur in broken areas in the interior and foothills. Among the plants found here are steppe feather grass, fescue, wormwood and solyanka, camel thorn, agave, and aloe. Animals include saigas, turtles, and many reptiles. The soils here are light chestnut and brown desert, often saline. Under conditions of sharp temperature fluctuations during the day with little moisture, a dark crust forms on the surface of deserts - a desert tan. It is sometimes called protective, as it protects rocks from rapid weathering and destruction.
The main use of semi-deserts is grazing livestock (camels, fine-wool sheep). Farming of drought-resistant crops is possible only in oases. Oasis (from Greek name several populated areas in the Libyan Desert) is a place where tree, shrub and herbaceous vegetation grows in deserts and semi-deserts, under conditions of more abundant surface and ground moisture compared to neighboring areas and areas. The sizes of oases vary: from ten to tens of thousands of kilometers. Oases are 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 areas located in both hemispheres, on all continents along tropical zones increased atmospheric pressure. Most often, semi-deserts of the subtropical zone are located in the transitional part from deserts to mountain steppes in the form of an altitudinal zone in the inland parts of the Cordillera and Andes of America, in western Asia, Australia and especially widely in Africa. The climate of the deserts and semi-deserts of these climatic zones is hot: the average temperature in summer rises to +35°C, and in the coldest months of winter it does not fall below +10°C. Precipitation is 50-200 mm, in semi-deserts up to 300 mm. Sometimes precipitation occurs in short bursts of rain, and in some areas there may be no precipitation for several years in a row. With a lack of moisture, the weathering crust is very thin.
Groundwater lies very deep and can be partially saline. Only plants that can tolerate overheating and dehydration can live in such conditions. They have a deeply branched root system and small leaves or spines that reduce evaporation from the leaf surface. Some plants have leaves that are pubescent or covered with a waxy coating, which protects them from sunlight. In the semi-deserts of the subtropical zone, cereals are common and cacti appear. In the tropical zone, the number of cacti increases, agaves and sand acacias grow, and various lichens are common on the stones. A characteristic plant for the Namib Desert, located in the tropical zone of South Africa, is amazing plant Velwigia, which has a short trunk, from the top of which two leathery leaves extend. Welwigia can be up to 150 years old. The soils are gray soils, gravelly, 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, and scorpions. There are camels, antelopes, and rodents are quite widespread. Agriculture in semi-deserts and deserts of the subtropical and tropical zones is also possible only in oases.
Hardleaf 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. Some fragments of these forests are found in California, Chile (south of the Atacama Desert). Hard-leaved forests grow in a mild, moderately warm climate with hot (+25°C) and dry summers and cool and rainy winters. The average precipitation is 400-600 mm per year with rare and short-lived snow cover. The rivers are mainly fed by rain, and floods occur in the winter months. In rainy winter conditions, grasses grow rapidly.
The fauna has been severely 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 is nocturnal. sedentary lifestyle life.
The territory of hard-leaved forests is well developed and has been significantly changed by human economic activity. Large areas of forest here have been cut down, and their place has been taken by oilseed plantations, orchards and pastures. Many tree species have hard wood, which is used as a building material, and oils, paints, and medicines are made from the leaves (eucalyptus). Large harvests of olives, citrus fruits, and grapes are harvested from the plantations of this zone.
Subtropical monsoon forests . This natural zone is located in the eastern parts of the continents (China, southeastern USA, eastern Australia, southern Brazil). It is located in conditions that are the most humid compared to other zones of the subtropical zone. The climate is characterized by dry winters and wet summers. Annual precipitation is greater than evaporation. The maximum amount of precipitation falls in summer due to the influence of monsoons, bringing moisture from the ocean. In the territory of monsoon forests, inland waters are quite rich, and fresh groundwater lies shallow.
Here, on red soils and yellow soils, tall mixed forests grow, among which there are evergreen and deciduous forests that shed their leaves during the dry season. Species composition plants may vary depending on soil conditions. The forests contain subtropical species of pines, magnolias, camphor laurel, and camellias. Swamp cypress forests are common on the flooded coasts of Florida in the United States and in the Mississippian lowlands.
The monsoon forest zone of the subtropical zone has been developed by man for a very long time. In place of cleared forests, there are field and pasture lands; rice, tea, citrus fruits, wheat, corn and industrial crops are grown here.
