Everyone knows that trees purify the air... Being in a forest or park, you can feel that the air is completely different, not the same as on the dusty city streets. It is much easier to breathe in the shady coolness of the trees. Why it happens?
The leaves of trees are small laboratories in which, under the influence of sunlight and heat, carbon dioxide in the air is converted into organic matter and oxygen.
Organic matter is processed into the material from which the plant is built, i.e. trunk, roots, etc. Oxygen is released from the leaves into the air. In one hour, one hectare of forest absorbs all the carbon dioxide that two hundred people can produce during this time!
Trees purify the air by absorbing pollutants
The surface of the leaves is capable of capturing airborne particles and removing them from the air (at least temporarily). Airborne microscopic particles can enter the lungs, which can lead to serious health problems or tissue irritation. So it is very important to reduce their concentration in the air, which trees do successfully. Trees can remove both gaseous pollutants (sulfur dioxide, nitrogen dioxide and carbon monoxide) and particulate dust. Cleansing mainly takes place with the help of the stomata. The stomata are small windows or pores on the leaf through which water evaporates and gas exchanges with the environment. Thus, dust particles, before reaching the ground, settle on the leaves of trees, and under their canopy the air is much cleaner than above the crowns. But not all trees can tolerate dusty and gassed conditions: ash, linden and spruce are very affected by them. Dust and gases can lead to blockage of the stomata. However, oak, poplar or maple are more resistant to the harmful effects of a polluted atmosphere.
Trees reduce temperatures during hot seasons
When you walk under the scorching sun, you always want to find a shady tree. And how pleasant it can be to walk in a cool forest on a hot day! Being under the crown of trees is more comfortable not only because of the shade. Due to transpiration (that is, the process of evaporation of water by a plant, which occurs mainly through the leaves), a lower wind speed and relative humidity, a certain microclimate is created for fallen leaves under the trees. Trees suck up a lot of water from the soil, which then evaporates through the leaves. All these factors combine to affect the air temperature under the trees, where it is usually 2 degrees lower than in the sun.
But how does a lower temperature affect air quality? Many pollutants are released more actively as temperatures rise. A perfect example of this is a car left in the sun in the summer. Hot seats and door handles create a stifling atmosphere in the car, so you want to turn on the air conditioner sooner. Especially in new cars, where the smell has not yet disappeared, it becomes especially strong. In particularly sensitive people, it can even lead to asthma.
Trees give off volatile organic matter
Most trees emit volatile organic matter called phytoncides. Sometimes these substances form a haze. Phytoncides are capable of destroying pathogenic microbes, many pathogenic fungi, have a strong effect on multicellular organisms, and even kill insects. The best producer of medicinal volatile organic compounds (VOCs) is the pine forest. In pine and cedar forests, the air is practically sterile. Pine phytoncides increase the general tone of a person, have a beneficial effect on the central and sympathetic nervous system. Trees such as cypress, maple, viburnum, magnolia, jasmine, white acacia, birch, alder, poplar and willow also have pronounced bactericidal properties.
Trees are vital to keep the air and the entire ecosystem on Earth clean. Everyone understands this, even small children. However, deforestation is not slowing down. The world's forests have decreased by 1.5 million square meters. km for 2000-2012 for non-anthropogenic (natural) and anthropogenic reasons. In Russia . now it is possible to look with the help of a service from Google and see the real state of affairs in forestry, which inspires great concern.
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Introduction
Cities are an integral part of the face of the Earth. Although they occupy only 2% of the land area, half of the world's population lives in them today. The main economic, scientific and cultural potential of society is concentrated in cities, therefore they play an important role in the economic, political, social life of each country individually and of all mankind as a whole.
By 2025, the urban population will be 2/3 of the world population. More than half of the city dwellers live in cities with a population of more than 500 thousand people, and every year the share of the population living in large cities is growing.
Large cities are characterized by a high population density, dense multi-storey (as a rule) buildings, extensive development of public transport and communication systems, the excess of the built-up and paved part of the territory over garden and park, greenery and free spaces, the concentration of sources of negative impact on the environment.
