Eurasia geographic location is a general characteristic of nature. Eurasia
I . Target block.
Theme of the lesson: "The diversity of the nature of Eurasia"
The purpose of the lesson: to acquaint students with the peculiarities of nature and typical representatives of the flora and fauna of Eurasia;deepen the concept of a natural zone.
Planned result: Mapping "Endemics of Eurasia", selection of indicators of the characteristics of the natural zone, the originality of the flora and fauna of the mainland.
knowledge : list of natural zones of Eurasia, characteristics their main indicators
skills : organization of their work in a strictly allotted time; map matching, work with contour maps
skills : work with thematic maps, characteristics of geographical objects
Personally formative orientation of the lesson:
personal: organization of purposeful cognitive activity.
communicative: the ability to work in a micro group, organize educational cooperation and joint activities, treat another person with respect, listen to his opinion;
formation of communicative competences in communication and presentation
information;
the ability to freely answer at the blackboard (to the public).
regulatory: the ability to plan ways to achieve the goal, correlate their actions in the process of achieving results.
cognitive: identification and formulation of a cognitive goal, structuring knowledge, choice effective ways problem solving, analysis and work with cartographic material;
reflection.
ІІ. Instrumental block.
Lesson objectives:
Tutorial: consideration common features placement of natural zones of Eurasia and confirmation of the manifestation of latitudinal zonality; familiarization of students with the peculiarities of nature and typical representatives of the flora and fauna of the arctic, subarctic and temperate zones.
Developing: improving the ability to reveal the connections and relationships between the components of the nature of individual zones, compiling a figurative description of the zones, developing monologue speech, skills in working with various sources information, the ability to analyze and communicate information.
Educators: the formation of a holistic emotional and sensory perception of the world.
Lesson type: problematic lesson
Training and metodology complex:
Sources of information-textbook 7th grade, E.M. Domogatskikh, N.I. Alekseevsky Geography Continents and oceans part 2 " Russian word»; Atlas of the 7th class "Bustard"
Equipment- computer, multimedia projector, map "Physical map of the world", presentation "Diversity of nature of Eurasia"
Didactic support - instructional cards for groups on the characteristics of the natural area.
Organizational structure of the lesson
1 Motivation
Hello guys! I want to start today's lesson with the statement of the great Russian traveler Nikolai Mikhailovich Przhevalsky "And life is beautiful, because you can travel." I invite you on a journey. Where will we go? (Eurasia)
Look who is in the photo.
The answer is PANDA, the bamboo bear.
The image of a panda has become the emblem of the World Wildlife Fund WWF - an international organization dedicated to the protection of rare and endangered animals. Panda - lives only on the mainland of Eurasia.
UUD: personal
self-determination
2. Determination of the goals and objectives of the lesson.
helps the student, if necessary, to formulate the topic and objectives of the lesson, begins the lesson with the question:
What will be the topic of our lesson?
The theme of the lesson is "The diversity of the nature of Eurasia."
What will be the purpose of the trip?
To get acquainted with the climatic features of the natural zones of Eurasia, the features of the flora and fauna.
Where can you use this knowledge? (In the course of studying the Geography of Russia. If you decide to go on a trip. See a panda or bison. The famous traveler Fedor Konyukhov.)
Let's clarify the itinerary.
To do this, we turn to the atlas. What card do we need.
S.40-41. Map « natural areas» What natural areas of Eurasia should we visit?Everything. This will be the uniqueness of the distribution of the natural zones of Eurasia.
What prevents travelers from laying direct routes? (Rivers)
3.Checking d / z
Let's determine which rivers can prevent us from traveling?
We will work according to the following plan.
Work plan.
1. What prevents travelers. Checking d / z.
2. Natural zones of the mainland. Working with a table.
3. Mark a natural area on the map.
4.Endemics of Eurasia. Message.
8.D/z item 53, prepare a report on the largest representatives of the fauna of Eurasia.
Checking d / s with the help of a multimedia textbook on geography for students of the 7th grade of educational institutions “Geography. Continents and oceans»
Conversation at the same time.
Which ocean basins do the rivers of Eurasia belong to?
Students' activities - formulate the topic of the lesson, set tasks to achieve the result, if necessary, answering the teacher's questions
Form of organization: frontal
UUD: personal
formation of educational motivation
regulatory
goal setting
communicative
4. Actualization of basic knowledge.
What is a natural area?part of the geographic envelope of the Earth and , which has its characteristic natural components and processes.
Give a definition of the concept - latitudinal zonality. interdependent set of climate, soils and vegetation, changing depending on the latitudinal distribution solar energy and transport of air masses around the globe.
Give a definition of the concept - altitudinal zonationregular change of natural conditions, natural zones and landscapes in the mountains as the absolute height increases
- What is the reason for the change of natural zones on the continents? (climatic zones)
Student activities - discuss the concepts necessary to study the material: natural areas, latitudinal zonality , altitudinal zonality;
together with the teacher draw up a plan for characterizing the natural area in terms of indicators
Form of organization: frontal
UUD: regulatory
planning
communicative
the ability to accurately express one's thoughts
cognitive
asking questions, setting goals
brain teaser
problem question .
You have repeatedly heard such a thing as "the lungs of the planet." This expression is used in relation to individual natural zones of the Earth. What natural areas do you think could qualify for such a title? On the mainland of Eurasia, several types of forests are distinguished. Which? Determine on the map of natural areas.
Now more and more often scientists say that "the lungs of the planet are sick." What do you think about this statement?
Can you explain this statement?
Fizminutka
And the seagulls are circling over the sea,
Let's follow them together.
Splashes of foam, the sound of the surf,
And over the sea - we are with you!
(wave hands)
We are now sailing on the sea
And frolic in space.
More fun rake
And chase the dolphins.
(swimming motions with hands)
Look: seagulls are important
They walk along the sea beach.
(walking in place)
Sit down, children, on the sand,
We continue our lesson. [
Like North America, Eurasia is also most elongated from west to east in temperate latitudes. Work with atlas and textbook. Enter the information in the table.
You have a map on your table, on which you must highlight your natural zone, fill in the table with flora and fauna and identify the endemics of this natural zone.
(slide 1,2) The large extent of Eurasia from north to south and from west to east, significant climatic differences within the mainland, the alternation of mountain systems and lowlands contribute to the consistent change of geographical zones from north to south and the rapid change of natural zones within geographical zones.There are seven geographical zones on the mainland:
arctic belt
subarctic belt
Temperate zone
subtropical belt
tropical belt
subequatorial belt
equatorial belt
Each geographic zone has its own natural features. Let us dwell in more detail on the distinctive features of each natural zone.
5. Primary check of understanding and primary consolidation
Student activities - coordinates group performances, asks questions if necessary
give a description of the natural zone, answering at the blackboard (since the groups are not large, the task was set to divide the presentation of natural zones so that all members of the micro group spoke);
each of the groups presents a characteristic of its natural zone, shows its location on the map projected on the board (after that, the boundaries appear on the map), and tells according to the plan
based on the results of the presentation of information by representatives of other groups, fill out a contour map
Form of organization: frontal, group , individual
UUD:regulatory
control, correction, evaluation
communicative
verbal presentation of information
cognitive
knowledge structuring
analysis and work with cartographic material
1.group In the Arctic and the subarctic belts of Eurasia, there are three natural zones:
Arctic desert zone
tundra zone,
Forest-tundra zone(slide 3-7) student performances.
Endemic messageTundra LEMMINGS , a group of mammals of the vole subfamily, includes four genera and about 20 species (including common, ungulate, forest lemmings). The most common genus of common lemmings with subspecies - Norwegian and Siberian. Body length 15 cm, tail up to 2 cm. Biologically, all forms of common lemmings are similar. The only exception is Amur form living in conditions of the taiga zone unusual for other forms.
Signs: Body length 13-15 cm, tail short, 1.5-2 cm long, weight 35-100 g. It resembles a vole in shape, but differs from it in variegated fur, yellow-brown with black spotted pattern. Cubs are lighter than adults. sounds; squeak, yelp or grunt.
musk ox - this is a rather large hoofed animal, leading a herd lifestyle, it lives in the Far North, it is the most furry animal on Earth. It got its strange name for its large size and "ram" head, which is decorated with "tightly" extended horns. The wool of the musk ox is outstanding - thick, most of it is made up of a thin undercoat, which forms under the cover of the outer hair, resembles a soft felt. On the belly and throat, guard hairs are half a meter long, in some individuals they reach up to 90 cm and hang almost to the ground. They are the best protection against frost, which is in those parts where the musk ox lives. Musk oxen tolerate frost and strong winds well.
2 group taiga, mixed and broad-leaved forests(slide 8-15) student performances.
Taiga Wolverine - the largest terrestrial species of the mustelid family. This is a stocky and muscular predator, outwardly more like a small bear than other members of its family.
The wolverine has short legs with large feet that allow it to move easily in the snow. The head is broad and rounded, the muzzle is elongated. The eyes are small, the ears are short and rounded. The back is curved due to the longer hind limbs. The teeth are powerful, with sharp edges. The upper molars at the end of the dentition are rotated 90 degrees in relation to the inside of the mouth, which allows the wolverine to tear meat from frozen carrion. Claws are sharp, hook-shaped. Like many other mustelids, it has a powerful smell of anal glands. Sense of smell and hearing are well developed. Vision is less developed.
An adult wolverine reaches the size of an average dog. The average length is 65-105 cm, the length of the tail is 17-26 cm, and the weight ranges from 9 to 25 kg, although sometimes the weight of males reaches 32 kg. The height at the withers is from 30 to 45 cm.
Mixed forests14. Amur tiger
Broad-leaved forests Bison . This wild bull, whose weight reaches a ton, has always been a desirable trophy for man. The extermination of the species took on rampant proportions after the advent of firearms. From the end of the XVIII century. bison were kept only in the places of royal hunting: 500-700 animals in Belovezhskaya Pushcha and the same number in the Caucasus.
Muskrat
- an animal from the order of insectivores. This species is a narrow endemic of Eastern Europe, its range covers mainly the basins of the Urals, Volga, Don and Dnieper. The muskrat leads a semi-aquatic lifestyle, preferring floodplain oxbow lakes, lakes and small forest rivers with a quiet course. She settles in burrows and preys on mollusks and other aquatic invertebrates.
Because of the beautiful silky fur, the desman was subjected to mass extermination.
3 group : Forest-steppes and steppes, semi-deserts and deserts(slide 16-23) student performances.
Steppe: Saiga – a small animal with an original appearance. It is recognizable by its swollen proboscis with close rounded nostrils.The rim is a continuation of the nasal cavity, in which cold air is warmed up when running in the winter. The body length of the saiga is 110-140 cm, the height at the withers is 60-70 cm, and the weight is 25-40 kg. The coat color in summer is yellowish-red, the fur is low and sparse. In winter, the saiga has thicker, taller, very light fur. Only males have horns. Horns, yellowish-white, lyre-shaped, reach 30 cm in length and are located almost vertically on the head.
African and Indian elephant, the differences between them are significant.
desert gecko- a genus of lizards from the family . Body length up to 8 cm. Fingers are long and curved, equipped with claws. The segmentation of the tail is well defined. The pupil is vertical, with jagged edges.
4 group The next natural area on our way- Subtropical and monsoon forests(slide 24-30) student performances.
Monsoon forests Panda , or a bamboo bear is a cute and pretty animal, which differs from the rest of its brethren in a kind of unusual color. Although not all zoologists attribute the panda to the bear family. Its length can be up to one and a half meters, and weight - up to one hundred and sixty kilograms. Thick and short paws with sharp, long claws help the bear climb trees and stay on the smooth trunks of bamboo, which it feeds on.
5 group The next natural area on our way -Subequatorial and equatorial, (slide 31-34) altitudinal zonality (slide 35-36) performances of students.
Equatorial forests live in the thick of tropical rainforests of Malaysia and Indonesia. They live alone, which is why they are so smart and attentive. The whole life of the orangutan passes on the branches of trees, because of this it is included in the category of tree monkeys. An orangutan can pick fruit from trees with either limb. Due to its arboreal lifestyle, this animal has very strong and long forelimbs, but the hind limbs are shorter and weaker. In order for the monkey to cling well to branches, nature gave her long and grasping fingers. Adult individuals weigh from 50 to 100 kg, and their height reaches a maximum of 150 cm. The female orangutan is much lighter and smaller than the male.
Altitudinal zonality
Caucasus Mountains Mouflon . The only wild sheep living in Europe. The male is easily recognizable by the horns, wide at the base and twisting in a spiral. The mouflon's horns grow throughout its life. Mouflon is a herbivore, sometimes gnaws at the bark of young trees.
Tibetan Yak Plateau - a large animal with a long body, relatively short legs, wide, rounded hooves and a heavy, low-set head. The height at the withers is up to 2 m, the weight of old bulls is up to a tone. The body length of an old male is up to 4.25 m, of which 0.75 m falls on the tail. The length of the female is up to 2.8 m, height 1.6 m, weight 325-360 kg.At the withers, the yak has a small hump, which makes the back seem sloping. The horns of both sexes are long, but not thick, widely spaced, from the base directed to the sides, and then bent forward and upward; their length is up to 95 cm, and the distance between the ends is 90 cm.
Conclusion: savannas and equatorial forests (everything is plowed , many large animals are preserved in the reserves: Keoladeo, Ranthambor - deer, elephants, hyenas, antelopes, buffaloes, rhinos) about 3 thousand species of palms. These forests are called the jungle. (orangutan, panther, parrots are walkingfelling ) . The same problem is the destruction of forests. As in the taiga zone.
6. The result of the lesson.
Now you can answer the question
Why do scientists call the lungs of the planet sick?
7. Reflection (summarizing the lesson)
What new did you learn in the lesson?
Did you like the lesson?
What mood are you in now, if good, raise your hands and wave to each other.
the teacher announces his grades for presenting the characteristics of natural areas
when putting a mark in the journal, self-analysis of groups with marks set to all members of the group is also taken into account
micro groups conduct self-analysis of work - compare their contour maps with the map on the board,
analyze the work of all members of the groups, evaluate the achievement of results according to a 5-point system
work in micro-groups
UUD: communicative
the ability to express one's thoughts with sufficient completeness and accuracy
cognitive
reflection
personal
meaning formation
self-esteem
groups
plan for the characteristics of the animal and plant world
Group message
completed contour map
7. Homework . §53.
Square - 54.9 million km (~ 1/3 of the entire land area of the Earth)
Population - about 4.9 billion inhabitants
1.1. Europe and Asia
Eurasia is the most big mainland Earth, consisting of two parts of the world - Europe and Asia. The border between them has a conditional meaning and runs along the eastern slope of the Ural Mountains, the Emba River, the northern coast of the Caspian Sea and the Kuma-Manych depression. Further, Asia and Europe are separated by the Azov and Black Seas. Together with the islands, Eurasia occupies an area of about 53.4 million km, of which the islands account for about 2.75 million km.
1.2. extreme points
Extreme continental points of Eurasia: in the north - Cape Chelyuskin, 77 98 "N, in the south - Cape Piai, 1 56 "N, in the west - Cape Roca, 9 76 "W, in the east - Cape Dezhnev, 169 64 "W. A number of islands in southeast Eurasia are located in the Southern Hemisphere. Eurasia is washed by such oceans: in the west - the Atlantic, in the north - the Arctic, in the south - Indian, in the east - Pacific, and their marginal seas In the southeast, the Australo-Asian seas separate Asia from Australia, in the northeast - the Bering Strait from North America, in the southwest - the Strait of Gibraltar, the Mediterranean and Red Seas from Africa, with which Eurasia is connected by the Suez Canal.
1.3. additional information
The continuity of the land mass, the modern tectonic consolidation of the continent, the unity of many climatic processes, the significant commonality in the development of the organic world, the manifestations of natural historical unity, as well as the need to take into account the importance of territorial integrity for assessing socio-historical phenomena, caused the need for a name that unites the entire continent. The concept of "Eurasia" introduced by E. Suess into geology and geography turned out to be convenient.
