Rainforests located in the tropical, equatorial and subequatorial zones between 25° north latitude. and 30° S, as if “surrounding” the surface of the Earth along the equator. Rainforests are broken only by oceans and mountains.
The general circulation of the atmosphere occurs from a zone of high atmospheric pressure in the tropical region in the zone low pressure in the equator region, evaporated moisture is transferred in the same direction. This leads to the existence of a humid equatorial zone and a dry tropical one. Between them is subequatorial belt, in which moisture depends on the direction of the monsoon, which depends on the time of year.
The vegetation of tropical forests is very diverse, depending mainly on the amount of precipitation and its distribution over the seasons. When abundant (more than 2000 mm), and relatively uniform distribution develop tropical humid evergreen forests.
Further from the equator, the rainy period gives way to a dry period, and forests are replaced by leaves falling during drought, and then these forests are replaced by savanna forests. At the same time, in Africa and South America there is a pattern: from west to east, monsoon and equatorial forests are replaced by savanna forests.
Classification of tropical forests
Tropical rainforest, tropical rain forest these are forests with specific biomes located in equatorial (equatorial rainforest), subequatorial and humid tropical areas with a very humid climate (2000-7000 mm of precipitation per year).
Wet rainforests characterized by enormous biodiversity. This is the most conducive to life natural area. Lives here a large number of own, including endemic species of animals and plants, as well as migrating animals. Two-thirds of all animal and plant species on the planet live in tropical rainforests. It is estimated that millions of animal and plant species remain undescribed.
These forests are sometimes called " jewels of the earth" And " the largest pharmacy in the world” as a large number of natural medicines have been found here. They are also called " lungs of the Earth“However, this statement is controversial because it has no scientific basis, since these forests either do not produce oxygen at all or produce extremely little of it.
But it should be borne in mind that a humid climate promotes effective air filtration due to the condensation of moisture on microparticles of pollution, which has a generally beneficial effect on the atmosphere.
Understory formation in tropical forests is severely limited in many places due to the lack of sunlight in the understory. This allows humans and animals to move through the forest. If for some reason the deciduous canopy is absent or weakened, the lower tier is quickly covered with a dense thicket of vines, shrubs and small trees - this formation is called a jungle.
The most large areas tropical rain forests are found in the Amazon River Basin (“ rain forests Amazon"), in Nicaragua, in the southern part of the Yucatan Peninsula (Guatemala, Belize), in most of Central America (where they are called "selvas"), in equatorial Africa from Cameroon to Democratic Republic Congo, in many areas of Southeast Asia from Myanmar to Indonesia and New Guinea, in the Australian state of Queensland.
For tropical rainforests characteristic:
- variety of flora,
- presence of 4-5 tree layers, absence of shrubs, large number of vines
- predominance evergreen trees with large evergreen leaves, poorly developed bark, buds not protected by bud scales, in monsoon forests– deciduous trees;
- the formation of flowers and then fruits directly on trunks and thick branches
Trees in tropical rainforests share several characteristics that are not seen in plants in less humid climates.
The base of the trunk in many species has wide, woody projections. Previously, it was assumed that these protrusions help the tree maintain balance, but now it is believed that water with dissolved nutrients flows along these protrusions to the roots of the tree. Characteristic of broad leaves of trees, shrubs and grasses lower tiers forests. Wide leaves help plants absorb better sunlight There are forests under the edges of the trees, and they are protected from the wind from above.
Tall young trees that have not yet reached the top tier also have wider foliage, which then decreases with height. The leaves of the upper tier, which form the canopy, are usually smaller and heavily cut to reduce wind pressure. On the lower floors, the leaves are often narrowed at the ends so that this facilitates the rapid drainage of water and prevents the growth of microbes and moss on them, which destroy the leaves.
Tree tops are often very well connected with each other using vine or epiphytic plants, fixed on them.
The trees of the tropical rainforest are characterized by unusually thin (1-2 mm) tree bark, sometimes covered with sharp thorns or prickles, the presence of flowers and fruits growing directly on the tree trunks, and a wide variety of juicy fruits that attract birds and mammals.
In tropical rainforests there are a lot of insects, especially butterflies (one of the richest faunas in the world) and beetles, and in rivers there are a lot of fish (about 2000 species, approximately a third of the world's freshwater fauna).
Despite the lush vegetation, the soil in tropical rainforests is thin and has a small humus horizon.
Rapid rotting caused by bacteria prevents the accumulation of a humus layer. The concentration of iron and aluminum oxides due to laterization Soil dehydration (the process of reducing silica in the soil while increasing iron and aluminum oxides) turns the soil bright red and sometimes forms mineral deposits (such as bauxite). But on rocks of volcanic origin, tropical soils can be quite fertile.
Levels (tiers) of tropical rainforest
The rainforest is divided into four main levels, each of which has its own characteristics and has different flora and fauna.
Top level
This tier consists of a small amount of very tall trees, towering above the forest canopy, reaching a height of 45-55 meters (rare species reach 60-70 meters). Most often the trees are evergreen, but some shed their leaves during the dry season. Such trees must withstand harsh temperatures and strong winds. This level is home to eagles, bats, some species of monkeys and butterflies.
Crown level (forest canopy)
The crown level is formed by most tall trees, usually 30-45 meters high. This is the densest layer known in all of Earth's biodiversity, with neighboring trees forming a more or less continuous layer of foliage.
According to some estimates, plants of this tier make up approximately 40 percent of the species of all plants on the planet - perhaps half of the entire flora of the Earth can be found here. The fauna is similar to the upper level, but more diverse. It is believed that a quarter of all insect species live here.
Scientists have long suspected the diversity of life at this level, but have only recently developed practical methods research. It was not until 1917 that the American naturalist William Beed declared that “another continent of life remains unknown, not on the earth, but 200 feet above its surface, extending over thousands of square miles.”
Real exploration of this layer only began in the 1980s, when scientists developed techniques to reach the forest canopy, such as shooting ropes into the treetops with crossbows. Forest canopy research is still in its early stages. Other research methods include hot air balloon travel or aircraft. The science of reaching treetops is called dendronautics.
