1. Structure and properties of the geographical shell
2. Natural complexes of land and ocean
3. Natural zoning
4. Human development of the Earth. Countries of the world
1. Structure and properties of the geographical shell
Before the appearance of life on Earth, its outer, single shell was made up of three interconnected shells: the lithosphere, the atmosphere and the hydrosphere. With the advent of living organisms - the biosphere, this outer shell has changed significantly. All its components - components - have also changed. The shell of the Earth, within which the lower layers of the atmosphere, the upper parts of the lithosphere, the entire hydrosphere and the biosphere mutually penetrate each other and interact, is called the geographic (earth) shell. All components of the geographic shell do not exist in isolation; they interact with each other. Thus, water and air, penetrating through cracks and pores deep into rocks, participate in weathering processes, change them and at the same time change themselves. Rivers and groundwater, moving minerals, participate in changes in relief. Rock particles rise high into the atmosphere during volcanic eruptions and strong winds. A lot of salts are contained in the hydrosphere. Water and minerals are part of all living organisms. Living organisms, dying, form huge strata of rocks. Different scientists draw the upper and lower boundaries of the geographic envelope in different ways. It has no sharp boundaries. Many scientists believe that its thickness is on average 55 km. Compared to the size of the Earth, it is a thin film.
As a result of the interaction of components, the geographical shell has properties inherent only to it.
Only here are substances present in solid, liquid and gaseous states, which is of great importance for all processes occurring in the geographical envelope, and above all for the emergence of life. Only here, near the solid surface of the Earth, life first arose, and then man and human society appeared, for the existence and development of which there are all the conditions: air, water, rocks and minerals, solar heat and light, soil, vegetation, bacterial and animal life .
All processes in the geographic envelope occur under the influence of solar energy and, to a lesser extent, internal earthly energy sources. Changes in solar activity affect all processes of the geographic envelope. For example, during periods of increased solar activity, magnetic storms increase, the rate of plant growth, reproduction and migration of insects changes, and the health of people, especially children and the elderly, worsens. The connection between the rhythms of solar activity and living organisms was shown by the Russian biophysicist Alexander Leonidovich Chizhevsky back in the 20-30s. XX century
The geographic envelope is sometimes called the natural environment or simply nature, meaning mainly the nature within the boundaries of the geographic envelope.
All components of the geographic shell are connected into a single whole through the circulation of substances and energy, due to which the exchange of substances between shells takes place. The circulation of matter and energy is the most important mechanism of natural processes of the geographical envelope. There are various cycles of substances and energy: air cycles in the atmosphere, the earth’s crust, water cycles, etc. For the geographic envelope, the water cycle, which occurs due to the movement of air masses, is of great importance. Water is one of the most amazing substances of nature, characterized by great mobility. The ability to change from a liquid to a solid or gaseous state with minor changes in temperature allows water to accelerate various natural processes. Without water there can be no life. Water, being in the cycle, enters into close interactions with other components, connects them with each other and is an important factor in the formation of the geographical envelope.
The biological cycle plays a huge role in the life of the geographic envelope. In green plants, as is known, organic substances are formed from carbon dioxide and water in the light, which serve as food for animals. Animals and plants, after they die, are decomposed by bacteria and fungi into minerals, which are then reabsorbed by green plants. The same elements repeatedly form the organic substances of living organisms and repeatedly return to the mineral state.
The leading role in all circulations belongs to the air circulation in the troposphere, which includes the entire system of winds and vertical air movement. The movement of air in the troposphere draws the hydrosphere into the global cycle, forming the global water cycle. The intensity of other cycles also depends on it. The most active cycles occur in the equatorial and subequatorial belts. In the polar regions, on the contrary, they proceed especially slowly. All cycles are interconnected.
Each subsequent cycle is different from the previous ones. It does not form a vicious circle. Plants, for example, take nutrients from the soil, and when they die, they give them back much more, since the organic mass of plants is created mainly by atmospheric carbon dioxide, and not by substances coming from the soil. Thanks to the cycles, the development of all components of nature and the geographic envelope as a whole occurs.