2. Exploration of the mainland
Scientific exploration of Asia begins in the 18th century. At present, the Northern and Kamchatka expeditions are being organized, during which the polar regions are being studied. Outstanding geographers O. Humboldt, P. Semenov-Tyan-Shansky, N. Przhevalsky, F. Wrangel, K. Arseniev, V. Obruchev and others studied natural conditions, made maps to unexplored corners of Eurasia.
3. Relief
3.1. General information
Eurasia is distinguished by a great variety of relief. On its territory are located the highest mountain systems of the globe - the Himalayas. The highest point on the globe is Mount Chomolungma (8850 m). The highlands of Tibet rise to 45 km. Lowlands and plateaus are huge and stretch for thousands of kilometers. 3/4 of the surface of Asia falls on the plateau, highlands and mountain ranges. There are fewer mountains in Europe, most of them are lowlands. The oldest parts of Eurasia are the East European and Western Plains. They are based on large and old platforms. The Arabian plateau and the Deccan also have an ancient origin. A fault in the earth's crust, occupied by the Red Sea, separates the Arabian Peninsula from Africa. Most of the lowlands are on the outskirts of the mainland. The Indo-Gangetic and Mesopotamian lowlands were formed in foothill troughs of the earth's crust between platforms and folded mountains.
3.2. Fold mountains
Folded mountains - mountains, the soaring of which occurred as a result of the wintering of layers of rocks into folds. The main mechanism for the formation of folded mountains is the horizontal compression of the layered strata, although vertical movements deep layers can also take part in this. Crumpled into folds is possible if the rocks are subjected to compressive forces, sufficiently plastic, which is characteristic of either young, recently formed sedimentary rocks, or strongly heated rocks saturated with liquid and gaseous inclusions. In its pure form, folded mountains are quite rare - as a rule, the formation of folds is accompanied by the appearance of faults. If displacements along faults make a significant contribution to the formation of a mountainous relief, such mountains are called blocky-folded. An example of folded mountains is the Swiss Jura mountains in the Alps, the Zagros mountain system in Iran, some ranges in the Appalachians (North America).
3.2.1. southern part
Young mountains of new folding extend in the form of two giant belts of folded mountains. In the southern part of Eurasia, from the Atlantic and almost to the Pacific Ocean, the Alpine-Himalayan belt stretches. It includes the Pyrenees, the Apennines, the Alps. Stara Planina (Balkan Mountains), Carpathians, Caucasus, Pamir Highlands, Himalayas. Between the marginal ridges lie large highlands, most of all - Iranian.
3.2.2. pacific belt
The Pacific belt of folded mountains begins in Kamchatka and ends on the islands of the Malay Archipelago. The oldest mountains are the Scandinavian mountains. The age of the Ural Mountains, Altai and Tien Shan, which appeared later, is almost 300 million years. For many millions of years, the ancient and most ancient mountains were destroyed by external processes and smoothed out. During subsequent uplifts, they were broken by faults into separate blocks, some of which rose to a considerable height (Altai, Tien Shan). Mountain formation continues to this day. = *
3.3. Glaciers
About 300 million years ago, a huge glacier formed on the territory of Eurasia. The British Isles were completely covered by the glacier; in two languages it descended the East European Plain, reaching the latitude of Dnepropetrovsk; Western lowland, he dropped to the sixtieth parallel. For the most part northern Asia The cold climate has led to the formation of permafrost. For the dry and hot deserts of Asia, characteristic landforms created by the activity of the wind. Huge spaces here are occupied by dunes and dunes.
3.4. earthquakes
Most of the earthquakes that accompany the formation of mountain systems occur on the territory of Eurasia in giant mountain belts of new folding. The Pacific seismic belt of the Earth surrounds the Pacific Ocean. On the mainland, which belongs to this belt, earthquakes occur very often, especially in the Japanese and Philippine Islands. The Euro-Asian seismic belt runs through the southern part of Eurasia and coincides with the Alpine-Himalayan belt of folded mountains.
3.5. Volcanoes
There are many active volcanoes on the territory of Eurasia. There are especially many of them in the Pacific volcanic belt, which is called the Pacific "Ring of Fire". The highest active volcano of Eurasia - Klyuchevskaya Sopka (56 in. Sh. And 161 s. DG.) On the Kamchatka Peninsula (4750 m). There are active volcanoes in the Alpine-Himalayan mountain belt. The Mediterranean is home to Europe's highest volcano, Etna, and the only active volcano in mainland Europe, Vesuvius. Off the Apennine Peninsula is the active island-volcano Stromboli. There are geysers in Kamchatka and Iceland. =)
4. Minerals, features of their origin
4.1. General information
Eurasia is exceptionally rich in various minerals. On its territory there are large deposits of coal, oil, natural gas, significant reserves of ores of ferrous and non-ferrous metals, and many places where gold and precious stones are mined. The diversity of the mineral wealth of the mainland is due to the huge size, complex structure of the earth's crust of Eurasia.
4.2. Deposits and basins
4.2.1. Coal, oil and gas
Hard coal deposits on the territory of Eurasia are located in foothill and intermountain troughs of the Paleozoic age (Donetsk basin in Ukraine, Karaganda in Kazakhstan, Pechora basin in Russia, Ruhr in Germany, etc.). Hindustan and Chinese platforms. Large brown coal basins - Kuznetsk and Kansk-Achinsk - in Siberia. Oil and gas fields are concentrated in troughs of the earth's crust filled with sedimentary rocks. The two largest oil and gas basins of the Earth are located in the Mesopotamian lowlands and the West Siberian Plain. There are oil and gas deposits on the Arabian Peninsula and the East European Plain.
4.2.2. ores
Most of the deposits of various ores associated with igneous and metamorphic rocks are located in the crystalline basement of ancient platforms, as well as where igneous and metamorphic rocks come to the surface in mountain ranges. The iron ores of the Kursk Magnetic Anomaly (KMA), the Krivoy Rog and Lorraine iron ore basins, the manganese Nikopol basin, the iron ores of Hindustan and Northeast China are of world importance. Through South China, the peninsulas of Indochina and Malacca and the islands of the Malay Archipelago, deposits of non-ferrous metal ores, such as tin and tungsten, stretch in a strip, forming the so-called tin-tungsten belt. Gold is found in the Asian part of the mainland. Deposits of non-ferrous metals are known in the Urals, in the folded mountains in the north and south of Europe there are deposits of polymetals, mercury, aluminum and uranium ores.
4.2.3. Other deposits
Deposits of rock and potassium salts were formed in shallow basins - lakes and shallow seas. The Iranian highlands are known for their rich sulfur reserves. In the Ukrainian Carpathian region there are unique deposits of native sulfur. On the Hindustan Peninsula, the island of Sri Lanka, there are deposits of diamonds, various precious stones. In many places of Eurasia there are deposits of various building materials(marble, granite, etc.). In Asia there are deposits of granite, saltpeter. Sedimentary origin are bauxites, the deposits of which are located along the Alps, south of the Carpathians and on the Indochina peninsula.
5. Climate
5.1. General information
On the territory of Eurasia, all types of climates found on other continents are formed. Svalbard and some islands in the Arctic Ocean are dominated by an arctic climate. In the temperate zone, moderate air masses prevail throughout the year. In the west of the temperate zone of Eurasia, a maritime climate is formed. In winter the temperature ranges from 0 C to +6 C. Average summer temperatures are +10 C ... +18 C. Precipitation is up to 1000 mm per year. In the central part of the temperate zone, in winter there is a strong cooling of the earth's surface, and in summer, on the contrary, strong warming. Therefore, continental air is formed here. The Mediterranean climate is shaped by two different types of air masses that change with the seasons. In winter, westerly winds blowing from the Atlantic Ocean bring humid oceanic air from temperate latitudes. As a result, the winter here is warm, rainy and windy. Average temperatures in winter vary from +8 C to +10 C. summer period dry tropical air dominates the Mediterranean. Therefore, the summer here is hot and dry.
5.2. Weather in different parts of the year
In winter, dry weather also prevails in the central part of the subtropical zone, but not as cold as in the temperate zone. In summer, tropical air reigns here, so hot and dry weather sets in. In the east of the temperate and subtropical zones, the climate is formed in summer under the influence of the Pacific monsoons, which bring humid sea air,
6. Inland waters, their distribution
6.1. General information
Eurasia has an extremely dense river network. Most of the major rivers are in Asia. Eurasia is characterized by the largest area of internal runoff basins. Differences in the regimes of the rivers of Eurasia are due to the diversity of the climatic conditions of the mainland.
6.2. Records
The short rivers of the Scandinavian Peninsula and the largest rivers of Eurasia - the Ob, Yenisei, Lena, Northern Dvina, Pechora - flow into the Arctic Ocean. Almost all of these rivers are dominated by snow feeding. They freeze for a long time in winter, and in spring they overflow strongly. The longest of them is the Lena (4400 km), and the full-flowing one is the Yenisei. For 5-6 months, the rivers of the far north - Yana, Indigirka, Kolyma - freeze. Lake Baikal belongs to the basin of the Arctic Ocean - the deepest lake in the world (1620 m).
6.3. Atlantic Ocean basin
The Atlantic Ocean basin includes the rivers of Western, Southern and partially Eastern Europe. The rivers of Western and Southern Europe mainly begin in the mountains. In the west of Europe, a dense network of rivers and many freshwater lakes are developed. In the extreme west, in the region of the maritime climate, the rivers do not freeze and are deep all year round. The largest of them is the Seine. Rivers that freeze for a short time include the Vistula, Oder, Elbe. The largest rivers of the Atlantic Ocean basin are the Danube, the Rhine, the Dnieper.
Introduction
1.2 Inland waters of Eurasia
1.3 Climate of Eurasia
2. natural characteristic Eurasia
2.1 Vegetable world Eurasia
2.2 Fauna of Eurasia
Conclusion
Bibliography
Applications
Introduction
Eurasia is the largest and most contrasting continent of the Earth in terms of natural conditions. More than 1/3 of the planet's land area is in Eurasia; its area, together with the adjacent islands, is about 54 million km 2. At the same time, 4/5 of them are in Asia and 1/5 part - in Europe - two parts of the world that are traditionally distinguished as part of Eurasia. The names of these parts of the world originated in ancient times and mean, translated from the Assyrian language: "Erebus - "west, sunset" and "asu" - "east, sunrise (of the Sun).
The nature of Eurasia has been studied more fully than other continents. This is especially true for the most populated regions of Europe and Asia. Many natural phenomena and processes were studied by scientists on the example of the territories of the Eurasian continent.
With the enormous size of Eurasia, its internal parts are separated from the seas and oceans by thousands of kilometers, which enhances the natural contrasts within the mainland. The nature of its surface also changes from west to east. The dissected relief of foreign Europe is being replaced by vast expanses of the East European Plain, the West Siberian and Turan lowlands and the Central Siberian Plateau. The belt of mountain structures, stretching across the entire southern part of Eurasia from the Atlantic to the Pacific Ocean, in the direction from west to east, is becoming more and more powerful and high, reaching the highest heights on Earth within the Himalayas and the Tibetan Plateau.
In the west and south of Eurasia, the sublatitudinal strike of the main orographic elements prevails; in the middle part of the continent and, especially, in the east, it is replaced by submeridional. Thus, the relief does not prevent the influence of the Atlantic and Arctic oceans from penetrating deep into the continent, while the internal parts of Eurasia are separated from the influence of the Pacific and Indian oceans by mountain uplifts and it manifests itself only on its margins.
The huge size of Eurasia, the complexity of its structure and relief, the position between the subpolar and equatorial latitudes, varying degrees The influence of the oceans creates a wide variety of zonal features of nature and significant differences in the manifestation of the zonal structure of the biosphere. On the mainland there are barren arctic deserts and humid equatorial forests; vast areas are occupied by drainless territories, where there is almost no rain, and on equally large areas the population suffers from excess moisture. Eurasia is characterized by the largest temperature and altitude contrasts on Earth. Within its limits are the highest mountain peak and the deepest dry depression of the globe. The unique dimensions of Eurasia and the complexity of natural conditions are its main feature, originality, and main difference from other continents. This makes it difficult to study, but at the same time very interesting.
Target term paper- to study the geography of Eurasia.
Work tasks:
to study the geographical characteristics of Eurasia: the history of formation, relief features, geological structure;
study hydrographic and climatic features;
explore the basic forms of the animal and plant world.
1. Physical geography of Eurasia
1.1 Physical and geographical position and main landforms of Eurasia
The complex history of the formation of the Eurasian continent is reflected in all components of its nature. But most clearly it manifests itself in the features of the structure of the surface, which is distinguished by complexity, diversity and contrasts that are more unique on Earth. Eurasia is characterized by the distribution of all types of tectonic structures known on Earth and all types of relief.
The basis of the greatest continent of the Earth was the Eurasian continental plate, the most ancient sections of which are the platforms (cratons) East European (Russian) and Siberian. Their central parts (cores), composed of Precambrian rocks, protrude to the surface in the form of crystalline (basement) massifs, plains and plateaus broken by tectonic faults. This type of relief is characteristic of the plains and uplands of the Baltic Shield in Sweden, Finland and northwestern Russia.
The history of the development and formation of Eurasia is closely connected with the history of another continent of the northern hemisphere - North America. At a certain period in the history of the Earth, Eurasia and North America were one whole, as were the continents of the southern hemisphere.
The basis of modern Eurasia is formed by the end of the Precambrian relatively stable ancient cores - the East European, Siberian and Chinese platforms, separated from each other (and from the North American platform) by ancient oceans. The gradual closure of these oceans at the end of the Proterozoic, Lower and Upper Paleozoic led to the growth of land and the formation of a huge continental mass, which, together with the continents of the southern hemisphere, formed by the beginning of the Mesozoic era a single pro-continent of the Earth - Pangea. Obviously, by that time there was already a basin of the Pacific Ocean, the bottom of which forms an oceanic-type crust.
At the end of the Proterozoic, the land area south of the Siberian Platform increased significantly. Mountain-building processes reached a particularly large scale at the end of the Silurian, when the European and North American platforms merged and the North Atlantic continent was formed. Folded structures also arose in the east. Angarida appeared, which included the Siberian platform and newly formed mountain structures. Tectonic activity was accompanied by the formation of intrusions and mineralization. The consequence of this orogenic cycle was the wide development of continental conditions and a sharply dissected relief. Platforms and newly formed mountain structures experienced uplifts accompanied by intense effusive activity. At the foot of mountain structures, troughs were laid, filled with thick layers of sediments, in which oil, bauxite, and iron ores were formed.
In the second half of the Carboniferous and in Perm, a new tectonic cycle was noted, which was of great importance for Eurasia. As a result of intense movements that continued until the beginning of the Triassic period, a mountainous land was formed between the European and Siberian platforms, as well as in most of the southern part of modern Eurasia. As a result, more and more ancient structures were soldered into one. The huge continent of Pangea was formed, which included most of modern Eurasia and North America, as well as the southern continents. This tectonic cycle was very long; it broke up into several phases that did not coincide in time and space. In earlier phases, mountain structures were formed in the south of foreign Europe and in Central Asia. At the same time, there were transgressions to the European Platform and to the area of distribution of the leveled structures of the Lower Paleozoic age. In the foothill troughs, which were laid at the foot of the rising mountains, accumulated plant remains, which gave rise to deposits hard coal. Further development of mountain building was accompanied by the introduction of powerful intrusions and mineralization. In the Permian period, the manifestation of mountain-building processes occurred simultaneously with the general uplift of the platforms, and by the end of the Permian, the Eurasian part of Pangea was a dry land, within which the previously formed mountains were destroyed and terrigenous sediments accumulated under conditions of a hot, at first humid, and then increasingly arid climate. The Triassic was characterized by the predominance of continental conditions and weak tectonic activity.
In the Triassic, the disintegration of Pangea and the formation of modern continents and oceans began. The first stage was the opening of Tethys (at first in the form of a bay of the already existing Pacific Ocean), which separated the northern part of Pangea from the southern in the east. Gradually developing to the west and expanding, Tethys divided Pangea into Laurasia and Gondwana in the Jura. At the same time, Laurasia retained its unity, and within Gondwana, the formation of the basin of the western part of the Indian Ocean began, dividing the southern parent continent into two parts - western and eastern.