Cities, especially large ones, are territories with profound anthropogenic changes. Industrial enterprises pollute the natural environment with dust, emissions and discharges of by-products and production wastes. In addition, cities are characterized by high levels of thermal, electromagnetic, noise and other types of pollution.
Cities affect the ecological situation of vast territories due to the transport of pollutants by surface water and air currents. In some cases, the direct negative impact of cities is manifested within a radius of 60–100 km. In Russia, according to existing estimates, about 1.2 million people of the urban population live in conditions of pronounced environmental discomfort, and about 50% of the urban population - in conditions of noise pollution.
Green spaces play a significant role in neutralizing and mitigating the negative impacts of the industrial zones of the city on people and wildlife in general. The green spaces planted on city streets and squares, in addition to decorative planning and recreation, play a very important protective and sanitary and hygienic role.
1. The role of green spaces in air purification
Green spaces in the city improve the microclimate of the urban area, create good conditions for outdoor recreation, protect the soil, walls of buildings and sidewalks from excessive overheating. This can be achieved while maintaining natural green spaces in residential areas. A person here is not divorced from nature: he is, as it were, dissolved in it, therefore he works and rests in a more interesting and productive way.
The role of green spaces in the purification of the air of cities is great. A tree of medium size in 24 hours restores as much oxygen as three people need to breathe. In one warm sunny day, a hectare of forest absorbs 220-280 kg of carbon dioxide from the air and releases 180-200 kg of oxygen. Up to 200 g / h of water evaporates from 1 m 2 of the lawn, which significantly humidifies the air. On hot summer days, on the path near the lawn, the air temperature at the height of a person's growth is almost 2.5 - degrees 0 C lower than on an asphalt pavement. The lawn traps the dust carried by the wind and has a phytoncidal (destroying microbes) effect. It is easy to breathe near a green carpet. It is no coincidence that in recent years, in the practice of gardening, preference is increasingly given to the landscape or free style of design, in which 60% of the landscaped area and more is allotted to the lawn. On a hot summer day, rising streams of warm air are formed over the heated asphalt and hot iron roofs of houses, raising the smallest particles of dust, which remain in the air for a long time. And over the park there are downdrafts of air, because the surface of the leaves is much cooler than asphalt and iron. Dust, carried away by the descending currents of air, settles on the leaves. One hectare of coniferous trees retains up to 40 tons of dust per year, and deciduous trees - about 100 tons.
Practice has shown that green spaces are a fairly effective means of combating harmful emissions from road transport, the efficiency of which can vary within a fairly wide range - from 7% to 35%.
Large forest park wedges can be active conductors of clean air to the central areas of the city. The quality of air masses is significantly improved if they pass over forest parks and parks, the area of which is 600-1000 hectares. At the same time, the amount of suspended impurities decreases by 10 - 40%.
Depending on the size of the city, its national economic profile, building density, natural and climatic features, the species composition of plantings will be different. In large industrial centers, where the greatest threat to the sanitary state of the air basin is created, to improve the urban environment in the vicinity of factories, it is recommended to plant American maple, white willow, Canadian poplar, brittle buckthorn, Cossack and Virginia juniper, pedunculate oak, red elderberry.
Arboreal and shrub vegetation has a selective ability in relation to harmful impurities and, therefore, has different resistance to them. The gas absorption capacity of individual rocks, depending on the various concentrations of harmful gases in the air, is not the same. Research conducted by Yu.Z. Kulagin (1968), showed that the balsam poplar is the best "orderly" in the zone of strong constant gas pollution. The best absorbing qualities are the small-leaved linden, ash, lilac and honeysuckle. In the zone of low periodic gas contamination, a greater amount of sulfur is absorbed by the leaves of poplar, ash, lilac, honeysuckle, linden, less - elm, bird cherry, maple.