What makes our planet unique? Life! It is difficult to imagine our planet without plants and animals. In a wide variety of forms, it permeates not only the water and air elements, but also the upper layers of the earth's crust. The emergence of the biosphere is a fundamentally important stage in the development of the geographical envelope and the entire Earth as a planet. The main role of living organisms is to ensure the development of all life processes, which are based on solar energy and the biological cycle of substances and energy. Life processes consist of three main stages: the creation of primary production as a result of photosynthesis of organic matter; transformation of primary (plant) products into secondary (animal) products; destruction of primary and secondary biological products by bacteria and fungi. Without these processes life is impossible. Living organisms include: plants, animals, bacteria and fungi. Each group (kingdom) of living organisms plays a specific role in the development of nature.
Life on our planet arose 3 billion years ago. All organisms over the course of billions of years developed, settled, changed in the process of development and, in turn, influenced the nature of the Earth - their habitat.
Under the influence of living organisms, there is more oxygen in the air and a decrease in carbon dioxide content. Green plants are the main source of atmospheric oxygen. Another thing was the composition of the World Ocean. Rocks of organic origin appeared in the lithosphere. Deposits of coal and oil, most limestone deposits are the result of the activity of living organisms. The result of the activity of living organisms is also the formation of soils, thanks to the fertility of which plant life is possible. Thus, living organisms are a powerful factor in the transformation and development of the geographical envelope. The brilliant Russian scientist V.I. Vernadsky considered living organisms to be the most powerful force on the earth's surface in terms of their final results, transforming nature.
2. Natural complexes of land and ocean
The geographical envelope, being integral, is heterogeneous at different latitudes, on land and in the ocean. Due to the uneven supply of solar heat to the earth's surface, the geographical envelope is very diverse. Near the equator, for example, where there is a lot of heat and moisture, nature is distinguished by the richness of living organisms, faster-moving natural processes, in the polar regions, on the contrary, slow-flowing processes and poverty of life. At the same latitudes, nature can also be different. It depends on the terrain and distance from the ocean. Therefore, the geographic envelope can be divided into areas, territories, or natural-territorial complexes of different sizes (abbreviated as natural complexes, or PC). The formation of any natural complex took a long time. On land, it was carried out under the influence of the interaction of natural components: rocks, climate, air masses, water, plants, animals, soils. All components in the natural complex, as in the geographical shell, are intertwined with each other and form an integral natural complex; metabolism and energy also occur in it. A natural complex is a section of the earth's surface that is distinguished by the characteristics of natural components that are in complex interaction. Each natural complex has more or less clearly defined boundaries and has a natural unity, manifested in its external appearance (for example, a forest, a swamp, a mountain range, a lake, etc.).
Natural complexes of the ocean, unlike land, consist of the following components: water with gases dissolved in it, plants and animals, rocks and bottom topography. In the World Ocean there are large natural complexes - individual oceans, smaller ones - seas, bays, straits, etc. In addition, in the ocean there are natural complexes of surface layers of water, various layers of water and the ocean floor.
Natural complexes come in different sizes. They also differ in education. Very large natural complexes are continents and oceans. Their formation is determined by the structure of the earth's crust. On continents and oceans, smaller complexes are distinguished - parts of continents and oceans. Depending on the amount of solar heat, i.e. on geographic latitude, there are natural complexes of equatorial forests, tropical deserts, taiga, etc. Examples of small ones include, for example, a ravine, lake, river valley, sea bay. And the largest natural complex of the Earth is the geographical envelope.
Obviously, the structure of the geographical shell depends on a specific region, therefore it consists of individual natural complexes.
Natural complexes of the Earth
The geographical envelope has a mosaic structure, this is due to the different natural complexes that are included in it. The part of the earth's surface that has the same natural conditions is usually called a natural complex.
Homogeneous natural conditions are relief, water, climate, soil, flora and fauna. Individually, natural complexes consist of components that are interconnected by historically established connections.
That is why, if a change occurs in one of the components of nature, then all the components of the natural complex change.
The geographic envelope is a planetary natural complex and the largest. The shell is divided into smaller natural complexes.
Types of natural complexes
The division of the shell into separate natural complexes is due to the heterogeneity of the earth's surface and the structure of the earth's crust, as well as the uneven amount of heat.