Average level
Between the forest canopy and the forest floor there is another level called the understory. It is home to a number of birds, snakes and lizards. Insect life at this level is also very extensive. The leaves in this tier are much wider than at the crown level.
forest floor
In Central Africa, in the tropical primary forest of Mount Virunga, illumination at ground level is 0.5%; in the forests of southern Nigeria and in the Santarem region (Brazil) 0.5-1%. In the north of the island of Sumatra in the dipterocarp forest, the illumination is about 0.1%.
Far from the banks of rivers, swamps and open spaces, where dense, low-growing vegetation grows, the forest floor is relatively free of plants. At this level you can see rotting plants and animal remains, which quickly disappear thanks to the warm, humid climate, promoting rapid decomposition.
Selva(Spanish: " selva" from lat. " silva"- forest) is equatorial rainforests in South America. Located in countries such as Brazil, Peru, Suriname, Venezuela, Guyana, Paraguay, Colombia, etc.
The selva is formed on vast low-lying areas of land under conditions of constant freshwater moisture, as a result of which the selva soil is extremely poor in minerals washed away by tropical rains. Selva is often swampy.
Vegetable and animal world The jungle is a riot of colors and a variety of species of plants, birds and mammals.
The largest village in terms of area is located in the Amazon basin in Brazil).
In the Atlantic jungle, precipitation reaches two thousand millimeters per year, and humidity fluctuates at 75-90 percent.
The village is divided into three levels. The soil is covered with leaves, branches, trunks of fallen trees, lichens, fungus and moss. The soil itself is reddish in color. The first level of the forest consists of low plants, ferns and grass. The second level is represented by shrubs, reeds and young trees. On the third level there are trees ranging in height from twelve to forty meters.
Mangroves – evergreen deciduous forests, common in the tidal zone of sea coasts in tropical and equatorial latitudes, as well as in areas with temperate climate, where warm currents favor this. They occupy the band between the lowest water level at low tide and the highest at high tide. These are trees or shrubs growing in mangroves, or mangrove swamps.
Mangrove plants live in sedimentary coastal environments where fine sediments, often high in organic matter, accumulate in areas protected from wave energy.
Mangroves have an exceptional ability to exist and develop in a saline environment on soils deprived of oxygen.
Once established, mangrove plant roots create habitat for oysters and help slow water flow, thereby increasing sedimentation in areas where it is already occurring.
Typically, fine, oxygen-poor sediments beneath mangroves act as reservoirs for a wide variety of heavy metals (trace metals) that are captured from sea water colloidal particles in sediments. In those areas of the world where mangroves were destroyed during the development of the territory, the violation of the integrity of these sedimentary rocks gives rise to the problem of heavy metal contamination of sea water and local flora and fauna.
It is often argued that mangroves provide significant coastal value, acting as a buffer against erosion, storms and tsunamis. Although there is a definite reduction in wave height and wave energy as seawater passes through mangroves, it must be recognized that mangroves typically grow in areas of the coastline where low wave energy is the norm. Therefore, their ability to withstand the powerful onslaught of storms and tsunamis is limited. Their long-term impact on erosion rates is also likely to be limited.
Many river channels meandering through mangrove areas are actively eroding the mangroves on the outside of all river bends, just as new mangroves appear on inside the same bends where deposition occurs.
Mangroves provide habitat for wildlife, including a number of commercial fish and crustacean species, and, in at least some cases, mangrove carbon export is associated with important in the coastal food web.
In Vietnam, Thailand, the Philippines and India, mangroves are grown in coastal areas for inshore fisheries.
Despite ongoing mangrove breeding programs, More than half of the world's mangroves have already been lost..
The floristic composition of mangrove forests is relatively uniform. Mangrove forests of the eastern formation (the shores of the Malacca Peninsula, etc.) are considered the most complex, tall and multi-species.
Misty forest (moss forest, nephelogia) – tropical moist montane evergreen forest. Located in the tropics on the slopes of mountains in a zone of fog condensation.
The foggy forest is located in the tropics on the slopes of mountains in a zone of fog condensation, usually starting at altitudes of 500-600 m and reaching heights of up to 3500 meters above sea level. It is much cooler here than in the jungles located in low-lying areas; at night the temperature can drop to almost 0 degrees. But it’s even more humid here, one year a year square meter falls before six cubic meters water. And if it doesn’t rain, then the moss-covered trees stand shrouded in fog caused by intense evaporation.
Foggy forest formed by trees with abundant lianas, with a dense cover of epiphytic mosses.
Tree ferns, magnolias, camellias are characteristic; the forest may also include non-tropical vegetation: evergreen oaks, podocarpus, which distinguishes this type of forest from lowland gils
Variable tropical rainforests– forests common in tropical and equatorial zones, in climates with a short dry season. Located south and north of the wetlands equatorial forests. Variably humid forests are found in Africa (CAR, DR Congo, Cameroon, northern Angola, extreme south of Sudan), South America, India, Sri Lanka, and Indochina.
Variable rainforests are partly deciduous, dense tropical forests. They differ from tropical rainforests in less species diversity, reducing the number of epiphytes and lianas.
Dry tropical evergreen forest. Located in areas with an arid climate, while remaining dense and evergreen, they become stunted and xeromorphic.
HUMAN IMPACT ON TROPICAL FORESTS
Contrary to popular belief, tropical rainforests are not major consumers carbon dioxide and, like other established forests, are carbon neutral.
Recent studies show that most rain forests are, on the contrary, intensively produce carbon dioxide, and swamps produce methane.
However, these forests play a significant role in the circulation of carbon dioxide because they are established reservoirs, and cutting down such forests leads to an increase in carbon dioxide in the Earth's atmosphere. Tropical rainforests also play a role in cooling the air that passes through them. That's why tropical rainforests - one of the most important ecosystems on the planet, the destruction of forests leads to soil erosion, a reduction in species of flora and fauna, and shifts in the ecological balance over large areas and on the planet as a whole.