The protective functions of plants depend on the degree of their sensitivity to various pollutants. V.M. Ryabinin (1965) established that the maximum permissible average daily concentration of sulfurous anhydride for Siberian larch is 0.25 mg / m 3, Scots pine - 0.40 mg / m 3, Small-leaved linden - 0.60 mg / m 3, Norway spruce and Norway maple - 0.70 mg / m 3. If the concentration of harmful gases exceeds the maximum permissible norms, then plant cells are destroyed and this leads to inhibition of growth and development, and sometimes to the death of plants.
2. Ionization of air by plants
There are light air ions, which can carry negative or positive charges, and heavy ones, which are positively charged. Light negative ions have the most beneficial effect on the environment. Carriers of positively charged heavy ions are usually ionized molecules of smoke, water dust, vapors that pollute the air. Consequently, the purity of the air is largely determined by the ratio of the number of light ions, which heals the atmosphere, and heavy ions, which pollute the air.
An essential qualitative feature of the oxygen produced by green spaces is its saturation with ions carrying a negative charge, which is the beneficial effect of vegetation on the state of the human body. For a clearer idea of the ability of plants to enrich the air with negative light ions, the following data can be cited: the number of light ions in 1 cm 3 of air above forests is 2000-3000, in a city park - 800, in an industrial area - 200-400, in a closed crowded room - 25-100.
The ionization of the air is influenced by both the degree of landscaping and the natural composition of plants. The best air ionizers are mixed coniferous-deciduous stands. Pine plantations only in mature age have a beneficial effect on its ionization, since the concentration of light ions in the atmosphere decreases due to the turpentine vapor released by young weeds. Volatile substances of flowering plants also increase the concentration of light ions in the air. According to V.N. Vlasyuk (1976), the ionization of forest oxygen is 2-3 times higher than that of sea oxygen and 5-10 times higher than that of oxygen in the atmosphere of cities. Therefore, forests that form a green belt around cities have a significant beneficial effect on the improvement of the urban environment, in particular, they enrich the air pool with light ions. White acacia, Karelian birch, poplar and Japanese birch, red and English oak, white and weeping willow, silver and red maple, Siberian larch, Siberian fir, mountain ash, common lilac, black poplar contribute to an increase in the concentration of light ions in the air to the greatest extent.
Plants also absorb solar energy and create carbohydrates and other organic substances from minerals of soil and water in the process of photosynthesis.
3. Plant phytoncides
The sanitary and hygienic properties of plants include their ability to release special volatile organic compounds called phytoncides, which kill pathogenic bacteria or delay their development. These properties are especially valuable in urban conditions, where the air contains 10 times more pathogenic plants than the air of fields and forests. In pure pine forests and forests with a predominance of pine (up to 60%), bacterial air pollution is 2 times less than in birch forests. Of the tree and shrub species that have antibacterial properties that positively affect the state of the air environment of cities, one should name white acacia, barberry, warty birch, pear, hornbeam, oak, spruce, jasmine, honeysuckle, willow, viburnum, chestnut, maple, larch, linden, juniper, fir, sycamore, lilac, pine, poplar, bird cherry, apple tree. Herbaceous plants - lawn grasses, flowers and lianas also have phytoncidal activity.
The intensity of the release of phytoncides by plants is influenced by seasonality, vegetation stages, soil and climatic conditions, and time of day.
Most plants exhibit maximum antibacterial activity in the summer. Therefore, some of them can be used as a healing material.
4. Influence of anthropogenic factors on landscaping.
Not all plants are able to survive in urban conditions. The trees and bushes planted in the dusty streets must withstand the powerful onslaught of civilization. We want plants to not only please our eyes, give coolness on a hot day, but also enrich the air with life-giving oxygen. Not every plant can do it.
Plants growing in a large city are real "Spartans". The growth of trees here is very difficult due to environmental pollution. Up to 30 tons of various substances fall out annually per 1 km2 of a large city, which is 4–6 times more than in rural areas. Scientists believe that a large proportion of deaths in cities around the world are associated with air pollution.