A significant part of Laurasia was covered by transgressions that spread to the European Platform and into the region of the Upper Paleozoic structures of Europe. During the Jurassic, Laurasia was dominated by a hot, humid climate. Woody vegetation represented by ancient gymnosperms predominated on land areas not covered by seas and lakes. In numerous lake basins, mainly in the Asian part of Laurasia, the formation of coal-bearing strata took place, in the west of Europe - sedimentary iron ores.
The first manifestations of orogeny in the Mediterranean occur in the Jurassic, and the main stages in the Cenozoic era.
In the Cretaceous, the formation of the Atlantic Ocean (its southern, and then the middle part) began, as a result of which North America began to separate from Eurasia, and the western (Caribbean) part of Tethys separated from the eastern (Mediterranean). In the northern part, the integrity of Laurasia was preserved until the Cenozoic.
The Cretaceous period saw important changes in the composition of the organic world, especially in the flora of Eurasia. Along with the ancient gymnosperms and ferns, which spread in the Paleozoic, angiosperms develop, which formed the basis of modern flora. In the animal kingdom, the appearance of the first birds and mammals (marsupials), as well as the development of fish, deserves attention. Birds and mammals have replaced large reptiles.
The final design of the contours of the mainland, the creation of its current relief, the formation of the organic world in a climate close to modern, took place during the Cenozoic era, so its history should be considered in more detail.
By the beginning of the Cenozoic, on the site of the greater northern part of modern Eurasia, there was a single consolidated dry land. It consisted of ancient cores, which were interconnected by structures of the Baikal, Caledonian and Hercynian age, leveled and greatly altered by subsequent processes. In the east and southeast of Eurasia, Mesozoic mountain structures were attached to more ancient structures. In the west, this complexly constructed land was separated from North America by the depression of the North Atlantic, which had already been outlined by that time. In the south and southeast, it was limited by the somewhat reduced Tethys. It separated Eurasia from the sections of the split Gondwana that existed to the south and southwest - the African-Arabian, Hindustan and Australian platforms, and in the east it freely connected with the Pacific Ocean.
The regression of the seas, which began in the Cretaceous, continued at the beginning of the Paleogene, but in the middle of the period it was replaced by a new transgression that covered a significant part of Eurasia: the southern part of the East European Plain, the plains of Central Asia and Western Siberia, the flat areas that separated the Paleozoic mountain uplifts of foreign Europe. At the same time, at the end of the Oligocene, tectonic processes began to develop within the Tethys and in the western part of the Pacific Ocean, which continued throughout the Neogene.
However, the nature of the processes in these regions was different. The closure of Tethys, of which the modern Mediterranean Sea is a relic, occurred as a result of the collision of the continental plates of Eurasia and Africa and was accompanied by the formation of ridges with the participation of fragments of the oceanic crust. In the east, i.e. along the western marginal part of the Pacific Ocean, the oceanic crust moved under the continental crust with the formation of deep-sea trenches, island arcs and volcanogenic mountains.
The climate and organic world of Eurasia north of the Mediterranean belt in the Cenozoic were different than at the end of the Mesozoic era. In the south, the climate is hot and relatively humid, in the northern regions it is moderately warm and also humid. Under such conditions, a rich, predominantly woody angiosperm flora was formed, which consisted of many genera and families that now exist. In the north, these are deciduous forests of oak, beech, walnut, chestnut with an admixture of conifers. To the south, palm trees, tropical conifers, and ferns dominated. herbaceous plants not yet widely used. At the same time, a fauna was formed, consisting mainly of mammals, among which the leading role belonged to predators (later extinct) and ungulates. Real birds also appeared. The flora and fauna of this area later developed into modern Holarctic flora and fauna.
To the south of the Mediterranean belt, climatic conditions remained almost unchanged. There, from the Mesozoic, the flora that gave rise to the paleotropic flora of Eurasia, and the fauna from which the modern Indo-Malay fauna was formed, continuously formed. It was characterized by proboscis and primates that appeared in the Paleogene. The Tethys Ocean served as an obstacle to the exchange of species between these various centers of the formation of the organic world. Later, the role of such an obstacle was performed by the mountains that arose in its place.
As a result of the tectonic activity of the Paleogene period, there was a significant increase in the land of Eurasia due to mountain structures that rose within the Mediterranean and Western Pacific belts. The Sunda archipelago was connected to the mainland; The Balkan Peninsula was one with Asia Minor, Europe was connected to Africa in the area of the modern Strait of Gibraltar. In the northwest, Eurasia again merged with North America.
In the second half of the Paleogene, differences in climatic conditions between north and south intensified, which was reflected in the organic world. In the southern part, tropical and subtropical Poltava flora has formed, consisting of palms, tree ferns, representatives of the families of laurel, myrtle, evergreen oaks, tropical pines and other tree species. It corresponded to a hot, not very humid climate. In the north of Eurasia, a deciduous Turgai flora of warm and humid temperate climate, which included mainly deciduous tree species - chestnut, beech, maple, liquidambr, ancient sequoia, swamp cypress, etc. Initially, the boundary between the areas of distribution of these floras passed along the line connecting the lower reaches of the Vistula and the lower reaches of the Yangtze, i.e. about 50° N. sh. in Europe and about 35 ° N. sh. in Asia. As a result of the gradual cooling of the climate, the Poltava flora began to retreat and die out, giving way to the Turgai flora that spread to the south and west. Due to further cooling, boreal (coniferous) flora began to spread from the north. In the extreme northeast of the mainland, a center of formation of the Arctic flora arose.
During the Neogene, mountain building in southern Eurasia continued, which led to the closure of the Tethys and the final formation of a belt of mountain structures in the southern regions of Europe and Asia. Simultaneously with the growth of geoanticlinal uplifts, which involved pre-existing synclinal troughs, the formation of extensive intermountain depressions began, which were superimposed on pre-existing structures. The boundaries of these intermountain basins have formed fault lines marked by intense volcanism. Along the margins of the Alpine-Himalayan orogenic belt, at the boundaries with the platforms, marginal troughs were formed, which were gradually filled with deposits of the molasse type.
At the end of the Neogene and the beginning of the Quaternary period, mountain structures within the Alpine-Himalayan belt, as well as outside it, were covered by uplifts. The tectonic activation of the interior regions of Asia was especially powerful, it led to the formation of the Himalayas, Tibet, Karakorum and the adjacent high and highest mountain structures of Central Asia - Kunlun, Tien Shan, etc. In Europe, the Alps, Carpathians, Caucasus, Apennines, Andalusian mountains, but all of them are almost half the height of the highest mountains of Asia. The Scandinavian mountains experienced a significant uplift, to a much lesser extent rejuvenation affected the Upper Paleozoic mountain structures of the middle part of Europe and the Baltic crystalline shield. The uplifts were combined with the subsidence of huge areas and the filling of foothill troughs. All this led to the final formation of the modern contours of the mainland.
The sinkings that engulfed the northern part of the Atlantic and the adjacent regions of the Arctic Ocean finally separated Eurasia from North America and isolated the Spitsbergen archipelago. At the beginning of the Quaternary, a group of the British Isles separated from the mainland, the Strait of Gibraltar and deep basins of the western Mediterranean Sea formed. In the eastern part of the Mediterranean basin, significant subsidence occurred in place of the Aegean Sea. The land that connected the Balkan Peninsula and Asia Minor underwent fragmentation, straits formed between the Aegean and Black Seas, as well as the basin of the Sea of Marmara. To the east of Asia, in the region of the island arcs of the Pacific Ocean, depressions deepened and seismic and volcanic manifestations intensified. To the southeast of the mainland, the land connecting Asia and Australia was fragmented, and the Malay Archipelago was formed. At the same time, deep-water depressions with suboceanic-type crust formed within some inland and marginal seas. Such depressions exist in the Mediterranean, Black, Japan, South China Seas and parts of the Pacific Ocean adjacent to the mainland.
The end of the Neogene is also characterized by great tectonic activity in the area of the African-Arabian platform, the formation of the Red Sea rift and, consequently, the separation of Arabia from Africa. Simultaneously with the uplift in the Alpine-Himalayan belt, the Indo-Gangetic and Mesopotamian foothill troughs were filled and Arabia and Hindustan were joined to the Eurasian continent.
Neotectonic processes and associated changes in the relief and contours of the Eurasian continent have led to significant changes in climatic conditions. Already in the second half of the Paleogene, a gradual cooling began in the entire northern part of the mainland, which led to the differentiation of the organic world and increased differences between north and south. The cooling was accompanied by the death or retreat to the south of heat-loving flora and fauna and the gradual introduction of boreal and arctic forms, the drying up of the interior of the continent, and the expansion of arid spaces. The greatest mountain structures that rose in the east and especially in the south fenced off the interior of Eurasia from the humid air currents coming from the Pacific and Indian oceans. Arid and sharply continental conditions spread over the vast expanses of Central Asia, in which the formation of the corresponding organic world took place: forests and forest animals disappeared, they were replaced by animals and plants adapted to a dry climate.
Only in the extreme south and southeast of the mainland, including the modern islands, climatic conditions have not experienced significant changes since the end of the Mesozoic. The process of development of the organic world went continuously towards the formation of tropical flora and fauna.
The cooling of the climate in the Pleistocene led to the expansion of continental ice sheets in the northern part of Eurasia and the glaciation of almost all the mountains of the mainland. Continental ice covers are most widespread in Europe and Western Siberia. Their advance was accompanied by the destruction of the vegetation cover and the disappearance of the fauna. Along the edge of the glaciers, the climate dried up and peculiar periglacial landscapes formed, combining the features of the tundra and cold steppes, which turned south into typical steppes. In these areas, loess and loess-like rocks were formed, a peculiar fauna developed, consisting of species that are now extinct (mammoths, woolly rhinos) or now living in the tundra (reindeer, musk oxen, arctic foxes, lemmings), as well as steppe and forest-steppe animals , now partially extinct (horses, saigas, bison, deer). In the more southern and inland regions of the mainland, which were not subjected to glaciation and the direct influence of ice sheets, periods of moistening (the so-called pluvials) were associated with the epochs of glaciation, during which a dense network of rivers and lakes arose and a significant enrichment of the organic world took place. The remains of the Turgai flora found refuge in places where climatic conditions have changed to a lesser extent. Such refugia ("shelters of life") were located in the Far East, in the Manchurian-Korean mountains, and in the west, in the Danube basin and in the Atlantic regions of Europe. The more heat-loving Poltava flora has almost completely died out, only some of its elements have survived to this day as part of the subtropical flora of Eurasia.
The continental glaciation was repeated, but in the relief and stratigraphy of the Quaternary deposits of foreign Europe, traces of the maximum, Middle Pleistocene, and the last, Upper Pleistocene, glaciation are well preserved. During the maximum glaciation (250-75 thousand years ago), glaciers spread from two centers - from the Scandinavian Peninsula and from the British Isles. Outside of Russia, ice covered the entire north of Europe to the foothills of the Carpathians and the mountains of Central Europe. From the lower reaches of the Rhine, the southern border of their distribution stretched to the south of the British Isles (the region of the lower reaches of the River Thames). Thus, ice covered the North Sea and the adjacent waters of the Atlantic Ocean.
The boundary of maximum glaciation is traced by the distribution of boulders and moraine deposits. The last glaciation (70-11 thousand years ago) captured a much smaller area. Its border is marked by a strip of terminal moraine formations, which are well expressed in the relief and are called the Baltic Ridge.
During the glacial epochs, the level of the World Ocean dropped, and the land surface increased accordingly. In this regard, the British Isles were repeatedly connected with the mainland, the continental shelf of the north of Eurasia was exposed, and a bridge between Eurasia and North America arose on the site of the Bering Strait. Animal exchange between the two continents took place along this bridge, a person came from Asia to North America along it. Ancestors modern people, gradually spreading from the southern, intratropical regions, mastered the Mediterranean and the middle part of Europe, during the interglacial and after the final retreat of the ice, they penetrated to the north of Europe and Asia, and from there to North America. Until the end of the last ice age (8-10 thousand years ago), the land area to the southeast of Asia was more extensive than now. This bridge was used for the exchange of species with Australia and the settlement of Australia by humans.
In the postglacial period, there was a general rise in the level of the World Ocean, and in connection with this, the size and shape of Eurasia somewhat changed: transgressions in the north and west of the mainland led to the formation of epicontinental seas of the Atlantic and Arctic oceans, and land communications with North America in the northeast were finally interrupted and with Australia in the southeast. The size and level of the inland seas - the Baltic, the Black - have repeatedly changed. There was a separation of the Caspian basin.
The disappearance of ice and the gradual warming of the climate caused the retreat to the north of representatives of the Arctic flora and fauna, as well as their partial resettlement in mountainous regions. From the forest "refuges of life" in the Far East, heat-loving species settled in more northern regions. The inner parts of the mainland, in full accordance with the arid conditions created there, were inhabited by xerophytes. During the Holocene in Eurasia, changes in climatic conditions occurred repeatedly, but they were no longer as sharp as during the Ice Age. The most significant changes were in the second half of the Atlantic period (5-5.5 thousand years ago), when, as a result of the long dominance of warm and humid climatic conditions, broad-leaved forests moved 500-800 km north compared to their modern distribution. In turn, the "Little Ice Age", which covered from the middle of the XVI century. until the middle of the 19th century. the mountainous territories of Europe, led to a widespread decrease in the boundaries of high-altitude plant belts.
1.2 Inland waters of Eurasia
About 40 thousand km fall on the surface of Eurasia 3 precipitation, 23.5 thousand km 3of this amount is spent on evaporation.
Annual stockfrom the territory of Eurasia together with the islands is more than 16 thousand km 3, i.e. slightly less than half of the total annual flow of all the rivers of the Earth. In terms of the runoff layer, this is equal to 300 mm, i.e. above the average for the entire Earth as a whole. In terms of the average height of the runoff layer, Eurasia is inferior to South and North America. However, these average values do not fully reflect the features of the distribution of inland waters within the largest continent of the Earth.
Significant differences in structure and relief, climatic contrasts and the resulting uneven precipitation and uneven evaporation create large differencesin the distribution of both surface and groundwater within the mainland. This is clearly seen on the map of the annual river runoff in millimeters of the layer (Appendix 1).
Maximumrunoff indicators (more than 1500 mm) are typical for the subequatorial and equatorial belts, especially for the islands of the Sunda archipelago, as well as for the west of Indochina and Hindustan, for the central part of the Himalayas. In other belts, such high runoff amounts are typical only for a few areas of the Japanese Islands, the Alps and the Scandinavian Highlands. Significant areas in these regions have an annual flow of less than 1500 mm (but not less than 600). Most of Europe, northern and East Asia the runoff layer is from 200 to 600 mm per year. For relatively small areas of the Iberian Peninsula, the Danube Plains, the middle part of the East European Plain, the runoff is less than 200 mm per year, i.e. slightly less than the average value for the entire land. The vast territories of Central and Central Asia, the lower Indus basin, the Iranian Highlands and the Arabian Peninsula have a runoff value less than 50 mm per year, and in many regions the layer height does not exceed 15 mm. These figures to some extent reflect differences in the density and nature of the network. surface water different parts mainland.
The territory of Eurasia belongs to poolsAtlantic, Arctic, Pacific and Indian oceans. The peripheral parts of the mainland, especially the west, east and southeast, have a dense water network, which includes the largest river systems. The interior and southwestern regions are almost devoid of surface water and have no runoff to the ocean. The territory of internal runoff (including the basin of the Caspian Sea) accounts for more than 30% of the total area of Eurasia.