Due to these differences, natural complexes are classified into zonal and azonal.
Azonal natural complexes
The main azonal natural complexes are oceans and continents. They are the largest in size. Smaller areas are considered to be flat and mountainous areas that are located on continents.
For example, the Caucasus, West Siberian Plain, Andes. And these natural complexes can be divided into even smaller ones - the Southern and Central Andes.
River valleys, hills, and various slopes that are located on their territory will be considered even smaller natural complexes.
Interrelation of components of natural complexes
The interrelation of the components of natural complexes is a unique phenomenon.
This can be seen using a simple example: if the amount of solar radiation and its impact on the earth’s surface changes, then the nature of vegetation in a given area will also change. This transformation will lead to changes in soil and relief formation.
Human impact on natural complexes
Human activities have had a significant impact on natural systems since ancient times. After all, man not only adapts to the nature of the Earth, but also exerts a constant and extensive influence on it.
Over the centuries, man has improved his skills and created different ways to use nature to his advantage. This had an extremely negative impact on the development of most natural complexes.
It is for this reason that people are increasingly talking about such a phenomenon as rational environmental management. This concept is usually understood as human activity aimed at careful development of natural complexes and conservation of natural resources in any circumstances.
Several million years ago, forests covered approximately 80% of the Earth's land area. Over the past 10 thousand years, our planet has lost 2/3 of the forest vegetation that covered it.
Currently, forests occupy about a third of the land surface (not including the area of Antarctica). The areas occupied by forests continue to decline every year.
Geographical feature (meaning of forests)
A forest is a natural complex that consists of woody plants of one or many species growing close to each other and forming a canopy of partially or completely closed crowns, many organisms of other kingdoms in combination with soils, surface waters and the adjacent layer of the atmosphere. All components of the forest ecosystem influence each other and also interact with all other ecosystems of the planet, including the human ecosystem.
The forest is of global importance because it has a significant impact on the Earth's climate, surface and underground water flows and soil formation. Russian scientists G.F. and V.N. Sukachev were the first to highlight the global role of forests as an accumulator of living matter in the planet’s biosphere.
Thanks to photosynthesis, the forest accumulates and transforms solar energy, producing oxygen. It is actively involved in global carbon cycles. Climate change and the problem of greenhouse gases are largely associated with the destruction of forest ecosystems.
Characteristics of forests
There are two world forest belts: Northern and Southern. The North includes Russia, Finland, Sweden, Canada and the United States, and the South includes Southeast Asia, the Amazon and the Congo Basin.
Based on natural-territorial characteristics, it is customary to distinguish forests by continents and large regions:
- European,
- forests of Eastern Europe,
- Far Eastern,
- Siberian,
- forests of Southeast Asia,
- forests of North America
and others.
Natural areas and forest types
Within natural territorial zones, a description of the tree species composition and climatic characteristics are used. The world's forests are divided into tropical forests and temperate forests.
Tropical rain forests have lower and montane zones. They grow during the rainy season. These equatorial evergreen forests are distinguished by a huge diversity of flora and fauna. These include the forests of the Amazon, the Congo Basin and the jungles of India. The height of the trees here reaches tens of meters. Ficus and palm trees grow in the upper tier, and lianas and tree ferns grow below. More than half of this type of forest has already been cleared.
Dry tropical deciduous and montane forests shed during drought and vegetate during the rainy season. They are also known as "caatinga", which means "white forest" in the Tupi-Guarani language.
Temperate forests include broad-leaved, small-leaved, taiga and mixed forest types.
Temperate broadleaf forests are located in Central Europe, eastern North America, eastern China, the mountainous regions of the Crimea, the Caucasus and the Carpathians, the Russian Far East, New Zealand, and Japan. The tree species include oak, elm, linden, chestnut, sycamore, and hornbeam. All that remains of the ancient broad-leaved forests are small green islands in nature reserves and rugged areas.
Taiga forests with coniferous trees occupy the most extensive area. They include most of the forests of Siberia.