The main cause of photochemical fog is car exhaust fumes. A passenger car emits about 10 g of nitric oxide for every kilometer of travel. Photochemical fog occurs in polluted air as a result of reactions that occur under the influence of solar radiation.
Sulfur dioxide, hydrogen fluoride, nitrogen oxides, heavy metals, various aerosols, salts and dust that enter the stomata of leaves and impede photosynthesis are added to the exhaust gases of cars. For example, on the streets of Moscow, the photosynthesis of 20–25-year-old lindens is about half that of the same trees in a suburban park. Along the central highways, as a rule, weakening and partial drying of the crowns of both deciduous and coniferous trees is more often observed. Due to the slowdown in the process of photosynthesis in urban trees, the annual growth of shoots is reduced. Shorter shoots are formed in the crown. Atmospheric pollution can cause other disturbances in growth and branching. So, for example, double buds are sometimes formed in linden. With an abundance of such violations, trees develop ugly forms of growth.
Unusual in cities and the thermal regime of the soil. On hot summer days, the asphalt pavement, when heated, gives off heat not only to the surface layer of the air, but also to the soil. At an air temperature of 26–27 oС, the soil temperature at a depth of 20 cm reaches 34–37 oС, and at a depth of 40 cm - 29–32 oС. These are the most real hot horizons - just those in which the bulk of plant roots is concentrated. It is not for nothing that the uppermost layers of urban soils practically do not contain living roots. An unusual thermal situation is created for outdoor plants: the temperature of underground organs is often higher than that of aboveground ones. In natural conditions, on the contrary, life processes in most plants of temperate latitudes proceed under the opposite temperature regime.
Due to the harvesting of fallen leaves in autumn and snow in winter during the cold winter period, urban soils are more cooled and freeze deeper than in forests. All this negatively affects the condition of the plant root system.
But not only the microclimate worsens the life of plants in the city. The most important environmental factor in plant life is water. In cities, plants often lack soil moisture due to its drainage into the sewer network.
This explains the fact that the species composition of the trees most often planted along the roads and on the streets is not very diverse. The main species in the middle lane are linden, poplar, maple, chestnut, birch, larch, ash, mountain ash, spruce, oak, about 30 species of shrubs. The latter are often used to create hedges.
The most difficult ecological situation has a negative effect on all living and inanimate nature, including humans. Since the level of pollution is higher in cities, the impact on nature is stronger.
Direct effects on plants can take various forms:
1) genetic changes;
2) species changes;
3) causing direct damage to vegetation.
Naturally, depending on the sensitivity of the species and the size of the load, the scale of the impact can range from recoverable (reversible) damage to the complete death of the plant.
The protective properties of plants largely depend on the environmental conditions in which they are found. In urban conditions, parks with an area of 50-100 hectares and gardens are optimal for the growth and development of many plants, somewhat worse - boulevards and squares and unfavorable - asphalt streets. In the composition of parks, plants exhibit more intensive processes of photosynthesis and respiration compared to those that grow on paved streets and near highways.
With the accumulation of pollutants in soils and plant tissues, forest stands lose their biological stability and, while maintaining the existing level of industrial and vehicle emissions in the city, they can degrade as forest ecosystems in a short time.
Under the influence of technogenic factors (near enterprises of ferrous and nonferrous metallurgy, machine building and printing, plants accumulate compounds of lead, tin, vanadium, cobalt, copper, zinc, etc.) in the green mass of vegetation, the content of chlorophyll decreases. The plant tissues change color to yellow, ocher, the plant is affected by chlorosis. More severe damage causes tissue necrosis. The leaves become ocher and yellow, covered with spots of red-brown or brown color. The degree of damage to green spaces differs significantly in different areas.
Coniferous forests - pine and spruce forests are in the most weakened state. Many trees have browning and shedding of needles, thinning of crowns and drying in the upper part.
Several sources of exposure to plants can be traced: from the atmosphere, from the soil, during irrigation, exposure to radiation, direct human influence.