This uneven distribution of surface water dependsnot only from modern natural conditions, but also from the features of the development of the mainland. Obviously, before the powerful uplifts that led to the formation of the highest mountain ranges in the southern part of the mainland, the climatic conditions of the inner parts of Eurasia, although characterized by greater dryness than the climates of its outskirts, were still not as arid as at present. Therefore, in the Cenozoic in the central part of the mainland there was a developed network of rivers and lakes, the flow of which was directed to the north, east and south. Tectonic movements, which had a greater scope in the marginal parts of the orogenic belt than in the interior, led to the fact that the latter turned out to be protected from the influence of the oceans. The resulting drying up of the climate has led to a reduction and disorganization surface runoff and the formation in the inner parts of the Eurasian continent of vast practically drainless regions (Iranian highlands, Tibet, plateaus of China, Mongolia, etc.).
The most powerful river arteries, which originated before the rise of high ridges, retained their original direction, cutting through these ridges with deep epigenetic valleys.
In the northern regions, especially in the northwest of the mainland, the formation of the water network was greatly influenced by glaciation.
Thus, within the vast Eurasian landmass, depending on the history of development and modern relief, as well as on climatic features, various regional types of water networks and river regimes have developed. Further, they will be considered for the foreign part of Eurasia.
North of Europerelatively recently released from under the ice cover, and the main feature of the water network is its morphological youth. River valleys and lake basins in the north of Europe in most cases are tectonic cracks processed by a glacier. The network of rivers and lakes is very dense, lakes are especially numerous, of which there are tens of thousands. Their sizes are different, the outlines are bizarre; most of the lakes are elongated from northwest to southeast, according to the main direction of tectonic lines and the movement of the glacier.
Rivers are usually short and often serve as channels between lakes. The valleys of the largest rivers have numerous lake-like extensions and undeveloped longitudinal profiles with numerous rapids, which were formed when the rivers crossed hard rock outcrops. Most of the rivers are full of water throughout the year, although the amount of precipitation is low. This is due to weak evaporation and the fact that rivers receive additional nutrition from lakes, swamps and due to ground water. The rivers of northern Europe (Oulujoki, Kemijoki, Ongermanelven, and others) have large reserves of hydropower, which is widely used in Finland, Sweden, and other countries. Most of the rivers have no navigable value, but in the past they were widely used for timber rafting.
On the western edge of Europethe relief is dominated by hilly plains, plateaus and low mountain ranges, not covered by continental ice. The rivers flow in wide terraced valleys and form branched systems. The mouths of rivers flowing into the Atlantic Ocean and its seas, under the influence of subsidence and under the influence of tidal waves, are estuaries.
The climate features of Western Europe are reflected in the regime of rivers. Constant and heavy rainfall, the absence of a frosty period create an exceptional uniformity of flow throughout the year. The water level rises in winter due to winter rains. If the winter precipitation is especially abundant, there are floods that come on gradually and also gradually stop. An example is the floods of the winter of 2000/2001. and 2004/2005 in France, Great Britain and other countries. In summer, there is a slight decrease in water flow in the rivers, but the period of shallowing, as a rule, is absent.
The uniformity of flow and the absence of ice cover make the rivers of western Europe navigable throughout the year. In the estuaries of many large rivers (Rhine, Seine, Scheldt, Loire) there are ports that are accessible to ocean-going vessels during high tides. The predominance of flat terrain in the basins of these rivers facilitates the construction of navigable canals connecting various river systems.
In the middle of Europethe relief is strongly dissected. Almost all rivers begin in low mountains and flow through the plains, linking the interior of Europe with the sea basins. The increase in the continentality of the climate from west to east is also reflected in the regime of rivers. All rivers freeze in winter for a period of 2-3 weeks to three months. Discharge maxima and floods occur in spring, as they depend on snowmelt in the mountains. By the end of summer, due to strong evaporation, there is a period of a significant decrease in the water level in the rivers, however, a strong shallowing is not observed due to the regulating influence of lakes.
On the plains of Poland and Germany, the watersheds between the river systems are poorly expressed in the relief, since in many cases they are crossed by wide hollows of the ancient glacial runoff. This creates favorable conditions for the construction of navigable canals and the creation of long waterways. The rivers of the central part of Europe (Elbe, Odra, Vistula and their tributaries) are of great transport importance, especially increased due to the creation of artificial waterways that supplement the network of natural water arteries. In their upper reaches, in the mountains, these rivers have large reserves of water energy, which is used by numerous hydroelectric power plants.
Southern Europe and Western Asiamountainous terrain and a subtropical climate with dry summers create unique conditions for the formation of a river network. Rivers, as a rule, are characterized by a large fall and an undeveloped profile. On many of them, especially on the Iberian Peninsula, there are rapids in the lower reaches, which are formed when crossing the steep ledges of the Meseta.
The water regime of rivers is characterized by sharp fluctuations in discharge. In winter, during rains, they overflow with water and carry a large amount of suspended material. In summer, during the period of almost complete absence of precipitation, the rivers become shallow. The difference in water flow between summer and winter periods can be 1:100 and even 1:200 (for example, the Ebro River). Small rivers in southern Italy, Greece, and Asia Minor dry up completely in the summer.
Large and small rivers of the eastern and southern outskirts of Asia have a pronounced monsoonal regime with a summer maximum flow and a strong decrease in the level in winter. Level fluctuations sometimes reach tens of meters, the minimum and maximum flow rates differ by hundreds and thousands of times. For many rivers originating in high mountains, the summer maximum intensifies due to the melting of snow and ice in the first half of summer. Such rivers often overflow their banks, causing floods. To combat floods and prevent rivers from wandering within the low plains, dams are erected along their channels, which, however, do not always reliably protect the surrounding area from spills.
In the northeast of overseas Asiain the monsoon climate of temperate latitudes with cold and long winters, rivers freeze for a long period. In spring, they have a small flood due to snowmelt, and in summer - the main flood associated with monsoon rains. This type of regime is typical for the Amur and its tributaries, for the rivers of Northeast and North China, the north of the Korean peninsula (Liaohe, Yalujiang, Weihe, etc.).
Rivers southeast Asiaalso have a pronounced monsoon regime with a summer maximum. However, a very strong shallowing in winter period they do not, because south of the Yangtze basin and in the south of the Japanese islands, cyclonic precipitation falls in winter. As an example, the Xijiang River, which is full-flowing throughout the year, can be mentioned. For rivers South-East Asia characteristic is the autumn flood, which is associated with the passage of typhoons and often takes on the character of a catastrophic disaster.
Peninsular rivers Indochina and Hindustandue to the sharp contrasts between the wet and dry seasons and strong evaporation during the dry season, they are characterized by particularly strong flow fluctuations. During the period of influence of the equatorial monsoon, they overflow with water, during the winter months they become shallow, and sometimes almost dry up. The monsoon regime is especially typical for the rivers of Hindustan (for example, for Godavari). The rivers of Indochina (Irrawaddy, Chao Phraya, Mekong) begin in the high mountains and have a more uniform regime, although they still have a clearly pronounced summer maximum.
A dense river network and a uniform regime of rivers are characteristic of the islands Indonesiawith their typical equatorial climate. The full-flowing and turbulent rivers of the islands have large reserves of hydropower.
Dry rivers interior regions of overseas Asiaalso differ in mode features. Those of them that begin in high mountains with powerful glaciation and large reserves of snow retain a constant stream. The maximum consumption occurs in late spring or summer - during periods of intense melting of mountain snows. In the desert regions, the waters of these rivers are used for irrigation (for example, the Tarim River in Kashgaria, the rivers of the eastern outskirts of the Iranian Highlands, etc.).
Rivers, whose sources are at low altitude and flow through highly arid regions, have only occasional rain and snow-rain supply. They are very shallow, characterized by sharp fluctuations in level and dry up for a long time. After rains, rivers often turn into mudflows carrying mud and stones. This type of watercourses is typical for dry and closed regions of Central Asia, the Near Asian highlands and the Arabian Peninsula.
Many rivers of Eurasia have predominantly glacial nutrition. The modern glaciation of Eurasia is associated, on the one hand, with the islands of the Arctic and Subarctic, on the other hand, with the highest mountain systems that receive abundant precipitation. The polar islands are characterized by glaciation of the cover type and the low position of the snow boundary. On Svalbard, it passes on average at an altitude of 300 m above sea level. Glaciation has the character of shields, from which powerful glacial tongues descend, breaking off into the sea. A major center of glaciation is located on the island of Iceland, where the position of the lower boundary of the nival belt varies between 700 and 1000 m. Higher up, the mountain ranges are covered with firn fields, from which glaciers flow, feeding numerous rivers.
In the mountains of Eurasia, the height of the snow boundary rises from north to south and from the marginal parts of the mainland to the interior. Therefore, the major centers of modern glaciation are not only such highest mountain systems as the Kunlun, Karakorum, Himalayas, Pamir, Tien Shan, but also much lower, but abundantly humidified mountains of the Atlantic regions. In the Scandinavian mountains, where the height of the snow line varies between 700 and 1900 m, a significant glaciation has developed, feeding a dense network of rivers. In the Alps, the snow limit rises to a height of 2500-3200 m; this is the largest center of mountain glaciation in Europe with valley-type glaciers, from which almost all significant rivers of Europe or their tributaries originate (Rhine, Rhone, Po, tributaries of the Danube).
Modern glaciationThe mountains of Asia, although significant, are still not as large as they might be, judging by their height. The highest mountains are located in the interior of the mainland, characterized by a sharp continental climate and low amounts of precipitation, so the snow border and the lower ends of the glaciers are at high altitude. The height of the snow border of the Karakoram, Kunlun is 5000-5500 m, the Himalayas - 4500-5000 m. Glaciers do not descend below 4000 m. The length of individual glaciers in the Karakorum reaches 60 km, the maximum length of the glaciers of the southern slope of the Himalayas is 26 km. In the Eastern Tien Shan, the height of the snow border is 3700 m and the length of the largest glacier is 40 km.
Thus, the glacial type of river feeding is characteristic of many regions of Eurasia with different natural conditions. Rivers fed by melting glaciers and snows are of great economic importance. In the countries of Europe, their energy resources are mainly used; in the arid regions of Asia, the waters of these rivers are used mainly for irrigation.
The main rivers of Eurasia will be characterized in the respective regional sections. The largest rivers of the mainland with a variety of sources of food and complex regimes, which are of the greatest economic importance and go beyond individual regions, require special consideration.
1.3 Climate of Eurasia
Analysis of meteorological indicators and their changes during the year give an idea of the wide variety of climates within Eurasia. Eurasia lies in all climatic zones of the Northern Hemisphere, and within each zone climatic regions have formed:
arctic belt. The northernmost islands of Eurasia, and in the east the strip of the mainland adjacent to the Arctic Ocean, are within the Arctic zone. In the Arctic zone, the maritime Arctic climate of the west of the European sector of the Arctic stands out: Svalbard and small oceanic islands in the western part of the Arctic Ocean. The maritime climate of these islands is due to the influence of the warm North Atlantic Current and is characterized by relatively high winter temperatures (from -16 0From to - 20 0C) and significant annual precipitation (300 mm). The rest of the territory of this belt has a continental arctic climate. Dry cold arctic air masses dominate here, due to which the entire water area of the Arctic Ocean, without coastal waters, is bound by dense powerful ice throughout the year. The Arctic belt is a supplier of cold air masses to the continent. In all seasons of the year, their movement is directed to the south.
subarctic belt. It stretches in a narrow strip along the entire continent and includes the island of Iceland, part of Scandinavia, located north of the Arctic Circle and, somewhat expanding in the east, goes to the Bering Strait. The subarctic zone is located between the summer and winter position of the Arctic front and is characterized by the influence of moderate air masses in summer and cold Arctic ones in winter. It also has a maritime and continental climate. The first includes Iceland and the islands adjacent to the west of the Scandinavian Peninsula. This type of climate is characterized by relatively mild (-5 0C - 10 0C) winter, cool (no more than +10 0C) summer and 300 to 700 mm of precipitation in all seasons in the form of rain and snow.
Temperate zone.The southern boundary of this belt is determined by the summer position of the front of temperate latitudes and runs from the southern coast of the Bay of Biscay through the middle of the Black and Caspian Seas to the north of the Korean Peninsula and the middle part of the island of Honshu.
Air masses of temperate latitudes dominate in this zone throughout the year. On the territory of Western Europe, in the temperate zone, two subregions are distinguished - northern and southern. The northern subregion includes Fennoscandia and the north of the island of Great Britain (Scotland). The climate here is temperate with cool summers. In the southern subregion the climate is temperate with warm summers. In the northern subregion, two climatic regions are distinguished: an area with a maritime (Norwegian) climate type and an area with a continental (Swedish) climate type. The first region includes Western Scandinavia and Scotland. The climate of this area is characterized by an abundance of precipitation throughout the year, short cool summers. It is dominated by constantly cloudy, damp, windy weather. Climate Swedish - continental formed in continental Scandinavia (Sweden, Finland), characterized by cold, long winters with stable snow cover, short cool summers. The summer maximum is clearly expressed in the annual distribution of precipitation. Against the background of the continental climate, the climate of the fjelds (flat peaks of the Scandinavian mountains) stands out - humid, cold with an average temperature of the summer months of less than + 10o WITH.
In the southern subregion of the temperate zone of Europe, the following climatic regions are distinguished: an area with a maritime climate, which includes Atlantic Europe, an area with a climate transitional from a maritime to a continental climate in Eastern Europe, and an area with a continental climate. Against the background of the transitional climate, the climate of the Hercynian middle mountains and the climate of the highlands (Alpine) stand out.
The maritime climate is characterized by mild Cold winter(the average temperatures of the winter months are positive), moderately warm summers, a small annual temperature range, an abundance of precipitation, and frequent strong winds. Ireland, England, France without the south, the west of the German-Polish Plain, the west of Jutland have this type of climate. The transitional climate from maritime to continental is characterized by negative average temperatures of two to three winter months, short but stable snow cover, relatively hot and humid summers, and clearly defined transitional (spring, autumn) seasons. This type of climate is represented in the east of the German-Polish lowland. The continental climate of the Danubian plains is characterized by rather high summer temperatures (+220C, +24 0C) with little rainfall. In winter, cold continental air masses from the east and north often invade here, causing sharp cooling.
The climate of the mid-altitude mountains is characterized by high humidity relative to the surrounding plains. The slopes of the western exposure receive more precipitation than the opposite - eastern ones. Temperatures are lower in the mountains, and the snow stays for three to five months.
The climate of the Alps is different high humidity, the presence of climatic zonality, low temperatures on the tops of the mountains and, as a result, the presence of snow and mountain glaciers. On the territory of the rest of Eurasia, the climate is temperate continental (Russian Plain), continental (Western, Central, Eastern Siberia, Central Asia, Central Asia itself) and monsoonal, which covers northeast China, the Korean Peninsula, Hokkaido Island and the northern half of the island of Honshu . In winter, cold and dry continental air dominates here, which comes from the Central Asian baric center. In summer, it is replaced by warm and humid air, which brings here the Pacific monsoon. The maximum precipitation occurs in the summer - from 60 to 70% per annum. Central Asia proper has a continental climate, on the territory of which the center of high pressure and the Central Asian anticyclone are located. Winters are cold and dry, and summers are dry and hot.
subtropical beltalso crosses Eurasia from the Atlantic to the Pacific. This belt contains the entire south of Western Europe, the Near Asian highlands up to 30 0With. sh., north of the Arabian Peninsula, Tibet and the Yangtze basin. It is characterized by a change in the types of air masses: in summer, tropical dry and hot prevail, in summer - humid air of temperate latitudes. The Mediterranean climate stands out in this zone, the main features of which are dry and hot summers, mild wet autumns and winters. It is divided into marine and continental. The western windward sections of the peninsulas of the Perinean, Apennine, Balkan have a maritime climate, the rest of the European Mediterranean has a continental climate.
In Asia, within the subtropical climate zone, several types of climate are also distinguished. In the west (the western and southern coasts of Asia Minor and the mountainous west of the Levant) the climate is Mediterranean with hot and dry summers and warm and humid winters. Winter temperatures range from +10 0From to +12 0C in the south, from 2 0From to 3 0C in the north. Annual precipitation amounts are 500-600 mm on the plains and up to 3000 mm on the windward slopes of the mountains. The continental climate of this belt is characterized by low annual precipitation (from 400 mm in the Anatolian Highlands to 200-100 mm in the Armenian and Iranian Highlands), the maximum of which occurs in autumn and winter, hot and dry summers. This type of climate is typical for all Western Asian highlands up to 30 0With. sh., Northern Arabia up to 30 0With. sh. without the west of the Levant. Throughout the year, the continental air of temperate latitudes dominates over the Near Asian highlands. In winter, there is a strong cooling of the surface of these highlands. In summer, this air warms up and acquires the properties of continental tropical. The annual temperature amplitudes are large (up to 900 ).