Tropical rainforests are often converted into plantations of cinchona and coffee tree, coconut palms, rubber plants. In South America, tropical rainforests are also seriously threatened by unsustainable mining.
A.A. Kazdym
List of used literature
- M. B. Gornung. Constantly humid tropics. M.: “Thought”, 1984.
- Hogarth, P. J. The Biology of Mangroves. Oxford University Press, 1999.
- Thanikaimoni, G., Mangrove Palynology, 1986
- Tomlinson, P. B. The Botany of Mangroves, Cambridge University Press. 1986:
- Jayatissa, L. P., Dahdouh-Guebas, F. & Koedam, N. A review of the floral composition and distribution of mangroves in Sri Lanka. Botanical Journal of the Linnean Society, 138, 2002, 29-43.
- http://www.glossary.ru/cgi-bin/gl_sch2.cgi?RSwuvo,lxqol!rlxg
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Study literary sources on this topic, find information on the Internet;
Study the effect of trees on human health;
Conduct observations of appearance trees within the city and beyond.
Main part
It is of great importance in the life of man and humanity. On the one hand, the forest, being one of the main components of the human environment, greatly influences the climate, the availability of clean water, clean air, protects agricultural lands, provides places for comfortable living and recreation for people, and preserves the diversity of wildlife. On the other hand, the forest is a source of many material resources, without which humanity cannot yet do and is unlikely to be able to do in the future - wood for construction, paper and furniture production, firewood, food and medicinal plants, and others. On the third hand, the forest is part of the cultural and historical environment, under the influence of which the culture and customs of entire peoples are formed, a source of work, independence and material well-being a significant part of the population, especially those living in forest villages and towns.
For humanity, the forest plays three roles - ecological, economic and social, but for everyone specific person, depending on where he lives and what he does, one or another role of the forest may play more or less importance. The smaller the forest, the more noticeable its environment-forming role, the higher the value of the forest’s role in preserving rivers and streams, protecting adjacent agricultural lands from drying out and erosion, beneficial influence for air, providing places for rest. The larger the forest, the less its environment-forming role is noticed, but the more important the forest is as a source of work, economic well-being, building materials, firewood, mushrooms, berries and other material resources. However, for every person, no matter where he lives and no matter what he does, the environment-forming, resource, and social roles of the forest are important to one degree or another.
The existence of the main share is associated with forests biological diversity Earth - the diversity of living organisms and ecosystems existing on our planet. Forests are the main habitat for approximately three-quarters of all species of plants, animals and fungi that exist on our planet, and most of these species simply cannot exist without forests. Preserving the diversity of the Earth's forests, and first of all - wild forests, still living according to the laws of the wild with minimal human intervention, is key to preserving the full diversity of life.
No less well known is the role of forests in preserving clean - main natural resource, the shortage of which is increasingly felt in various parts of the Earth, including in many regions of Russia. Forests play a large role in the global distribution of precipitation: moisture evaporated by trees returns to the atmospheric cycle, which creates conditions for its further transport from the oceans and seas inland to the continents. Modern research shows that if there were no forests, then the territories remote from the seas and oceans would be much more arid or even deserted, unsuitable for human life and for the development of agriculture. The forest effectively delays the melting of snow in the spring and the runoff of water after heavy rainfalls, thereby “smoothing out” the rise of water in rivers, preventing destructive floods and drying up of rivers and streams during drought. The forest reliably protects the banks of rivers and streams from erosion, thereby preventing the pollution of water bodies by soil particles.
The role of forests as “green ": the forest absorbs and binds carbon dioxide from the atmosphere, accumulates carbon in the organic matter of living plants, their residues and soil, and releases oxygen back, which is necessary for all living beings to breathe. There are more than 300 different chemical compounds in the air of natural forests.
At the same time, the forest very effectively cleans the air of dust and other harmful impurities - they easily settle on the surface of leaves and needles and are washed off to the ground by rain. The forest, by evaporating large amounts of water, maintains high humidity air, protecting not only yourself, but also the surrounding areas from drying out.
Forests, especially coniferous ones, highlight - volatile substances that have bactericidal properties. Phytoncides kill pathogenic microbes. In certain doses, they have a beneficial effect on the nervous system, enhance motor and secretory functions. gastrointestinal tract, help improve metabolism and stimulate cardiac activity. Many of them are enemies of pathogens of infectious diseases. But only if there are few of them.
Phytoncides from poplar buds, Antonov apples, and eucalyptus have a detrimental effect on the influenza virus. Twig , brought into the room, reduces the content of microbes in the air by 10 times, especially whooping cough and diphtheria. Leaves destroy typhoid and dysentery bacteria.
Thanks to powerful root systems that penetrate the soil, trees strengthen river banks and mountain slopes, preventing water from eroding them. The protective role of forests is especially important in the mountains, where trees resist snow avalanches, and on sea coasts, where they hold back the advance of sand dunes. Trees strengthen the soil, protecting settlements and roads from landslides, mudflows and sand drifts.
As human civilization develops, population increases, environmental quality requirements, and needs for clean water, air and similar benefits provided by the forest, the environment-forming importance of the forest in the life of mankind is increasing. And most importantly, simple awareness of this role is gradually, albeit very slowly, replaced by a willingness to do something to ensure that the role of the forest in preserving a favorable environment never dries up. Fortunately, there are still huge forests on Earth - natural carbon dioxide sinks. Our country is often called a great forest power. Indeed, the forest zone occupies more than half of the territory of Russia.
Research and experiments
Experience No. 1
I made observations of coniferous plants. in winter conifers discard old yellowed needles. In the depths of the forest, the trees are taller and fluffier. Near the road they are dusty and limp. I collected the needles along with the snow near the road and in the depths of the forest. I placed them in a glass of water. When the snow melted, sediment appeared. There was more sediment in the glass with needles collected near the road. The water in the glass was cloudy.
Experience No. 2
Observation of tree bark. Bark in the depths of the forest: white, clean, beautiful. Birch bark near the road: with a grayish tint, unattractive, with many cracks.
Conclusion: Air containing emissions from metal processing has a bad effect on the condition of trees.
How can a person influence nature?