1) Exposure from the atmosphere. One of the strongest influences on plants comes from the atmosphere. It can be in the form of acid precipitation, dust deposition, direct gas exposure. Acid rain has an extremely negative effect on plants. The most striking example of this impact is forest degradation. The term forest degradation has two meanings. It can simply mean a slowdown in tree growth, which translates into a decrease in the thickness of the tree rings at the cut of the trunk. Formally, it sounds like this: “decline in forest productivity”. Another meaning of the term forest degradation is the actual damage to trees or even their death.
Today, the area of forests damaged by acid rain is estimated at millions of hectares.
Sulfur dioxide is especially affected. This compound is adsorbed on the surface of the plant, mainly on its leaves, and has a harmful effect on it. Sulfur dioxide, penetrating into the plant's body, takes part in various oxidative processes. These processes take place with the participation of free radicals formed from sulfur dioxide as a result of chemical reactions. They oxidize unsaturated fatty acids of membranes, thereby changing their permeability, which further negatively affects many processes (respiration, photosynthesis, etc.).
Acid rain is more common in cities than elsewhere, so the impact on green spaces is greater. The oppression is quite noticeable: in industrial cities, where emissions of sulfur and nitrogen oxides take place, plants are almost never found, and around such cities man-made wastelands stretch for many kilometers.
In all cities there is a slowdown in plant growth. This is especially noticeable in trees and shrubs growing near highways. Exhaust gases, namely the salts of heavy metals contained in them, especially lead, settling on the leaves, oppress all living things and plants. Maple is the least susceptible to lead, while hazel and spruce are the most susceptible. The side of the trees facing the highways is 30-60% more metallic. Spruce and pine needles have good filter properties in relation to lead. It accumulates it and does not exchange it with the environment. The "road" has an extremely negative effect on the landings located on its sides. They are one of the first to take the "blow" of vehicles on the environment.
Great harm is caused by dust (asphalt and concrete sprayed in the air of roads, rubber of car tires) and soot greatly weakens gas exchange, respiration and assimilation processes, causes oppression of plants and weakening of their growth, complicates the processes of photosynthesis and respiration, which also cannot but affect the condition vegetation.
The reason for the summer leaf fall is the high content of lead in the air. Lead poisoning is difficult for trees. By concentrating lead, they purify the air. During the growing season, one tree neutralizes lead compounds contained in 130 liters of gasoline.
Plants are significantly affected in areas with a high content of nitrogen oxides in the atmosphere. In them, almost everywhere there is a "greening" of stems and lower branches of trees. The increased content of nitrogen oxides in the air of the city contributes to the intensive growth of small green algae on the bark of trees. They get the abundant nitrogen supply they need directly from the air.
The effect of atmospheric pollution on plants directly depends on the sources of pollution and on the spread of pollution. Dissipation of impurities from local sources of pollution depends on many reasons, which primarily include the features of the impurity and the source, the nature of the mixing of the atmosphere, the speed of wind transfer, and the terrain. The combination of meteorological factors actually makes it possible to assess the potential for atmospheric pollution and fallout from it.
The study of the directions of the prevailing winds makes it possible to assess the supply of technogenic elements from both local sources of pollution and from hundreds of kilometers away. The territory of the Kola Peninsula is characterized by a seasonal change in the directions of the prevailing winds from winter to summer. For the winter period, winds of the southwestern points are characteristic, for the summer - northeastern ones. This wind direction determines the seasonal accumulation of anthropogenic impurities from winter to summer due to the passage of air masses over the industrially developed regions of the European part of Russia and Western Europe.
2) Impact from soil. In cities, all industrial effluents end up in the soil. All pollutants through the root system, together with mineral salts, reach plants and begin to destroy them from the inside; root growth is weakened and trees are at risk.