The territory of Tibet stands out in the high-mountain subregion of the subtropical belt, which is characterized by cold winters with little snow and rather cool and dry (in most of the territory of Tibet) summer. Only in the eastern regions of Tibet increases the amount of precipitation brought by the Pacific monsoon. Their maximum here is in the summer. In general, the relative humidity of the air in Tibet is very low. The air is dry and cold throughout the year.
In the east, in the Yangtze basin, the climate is monsoonal and humid. In summer, precipitation is brought by the Pacific monsoon, and in winter it rains due to frontal processes. Up to 75% of the annual precipitation occurs in the summer. On the windward slopes falls up to 2000 mm, on the plains - from 700 to 900 mm.
Tropical trade wind climate belt. This belt contains the southern half of Arabia, the south of the Iranian Highlands and the Thar Desert. Continental tropical air prevails here throughout the year. The weather is dry and warm in winter, and dry and hot in summer. The daily temperature ranges are large. Precipitation in most areas falls below 100 mm. Only in the mountains of Yemen from 400 mm to 1000 mm. This is a zone of negligible moisture.
Subequatorial belt or otherwise the climate of the equatorial monsoons. On its territory are the Hindustan Peninsula without the Thar Desert, the island of Ceylon without the southwest, the Indochina Peninsula, South China, the Philippine Islands without the south, Mindanao, the islands of the southeast of the Malay Archipelago. In winter, continental dry air is brought here with the trade wind of the northern hemisphere. In summer - humid equatorial air and Indian Ocean monsoon. Winter and spring are dry. The dry season lasts until May-June. Summer and autumn are wet. The hottest time of the year is spring, when the Indus Plain heats up more than the regions of the equator. In April and May temperatures reach 40 0From and even up to 52 0C. On the windward slopes of the Assam Mountains in Cherrakunji, an average of 12666 mm of precipitation falls annually, and on the leeward slope of the same mountains - 1700 mm. But there are areas of this belt that receive only 81 mm per year (the upper reaches of the Indus River).
equatorial belt. Most of the Malay Archipelago (without the eastern half of Java, the Lesser Sunda Islands), the Malay Peninsula, the southwest of Ceylon, and the south of the Philippine Islands are located in this belt. Equatorial air dominates here throughout the year. This belt is characterized by uniform moisture throughout the year with two maxima, heavy rainfall - from 1500 mm to 4000 mm or more (in the mountains), convective rains, insignificant annual temperature amplitudes (2 0C - 3 0WITH). Average temperatures of the warmest month 27 0C - 28 0C, and the coldest - 25 0C - 26 0C. Precipitation predominates over evaporation. Humidification is excessive.
2 . Natural characteristic of Eurasia
2.1 Flora of Eurasia
The position of Eurasia in all climatic zones of the northern hemisphere determined the distribution of all the main natural zones of the Earth on its territory.
Most of the zones stretch from west to east. Some of them (tundra, taiga) form continuous bands. But due to the large size of the continent, the diversity of climate and relief, the structure of zonality is greatly complicated. A variety of forests are located on the western and eastern coasts of the mainland, that is, in areas where the marine and monsoon climate types are distributed. The central parts of Eurasia with a continental climate are occupied by treeless zones - steppes, semi-deserts and deserts. In areas of subequatorial climate in the south of the mainland there are palm savannahs. Large areas are occupied by areas of altitudinal zonation. The largest number of altitudinal belts is characteristic of the southern slopes of the Himalayas.
The position of Eurasia within the Holarctic and Paleotropic floristic kingdoms (Appendix 2) reflects the differences in the history of the formation of the flora of the northern and southern parts of the mainland: the continuity of development throughout the Cenozoic and the tropical nature of the flora of the south of the mainland and southeastern islands, on the one hand, and relative youth flora of the northern part and its complex genesis associated with abrupt changes in climatic conditions, on the other hand.
The Holarctic flora of Eurasia incorporates elements of ancient heat-loving forest floras that developed on its territory in the first half of the Cenozoic before the general cooling, which led to the formation of Pleistocene ice sheets.
Eurasia natural zone climatic
Elements of these floras have been preserved mainly in two near-oceanic sectors - the Atlantic and the Pacific. For the formation of the flora and soil and vegetation cover of the interior regions of the mainland, the cooling and subsequent drying of the climate, due to the uplift of mountain systems in the south of the mainland, was of great importance.
Due to sharp changes in the relief and climate of the interior regions, the oceanic centers of flora formation were separated from each other by vast expanses of land and during the second half of the Cenozoic developed independently of each other. In the western sector of the mainland, the exchange of species with the tropical regions of Eurasia and Africa was hampered by the seas, and in its inner parts by vast expanses of deserts. In the eastern, Pacific sector, there was an exchange of floristic elements between the Holarctic and Paleotropics. This determined the species richness of the flora, which is typical for the east of Asia, including both boreal and tropical elements.
In view of the vast size of Eurasia and the great differences in the soils and vegetation of its various regions, it is expedient to consider the features of the soil and vegetation cover separately for each of the oceanic sectors and for the interior parts of the continent.
Let's start with a consideration of the western, Atlantic sector, corresponding mainly to the west of Europe.
In the ice-free spaces of the polar archipelago of Svalbard, the arctic tundra is widespread, the vegetation of which consists of mosses, lichens and perennial low-growing grasses that do not form a continuous cover: saxifrage, polar poppy, and some cereals.
Typical tundras with dwarf birches and berry shrubs on weakly podzolic or peat-gley soils are found in the north of the Scandinavian Peninsula and Finland, and to the east - in the north of the European territory of Russia and Siberia. In foreign Europe, flat typical tundras are not widely spread due to the peculiarities of the climate caused by the influence of the warm North Atlantic Current. At those latitudes where tundras dominate in Eastern Europe, forest-tundras or even forests are common in the west.
Tundra, disappearing on the plains, pass into the mountainous regions of Scandinavia and Iceland, where they form a belt of mountain tundra.
A narrow strip of forest-tundra is characterized by groves of twisted birches and alders, which appear against the background of tundra vegetation, going far to the north along river valleys. Plain forest tundra in Western Europe are common in Iceland, Scandinavia and especially Finland.
The most important type of zonal vegetation in the temperate zone of Eurasia is coniferous forests. They occupy large areas in foreign Europe, in the European territory of Russia and in Siberia. Depending on the origin, geographic location and modern natural conditions, the composition of forests and the types of soils formed under them are different, therefore, it is possible to speak of a single zone of Eurasian coniferous forests only with a very large generalization.
In foreign Europe, coniferous forests cover most of the Scandinavian Peninsula and Finland. They occupy the plains and move onto the slopes of the Scandinavian mountains, rising in the north to a height of 400-500 m, in the south - about 900 m. A continuous cover of coniferous forests exists in northern Europe up to about a latitude of 61 °, and to the south, broad-leaved species appear in the composition of forests. Main coniferous trees These forests are European spruce (Picea excelsa), Scots pine (Pinus sylvestris), and the closer to the coast of the ocean, the greater the role of spruce in the composition of forests. In the west, in Norway, it prevails. In the more eastern regions of Sweden, spruce and pine are distributed approximately equally, although they do not form mixed stands, while pine dominates in Finland. This is due to a decrease in precipitation and an increase in the continentality of the climate from west to east.
Podzolic type soils are common under coniferous forests. Depending on temperatures, moisture conditions, as well as the predominance of certain forms of relief and the nature of surface deposits, these soils are represented various options, but all of them are characterized by a low content of humus, an unstable fine-lumpy structure, a high content of silica and a very low content of elements such as phosphorus and calcium, and an intensely acidic reaction of the soil solution. Most of Scandinavia and Finland are occupied by typically podzolic soils, among which there are areas of sphagnum or lowland bogs with peat-humus soils. Wet forests and forest swamps, formed on impermeable crystalline rocks under conditions of excessive moisture, occupy more than 18 million hectares in Fennoscandia. In the north, gley-podzolic soils predominate. Due to the peculiarities chemical composition and structures, all of them are infertile and require significant reclamation work during development.
Cutting down forests and exporting timber in the countries of Northern Europe began in the early Middle Ages. At present, the forests on the western coast of the Scandinavian Peninsula are almost completely destroyed. They were replaced by meadows and moorlands. The coasts of the Gulf of Bothnia and the Gulf of Finland are also deforested and occupied by cultivated lands, which in Sweden and Finland account for less than 10% of the territory. In the hinterland, despite long-standing logging, forests still cover most of the area (62% in Sweden and almost 70% in Finland), interspersed with lakes and swamps. Artificial plantings are carried out on the site of clearings and drained swamps, and at present, forest areas and timber reserves in the area of coniferous forests are not decreasing, but even increasing.
As already mentioned, around the 60th parallel, deciduous species (primarily oak) begin to be mixed with conifers; there is a change of coniferous forests mixed. These forests are distributed mainly in the eastern, more continental regions of foreign Europe and on the East European Plain. In the south of the Scandinavian Peninsula, spruce-broad-leaved forests predominate, and in the east of the Central European Plain (in Poland), instead of spruce, pine dominates.
To the west and south, mixed forests are replaced by deciduous forests, among which several types can be distinguished depending on the species composition: oak-birch, oak, beech and beech-birch. Broad-leaved forests can be considered the dominant type of natural vegetation in foreign Europe. At the basis of their species composition, an important role is played by elements of the ancient Turgai flora, which survived the glacial cooling in the "shelters of life". Like the Turgai, modern European broad-leaved forests grow in a warm temperate oceanic climate.
Once deciduous forests covered foreign Europe from the British Isles and the Atlantic coast of France to the borders of Russia. They were distributed not only in the lowlands, but climbed the mountain slopes to a height of several hundred meters above sea level, giving way at high altitudes to mixed and coniferous forests. Broad-leaved forests dominated by oak were distributed throughout Great Britain and Western France, beech and oak-beech occupied the north of France, the Rhine regions, Jutland, southern Scandinavia and the southern coast of the Baltic Sea. Their main forest-forming species - forest, or European, beech (Fagus sylvatica) - a tree of the oceanic climate, does not tolerate sharp fluctuations in temperature, severe frosts, and dryness. To the east, it does not extend beyond the lower Vistula and the Carpathians. Oak grows well in both western and eastern regions of Europe. Dark, shady, without undergrowth and grass cover, beech forests prefer the northern, wetter, slopes of the mountain ranges, while on the sunny slopes of the southern or eastern exposure, light oak groves with an admixture of other deciduous species, with lush shrubs and rich grass cover, predominate.
The climatic conditions of the southern part of the temperate zone in the Atlantic regions of foreign Europe favor the decomposition of fallen leaves and grass cover and the activity of microorganisms. The parent rocks for soils are loams rich in carbonate compounds. This contributes to the formation of soils more fertile than under coniferous forests, rich in humus and calcium compounds. The areas adjacent to the North and Baltic Seas are characterized by the distribution of soddy-podzolic soils, and to the south and west - brown forest soils containing up to 6% humus, having a good structure, close to neutral reaction and having significant fertility.
The areas of foreign Europe, occupied by broad-leaved and mixed forests with soddy-podzolic and brown forest soils, have long been densely populated, agriculture and cattle breeding are developed in them. At the same time, these are areas of developed industry - a major consumer of wood. The first period of significant deforestation dates back to the Middle Ages. Large areas of land were plowed up, part of the forests were destroyed by livestock. Deforestation spread from west to east. Already in the 16th century, when a lot of wood was required for the development of metallurgy and shipbuilding, a shortage of wood began to be felt. Industrial revolution of the XVIII-XIX centuries. led to a real crisis in the forestry of foreign Europe. Mass plantings of conifers helped to solve the problem, especially spruce, which quickly gives good commercial wood.
Now in the temperate zone of foreign Europe, forests cover about a third of the surface, and they are very different from the primary ones. A significant part of modern broad-leaved forests is a low-growing secondary growth that arose on the site of exterminated tall forests. Most of the forested areas are occupied by artificial plantations, and coniferous species (spruce, fir, Scots pine, seaside pine, etc.) predominate in them. The inconsistency of their environmental requirements with growing conditions worsens the condition of forests, makes them more susceptible to the harmful effects of pests and diseases, natural disasters (hurricanes, snowfalls, etc.) and anthropogenic air and water pollution. In most regions of Central Europe, about a quarter of the stands are damaged, and in some countries (Poland, Czech Republic, Slovakia), the share of damaged and dead forests is from 40 to 60% of their total area (Appendix 3).
At the same time, the presence of serious environmental issues in the densely populated territory of Europe, the importance of the conservation functions of forests is constantly increasing - water and soil protection, sanitary and hygienic, recreational.
The most forested at present are the areas with a predominance of mountainous relief between the middle course of the Rhine and the border of Russia. In some places, the forest cover is up to 30 and even 50%. Separate areas of indigenous broad-leaved forests, taken under protection at the end of the 19th century, have also been preserved here. There are large areas of artificial plantations in the south-west of France, in the Landes, where pine plantations on an area of more than 1 million hectares have made it possible to fix the moving sands of the coastal lowland and increase the supply of timber to the country's domestic market. The British Isles, north-west of France, Jutland are the poorest in forests. The degree of afforestation there is much less than 10%. The coasts of the Atlantic Ocean and the North Sea, primordially treeless due to strong winds, excessive moisture, acidity or salinity of the soil, or have long been deforested, are covered with heaths.
In the more eastern regions of Eurasia, broad-leaved forests give way to forest-steppes and steppes. The steppes were widely developed in the interior regions of Eurasia in conditions of a continental climate and insufficient moisture. In foreign Europe, the original steppes and forest-steppes existed only on the alluvial plains of the middle and lower Danube with a temperate continental climate and moderate moisture.
Soils are represented by chernozems of various types. The most fertile typical chernozems with a humus content of more than 6% are characteristic of the Lower Danube Plain within Romania. To the south, in northern Bulgaria, they are replaced by low-humus southern chernozems. In the Middle Danube lowland, leached chernozems with a humus content of 3-6% and significantly saline are common. In all these areas, meadow steppes with separate patches of broad-leaved forests were common in the past. High soil fertility and favorable climatic conditions contributed to the development of agriculture, horticulture and viticulture. At present, the Danube plains are dominated by cultivated land and artificial tree plantations of oak, poplar and black locust (Robinia pseudacacia). Thanks to special reclamation and agrotechnical measures, up to 70% of the land fund is involved in agricultural production.
For the western, Atlantic, sector of the subtropical belt on the shores of the Mediterranean Sea, with warm, wet winters and dry summers, special types of soils and vegetation are characteristic. The floristic composition of the vegetation of the Mediterranean, in addition to modern conditions, is also determined by the presence of ancient tropical elements, both evergreen and deciduous. Basically, the Mediterranean flora was formed already in the Neogene, but then it was somewhat transformed under the influence of climate changes during the Pleistocene. In this regard, the Mediterranean flora is characterized by a great complexity of species composition (Appendix 4).
Modern climatic conditions (lack of moisture during the period of the most intense solar radiation) contributed to the development of a number of adaptive traits in plants that reduce evaporation and compensate for the lack of moisture: corking of the bark, pubescence, the formation of small thick leathery leaves, thorns and prickles, the release of resinous and ethereal substances, creating a kind of protective cloud around the plant, etc. At the same time, warm, frost-free and wet winters allow trees and shrubs to keep their leaves throughout the year.
The most typical forest formations of the Mediterranean coast are sparse forests of various evergreen oaks: holm (Quercus ilex), cork (Quercus suber), common in the western part, boulder (Quercus aeguilops); noble laurel (Laurus nobilis), Mediterranean pine pine with an umbrella-shaped crown (Pinus pinea) or juniper arborescens. The river valleys are characterized by thickets of oleanders, which bloom brightly in spring.