He can influence well, i.e. help nature: a person plants trees, cares for plants and animals, feeds birds. It can influence badly, i.e. harming nature, spoiling it, destroying it; people can cut down trees, destroy animals, throw out garbage, pollute the air with smoke, car exhaust gases, so environmental problems arise. A man cuts down trees: the trees themselves die, the birds and insects die, the squirrels that lived in the trees die, the streams that flow at the foot of the trees dry up, the fish that lived in these streams die. Thus, an environmental problem arises: how to preserve forests and their inhabitants?
A person heats houses: he burns coal, wood, smoke comes out, factory chimneys smoke, car exhaust pipes emit gases. Some of these gases are very poisonous. Trees die from them, animals and people get sick. How to keep the air clean? We, people, pollute and destroy nature, and almost every schoolchild, knowing it or not, also pollutes nature. How do we pollute nature? Surely some of you have thrown away plastic bags and plastic bottles out into the street, into a ditch, into the bushes. Is it possible to do this? Of course not. And why? Firstly, it is simply ugly, and secondly, it destroys nature.
Experience No. 3
You see a light. He is alive, he dances, dances, breathes air. Now let’s cover this living light with a plastic bag or bottle. What happened to the light? He died. He didn't have enough air to breathe. In the same way, blades of grass, flowers, and insects can die from lack of air. Also, all living things die under scattered bags and bottles. Tell me, do you like candy, chocolate, and chewing gum? Where do you throw away the candy wrappers? Have you ever drunk lemonade from jars? Where did you put the jar? Many schoolchildren throw candy wrappers, bottles, and jars directly onto the street, into bushes, ditches, and under trees. Some people think that trees also litter, because they also shed their leaves on the ground, therefore, they think, a person can litter too. Are these guys right? No, these guys are wrong. You can't do that. In the fall, candy wrappers and bottles are invisible in the foliage, but in the spring... Remember how dirty it is on the street in the spring. The leaves of the trees rot, the paper turns slightly yellow, but nothing happens to the jars and bottles.
Experience No. 4
Let's take a dry leaf, try to crumble it, you get a light, imperceptible dust, which will immediately be blown away by the wind. Now let's try to crumble a piece of paper. It only crumpled, but did not turn into dust. But nothing happened to the jar and bottle at all. Now let's try to wet a piece of wood, paper and a jar. What happens? The sheet gets wet and tears easily, a piece of toilet paper is also easy to tear, but regular paper does not tear so easily. The film and the jar are just wet, and we won’t be able to tear or break them. It’s the same in nature - only leaves and toilet paper will quickly rot and disappear, and it will take years for paper, plastic film or a bottle to rot and disappear. So, paper decomposes in 3 - 4 years, an iron can decomposes and rusts in 6 - 10 years, plastic film will decompose in 60 - 100 years, and glass will lie in the ground for 600 years. Therefore, if you throw out all this garbage today, then After 2 years the paper will rot. When you graduate from school, the iron can will rust and fall apart. When you grow old and become ancient grandfathers and old women, only then will the plastic bag disappear into the ground, and the broken glass or bottle will lie in the ground for many, many years after you and only then will it turn into sand.
Experience No. 5
Let's take a plastic bag and try to burn a piece of it. And hold a white cloth over the smoke from this fire. Look at the rag. She got smokey. Which one then bad smell! This means that when burned, harmful substances are released. This soot and soot settle on trees, making it difficult for green leaves to breathe, entering the lungs of animals and people, leading to severe poisoning and illness. What to do with the garbage anyway? It turns out that each type of garbage needs special processing. Food waste You can give it to cats and dogs, they often run around hungry and will be very grateful to you. Paper must be collected and returned to waste paper. For what? Again, double benefit. You get money for waste paper. And the most important thing is that notebooks, books, and newspapers will again be made from waste paper in factories and factories. 15 textbooks are made from one tree. By recycling 5 kg of paper, you will save a tree! Metal cans are scrapped and new metal is smelted from them. But if you still have any garbage left, do not throw it into the ditch, collect it and take it to trash container. This garbage will be taken to garbage dumps, to specially equipped places, where it will be processed, buried and it will no longer cause enormous harm to nature.
Conclusion
The higher the better...
– our helpers, their leaves are organs that produce organic substances during photosynthesis to feed the plant. A by-product of this process is oxygen gas, which is released through stomata - tiny pores in the skin of leaves. By absorbing carbon dioxide and releasing oxygen, trees maintain a favorable air composition for most organisms. That's why forests are called the lungs of the planet.
It turns out that with the help of plants, there is more oxygen on our planet, which means that people can continue to live. I what would happen if all the forests on our planet disappeared? Then, after a few years, the entire supply of oxygen on the planet ran out. People would use up oxygen, and if there is no oxygen, then humans and even animals will not be able to live on Earth.
By protecting forests, we help ourselves and provide everyone with fresh air. Take care of the forests, because they are our life! And if you meet people who harm nature, conduct experiments for them, they are more convincing than all words.
Nature has created a magnificent forest country for us. He greets us with a sea of sounds and smells, hundreds of riddles and secrets. The forest is a home for birds, animals and other animals. Here they feed, hide from their enemies, and raise their offspring. The more diverse the forest, the more species of trees, shrubs, and grasses it contains, the richer the fauna. All components of the forest are in a certain biological balance. If this balance is disturbed, nature itself restores it. For example, if there is a wolf in the forest, there is always a normal elk herd. Learn to walk in the forest. Yes, you need to be able to walk through the forest in order not only to notice the beauty around you, but also to penetrate its secrets without disturbing the usual routine of life of its inhabitants. You need to firmly remember the rule: he who walks slowly and silently sees and hears a lot. Then you will certainly be lucky: you will see how the birds feed their chicks in the nests, how the prickly family of hedgehogs and hedgehogs travel in a row.....
Forests are the invaluable wealth of our Motherland. They protect and regulate the life of rivers, have a positive effect on the climate, soil, and water regime of fields. Forests are the lungs of our planet. They supply oxygen and absorb carbon dioxide. How to get acquainted with the forest? It is best to consider its tiers - “floors”. The tallest ones are formed by trees; under the canopy of the tree stand, undergrowth, shrubs, grass and moss cover grow. There are many beautiful herbs growing in the forest.