Large amounts of chlorides are scattered on the streets of the city to combat icing. Salt has a negative effect on plants. Therefore, to combat soil salinization, it is necessary to plaster them. In addition, since the leaves of trees accumulate salts in themselves, in autumn you should collect leaves from saline places and destroy them. Moreover, they need to be buried, since when burned, all the harmful substances accumulated in the leaves will enter the atmosphere. Salt-tolerant plant species can be planted on saline soils. These include balsam poplar, elm, ash, warty birch.
An increase in lead content in soil, as a rule, but not always leads to its accumulation by plants both on unpolluted soils and soils of natural geochemical anomalies. In accordance with the content of lead in plants grown on soils of light texture (sandy and sandy loam) ranges from 0.13 to 0.96 μ / kg; in heavy loamy soils (with a pH of 5.5) in a wider range of 0.34 - 7.0 μ / hq.
Higher concentrations of lead (up to 1000 μ / gq) are characteristic of vegetation in technologically contaminated areas: in the vicinity of metallurgical enterprises, mines for the extraction of polymetals, and mainly along highways.
Soil acidification is determined by various factors. Unlike water, soil has the ability to equalize the acidity of the environment, i.e. to a certain extent, it resists an increase in acidity. Acids trapped in the soil are neutralized, which leads to the maintenance of significant acidification. However, along with natural processes, anthropogenic factors affect soils in forests and arable lands.
Chemical stability, leveling ability, tendency of soils to acidify are variable and depend on the quality of the subsoil, the genetic type of the soil, the method of its cultivation (cultivation), as well as the presence of a significant source of pollution nearby. In addition, the ability of the soil to resist the effects of acidity depends on the chemical and physical properties of the underlying layers.
The solubility of heavy metals is also highly dependent on pH. Dissolved heavy metals that are easily absorbed by plants are poisonous to plants and can lead to their death.
3) Exposure to radiation. In recent years, radioactive contamination has become a significant factor in forest degradation. Of the plants, trees are the least resistant to radiation and grasses are the most resistant.
4) Human influence. Increasing recreational loads have a significant negative impact on the vegetation of forests and parks. Overconsolidation of the soil in places of mass festivities worsens its water-air properties and is accompanied by the death of plants, including trees. In order to protect plants from such influences, paved paths should be laid in forests and parks. They take over the main flow of tourists and thereby protect the vegetation from damage.
At the population-species level, the negative impact of humans on biotic communities is manifested in the loss of biological diversity, in the decline in the number and extinction of certain species. According to botanists, flora depletion is observed in all plant zones.
The greenery of gardens, forests and parks can be preserved and developed only with a generally favorable state of the environment. Therefore, all measures aimed at improving the ecological quality of air, water and soil have a beneficial effect on green spaces.
Conclusion
Thus, green spaces are of great importance in human life. Greening is one of the ways to improve the urban environment. Green spaces absorb dust and toxic gases. They participate in the formation of soil humus, which ensures its fertility. The formation of the gas composition of the atmospheric air is directly dependent on the flora: plants enrich the air with oxygen, phytoncides and light ions useful for human health, and absorb carbon dioxide. Green plants soften the climate. Plants absorb solar energy and create carbohydrates and other organic substances from minerals of soil and water in the process of photosynthesis. Without the plant world, the life of man and the animal world is impossible. Plants not only fulfill their biological and ecological function, but their diversity and colorfulness always "pleases the eye" of a person.
Plants, especially in cities, are subjected to harsh influence from humans: pollution of air, soil, water oppresses the existence of trees and shrubs, and sometimes even leads to their death. In addition, a person often deliberately destroys green spaces, for example, clearing an area for the construction of stalls and shopping pavilions. Children destroy plants, playing and indulging. And the sooner each person realizes his responsibility to nature, the sooner the potential threat of the death of all mankind will disappear and the possibility of a full life in harmony with the surrounding world will appear.
Bibliography
1) Gorokhov V.A., Green nature of the city
2) Luntz LB, Urban green building.
3) Yu.V. Novikov Nature and man.
4) Mashinsky L.O., City and nature (urban natural plantings).