Broad-leaved and coniferous forests are usually replaced by small-leaved forests. This type of forest is characterized by various species of birch, alder, poplar, aspen, and willow. Their wood is much softer than that of broad-leaved trees, which is why these forests are also called soft-leaved. They make up a significant part of Russia's forests, with birch forests predominating.
Mixed forests include broad-leaved, coniferous and small-leaved and coniferous tree species and occupy a range in Central and Western Europe.
Forest climate
A humid and hot equatorial climate, where all year round the temperature does not drop below 24 - 28 ° C - conditions for the growth of tropical rainforests. Heavy rains occur here often, the amount of precipitation is up to 10,000 mm per year. The dry season alternates here with tropical downpours with air humidity of 80%.
Dry tropical forests have to overcome drought and heat for 4 to 6 months a year. They receive from 800 to 1300 mm of precipitation per year.
The climate of the taiga ranges from mild maritime in the west to sharply continental in the east, where in winter frosts can reach -60°C. The amount of precipitation ranges from 200 to 1000 mm. In permafrost conditions, moisture stagnates, which leads to the formation of swampy woodlands.
The temperate continental climate of mixed and deciduous forests is relatively mild and quite warm in summer, with long and cold winters. The average annual precipitation is approximately 700 mm. If humidity is excessive and evaporation is insufficient, waterlogging processes begin.
The largest forests in the world
Even in authoritative sources there is a statement that the largest forests are located in the Amazon basin. But actually it is not. The primacy belongs to the taiga. It occupied the boreal zone of Eurasia, Canada and Alaska, was located in North America, on large territories in Finland, Sweden and Norway, and stretched across the entire territory of Russia. Its area is 10.7 million square meters. km.
- Name several natural complexes in your area. Briefly describe one of them and indicate the relationships between the components.
- From natural history and biology courses, remember how soils are formed and what kind of soils you know.
Natural sushi complexes. The geographical envelope, being integral, is heterogeneous at different latitudes, on land and in the ocean.
Due to the uneven supply of solar heat to the earth's surface, the geographical envelope is very diverse. Near the equator, for example, where there is a lot of heat and moisture, nature is distinguished by the richness of living organisms, faster-moving natural processes, in the polar regions, on the contrary, slow-flowing processes and poverty of life. At the same latitudes, nature can also be different. It depends on the terrain, on the distance from the ocean. Therefore, the geographic envelope can be divided into areas, territories, or natural-territorial complexes of different sizes (abbreviated as natural complexes, or PC).
The formation of any natural complex took a long time. On land, it was carried out under the influence of the interaction of natural components: rocks, climate, air masses, water, plants, animals, soils (Fig. 32). All components in the natural complex, as in the geographical shell, are intertwined with each other and form an integral natural complex; metabolism and energy also occur in it. A natural complex is a section of the earth's surface that is distinguished by the characteristics of natural components that are in complex interaction. Each natural complex has more or less clearly defined boundaries and has a natural unity, manifested in its external appearance (for example, a forest, a swamp, a mountain range, a lake, etc.).
Rice. 32. Relationships between the components of the natural complex
Natural complexes of the ocean, unlike land, consist of the following components: water with gases dissolved in it, plants and animals, rocks and bottom topography. In the World Ocean there are large natural complexes - individual oceans, smaller ones - seas, bays, straits, etc. In addition, in the ocean there are natural complexes of surface layers of water, various layers of water and the ocean floor.
Variety of natural complexes. Natural complexes come in different sizes. They also differ in education. Very large natural complexes are continents and oceans. Their formation is determined by the structure of the earth's crust. On continents and oceans, smaller complexes are distinguished - parts of continents and oceans. Depending on the amount of solar heat, i.e. on geographic latitude, there are natural complexes of equatorial forests, tropical deserts, taiga, etc. Examples of small ones include, for example, a ravine, lake, river valley, sea bay. And the largest natural complex of the Earth is the geographical envelope.
All natural complexes experience enormous human influence. Many of them have already been greatly changed by centuries of human activity. Man has created new natural complexes: fields, gardens, cities, parks, etc. Such natural complexes are called anthropogenic (from the Greek “anthropos” - man).