So what is a forest? This is not just a collection of trees and shrubs, but thousands of organisms connected to each other. These include soils, grass cover, mosses, lichens, mushrooms, insects, animals, birds, etc. Forest - the whole complex organisms living according to their own laws and rules. Everything in the forest is so interconnected that as soon as one “particle” changes, everything else changes. For example, forests protect the full flow of rivers, which means that ships are not afraid of shoals and riffles, fields are not afraid of a lack of moisture, fish are provided with good spawning grounds, and meadows are provided with lush grass. If you cut down a forest along a river, you will lose water natural defense: evaporation from the surface of the water will increase, shallows will appear, it will become difficult for the fish to breathe, and they will gradually die. And if so, the animals and birds that ate fish gradually disappear. Forests appeared on Earth 300 million years ago. More than 30 thousand various types trees and shrubs form the basis of the forests of our planet. Under the influence of wind, sun and moisture, they form Various types forests: coniferous, broad-leaved, mixed, tropical and others, characteristic of each natural belt. Forests are the lungs of our planet, helping all living things breathe. The fate of oxygen on our planet worries people more and more. If the entire population globe consumes 1.2 billion tons of oxygen per year, then transport is many times more. So a car, having covered 1000 km, consumes as much oxygen as one person needs to breathe for a year. An airplane in flight burns 50-100 tons of oxygen in 8 hours. On average, forests emit more than 55 billion tons of oxygen per year. Just one hectare of forest supplies oxygen to up to 2000 people per year, purifies 18 million m3 of air from carbon dioxide, and absorbs 64 tons of other gases and dust. Rainwater, taking particles of dust, dirt, and gases from the air, falls onto the leaves and flows down them to the ground. As a result, accumulating in forest reservoirs, it contains 20-30 times less dirt and bacteria than drops of the same rain falling over a meadow or arable land. IN forest air bacteria are 300 times less than in the city. Forests clean the air of dust, increasing the transparency of the atmosphere, and at the same time reducing harmful effects direct solar radiation, reducing it by 7 times. Scientists have found that a dense spruce forest retains up to 99% of solar radiation, and a pine forest - 96%.
This rebus contains an encrypted appeal to all people living on the planet.
The forest brings many gifts to people: wood and its products, as well as fruits. mushrooms, berries and nuts. Each forest has its own world of animals. Wood occupies the main place among forest products. From it, man learned to produce various products. As a result of chemical processing of wood, we obtain rubber, resins, glue, paper, soap, medicines, etc.
Question: What is a forest? Why are forests called “the lungs of the planet”?
Think about it!
The area of forests on Earth is being halved. They are cut down and burned so that after a certain time they can disappear from the face of the earth.
ABC of folk wisdom
A man chops a birch tree, and the wood chips hit the mushrooms and berries.
"In the forest"
One is a path; a thousand people - a trail in the forest; leaves a hundred desert.
Here, by rearranging words and signs, a saying is encrypted about how people can cause irreparable harm to the forest.
Since ancient times, people have been going to the forest for its gifts or just to relax and enjoy the singing of birds. “Love” for the forest sometimes turns to its detriment. Imagine how, on a fine sunny day, hundreds and even thousands of people rush into the forest. Suburban forests have long been unable to withstand such loads. Particularly vulnerable Pinery. It gets sick from trampling faster than a spruce or birch forest. The forest soil, compacted by thousands of feet, loses its structure and air does not pass through it well. Because of this, tree seedlings die, and plants from other communities that are less demanding on soil quality, for example, meadows, settle in the forest. They, in turn, choke out tiny trees and shrubs. Many people like to make fires in the forest. And the “wound” from a fire on the ground does not heal for 5–7 years. Each of you has probably paid attention to knocked down fly agarics or, more simply, “bad” mushrooms, uprooted strawberry plants, moss turned upside down in search of mushrooms. If you were in a cedar forest during the ripening of cones (pine nuts), then you probably felt uneasy at the sight. Broken and sawn branches, and even the tops of cedars, lie under the trunks of cedars. People take gifts from the forest, not caring at all about the consequences. If something like a fly agaric is not edible for humans, then it must be destroyed and trampled. Such people have no place in the forest. A man in the forest is a guest, and he must behave appropriately. You need to pick mushrooms, berries and nuts very carefully so as not to harm the plant as a whole. If you collect mushrooms correctly, without damaging the mycelium, then they will grow in this place not only for one mushroom season, but also within several years! And ripe cedar cones can be collected at the end of August - at the beginning of September under the canopy of trees. At this time, they ripen and easily separate from the branches and fall to the ground. Enjoy your health! Imagine how many ants and other beneficial insects perishing under our feet! By talking loudly, you can scare away birds that are hatching or even feeding chicks from their nests. So – what to do? Don't go into the forest at all! Of course not. But you need to respect its laws and its inhabitants.
Exercise: /Choose the correct answer/
In order not to harm the forest we must:
1. Don’t go into the forest at all.
2. Go to the forest 3-4 times a year.
3. Walk into the forest and respect its laws and its inhabitants.
ABC of folk wisdom
1. He who cuts down forests dries out places.
2. A swan in the sky, a butterfly above the earth - each has its place.
There is a journalistic cliche that forests are the lungs of planet Earth. But what then to do with the data of science, which suggests that the oxygen atmosphere arose on our planet long before photosynthesis?
In fact, plants of both land and oceans produce approximately as much oxygen through the process of photosynthesis as they then consume during respiration.
Initially, the Earth's atmosphere was generally reducing in nature: methane + ammonia + water + carbon dioxide.
The earth's crust should also have had a restorative character - after all, it was in equilibrium with the atmosphere.
And today we have that the atmosphere contains 20% free oxygen, and most rocks are completely oxidized and the system is in a state of equilibrium (the composition of the atmosphere has not changed significantly for several hundred million years).