5) G.P. Zarubin, Yu.V. Novikov City hygiene
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Instructions
Poplars begin to bloom in early summer. Their fluff swirls through the streets, annoying many residents. However, local authorities are not always in a hurry to cut down these trees. There is a good reason for this: the poplar can be called the record holder among trees for air purification. Its wide and sticky leaves successfully trap dust by filtering the air.
Poplar grows rapidly and gains a green mass, which absorbs carbon dioxide and produces oxygen through photosynthesis. A hectare of poplars produces 40 times more oxygen than a hectare of conifers. The oxygen that one adult tree gives off per day is enough for 3 people during this time. At the same time, one car burns as much oxygen in 2 hours of operation as one poplar synthesizes in 2 years. In addition, poplar successfully humidifies the air around it.
A special advantage of poplar is its unpretentiousness and resilience: it survives along highways and next to smoking factories. Lindens and birches die under these conditions. The problem of poplar fluff, annoying to many, can be solved by replacing black poplar with "non-fluffing" species - silver and white.
Rosehip, lilac, acacia, elm are good at absorbing harmful substances from the air. These plants also survive in dusty environments. They can be planted along motorway sides as a green shield against exhaust fumes. Elms with their wide leaves retain 6 times more dust than poplars.
Chestnut is very useful in urban conditions. It is almost as unpretentious as a poplar. At the same time, an adult tree cleans about 20 cubic meters of air from exhaust gases and dust per year. It is estimated that a hectare of deciduous trees traps up to 100 tons of dust and airborne particulate matter per year.
Although conifers are not as good at trapping dust as deciduous trees, they produce phytoncides - biologically, inhibiting pathogens. Thuja, juniper, fir and spruce will help residents to cope with disease-causing microbes. In addition, they purify the air throughout the year, and not only in warm weather. Birches also produce phytoncides, but these trees, like lindens, are best planted away from roads and "dirty" industries - they are not as viable as poplars or chestnuts.
Lead, which is released into the atmosphere as a result of fuel combustion in automobiles, is very good for health. One car can emit up to 1 kg of this metal per year. Leaves on trees along highways can often be seen collapsing and falling off as a result of lead poisoning. Lead is best absorbed by larch and various mosses. It takes 10 trees to neutralize the damage from 1 car.
If you want to decorate your backyard with plants and at the same time not spend a lot of time and effort caring for them, then thuja is perfect for this. Such shrubs grow on almost any soil, withstand any weather, remaining green and vibrant.
You will need
- - shovel;
- - gravel;
- - fertilizer;
- - peat;
- - sod soil;
- - sand.
Instructions
Inspect the roots of the seedling before purchasing it. The root system should be well developed, with young roots and no visible damage. Check if the seedling is dry. To do this, run along the root with a fingernail or a sharp object, if there is enough moisture, then the scratch site will become wet, and the top layer will be easily removed. Examine the plant for harmful insects, diseases, and growths. An earthen lump should be kept around the roots.
Choose in your place where it will grow. Thuja in any soil and in any, but it is desirable that it was a shady, windless place. Dig a hole 70-80 cm in size. Place a 10-15 cm layer of gravel on the bottom. Mix turf, peat and sand in a 2: 1: 1 ratio. Lower the seedling into the hole and fill it with this mixture so that the root collar is at ground level. Add. If you want several shrubs, leave about 4 meters between them. If you want to make live from thuja, then there should be a distance of about a meter between the bushes.
Water the shrub once a week for the first month. If the weather is humid, then 10 liters of water per plant is enough, and in dry weather 20 liters. Water not only the roots, but also the crown itself, spraying it from a hose or watering can. Further watering thuja only needed in dry and hot weather.
note
Cover the shrub with light covering material for the first winter.
If you applied fertilizer during planting, then in the first two years this is no longer necessary.
It is better to plant thuja in spring or summer.
Cover the soil with peat, sawdust, humus, or wood chips around the plant. This will help keep shrubs from overheating or freezing.