- Using the text of the textbook, write down the components of the geographical shell in the left column of your notebook, the components of the natural complexes of the land in the middle column, and the components of the natural complexes of the ocean in the right column. What do the components of each natural complex have in common?
- What is a natural complex?
- How do natural complexes differ?
The geographical envelope is not tripled equally everywhere, it has
"mosaic" structure and consists of individual natural complexes
(landscapes). Natural complex – This is a part of the earth's surface with relatively homogeneous natural conditions: climate, topography, soils, waters, flora and fauna.
Each natural complex consists of components between which there are close, historically established relationships, and a change in one of the components sooner or later leads to a change in the others.
The largest planetary natural complex is
geographical envelope, it is divided into natural complexes of a smaller rank. The division of the geographical envelope into natural complexes is due to two reasons: on the one hand, differences in the structure of the earth's crust and the heterogeneity of the earth's surface, and on the other, the unequal amount of solar heat received by its different parts. In accordance with this, zonal and azonal natural complexes are distinguished.
The largest azonal natural complexes are continents and oceans. Smaller ones are mountainous and flat areas within the continents (West Siberian Plain, Caucasus, Andes, Amazonian Lowland). The latter are divided into even smaller natural complexes (Northern, Central, Southern Andes). Natural complexes of the lowest rank include individual hills, river valleys, their slopes, etc.
The largest of the zonal natural complexes are geographical zones. They coincide with climatic zones and have the same names (equatorial, tropical, etc.). In turn, geographical zones consist of natural zones, which are distinguished by the ratio of heat and moisture.
Natural area is a large area of land with similar natural components - soils, vegetation, wildlife, which are formed depending on the combination of heat and moisture.
The main component of a natural area is climate, since all other components depend on it. Vegetation has a great influence on the formation of soils and fauna and is itself dependent on soils. Natural zones are named according to the nature of their vegetation, since it most obviously reflects other features of nature.
The climate naturally changes as it moves from the equator to the poles. Soil, vegetation and fauna are determined by climate. This means that these components should change latitudinally, following climate change. The natural change of natural zones when moving from the equator to the poles is called latitudinal zonality. At the equator there are humid equatorial forests, and at the poles there are icy arctic deserts. Between them are other types of forests, savannas, deserts, and tundra. Forest zones, as a rule, are located in areas where the ratio of heat and moisture is balanced (equatorial and most of the temperate zone, eastern coasts of continents in the tropical and subtropical zone). Treeless zones form where there is a lack of heat (tundra) or moisture (steppes, deserts). These are continental regions of the tropical and temperate zones, as well as the subarctic climate zone.
The climate changes not only in latitude, but also due to changes in altitude. As you go up the mountains, the temperature drops. Up to an altitude of 2000-3000 m, the amount of precipitation increases. A change in the ratio of heat and moisture causes a change in soil and vegetation cover. Thus, different natural zones are located in the mountains at different altitudes. This pattern is called altitudinal zone.
The change in altitudinal zones in the mountains occurs in approximately the same sequence as on the plains, when moving from the equator to the poles. At the foot of the mountains there is a natural area in which they are located. The number of altitudinal zones is determined by the height of the mountains and their geographical location. The higher the mountains, and the closer they are located to the equator, the more diverse the set of altitudinal zones. Vertical zonality is most fully expressed in the Northern Andes. In the foothills there are moist equatorial forests, then there is a belt of mountain forests, and even higher - thickets of bamboo and tree ferns. With an increase in altitude and a decrease in average annual temperatures, coniferous forests appear, which are replaced by mountain meadows, often turning into rocky areas covered with moss and lichens. The peaks of the mountains are crowned with snow and glaciers.
Ice zone
Ice zone occupies the very north of our country and includes the Arctic Ocean and islands. Its southern border runs approximately along the parallel of 71° N. w. The northern position determines the severity of the natural conditions of the zone; ice and snow cover lies here almost throughout the year.
Seasons in the ice zone they are very peculiar. in winter The polar night prevails, which is at a latitude of 75° N. w. lasts 98 days, at latitude 80° - 127 days, and in the pole area - six months. At this time, auroras often flash in the sky. At times they illuminate the sky for several days, but more often the radiance lasts an hour and a half.