Under the Mediterranean vegetation, very peculiar soils are formed, which are formed under conditions of variable moisture. Particularly characteristic are dark-colored brown soils with a well-defined humus horizon, with a humus content of up to 4-7% and a large amount of calcium. Red-colored soils are formed on the weathering crust of limestones (terra rossa). Both are fertile and, when irrigated, are favorable for the cultivation of many subtropical and temperate crops. Evergreen forests and subtropical soils are limited in their distribution to coastal areas and heights of no more than 300-400 m in the north and 1000 m in the south. Higher up, the natural vegetation cover is characterized by broad-leaved and mixed forests on mountain burozems.
The shores of the Mediterranean Sea, which became the cradle of ancient civilizations with a high development of agriculture, cattle breeding and navigation, largely lost their natural vegetation even before the beginning of our era. Already at the time when Central Europe was almost entirely covered with forests, in the Mediterranean there were completely deforested mountain slopes and coastal plains, partly cultivated, and partly turned into barren barren spaces. Deforestation, livestock damage and fires have become the main reasons for the disappearance of the primary vegetation cover in Southern Europe and Western Asia. In place of the former evergreen forests, secondary low-growing forests or thickets of shrubs have appeared, which to this day cover large areas. Depending on the amount of precipitation, the composition of the underlying rocks and soil types appearance and the floristic composition of these thickets are diverse.
The richest in species composition is the so-called maquis, or machia, common in the Mediterranean in all areas with abundant rainfall and well-developed soils. Extensive thickets of maquis have been preserved in Corsica, the south of the Iberian Peninsula and in Greece. They consist of low trees or tall shrubs, reaching 3-5 m in height. Despite regional differences, evergreen oaks dominate almost everywhere. arbutus(Arbutus andrachne), wild pistachio (Pistacia lentiscus), rosemary (Rosmarinus officinalis), juniper (Juniperus macrocarpa), heather tree (Erica arborea), wild olive (Olea oleaster). Many maquis plants are aromatic, some have large bright flowers.
Dry stony limestone slopes with discontinuous soil cover are characterized by thickets consisting of rare low-growing xerophytic shrubs and subshrubs of the legume, labiate, cistus, and other families. In the west (in Spain and France), thickets of this type are called garriga, on the Balkan Peninsula and in Asia Minor - freegan. Their species composition is somewhat different. In the eastern part of the Mediterranean, shrub thickets are common, consisting not only of evergreen, but also deciduous species: hold the tree (Paliurus aculeatus), sumac (Rhus coriaria), lilac (Syringa vulgaris). These thickets, sometimes found at a considerable height, are called shilyak.
In places that are least favorable for revegetation, after the destruction of forests, mountain slopes are quickly eroded, ravines and landslides develop. Karst processes are intensively taking place on limestones. Therefore, in the Mediterranean there are a lot of barren areas, devoid of soil and vegetation. In many respects, this was facilitated by accelerated erosion, due to significant slopes of mountain slopes and heavy rainfall in winter time of the year. But along with this, on the coastal lowlands and terraced mountain slopes on carefully cultivated lands, olive groves, vineyards, fields of wheat and corn are common. In the southern regions, citrus fruits predominate - oranges, lemons, oranges, on which you can see flowers and ripe fruits almost all year round. There are lush plantings around the settlements. ornamental plants from local and tropical species - palm trees, bougainvillea, roses, etc.
The inland sector of Eurasia, which includes the main part of Asia, with the exception of its extreme east and southeast, has significant differences in terms of the species composition of the flora and the distribution of zonal types of soil and vegetation cover. The soil and vegetation cover of this part of the continent, as already mentioned, was finally formed relatively recently under the influence of strong changes in climate and relief in the Neogene-Quaternary.
Modern climatic conditions are characterized by continentality and aridity, which manifest themselves from the temperate to the tropical zone and are intensified due to the peculiarities of orography. Therefore, in contrast to the Atlantic part, the interior regions of the continent are characterized by a smaller distribution of forest types of soils and vegetation and a wide distribution of steppes, semi-deserts and deserts.
The northern part of Asia within Russia is characterized by the expansion of tundra and forest-tundra, the spread of taiga, and the absence of mixed and broad-leaved forests. A narrow strip of forest-steppe passes into the steppe, which in Asia does not form a continuous strip, interrupted by mountains covered with coniferous forests. The land cover of Asia within Russia is studied in detail in the corresponding course. Here we will consider the soils and vegetation of foreign Asia.
In the north of Mongolia, in the basin of the Selenga River, steppe flat areas alternate with mountain ranges overgrown with coniferous forests or covered with mountain-steppe vegetation. In the steppes of the temperate zone, varieties of dry cereal and shrub-grass steppes on chestnut soils predominate. To the east, on the plains of Northeast China, as moisture increases, they are replaced by forb-cereal steppes on chernozems or chernozem-like soils. Such a pattern in the distribution of soil and vegetation types is due to the fact that the climate in the temperate zone of Asia becomes drier and more continental, when moving from the oceans to the interior of the mainland, the excess of evaporation over actual evaporation increases and, consequently, the moisture deficit increases. Therefore, changes in the soil and vegetation cover along the parallels are much more pronounced in this area than from north to south. Dry steppes give way to desert steppes, where massifs of brown low-humus soils alternate with solonetzes and solonchaks. Particularly large areas in Central Asia, Southern Mongolia and Northwestern China, i.e. on the southern edge of the temperate zone, deserts occupy. Only on the most humid mountain slopes do sparse coniferous and deciduous forests grow.
The deserts of the temperate zone of foreign Asia are formed in conditions of a sharply continental climate with hot summers and cold winters, with an annual rainfall of no more than 200 mm (mostly less than 100 mm), fairly evenly distributed throughout the year and ensuring soil wetting by only 0.5 m. The vegetation and soils of deserts present an exceptionally variegated picture, since the slightest change in soil, topography or moisture affects the features of the soil and vegetation cover. Saltwort-shrub and ephemeral formations are most widespread on gray-brown highly carbonate soils formed on ancient loams and loess. There are vast arrays of wind-blown sands (Karakum and Kyzylkum, Takla-Makan, Alashan, certain areas of the Dzhungar basin), not fixed by vegetation or overgrown with tamarisk, dzhuzgun and saxaul, as well as areas of stony and gravelly deserts, almost devoid of soil and vegetation. Soils are widespread different stages salinity. Takyrs with sagebrush-saltwort vegetation are formed on the silt-silty proluvial plumes of the foothills. The most valuable plant of Asian deserts is saxaul. Its wood is used as fuel, young shoots serve as food for camels. White saxaul (Haloxylonn persicum) is planted to fix the sands, and black (Haloxylon aphyllum) is planted on salt marshes.
Along dry channels, periodically filled with water after rains and often having an underground stream, as well as along rare constantly flowing rivers, especially when they exit the mountains to the plains, there are oases that stand out with bright greenery against the monotonous background of deserts. The natural vegetation of the oases (tugay) is dominated by reeds and poplars, cultivated plants grow there vine, fruit trees, cotton, tobacco.
The arid conditions that have been established since the Pliocene are also characteristic of the inner part of the subtropical zone of Eurasia, and the transition from the Mediterranean to the continental arid subtropical climate of the inner parts of the Near Asian highlands is very gradual. Aridity already manifests itself on the Anatolian Plateau and intensifies to the east in Mesopotamia and the Iranian Highlands. But in all these areas, the spring-winter maximum of precipitation is preserved, which significantly affects the nature of vegetation and soils. For areas with moisture over 300 mm per year, gray-brown soils and vegetation of shrubby dry steppes are characteristic. With a rainfall of 300 mm or less, serozems of subtropical semi-deserts and vegetation of thorny cushion-shaped shrubs from the genus Astragalus, tragacanth and other low-growing xerophytes develop, adapted to strong evaporation, sharp fluctuations in temperature and relatively low temperatures winters. This formation is known as upland xerophytes. Gray-brown soils and gray soils contain somewhat less humus than brown, but more than gray-brown soils (about 2-4%), and have a reserve of almost all chemical elements required by plants. For their effective agricultural use, artificial irrigation is necessary, the use of which in the arid regions of Turkey and Iran makes it possible to grow crops, fruit trees, rice, and cotton. In areas of the Iranian Highlands isolated by mountains, the amount of precipitation decreases to 100 mm or less. Rocky and saline sandy deserts, almost devoid of vegetation, are widespread there.
In the more eastern regions of the subtropical belt, the highest highlands of the world (Tibetan, etc.) rise. They are characterized by cold high-altitude deserts with extremely sparse vegetation, which is dominated by hard grasses, cushions and thorny shrubs. Along the river valleys there are undersized bushes of sea buckthorn (Hippophae rhamnoides), meadows of hard Tibetan kobresia sedge appear. Swamps form on flat, better moistened areas.
Forests in the inland part of the subtropical belt occupy an insignificant part of the surface, mainly on the slopes of the most abundantly irrigated mountain ranges, along river valleys, and also in the conditions of the so-called "barrier foot". The latter are most characteristic of the Colchis and Lankaran lowlands, adjacent to the mountain ranges of the Greater Caucasus, and the southern coast of the Caspian Sea. In these areas, moist forest subtropical landscapes have been preserved since the Neogene. Vast and dense tracts of deciduous mesophilic forests with evergreen species of shrubs, lianas and epiphytes also grow on the southern slopes of the Greater Caucasus, the northern slopes of the Lesser Caucasus, the Talysh Mountains and the Elburs Range, where there is a large amount of precipitation and the climate has not experienced significant changes since pre-glacial time.
Arid conditions persist in the tropical zone of Eurasia, covering the Arabian Peninsula, Mesopotamia and a significant part of the Indus River basin. In a dry and hot tropical climate with warm winters, in the lower parts of the mountain slopes, soils of the gray-brown type are formed, close to the soils of the deserts of the subtropical and temperate zones. On the plains, vast expanses are occupied by sandy and rocky deserts. The plants are dominated by ephemerals that germinate after short-term, rarely falling rains, tough semi-shrubs and dry grasses. Mimosa and acacia are found along dry riverbeds, and grows in oases. date palm(Phoenix dactilifera), whose fruits (dates) are of great importance to the local population and are exported.
The vegetation of the subequatorial and equatorial belts is represented by various types of tropical forests and savannah associations (grasslands). In the distribution and correlation of these types of vegetation and the soils corresponding to them, there is a very clear dependence on the amount and period of precipitation, on the relief and underlying rocks. On the plains of the Indus and the Ganges and the Hindustan Peninsula, due to the features of the relief, its interaction with monsoon air currents and the predominance of areas with insufficient moisture, more xerophytic formations are common than in the southeastern regions of Asia. They are, as it were, a continuation of the arid regions of the inner parts of the mainland, while Southeast Asia serves as a continuation of the much more humid and predominantly forested Pacific sector of the mainland.
The natural vegetation of the Indus and Ganges basins is characterized by monsoon forests replacing each other, depending on the amount of summer precipitation, with a predominance of deciduous species in the upper tiers and evergreen in the undergrowth, dry deciduous forests, deserted savannas, xerophilic light forests and shrubs, consisting of undersized prickly deciduous species and evergreen succulents. As part of the flora of forests, the most common trees that give valuable wood are teak (Tectona grandis), sal (Shorea robusta), terminalia (Terminalia), etc. Acacias and albizia grow in the undergrowth. With a decrease in moisture, the average height of the stand decreases to 12-15 m, the trees become umbrella-shaped, high grasses are typical for the grass cover. The modern vegetation of Hindustan and the Indus basin, as well as the lowlands of the Ayeyarwaddy and Mekong, the "dry zone" of Myanmar, the Korat plateau, the lowlands of Vietnam and Laos, are characterized by secondary savannahs that arose on the site of seasonally humid tropical forests as a result of repeated fires, grazing or periodic plowing. The species composition of the savanna vegetation is represented by pyrophytes, which confirms their anthropogenic origin. Differences are manifested in the height and density of the herbage, the distribution of the tree-shrub layer, and depend primarily on the nature and intensity of anthropogenic impact. In the savannahs of Hindustan, tall grasses are common, including the environmentally aggressive alang-alang (Imperata cylindrica); the tree cover is dominated by various acacias, myrtle, dipterous, which once grew in the lower tier of the forests that dominated here. Thus, modern savannahs (with the exception of deserted ones) can be considered long-term derived communities secondary to different types tropical forests.
The soils of the considered regions are formed on ancient weathering crusts covering crystalline and ancient sedimentary formations. They are enriched with iron and aluminum hydroxides, giving them various shades of red color, the humus content reaches 2-4%. Depending on the moisture conditions, red lateritic (ferralitic) soils are formed under seasonally wet forests, brown-red soils under xerophytic forests, and red-brown soils under dry savannahs. All of them, especially red soils, have significant fertility under the condition of artificial irrigation. special properties the soils of the central part of Hindustan, which form on the surface of basalt covers and weathering products of basalts, differ. These soils have an intense black color, contain a large amount of calcium, hold water well and are highly fertile. They are especially favorable for growing cotton, for which they received the name of cotton soils. Their local name, regura, entered the special literature.
Tropical rainforests grow on the abundantly irrigated slopes of the Himalayas, on the slopes of the Western Ghats, on the Malabar coast and in the southwest of Sri Lanka, i.e. in areas windward of the summer monsoons and having the longest rainy season. Usually these are polydominant forests of complex composition with a large number of endemics, more than 100 species of palms, various lianas and epiphytes. Along the sea coasts, flooded by the tides, stripes of mangroves stretch. Trees that grow in the intertidal zone have aerial stilted roots that allow them to hold on to the muddy ground.
The natural vegetation cover in South Asia has been heavily modified by humans. For thousands of years, forests in India, Pakistan, Sri Lanka were cut down for the needs of shipbuilding, for fuel and for arable land. On the Indo-Gangetic plain, in the northern part of the Deccan, in Sri Lanka, vast areas are occupied by rice, millet, cotton, tea bush and hevea plantations. The threatening pace of deforestation is evidenced by the constant increase in the area of deforested land: in the late 70s. 20th century in Asia, 2 million hectares of forests were destroyed annually, and in the 90s. - already more than 3 million hectares. The highest rates of deforestation are characteristic of Bangladesh and Pakistan, where forest areas are declining by 2-2.5% annually. In many areas, in place of the exterminated tall forests, secondary jungles appear, which are of no economic importance. As a result of deforestation, soil fertility is quickly lost, floods intensify in the lower densely populated parts of river valleys, there is a general drying up of the territory, and there is a real threat of losing the Unique Gene Pool. Attempts are being made to restore forest vegetation by planting the most valuable species (for example, teak), but the scale of forest plantations lags far behind the rate of deforestation.
The eastern, Pacific sector of Eurasia is located in special conditions for the formation of flora and modern natural vegetation. The eastern part of Asia is characterized by monsoon circulation of the atmosphere, which is clearly expressed in all climatic zones, and the temperature conditions change gradually from north to south, which is favored by the structure of the surface with a predominance of submeridional strike of the main orographic elements. The natural sublatitudinal boundary is the Qinling Range, but it does not reach the Pacific Ocean either. Such conditions facilitate the exchange of floristic species between north and south, i.e. between the Holarctic and Paleotropics, and contribute to the enrichment of the floras of regions located at different latitudes. The climatic conditions of eastern Asia have not experienced significant changes since the Pliocene, and the pre-glacial Turgai flora found refuge there, completely disappearing in the more northern and western regions due to cooling and drying up of the climate. Therefore, the east and southeast of Asia are characterized by antiquity and richness of flora, the predominance of forest types of soils and vegetation in all latitudes.
In the foreign part of East Asia, from north to south, there is a change in the types of soil and vegetation cover from temperate coniferous forests in the north to moist equatorial forests in the south.