In order to oxidize the entire primary atmosphere and lithosphere, it is necessary great amount free oxygen.
The balances don't add up
According to the generally accepted hypothesis, it is believed that living organisms are responsible for the release of oxygen.
But they are not suitable for this role, since despite the fact that plants release a significant amount of oxygen per unit of time, in general the biosphere is quite stable - the circulation of substances occurs in it. The release of free oxygen can only be achieved through the accumulation of undecomposed residues (mainly in the form of coal). In other words:
H2O + CO2 = biomass(C + O + H) + O2 + C + CH4.
Considering that the current biomass is small compared to the mass of even free oxygen in the atmosphere (it is approximately one hundred times less), we obtain that in order for all the atmospheric and lithospheric (for the oxidation of the primary lithosphere) oxygen to be formed, it is necessary to store it somewhere in the Earth there would be similar mass reserves of coal and hydrocarbons - and this is a layer of several meters only for atmospheric oxygen, and for lithospheric oxygen it is orders of magnitude larger. No such reserves are observed (estimated reserves of coal and other hydrocarbons approximately correspond to the total biomass).
So, our balance sheets clearly don’t add up.
In the bright sun
Note that another source of oxygen is the dissociation of water molecules under the influence of solar radiation.
As is known, the speed of molecules in a gas obeys the Maxwell distribution. According to this distribution, there is always a certain proportion of molecules whose speed exceeds the second cosmic speed. And such molecules can leave the Earth freely. Moreover, light gases—hydrogen and helium—are the first to escape from the atmosphere. Calculations show that the time for complete evaporation of hydrogen from the earth's atmosphere is only a few years. But hydrogen is still present in the atmosphere. Why? For oxygen and other gases, this time exceeds the lifetime of the Earth. million years. In the earth's atmosphere, hydrogen and helium are constantly renewed due to intake from the earth's interior and a number of atmospheric processes. The hydrogen that forms the “corona” around the Earth is a product of the dissociation of water molecules under the influence of ultraviolet and X-ray radiation from the Sun.
Calculations show that over a period of about ten million years, an amount of oxygen equal to the current value appears in the atmosphere due to photodissociation.
So we get:
1) Initially, the atmosphere, lithosphere and entire mantle of the Earth are of a reducing nature.
2) Due to photodissociation, water (which, by the way, came as a result volcanic activity from the mantle) decomposes into oxygen and hydrogen. The latter leaves the Earth.
3) The remaining oxygen oxidizes the primary lithosphere and atmosphere to its current state.
4) Why does oxygen not accumulate, since it is constantly supplied as a result of photodissociation (the current amount accumulates in 10 million years, and the age of the Earth is 4.5 billion)? It goes towards oxidation of the mantle. As a result of the movement of continents in subduction zones, new crust is formed from the mantle. The rocks of this crust are oxidized under the influence of the atmosphere and hydrosphere. These oxidized rocks from oceanic plates at subduction zones are then released back into the mantle.
Statistics of the universe
Well, what about living organisms, you ask? They actually play the role of extras - there was no free oxygen, they lived without it - at the primitive single-cell level. It appeared - they adapted and began to live with it - but in the form of advanced multicellular organisms.
So whether there are forests on Earth or not, this will not affect the oxygen content in the planet’s atmosphere. Another thing is that the forest clears the air of dust, saturates it with phytoncides, provides shelter and food for many animals and birds, and gives people aesthetic pleasure... But calling the forest “green lungs” is, at the very least, illiterate.
Introduction
Forest is a special wealth of any country. It's beautiful, recoverable natural complex, on which the entire ecosystem often rests.
The term “forest management” usually refers to the use of all forest resources, all types of forest wealth.
Several adverse effects can be identified that have a detrimental effect on the forest. The first unfavorable factor is the cutting of wood. Usually, a cut is usually called the moment when a more trees than what grows in a year, but sometimes this is not the most important factor critical attitude towards the forest. The fact is that in most cases, when cutting down, good, strong trees are taken away, leaving sick ones, and this in turn leads to even more environmental damage. When logging is lagging behind in terms of wood growth, a second unfavorable factor is observed - undercutting, which, in particular, leads to aging of the forest, a decrease in its productivity, and diseases of old trees. Therefore, like overcutting, it leads to exhaustion forest resources and undercutting leads to underutilization of forestry.
For now, deforestation prevails on the planet. The emergence of environmental problems may be associated not only with the scale of forest cutting, but also with the methods of cutting. Today, selective logging, although a more expensive form, is characterized by significantly less environmental damage. For renewal forest areas should be given at least 80-100 years. Along with the problems of reforestation, which can be carried out through self-regeneration of forest plantations and, for acceleration, through the creation of forest plantations, the problem of careful use of harvested wood arises. Deforestation must be countered by the desire for the full use of wood, the use of gentle methods of logging, as well as constructive activities - reforestation.
Global ecological disaster in forestry
The state of forests in the world cannot be considered favorable. Forests are being intensively cut down and are not always restored. The annual felling volume is more than 4.5 billion m3.
To date, about 160 million hectares of tropical forests have been degraded, and of the 11 million hectares cut down annually, only a tenth is restored by plantations. These facts are very disturbing global community. Rainforest covering 7% earth's surface in areas close to the equator, they are often called the lungs of our planet. Their role in enriching the atmosphere with oxygen and absorbing carbon dioxide is exceptionally great. Tropical forests are home to 3–4 million species of living organisms. 80% of insect species live here, and 2/3 of known plant species grow. These forests supply 1/4 of the oxygen reserves. For rational use All forests are divided into three groups.
First group . Forests of great importance in water protection and soil protection, green areas of resorts, cities and other settlements, protected forests, protective strips along rivers, highways and railways, steppe forests, ribbon forests Western Siberia, tundra and subalpine forests, natural monuments and some others.
Second group . Plantations of a sparsely wooded zone, located mainly in the central and western regions of the country, having protective and limited operational value. Third group. Production forests of the country's multi-forest zones are areas of the European North, the Urals, Siberia, and the Far East.
Third group . This group includes the industrial felling regime. It is the main base for timber harvesting.