Summer characterized by bright round-the-clock lighting, but lack of heat. The air temperature remains very low in summer and rarely rises above 0°. the average temperature of the warmest month does not exceed +5°C. The sky is sometimes overcast with gray low clouds, and for several days there is drizzling rain, turning into snow. Fogs are frequent. There are almost no thunderstorms or showers. Despite the cold summer, the snow cover in open areas melts and the surface soil thaws. Before the snow has melted, arctic plants begin to turn green and bloom on the islands: poppies and saxifrage. Bright flowers next to snow are a common summer sight.
Appear in summer animals, which are almost invisible in winter: polar bear, arctic fox, pied, as well as birds arriving from the south: gulls, guillemots, guillemots, auks, etc. Many birds They make nests on coastal rocks and form so-called bird colonies. Summer is short. In August, the temperature already drops below 0°, the frosts intensify, and snow covers the ground with a continuous blanket. In spring and autumn, for some time there is a change of day and night during the day.
Much of the Arctic Ocean is covered with floating ice throughout the year. The thickness of first-year ice reaches 1.8 m, multi-year ice - 3-4 m, hummocky ice - up to 20-25 m.
There is almost no permanent population in the ice zone. Weather stations have been built on the islands and the mainland to monitor the weather and ice movement. Observational data is transmitted to Moscow, to the hydrometeorological center, where they are processed and plotted on special maps.
In the central part of the Arctic Ocean, “North Pole” stations are set up, drifting on ice fields. Winterers at these stations study the condition of the ice, take measurements of the seabed, establish the direction of ice drift and make many other important scientific observations. The first station was organized in 1937. Since 1975, the North Pole - 23 station has been operating.
On the Arctic islands they hunt Arctic foxes in winter and game birds in summer. There are many different fish in the waters of the Barents Sea, which are caught and processed on special vessels. The base of the trawl fishing fleet is the port of Murmansk.
Tundra zone
Word " tundra" comes from Finnish " tunturi", which means " flat treeless hill" Indeed, the absence of trees is the most striking, eye-catching feature tundra zones.
Tundras are widespread mainly in the Northern Hemisphere - in Eurasia and North America. The tundra zone, an almost continuous belt, stretches across the northernmost territories of the continents around the North Pole, as scientists say, circumpolarly (“circum” in Latin - “around”: remember the round arena of the circus).
In the Southern Hemisphere there is very little land near Antarctica - mostly ocean. Therefore, there are very few tundras there and they are located on small islands around the southern mainland and in the mountains of Patagonia.
The areas occupied by tundra zones are much larger than is commonly believed. In Russia, tundras occupy the second largest area after the taiga (although together with the forest-tundra - the transition zone from it to the forest). In North America, they also occupy vast areas. Along mountain ranges, tundra landscapes in some places extend far to the south, to where on the plain taiga forests have long been replaced by steppes.
With the word " Arctic"usually associated with the idea of severe cold, snowstorms and the lack of "necessary conditions for life. And indeed, such an opinion is not without foundation - after all, summer in the tundra it is cold, short and light. Cold - because even in summer frosts are not uncommon, and the average monthly temperature of the warmest month does not exceed 10 C. Short - because it lasts no more than 2 - 2.5 months. And it’s bright because at this time the sun does not set below the horizon and stays there all day long polar day. In addition, there is very little precipitation in the tundra, no more than in the desert. But it seems like there is a lot of water. There are large and small lakes, rivers, swamps all around, wet moss squelches under your feet. This is due to the fact that the sun, although it does not set beyond the horizon, still heats weakly and evaporates very slowly. In addition, in the summer in the tundra, only the top layer of permafrost thaws, and even then not for long, while the lower, icy layer does not allow water to seep deeper.
The surrounding tundra zone is cold and damp. In such harsh conditions, it is difficult for true soil to develop. All processes proceed sluggishly, as if reluctantly, and the result is appropriate - the soils are only primitive, with barely defined layers, most of which are occupied by the semi-decomposed remains of mosses, grasses and shrubs - peat.