Coniferous forests, similar in composition to the forests of Southern Siberia, cover the slopes of the Greater Khingan in the north and the areas adjacent to it from the northeast. They also occupy the north of the island of Hokkaido, where fir, Siberian and local spruce species, Far Eastern yew and small-leaved trees (birch, alder, aspen, willow) grow. On the more southerly islands of Japan, Korea, and northeast China, coniferous forests move into the upper parts of the mountains, while the lower parts of the mountain slopes and plains were in the past, and in part now, covered with deciduous broad-leaved forests with an admixture of conifers with a rich undergrowth. These forests are largely a relic of the Turgai flora and have many common birth with the Atlantic forests of Europe, represented, however, by other, mostly endemic species. The soils of these forests are also analogous to the forest burozems of Western Europe.
The main deciduous species in the forests of the region under consideration are oak, beech, maple, ash, linden, and walnut. Of the conifers, pines, fir, spruce, arborvitae are characteristic. In addition, there are magnolias, paulownias, tulip trees (Liriodendron chinense) with beautiful, brightly colored flowers (Appendix 5). Lush undergrowth is formed by rhododendrons, privet, Amur lilac, honeysuckle. Numerous creepers and epiphytes give the forest a tropical look. Rich meadow vegetation is developed along the river valleys on alluvial soils.
The valleys and lowlands in East Asia are densely populated and cultivated, the share of agricultural land is 60 96, and in some places up to 80% of the territory. Forests are preserved almost exclusively in the mountains. In many areas they have been replaced by artificial plantations of predominantly coniferous species, among which the first place belongs to the most valuable cryptomeria. On the Great Plain of China, a thousand-year-old agricultural culture has changed natural conditions to such an extent that it is impossible to reconstruct the picture of the natural vegetation cover. At the same time, Japan, for example, has significant forests, accounting for almost 67% of its total area. The forest cover of the Korean Peninsula is even higher (75%), but the forests there are largely secondary thickets or artificial plantations.
South of the Qinling Range, in the Yangtze River basin, temperate deciduous forests are gradually replaced by evergreen subtropical forests on red and yellow earth soils. In the composition of these forests, along with such broad-leaved genera as beech and oak, ancient heat-loving forms - camphor laurel, cycads, representatives of the magnolia family, and some palm trees - gradually occupy an increasing place. The northern limit of distribution of the latter in East Asia reaches 45°N in the Japanese Islands. sh. But in the subtropical forests, you can also meet some representatives of the northern flora, which give these forests their originality and create extraordinary floristic contrasts.
At present, evergreen subtropical forests, especially on the Chinese mainland, are preserved only in the mountains. The lower parts of the slopes and plains are occupied by cultivated lands with a very diverse set of cultivated plants. The low per capita land availability and the shortage of arable land on the plains have led to the widespread use of mountain-terraced agriculture in East China, which accounts for about a quarter of the total arable land.
A significant part of the Indochina Peninsula and the islands of the Malay and Philippine archipelagos are covered with tropical rainforests. In these regions, they occupy relatively larger areas than at the corresponding latitudes in South Asia, alternating, as there, with deciduous forests and secondary savannahs.
The tropical rainforests of Southeast Asia are exceptionally lush and rich in species. They contain up to 300 species of palms, ranging from tall, slender palmyra (Borassus flabelliformis) to liana palms (the length of a rattan palm, for example, reaches 300 m). There are numerous species of the families of dipterocarp, bignoniaceae, anacardiaceae, and others. These forests, like nowhere else in the world, are distinguished species diversity bamboos, which are widely used here. They are used for the construction of dwellings, the production of furniture, high-grade paper; young shoots are used for food, and thin branches are used for weaving various products. Bamboo in Southeast and East Asia is distributed not only in the wild, but also in cultivation.
In the cleared areas, various plants of local origin or imported from other tropical countries are cultivated. In the coastal areas of the Philippines and the Sunda Islands, plantations of coconut palm (Cocos nucifera) are widespread. In Indonesia, large areas are set aside for plantations of Hevea rubber (Hevea brasiliensis), plants are grown on many islands, various parts of which are used as spices. Rice is sown on the flooded alluvial lowlands, the terraces on the slopes of the mountains are occupied by plantings of the tea bush. Many valuable fruit trees also grow in tropical forests, which are widely cultivated - melon (Carica papaya), grain (Artocarpus species), mango (Mangifera indica), mangosteen (Garcinia mangostana).
Eurasia, with its richest and most diverse flora, is home to the vast majority of ancestors of cultivated plants and wild species with useful traits: rye, wheat, millet, buckwheat, rice, many legumes (including soybeans), root crops, tea bush, sugarcane, many fruit trees. trees (including citrus), plants used as spices, a huge number of ornamental plants. Of the seven centers of origin of cultivated plants identified by N.I. Vavilov, four are in Eurasia (South Asian tropical, East Asian, Southwest Asian and Mediterranean, which also includes the northern coast of Africa (Appendix 6).
The history of cultivation of many widespread cultivated plants is calculated in some countries for centuries and even millennia. It is known that rice has been grown in India and China for seven thousand years, in Indonesia - at least a thousand years, wheat in some countries of Western Asia has been known for 5-7 thousand years. The tea bush, which became widely cultivated in China around the 4th century BC. AD, obviously, was known much earlier.
2.2 Fauna of Eurasia
The fauna of Eurasia is very diverse. The distribution of modern wild fauna across the territory depends on the characteristics of natural conditions and on the results of human activity. The most common large mammal of the tundra is the reindeer. Arctic fox, lemming and white hare are also found in the tundra. Of the birds, the white and tundra partridges are the most common. For the summer period, gulls, loons, eiders, geese, ducks, swans fly to the tundra. The fauna of the forest zone is best preserved in the taiga. Wolves, brown bears, moose, lynxes, foxes, squirrels, wolverines, martens live here. Of the birds - black grouse, capercaillie, hazel grouse, crossbill. Steppe animals - steppe ferret, ground squirrels, various mice. Of the large animals, the saiga has been preserved. Diverse birds - larks, swallows, falcons. Reptiles, rodents, and ungulates predominate in semi-deserts and deserts. Bactrian camels live in Central Asia, wild donkeys - kulans. In the mountain forests of South China, the panda bamboo bear, the black Himalayan bear, and the leopard have been preserved. Wild elephants still live in Hindustan and on the island of Sri Lanka. India and Indochina are characterized by an abundance of monkeys, a large number of various reptiles, especially poisonous snakes. Many animals living in Eurasia are listed in the Red Book: bison, Ussuri tiger, kulan, etc.
A large, northern, part of Eurasia belongs to the Holarctic zoogeographic region; the smaller, southern one, to the Indo-Malayan and Ethiopian regions (Appendix 7).
The Indo-Malay region includes the Hindustan and Indo-China peninsulas, together with the adjacent part of the mainland, the Taiwan, Philippine and Sunda islands, South Arabia, together with most of Africa, is included in the Ethiopian region. Some southeastern islands of the Malay Archipelago are classified by most zoogeographers as part of the Australian zoogeographic region. This division reflects the features of the development of the Eurasian fauna in the process of changing natural conditions during the end of the Mesozoic and the entire Cenozoic, as well as connections with other continents. To characterize modern natural conditions, the ancient extinct fauna known only in the fossil state, the fauna that disappeared in historical time as a result of human activity, and modern fauna are of interest.
At the end of the Mesozoic, a diverse fauna formed on the territory of Eurasia, consisting of monotremes and marsupials, snakes, turtles, etc. With the advent of placental mammals, especially predators, lower mammals retreated south to Africa and Australia. They were replaced by proboscis, camels, horses, rhinos, which inhabited most of Eurasia in the Cenozoic. The cooling of the climate at the end of the Cenozoic led to the extinction of many of them or retreat to the south. Proboscis, rhinos, etc. in the north of Eurasia are known only in the fossil state, and now they live only in South and Southeast Asia. Until recently, camels and wild horses were widespread in the interior arid parts of Eurasia.
The cooling of the climate led to the settlement of Eurasia by animals adapted to harsh climatic conditions (mammoth, aurochs, etc.). This northern fauna, the center of formation of which was in the area of the Bering Sea and was common with North America, gradually pushed the heat-loving fauna to the south. Many of its representatives have died out, some have survived in the composition of the modern fauna of the tundra and taiga forests. The drying up of the climate of the interior regions of the mainland was accompanied by the spread of the steppe and desert fauna, which survived mainly in the steppes and deserts of Asia, and partially died out in Europe.
In the eastern part of Asia, where climatic conditions did not undergo significant changes during the Cenozoic, many pre-glacial animals found refuge. In addition, through East Asia there was an exchange of animals between the Holarctic and Indo-Malay regions. Within its limits, such tropical forms as the tiger, the Japanese macaque, and others penetrate far to the north.
The distribution of modern wild fauna across the territory of Eurasia reflects both the history of its development and the characteristics of natural conditions and the results of human activity.
On the northern islands and in the extreme north of the mainland, the composition of the fauna almost does not change from west to east. The fauna of the tundra and taiga forests has minor internal differences. The farther to the south, the differences in latitude within the Holarctic become more and more significant. The fauna of the extreme south of Eurasia is already so specific and so different from the tropical fauna of Africa and even Arabia that they are assigned to different zoogeographic regions.
The fauna of the tundra is especially monotonous throughout Eurasia (as well as North America).
The most common large mammal in the tundra is the reindeer (Rangifer tarandus). It is almost never found in Europe in the wild; this is the most common and valuable domestic animal in the north of Eurasia. The tundra is characterized by arctic fox, lemming and white hare (Appendix 8).
Of the land birds, the most common partridge and tundra (Lagopus lagopus and Lagopus mutus), plantains and horned larks. For a short summer period, numerous migratory waterfowl fly into the tundra to breed chicks: gulls, guillemots, loons, eiders, geese, ducks, and swans. Gulls and gulls usually settle on high rocky shores, lay their eggs on cornices and in crevices of rocky cliffs. Hundreds of thousands of them gather in such places, so-called bird colonies are formed. During the nesting period, birds are easy to catch, and the population, taking advantage of this, exterminates them and collects eggs. The most valuable birds of the sea coasts are common eiders (Somateria mollissima), which have a light and exceptionally warm down, with which they cover their nests. In some countries (Iceland, Norway, Russia), eiders are under surveillance and protection, and the collection of their down, which is highly valued on the world market, is controlled by the state. Ducks, geese and other birds nest on the banks of lakes, rivers and swamps.
Coastal waters, rivers and lakes of the north of Eurasia are rich in fish, mainly from the salmon family.
During the Ice Age, mammoths, woolly rhinos, and musk oxen lived in the modern tundra. Now their remains are found only in a fossil state. In some places (for example, on Spitsbergen), musk ox, taken from Arctic America, is artificially bred.
The fauna of the forests of Eurasia is somewhat more differentiated. The differences between the fauna of broad-leaved forests of the west and east, separated by vast expanses of steppes and deserts, are especially pronounced. The taiga forests, stretching across the entire continent, are characterized by the comparative uniformity of the animal world.
The most typical representatives of the taiga fauna of Eurasia can be considered the elk, brown bear, lynx, wolverine, squirrel, chipmunk, bank voles; from birds - black grouse, capercaillie, hazel grouse, crossbills. These animals are common in the lowland taiga, as well as in the coniferous forests of the mountainous regions of Europe and Asia.
Between the mixed and broad-leaved forests of Atlantic Europe, on the one hand, and the Far East, on the other, there are, as already mentioned, great differences in the composition of the animal world.
The forests of Europe were once inhabited by numerous large mammals - predators and herbivores, which were hunted for their meat or valuable fur. The most characteristic representatives of the forest fauna are the brown bear, bison (Bison bonasus), roe deer (Capreolus capreolus), red deer (Cervus elaphus), wolverine, pine marten (Martes martes), forest polecat (Mustela putorius), weasel (Mustela nivalis), wild cat (Felis silvestris), fox, hedgehog, mountain hare and European hare. The brown bear (Ursus arctos), which has completely disappeared from the plains, is still found in the mountains, especially in the Carpathians. Endemic mountain species include chamois (Rupicapra rupicapra), mountain goats (Capra ibex, Capra pyrenaica) and marmots (Marmota marmota). Deforestation and plowing of large areas have led to a wide distribution of small rodents - voles, shrews, ground squirrels, which cause great harm to agriculture.
Great wealth of avifauna. Mixed and broad-leaved forests are inhabited by partridges, black grouse, capercaillie, hazel grouse, which are valuable game; many songbirds are also widespread - thrushes, orioles, warblers, warblers, etc. Owls, owls, pigeons and cuckoos are often found. Waterfowl nest in the ponds. Swallows, rooks and storks settle near settlements. Most birds are migratory. In autumn, along strictly defined routes, caravans of geese, ducks, cranes, flocks of rooks and other birds stretch to the south in order to return to their nesting places in the spring.
In rivers and lakes, mainly cyprinids are found, but salmonids are also found.
Some of the large animals that used to live in European forests are now gone, while others have survived only in specially protected areas. Among the first it is necessary to name the tour (Bos primigenius) - a huge wild bull. The last tour perished in Europe at the beginning of the 17th century. On the verge of complete extinction was the bison, which used to live in vast expanses from France and Belgium to the Caucasus. Systematically exterminated during knightly, royal and royal hunts, severely damaged during the First and Second World Wars, the bison was saved from complete extermination by the joint efforts of Soviet and Polish scientists. The largest bison population currently lives in the Belovezhsky Biosphere Reserve on the border of Poland and Belarus. The number of deer, mountain goats, and chamois has greatly decreased. Wolves have been exterminated almost everywhere, and bears have retreated to the mountainous regions, and even there they are extremely rare.
The fauna of the forests of eastern Asia, identified in the Manchurian-Chinese subregion of the Holarctic, has a pronounced mountain-forest character and is distinguished by high species richness. This is due, on the one hand, to the fact that the east of Asia did not experience significant climate fluctuations during the ice age, and some representatives of the heat-loving ancient fauna found refuge within its boundaries. On the other hand, the climatic conditions of this part of Asia change gradually from north to south, contributing to the penetration of northern taiga forms to the south, and tropical forms to the north, which creates a mixture of faunas characteristic of East Asia and leads to great species richness.
One of the most characteristic representatives of the mammalian fauna of the mountain forests of China and the Himalayas is the Himalayan black bear (Ursus thibetanus), which lives in the mountains up to an altitude of 4000 m, eating plant foods, insects and small animals. Bamboo bear, or giant panda (Ailuropoda melanoleuca) lives in the bamboo thickets of Eastern Tibet and Southeast China. In dense riverine bamboo and reed thickets and mountain forests, sometimes rising to the upper forest boundary, there is a tiger (Panthera tigris) - the most dangerous predator of Asia, there are also a leopard (Panthera pardus) and a marten marten (Martes flavigula). Characteristic representatives of the fauna of deciduous forests are the endemic raccoon dog (Nyctereutes procyonoides) and the Far Eastern forest cat. In the River Valleys of China and the Korean Peninsula, there is a small hornless water deer (Hydropotes inermis); in the north, spotted deer (Cervus nippon) is common, whose young antlers - antlers - are valued as medicinal raw materials. Some monkeys (from the macaque genus) come from South Asia. In the Manchurian-Chinese subregion, at 40° N. sh., passes the northern limit of their distribution on the globe. Representatives of the taiga fauna of the neighboring European-Siberian subregion - flying squirrel and chipmunk.
The forests of East Asia are inhabited by various birds. Pheasants stand out with their bright plumage (golden, royal, etc.), the colorfully colored mandarin duck (Aix galericulata) is the most beautiful representative of this family, the endemic Japanese crane (Grus japonensis). Numerous are various passerines - white-eyes, larvae, thymelia.
Among the reptiles there are many lizards and snakes, which are represented by genera common with the Indo-Malayan region. In addition, one species of alligator and a land tortoise are found. Of the amphibians, tree frogs and the endemic giant salamander (Andrias japonicus) living on the Japanese islands are characteristic.
The fauna of the Mediterranean, the Near Asian highlands and Arabia is peculiar, which gave grounds for distinguishing a special Mediterranean subregion of the Holarctic. There are endemic mountain and lowland species, as well as species common with North Africa. The fauna of southern Europe includes monkeys, primitive predators, birds, and a large number of amphibians and reptiles, which are almost completely absent in the more northern parts of Eurasia.