Forests of tropical and subequatorial zones . They are located along eastern Central America, the Caribbean islands, Madagascar, southeast Asia, and northeast Australia. There are clearly two seasons 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 from the oceans in summer. In the subequatorial belt, precipitation occurs in the summer, when equatorial air masses dominate here. Depending on the degree of moisture, forests of the tropical and subequatorial zones are distinguished permanently wet and seasonally wet(or variable-humid) 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 laurels. Often in seasonally wet forests there are areas where teak and sal grow. There are very few palm trees in the forests of this group. According to its species diversity of flora and fauna permanently moist forests close to equatorial. There are many palm trees, evergreen oaks, and tree ferns. There are many lianas and epiphytes of orchids and ferns. The soils located under forests are mainly 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 found within the tropical and subtropical zones. In the climate of this zone, the change in wet and dry seasons of the year is clearly expressed at consistently high temperatures (from + 15 ° C to + 32 ° C). As you move away from the equator, the period of the wet season decreases from 8-9 months to 2-3, and precipitation decreases from 2000 to 250 mm per year.
Savannas are characterized by a predominance of herbaceous cover, among which tall (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 thick and high, and near the borders with semi-deserts it is sparse. A similar pattern can be seen 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 trees, and baobab trees that store water.
Savannah soils depend on the length of the rainy season. Closer to the equatorial forests, where the rainy season lasts up to 9 months, are red ferralite soils. Closer to the border of savannas and semi-deserts there are red-brown soils, and even closer to the border, where rain falls for 2-3 months, unproductive soils with a thin layer of humus are formed.
The fauna of savannas is very rich and diverse, as the high grass cover provides food for the animals. Elephants, giraffes, hippos, and zebras live here, which in turn attract lions, hyenas and other predators. The bird world of this zone is also rich. Sunbirds live here, ostriches - the largest birds on Earth, a secretary bird that hunts small animals and reptiles. There are a lot of termites in the savannah.
Savannas are widespread in Africa, where they occupy 40% of the continent's territory, in South America, Australia and India.
Tall grass savannas in South America, on the left bank of the Orinoco River, with a dense, mainly cereal grass cover, with individual specimens or groups of trees, are called llanos (from the Spanish plural of “plains”). The savannas of the Brazilian plateau, where the area of intensive livestock farming is located, are called campos .
Today, savannas play a very important role in human economic life. Significant areas of this zone are plowed, grains, cotton, peanuts, jute, and sugar cane are grown here. In drier areas, livestock farming is developed. Many tree species are used on the farm, since their wood does not rot in water. Human activities often lead to desertification of savannas.
Equatorial rainforests . This natural zone is located in an equatorial and partly subequatorial climate. These forests are found in the Amazon, Congo, Malay Peninsula and Sunda Islands, as well as other smaller islands.
The climate here is hot and humid. Temperature all year round is +24-28°C. The seasons are not expressed here. Humid equatorial forests are located within an area of low pressure, where, as a result of intense heating, upward air currents are formed and a lot of precipitation falls (up to 1500 mm per year) throughout the year.
On the coasts, where the wind from the ocean influences, precipitation falls 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 leaves: some shed them every six months, others after a completely arbitrary period, and others replace their leaves in parts. Flowering periods also vary, and are even more erratic. The most common 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.
The trees of humid equatorial forests have disc-shaped roots, large leathery leaves, the shiny surface of which saves them from excessive evaporation and scorching rays of the sun, from the impact of rain jets during heavy downpours. Many leaves end in a graceful spine. It's 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 ficus and palm trees. 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 equatorial forests, epiphytes are also found, and sometimes flowers form directly on the trunks. For example, cocoa tree flowers. In the forest of the equatorial belt it is so hot and humid that they create favorable conditions for the development of moss and algae that cling to the crown and hang from the branches. They are epiphytes. Tree flowers 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 their brightly colored corolla or sweet scent. The fruits of the 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 and animals; the seeds are not digested and, together with the droppings, end up far from the parent plant.
There are many native plants in equatorial forests. These are primarily 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’s nutrition does not come from the giant tree, but sometimes the use of these trees for support by vines can lead to oppression and death. Some ficus trees are also “robbers”. Their seeds germinate on the bark of a tree, the roots tightly grip 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.
Equatorial forests are home to many valuable plants, such as the oil palm, from the fruits of which palm oil is obtained. The wood from 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 equatorial forests produce valuable fruits, seeds, juice, and 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 moist equatorial forests, the name is used hylea , sometimes these forests are called jungle , although, strictly speaking, jungles are the forest thickets of South and Southeast Asia located within the subequatorial and tropical climate.
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