Although the tundra zone is spread over vast areas, the diversity of plant species here is very small. In some areas their number is 200 - 300, and in the north - less than 100. No other landscapes, except desert ones, seem so monotonous. It is interesting that tundra landscapes located far from each other, even at different ends of the continents, have almost the same set of plant species. One of the explanations for this “unanimity” is that in winter, the fruits and seeds of tundra plants are well spread by the wind over snow or ice, crossing land and sea without hindrance.
On the southern border of the tundra zone, small groups of trees are occasionally found. They made a depressing impression on the Russian ethnographer V.L. Seroshevsky: “ This forest is pathetic. Prematurely aged, covered with bearded lichens, with liquid, yellowish greenery on the few living shoots. The trees are sick, ugly, covered with a mass of warts, twigs, and branches. They provide almost no shade or protection at all; in such a forest you see the sky everywhere in front of you».
And yet the tundra can be attractive and understandable to the eye. Imagine the never setting sun, small courageous plants rushing to bloom their dim but numerous flowers, the blue surface of the water. Alas, this beauty is short-lived. Both herbaceous plants and dwarf trees, hardly taller than grasses, are all in a hurry, in a hurry, in a hurry.
They are in a hurry to open the leaves, they are in a hurry to bloom and set seeds, they are in a hurry to drop them - to sow them in the inhospitable frozen soil saturated with water. If they didn’t have time, the frost was merciless, the sun would also disappear for a long time, and life would freeze for many months in anticipation of a new, such a short summer.
Topic 2. Forest zone
Forest- this is a natural (geographical) zone represented by more or less closely growing trees and shrubs of one or more species. The forest has the ability to constantly renew itself.
Mosses, lichens, grasses, and shrubs play a secondary role in the forest. Plants here influence each other, interact with their environment, forming a community of plants.
A significant area of forest with more or less clear boundaries is called a forest area. The following types of forests are distinguished:
Gallery forest. It is stretched out in a narrow strip along the river flowing among treeless spaces (in Central Asia it is called tugai forest, or tugai);
Belt bur. This is the name given to pine forests that grow in the form of a narrow and long strip on the sand. They are of great water conservation importance; their logging is prohibited;
Park forest. This is an array of natural or artificial origin with rare, individually scattered trees (for example, a park forest of stone birch in Kamchatka);
Coppices. These are small forests connecting forest areas; Grove- a section of forest, usually isolated from the main tract.
The forest is characterized by tiers - vertical division of the forest, as if into separate floors. One or more upper tiers form the crowns of trees, then there are tiers of shrubs (undergrowth), herbaceous plants and, finally, a tier of mosses and lichens. The lower the tier, the less demanding of light are its components.
kinds. Plants of different tiers interact closely and are mutually dependent. The strong growth of the upper tiers reduces the density of the lower ones, up to their complete disappearance, and vice versa. There is also an underground layering in the soil: the roots of plants are located here at different depths, so numerous plants coexist well in one area. Man, by regulating the density of crops, forces the development of those tiers of the community that are valuable for the economy.
Depending on climatic, soil and other natural conditions, various forests arise.
Equatorial rainforests
This is a natural (geographical) zone stretching along the equator with some displacement south of 8° N latitude. to 11° S The climate is hot and humid. All year round, average air temperatures are 24-28 C. The seasons are not defined. At least 1500 mm of atmospheric precipitation falls, since there is an area of low pressure (see Atmospheric pressure), and on the coast the amount of atmospheric precipitation increases to 10,000 mm. Precipitation falls evenly throughout the year.
Such climatic conditions in this zone contribute to the development of lush evergreen vegetation with a complex layered forest structure. The trees here have few branches. They have disc-shaped roots, large leathery leaves, tree trunks rise like columns and only spread their thick crown at the top. The shiny, as if varnished surface of the leaves saves them from excessive evaporation and burns from the scorching sun, from the impacts of rain jets during heavy downpours. In plants of the lower tier, the leaves, on the contrary, are thin and delicate.
The equatorial forests of South America are called selva (port. - forest). This zone occupies much larger areas here than in Africa. The selva is wetter than African equatorial forests and richer in plant and animal species.
The soils under the forest canopy are red-yellow, ferrolitic (containing aluminum and iron).