On the Iberian Peninsula and in the south of France, a representative of the viverrid family lives - an ordinary genet (Genetta genetta), a small predator that eats rodents and is therefore considered a useful animal. In the south of the Iberian Peninsula, the only species of monkeys found in the wild in Europe, the macaque macaque, or tailless macaque, lives.
The wild mountain sheep (Ovis ammon), which used to live in mountain forests or on open mountain peaks, which used to live on the islands of Corsica and Sardinia, is almost completely exterminated. On the islands of the Aegean Sea and in the south of the Balkan Peninsula, in mountainous areas with very sparse vegetation, wild goats are still found. Goats are generally widespread in the Mediterranean, in some areas they are the only domestic animals. Only in Southern Europe do the Pyrenean desman, porcupine, jackal, and wild rabbit live.
The birds of the Mediterranean are no less peculiar than the mammals. The most characteristic are the blue magpie, the mountain hen, the Sardinian warbler, the Spanish and stone sparrow, and many others. Of the birds of prey, the black vulture, vulture, and lamb are common, attacking small livestock.
Reptiles feel good in a dry climate. Among them there are endemic forms: gecko lizards, chameleons, Mediterranean viper and some other snake species; from land turtles - the Greek tortoise. Arthropods are also numerous - scorpions, freshwater crabs, various beetles, cicadas, brightly colored butterflies.
The composition of the fauna of the Near Asian highlands, in addition to typical Mediterranean elements, includes some representatives of the Central Asian subregion, as well as the Ethiopian region of Africa. Of the ungulates, gazelles, antelopes, wild donkeys, Central Asian mountain sheep and goats are characteristic. Representatives of the Ethiopian region are peculiar ungulates - hyraxes (Hyracoidea), living in rocky mountainous regions at a considerable height. Of the predators, leopards, lynx, caracal, jackal, hyena, and some species of foxes are often found. There are numerous rodents - hares, jerboas, gerbils, one species of porcupine. Among the birds of Western Asia, there are many representatives of the Central Asian deserts and steppes: bustards, sand grouses, larks, desert jays, etc. Herons, flamingos, and pelicans are found near water bodies. The diversity of reptiles, especially lizards, snakes is also very large: steppe boa constrictor, viper viper (Vipera lebetina), horned viper (Vipera ammodites), snakes, snakes. An abundance of arthropods is characteristic, often causing great harm to people. Among them are phalanxes, scorpions, tarantulas. Crops of agricultural crops periodically suffer from locusts.
The desert plateaus and mountain ranges of Central Asia have a peculiar fauna and stand out as a special Central Asian zoogeographic subregion. It is characterized by the general relative poverty of the species composition and the predominance of ungulates and rodents, which are adapted to exist in the vast treeless and waterless spaces of the central regions of Asia.
Some animals are limited in their distribution to certain regions of Central Asia, while others are settled throughout it. So, only in Tibet and Kunlun is the wild yak (Bos mutus) found, and even there it is gradually disappearing. This large animal is content with the meager food of the high desert plateaus and feels great in the harsh continental climate, but does not tolerate high temperatures at all. The yak is one of the most common domestic animals in Central Asia. They are used for carrying heavy loads and as riding animals. Local residents eat their milk and meat, skins and wool are used to make clothes.
Orongo (Pantholops hodgsoni), addax (Addax nasomaculatus), mountain sheep argali, or argali (Ovis ammon), reaching enormous sizes, mountain goats are widespread in the Tibetan Plateau and in the mountains of Central Asia. On the steppe and semi-desert plains of Mongolia and Northwest China, there are gazelles (Procapra gutturosa), wild ass, kulan (Equus hemmionus) and the extremely rare kiang (Equus kiang), as well as the wild Bactrian camel (Camelus bactrianus) - the ancestor of the domestic camel. This typical animal of deserts and dry steppes does not live in mountains and areas with a humid climate. Camels are used on the plains of Central and Central Asia as a means of transportation and draft power. Local residents feed on their milk, fat and meat, and make clothes from wool.
Predators are not as diverse in Central Asia as ungulates. Snow leopard irbis (Uncia uncia), Tibetan subspecies of brown bear and wolf are found in the mountains. Almost everywhere there are foxes, common wolf, weasel, jackal.
On the plains and in the mountainous regions, both in terms of the number of species and the number of individuals, rodents are abundantly represented.
Birds are especially diverse in mountainous areas. These are mountain turkeys, snowcocks, Tibetan saja (Syrrhaptes tibetanus), alpine jackdaws, vulture, lamb, chough, wall climber. Bustards, sandgrouse, and larks (small, crested, etc.) are found on the plains.
There are few reptiles and amphibians in Central Asia. Some lizards and snakes, a land tortoise are widespread.
The rest of the southern part of Eurasia falls within the limits of the Indo-Malayan zoogeographical region and is characterized by especially great richness, diversity and antiquity of the animal world. The fauna of the region has a pronounced tropical character and features common with other tropical regions of the globe, for example, with the Ethiopian region of Africa, with the Neotropics. In addition, former ties with Australia had a significant impact on the fauna. The Malay Peninsula, the Sunda and Philippine Islands, united in the Malay subregion, are distinguished by the greatest wealth and colorfulness of the animal world. The uniformly hot and humid climate and the predominance of tropical rainforests, as well as the insular nature of the territory, which had lost land connections with other parts of Asia since the beginning of the Quaternary, determined the great originality and endemism of the fauna of this subregion.
The most prominent representatives of the ungulates of the Malay Archipelago are the black-backed, or two-colored, tapir (Tapirus indicus), which has relatives in South America, the one-horned Indian and two-horned Sumatran rhinoceros (Rhinoceros unicornis and Dicerorhinus sumatrensis), the banteng wild bull (Bos javanicus), which became the ancestor of the Balinese domestic cattle, Indian buffalo (Bubalus arnee), gaur (Bos gaurus). In the mountains and uplands, in forests little visited by people, a small muntjac deer (Muntiacus muntjak) is common.
Of the predators, the Malayan short-haired "sunny" bear (Helarctos malayanus) and the tiger should be mentioned. On the islands of Sumatra and Kalimantan, there is a great ape orangutan ("forest man"), which is now extremely rare (Appendix 9).
Representatives of the gibbon family, the subfamily of marmosets, and some species of macaques are ubiquitous. Tupai, close to primates and insectivores, and primitive primates, tarsiers, are characteristic.
A feature of the fauna of the islands is the presence of a large number of species of "planning" animals. Among them are mammals - flying squirrels and woolly wings, which are a form intermediate between insectivores, bats and semi-monkeys; reptiles - a flying dragon (Dracovolans) - a lizard whose limbs are equipped with a flying membrane.
Among the birds, the bright argus pheasant (Argusianus argus), the blue-winged peacock (Pavo muticus) and immigrants from Australia - birds of paradise and big-legged chickens are remarkable.
Reptiles amaze with an abundance of species and large sizes. On the small island of Komodo lives the greatest of modern lizards - a giant Komodo monitor lizard (Varanus Komodensis), reaching 3-4 m in length. A large gharial crocodile lives in the rivers of Kalimantan. There are many poisonous snakes, of which the most dangerous to humans are spectacled snakes, or cobras. Boas are also common. The largest of them - the reticulated python (Python reticulatus) - reaches a length of 8-10 m and a mass of 100 kg. It is dangerous not only for large animals, but also for humans.
Among the various arthropods, large and brightly colored butterflies are especially significant. Scorpions and huge tarantulas are also common.
The islands of Sulawesi and Lesser Sunda occupy a special place in zoological terms. Sulawesi's endemic animals include the wild boar babirussa (Babyrossa babyrussa), the dwarf anoa buffalo (Bubalus depressicornis) and black macaques, while the Australian fauna includes marsupial couscous, large-legged chickens and many other birds.
In a special Indian subregion, India, Sri Lanka and Indochina are distinguished. In the composition of the fauna of this subregion, along with many typical representatives of the Indo-Malay region, there are immigrants from the Ethiopian region and the Holarctic. The fauna of the Indian subregion is distinguished by species diversity and a large number of individuals. This is especially true for India, where the killing of any living beings is prohibited by religion, so even harmful animals are very rarely exterminated here.
In the fauna of India and Indochina, the presence of the Indian elephant is characteristic. Wild elephants are still found in the sparsely populated areas of the foothills of the Himalayas, in the forests of Sri Lanka and other places. The domestic elephant, accustomed to perform difficult and complex work, is one of the most typical animals of India and the countries of Indochina.
The local population also tames a wild bull - gaura (gayala). The Indian buffalo is domesticated and widely distributed as working cattle. Wild Indian wild boar is often found in dense riverside thickets. Large nilgai (Boselaphus tragocamelus) and four-horned antelope (Tetracerus quadricornis), muntjac and axis deer (Cervus axis) live in those areas where significant forests have been preserved - one of the most beautiful representatives of this family, living in forest areas rich in water . Of the predators, the tiger, leopard and a special form of the leopard, the black panther, are common, causing significant damage to cattle breeding. Within the Thar Desert, a lion is occasionally found, which has penetrated here from the Ethiopian region.
India and Indochina are characterized by an abundance of monkeys, which are distributed everywhere: in forests, savannahs, gardens, near settlements and even in cities. They eat fruits and spoil crops, causing great damage to the population. Dog-like monkeys are found in India, and gibbons, macaques, and others are found in Indo-China. Within the subregion, both in forests and near human habitation, semi-monkeys, or lemurs, live. For Indochina, as well as for the islands, woolly wings are characteristic.
The real disaster for the local population is the abundance of various reptiles, especially poisonous snakes, from the bites of which thousands of people die every year. In the waters of the Ganges and other large rivers, giant crocodiles (Gavialis gangeticus) are found, reaching 6 m in length.
The world of birds amazes with the brightness of plumage and variety of forms. Among them are the common peacock (Pavo cristatus), pheasant, species of wild chickens from which domestic breeds originate, various thrushes, etc. Of the insects, there are especially many different motley-colored butterflies, giant tarantulas that feed on small birds. In India, there is a wild bee - the ancestor of the domestic bee.
The direct destruction of valuable species of plants and animals (hunting, poaching, illegal trade), and most importantly, the change in their habitats as a result of anthropogenic impact, have led to the fact that many species of Eurasian fauna are endangered. These are 471 species of mammals, 389 species of birds, 276 species of fish, 85 species of reptiles and 33 species of amphibians. About two thirds of all Asian wildlife habitats have been destroyed. In China, one of the 12 "megadiverse" countries in the world, 15-20% of species are threatened with extinction. Of the seven endemic mammal species of Western Asia, four (Arabian leopard, striped hyena, Arabian tahr and Arabian wolf) are endangered. The situation with the loss of species and their habitats in Western Europe is practically not improving.
Conclusion
As a result of writing the work, the following conclusions can be drawn.
Eurasia with islands accounts for 53.4 million km 2, i.e. 37% of the land area. It stretches from the Atlantic to the Pacific, from the Arctic to the equator. It is crossed by all geographical zones and zones of the Northern Hemisphere. This continent includes two large regions - Europe and Asia.
Eurasia is distinguished by a significant complexity of its geological history and a mosaic of geological structure. The surface of Eurasia has a complex structure. Vast plains and mountain belts are located differently than on other continents, where mountains are located on the outskirts of the continents. The mountains in Eurasia are also located in the depths of the mainland, they seem to connect two huge mountain belts. One (Pacific) stretches from north to south to the east of the continent. It is formed at the boundaries of the lithospheric plates, where intensive movements of the earth's crust take place. Another mountain belt (Albian-Himalayan) is located in the south and stretches from the Atlantic Ocean to the Pacific. It is this belt that conditionally connects the two strips of plains. To the north of it lie the East European, West Siberian, Turan plains, the Kazakh hills, the Central Siberian plateau and the Great Chinese Plain. To the south are the Arabian and Deccan plateaus, the Mesopotamian and Indo-Gangetic lowlands. The relief of Eurasia was formed around several lithospheric plates, which were connected by folded belts of different ages. Eurasia is similar to several continents soldered into a single whole. Earthquakes are frequent in folded belts, volcanoes erupt. In addition to internal processes, external processes also had a great influence on the relief: ancient glaciation, the work of flowing waters, winds, weathering processes, which are especially intense in areas with a continental climate. The complex structure of the earth's crust is the reason for the wide variety of minerals in Eurasia.
In Eurasia, from south to north, there are geographical zones of the equatorial, subequatorial, tropical, subtropical, temperate and subarctic zones. On the humid oceanic margins, they are represented mainly by various forest zones, and inside the mainland they are replaced by steppes, semi-deserts and deserts.
Climatic conditions in Eurasia change more sharply than on other continents, not only from north to south, but also from west to east.
Eurasia is rich in inland waters. Many of the world's major rivers flow through it. The lakes of Eurasia stand out for their size and depth. Since the relief and climate of different parts of Eurasia are not the same, rivers and lakes are distributed very unevenly across the mainland.
More than half of Eurasia in floristic and faunal terms belongs to the Holarctic, in many areas of which there is a depletion of the organic world as a result of recent uplifts, glaciations, and the advance of the seas. The south of Eurasia is occupied by the flora of the Paleotropical region and the fauna of the Indo-Malay region mainly. Eurasia differs from other continents in the particularly extensive distribution of taiga-frozen, podzolic, and desert-steppe types of soil formation, as well as in the variety of types of mountain soils. The main changes in soils and in the organic world occur with a change in latitude (from the tundra, through the forest zones of the temperate zone to the steppes, deserts, various zones of the subtropical belt, savannahs, dry tropical and humid equatorial forests), as well as with distance from the oceans and with the change high-altitude zones in the mountains.
On the vast territory of Eurasia, more fully than on other continents, the planetary law of the geographical zonality of the land landscapes of the Earth is manifested. All geographic zones of the northern hemisphere and the corresponding types of natural zones are expressed here.
As a rule, the zones are latitudinally extended from west to east. However, the large extent of Eurasia from west to east causes significant differences in nature between the oceanic and continental sectors of the continent. On the humid oceanic margins forest natural zones predominate, in the interior of the mainland they are replaced by steppes, semi-deserts and deserts.
The widest part of Eurasia is located in the temperate and subtropical zones. Due to the complexity of the relief of this territory, the alternation of vast plains and high uplands, framed by high mountain ranges, the natural zones are not only elongated in the latitudinal direction, but also have the shape of concentric circles or giant ovals.
In the tropical latitudes of the mainland, the monsoon type of climate and the meridional arrangement of mountain ranges-barriers contribute to the change of natural zones in the meridional direction.
In areas of mountainous relief, widely represented in Eurasia, latitudinal and meridional zonality are combined with vertical zonality of landscapes. The number of altitudinal belts increases with the transition from high to low latitudes (from arctic to equatorial latitudes).
More than half of Eurasia in floristic and faunal terms belongs to the Holarctic, in many areas of which there is a depletion of the organic world as a result of the latest uplift, glaciation, and the advance of the seas. The south of Eurasia is occupied by the flora of the Paleotropical region and the fauna mainly of the Indo-Malay region. Eurasia differs from other continents in the particularly extensive distribution of taiga-frozen, podzolic and desert-steppe types of soil formation, as well as in the diversity of mountain soil types. The main changes in soils and in the organic world occur with a change in latitude (from the tundra, through the forest zones of the temperate zone to the steppes, deserts, various zones of the subtropical belt, savannahs, dry tropical and humid equatorial forests), as well as with distance from the oceans and with the change high-altitude zones in the mountains.
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Applications
Annex 1
Average annual runoff layer in Eurasia
Appendix 2
Floristic zoning of Eurasia
Annex 3
European forest damage (% of total forest area)
. Appendix 4
Distribution of some plants in foreign Europe
Annex 5
Distribution of some plants in overseas Asia
Appendix 6
Centers of origin of cultivated plants (according to N.I. Vavilov)
Annex 7
Faunistic zoning of Eurasia
Annex 8
Distribution of some animals in foreign Europe
Annex 9
Distribution of some animals in overseas Asia