The forests of the first group are not used, they are only cut for sanitary purposes, rejuvenation, care, lightening, etc. In the second group, the felling regime is limited, use is in the amount of forest growth.
The importance of forests in the formation of the biosphere
A review of the literature and the author’s logical constructions show that in the life cycle of an individual tree and their totality, the amount of oxygen released by their living mass due to photosynthesis exactly corresponds to the amount of oxygen consumed by the plant for respiration during life and for its decay after death.
With the complete destruction of the planet's forests, the oxygen concentration, in accordance with the author's calculations, will decrease by 0.001%.
Atmospheric oxygen – necessary condition preservation of many forms of life on Earth, in particular humanity. At the same time, ever-increasing flows of fuel involved in the combustion process (oil, gas, coal, etc.) increase the alarmist sentiments of a certain part of the planet’s population, fueled by emotional publications of the media. mass media and some specialized publications. For example, there is a well-known point of view according to which the consumption of oxygen is an order of magnitude higher than its supply, amounting to 1.16·1010 and 1.55·109 t/year, respectively.
According to many, the trend towards a decrease in the amount of oxygen in the atmosphere is all the more dangerous because it develops against the backdrop of a reduction in the forest cover of the planet. It originally made up 75% of its surface, but has now fallen to less than 27%. The area of tropical forests is declining especially rapidly, amounting to 0.95 billion hectares, or 56% of the total forest area. Of these, 11 million are cut down annually, and only 1 million hectares are restored.
On this basis, it is concluded that humanity is worsening the conditions of its existence, since vegetation, and above all the huge mass of forests, - powerful source oxygen production through the reaction of photosynthesis:
6 CO2 + 6 H2O + 2822 kJ 6 C6H12O6 + 6 O2 – chlorophyll light.
Because the positive role forests in O2 production is usually not questioned, it is believed that measures to stimulate international community those countries on whose territory the “lungs” of the planet are located. One of them is the tropical forests of the river basin. The Amazon (Brazil), another – the vast forests of Russia, primarily Siberian. The number of articles on the topic “Russia – the lungs of the planet” is impossible to list. Let us point out only the last two in one of the issues of the magazine, which claims to be a leader in ecology and environmental management:
“Russia, which has large forested areas where carbon dioxide is converted into plant fiber carbon and free oxygen, should have preferential quotas to reduce CO2 emissions”; “It seems appropriate that oxygen producing countries should receive payment for it and use these funds to maintain forests.”
It is noted that within the framework of the UN, proposals from “low-forest” countries (Germany, etc.) to preserve and increase Russian forests in the interests of the entire planet are being considered. And regarding tropical forests, a similar agreement was adopted in the early 90s. Developed Nordic countries pledged to pay developing African countries a bonus of $10 for every ton of carbon dioxide converted into oxygen. And such payments began in 1996. “It has been calculated,” continues V.M. Garin and co-authors, “that one hectare of forest absorbs about 8 liters of carbon dioxide per hour (the same volume is released when two hundred people breathe during the same time).”
At the same time, such widespread alarmist expectations are not confirmed by data from fundamental science.
Thus, fears about a possible decrease in the amount of atmospheric oxygen due to increased combustion of fossil carbon are not justified. It is estimated that the simultaneous use of all deposits of coal, oil and natural gas available to mankind will reduce the average oxygen content in the air from 20.95 to 20.80%. Comparison with the most accurate analyzes from 1910 shows that, within the limits of measurement error, there was no change in atmospheric oxygen by 1980.
The disappearance of oxygen in the hydrosphere, even when most modern waste is dumped into it, is also not dangerous. From Broker’s calculations it follows that with a ten billion population of the planet (about 1.7 times more than now), the annual discharge into the sea of 100 kg of dry organic waste per inhabitant (significantly higher than the current norm) it will take about 2500 years to consume the entire supply of oxygen in the hydrosphere. This is longer than the duration of its resumption.
Broker concludes that the amount of O2 in the atmosphere is not limited in comparison with human requirements for it and that an almost similar picture is observed for the hydrosphere. He writes: “if the existence of the human race is seriously threatened by the danger of environmental pollution, then it will more likely die for some other reason than due to lack of oxygen” (quoted in).
The role of forests in improving the atmosphere (absorption of CO2 and production of oxygen) is also not as clear as it seems to alarmists. The spread of emotional points of view is a consequence of an unprofessional assessment of the impact of forests on the environment. Let us note the features of the problem, which are usually not noticed intentionally or consciously in such cases.
Yes, indeed, the reaction of photosynthesis is indisputable. But the opposite reaction is also undeniable, manifesting itself in the process of respiration of living organisms and during the decay (oxidation) of mortmass (soil respiration). Therefore, at present in nature there is a stable balance between the amount of oxygen formed during photosynthesis and absorbed during the respiration of living organisms and soil (rotting)
After the death of a plant due to rotting of the mortmass, it is very complex structure organic matter is converted into simple compounds such as CO2, H2O, N2, etc. The source of mortmass oxidation is oxygen produced in excess of what is necessary for plant respiration. At the same stage, CO2, previously bound during photosynthesis, is released and enters the environment. In other words, after the death of an organism, all of its carbon is oxidized again, binding the amount of oxygen, which is the difference between its mass released during photosynthesis and used for plant respiration during their life.
Free oxygen from photosynthesis, as noted by S.I. Rozanov, can accumulate in the atmosphere only under the condition that part of the resulting organic matter does not decompose again, but is deposited and isolated from interaction with oxygen. An example of this is the huge reserves of fossil organic substances - coal, liquid and gaseous hydrocarbons, accumulated in sedimentary rocks for more than 2 billion years. The observed increase in oxygen content in the atmosphere is fifteen millionth of its amount. However, it cannot be unambiguously considered as the result of isolating part of the mortmass from contact with oxygen. Moreover. Plant photosynthesis is a consequence, not a cause, of the appearance of oxygen in the atmosphere. The latter arose earlier than photosynthesis. And although the sources of non-photosynthetic oxygen are not yet well established modern science, however, some of them are quite real. In particular, oxygen could be released from rocks during the formation of the Earth's crystalline core. Oxygen in molecular form is also formed during the dissociation of water and ozone molecules in the upper layers of the atmosphere under the influence of ultraviolet radiation.
The above considerations make it possible to identify three generally known periods in the development and death of forests and to demonstrate their role in the balance of O2 and CO2 in the environment.
First period. Increase in the mass of woody vegetation in an ecosystem. The amounts of oxygen and bound CO2 increase in proportion to the increase in the mass of forest plantations. At the same time, attempts to increase the mass of the latter give only short-term results, since the land surface is limited. As a result, the forests move into the second period.
Second period. Constant mass of forests in an ecosystem. The supply and consumption of oxygen and carbon dioxide in the forward and reverse processes of photosynthesis are equal. In this case, forest plantations do not affect the oxygen balance of the planet.
Third period. Reducing the mass of forests, for example through cutting down. The remaining part of mature forests is still in the second period. Timber thrown into the national economy rots or is burned, releasing CO2 from the photosynthesis process into the environment and consuming excess oxygen from the first period.
Thus, the continuous reproduction of the first, second and third periods leads to a zero balance of oxygen released in the forest zone and carbon dioxide absorbed by it.
The foregoing allows us to more accurately assess the importance of Amazonian and Siberian forests in enriching the atmosphere with oxygen. It is known that the area of Amazonian forests is decreasing as a result of uncontrolled mining (third period), the mass Siberian taiga is in the second period, since no such trend is detected.
It follows that statements about the forests of the Amazon and Siberia as the “lungs” of the planet are nothing more than sonorous phrases. Claims for benefits for countries with such “lungs” have no objective basis.
Moreover. From an educational point of view, it is interesting to see the change in oxygen content in the atmosphere that will take place if the “lungs” of the planet disappear, i.e. forests, for example, will be destroyed by humanity.
It is obvious that oxygen will be required to convert forest mortmass into the initial products of photosynthesis (CO2, H2O). To estimate its quantity, we take the following initial data:
The amount of oxygen in the atmosphere is 5.16·1021 g, its volumetric content in it is 21%;
The volume of wood in Russian forests is 81 billion m3, or 22% of world reserves. The latter, with an average wood density of 0.6 t/m3, are equal to 220 billion tons;
Wood is 100% represented by cellulose (C6H5O5)n with a carbon content of 46%, hemicellulose, which is similar in composition, as well as lignin with a higher carbon fraction (61-64%) than cellulose.
Let us take the average carbon content in wood to be 50%. This corresponds to the ratio of the masses of cellulose and lignin and amounts to about 110 billion tons of carbon in the planet’s forests. Then, in accordance with the reaction of reverse photosynthesis, the oxidation of this mass of carbon will require 294 billion tons of oxygen (2.94 1017 g). In relation to the mass of atmospheric oxygen, this will be 2.94·1017/5.16·1021, or 0.57·10-4. The decrease in atmospheric oxygen content in this case is equal to 21·0.57·10-4%, or about 0.001%.
It can be assumed that a reduction in oxygen content in the atmosphere of 0.001% will not be noticed even by the most ardent supporters of preserving forests as “generators” of oxygen.
However, despite the insignificant role of forests in the biosphere oxygen balance, their influence on humans through a number of other environmental factors is undoubtedly positive. Woodlands reduce dust, gas and noise pollution of the environment. They, like other vegetation, emit phytoncides - biologically active, including gaseous, substances that kill microorganisms. This makes the environment healthier. Forests increase decorative variety shapes, colors and textures of the world around us. They are simply beautiful and powerful. Their removal will significantly reduce the Earth's biodiversity, i.e. will blow up fundamental principle concepts of sustainable development – the alpha and omega of modern civilization.
Reflections on the role of the forest are reflections on the proportionality of Beauty and Rationality in the coming era of the Noosphere.
Conclusion
Today, it is very difficult to satisfy the growing demand not through a sharp increase in cutting, but through more complete use of wood. The main direction of solving this problem may be the introduction of low-waste and completely waste-free technology. This, of course, also provides additional environmental benefits.
The main factor, in our opinion, contributing to the solution of the issue environmental disaster, will be the reconstruction of forest industry enterprises. It is necessary to look for new ways to solve problems of proper forest management. Establish the production of materials from sawdust and other so-called wood waste. It should cut down, kill less, and use it more fully, in the future, this should become a major trend in the global industry.
List of used literature
1. Abramson N.G., Bernstein L.G. Global environmental problems of thermal power engineering and cement production // Ecology and industry of Russia. – 2005. – July. – pp. 29-31.
2. Garin V.M., Klenova I.A., Kolesnikov V.I. Ecology for technical universities. – Rostov-on-Don: Phoenix, 2001.
3. Ramad F. Fundamentals of applied ecology: Transl. from fr. – L.: Gidrometeoizdat, 1991.
4. Ramad F. Fundamentals of applied ecology: Transl. from fr. – L.: Gidrometeoizdat, 1991.
5. Reimers N.F. Nature management: Slov.-reference. – M.: Mysl, 1990. Kreinin E.V. Greenhouse effect: reasons, forecasts, recommendations // Ecology and industry of Russia. – 2005. – July. – pp. 18-23.
Reimers N.F. Nature management: Slov.-reference. – M.: Mysl, 1990. – P.421
Kreinin E.V. Greenhouse effect: causes, forecasts, recommendations // Ecology and industry of Russia. – 2005. – July. – pp. 18-23.
Abramson N.G., Bernstein L.G. Global environmental problems of thermal power engineering and cement production // Ecology and industry of Russia. – 2005. – July. – pp. 29-31.
Garin V.M., Klenova I.A., Kolesnikov V.I. Ecology for technical universities. – Rostov-on-Don: Phoenix, 2001. – 384 p.
Ramad F. Fundamentals of applied ecology: Trans. from fr. – L.: Gidrometeoizdat, 1981. – P.82
Ramad F. Fundamentals of applied ecology: Trans. from fr. – L.: Gidrometeoizdat, 1981. – 544 p.
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