Helpful advice
Sod soil is prepared in spring or summer. Cut the sod of the perennial grasses into slices. Lay the first layer with the grass up, on it 5-7 cm of manure and slaked lime (at the rate of 3 kg per 1 sq. M.) On top of another layer of turf with the grass down. In the last layer, make some holes so that water can accumulate in them.
Sources:
- how to plant thuja seeds
In the world of plants, as in the world of people, there are the fastest and largest. Among trees that live much longer than humans, growth rates are sometimes record-breaking on the planet.
Hardwood
If we compare deciduous and coniferous species, then representatives of deciduous species grow faster. Poplars can be called record holders among all trees in terms of growth rate, which, depending on the species, can grow up to 2 meters per year. Only willow, eucalyptus and acacia can boast of such speeds.
The fastest growing can be called Toropogritsky's poplar, artificially bred in Ukraine, which is capable of growing up to 4 meters annually. In addition, he calmly overcomes a height of 40 meters and is the tallest of the fast-growing trees. This is an absolute record among all trees. This species is distributed only in several districts of the Kherson region.
Conifers
Although deciduous trees grow faster than conifers, it is worth noting this species as striving to keep up with its hardwood competitors. The fastest growing coniferous tree is larch, which can grow up to 1 meter per year. If we consider that active growth is observed only in late spring and early summer, then every day the tree grows by 2.3 cm. At the same time, it reaches a height of up to meters, but in the most favorable conditions it can grow up to 50 meters.
The common pine is also trying to keep up. During the period of active growth, this tree can also grow about a meter per year. The pine begins to grow actively only after reaching the age of 5 years. The height that a pine tree can reach is 35-40 meters. This is a good indicator among fast growing trees.
These trees are quite widespread. So larch grows in regions of Siberia and the Far East. Whole forests of these trees grow there. Pine grows on the territory of the Scandinavian Peninsula and throughout the central strip of the Eurasian continent.
In terms of their prevalence, these trees are not inferior to poplars and are superior to acacia and eucalyptus. But all these "champions" are significantly inferior to one representative of the plant family, which, although not a tree, is very close to it.
The main record holder of the plant world
This record holder is rightfully bamboo, which can grow up to 1.25 meters per day. More than one plant cannot compare with it. The tree-like bamboo can grow up to 38 meters in size.
According to the World Health Organization, mortality and disease duration are inversely proportional to the area of the city's green spaces. Green spaces- "lungs" of cities, they contribute to the improvement of the microclimate, reduce the noise level, remarkably clean the polluted air from microbes and dust.
Hectare forests within an hour absorbs about 8 kg of carbon dioxide, this amount is exhaled by 200 people. The air-protective effect of green spaces depends on their age, composition, state, nature of planting (massif, row), location in relation to the source of pollution. In particular, a multi-row tree-shrub strip of gas-resistant species provides effective protection of the air environment of residential areas from vehicle pollution.
Scientists have conducted studies showing impact of forests on pollution air- up to 30-40% less such pollution under trees. It is estimated that a hectare forests during the year absorbs at least a ton of harmful gases and purifies up to 18 million m 3 of air. The forest massif is capable of capturing up to 22% of suspended harmful substances contained in the air.
Near highways, plants with hairy leaves take up lead about ten times faster than those with smooth leaves, and the rate of lead settling on grass is 4 times faster than on bare soil. It is estimated that one hectare of pine forest can bind up to 30 kg of sulfur dioxide per hectare per year, deciduous forest - up to 72 kg, spruce - up to 150 kg.
The forest clears the air from harmful substances, from dust, aerosols. It turns out that one hectare of coniferous forests can deposit up to 30-35 tons of dust per year, deciduous forest - up to 70 tons.
In an industrial city, 1 cm 3 of air contains from 10 to 100 thousand tiny dust particles, in a forest, mountains, field - about 5 thousand. The bacteria in the forest air are hundreds of times less than in the city air. In birch plantations in a cube of air, there are up to 450 different bacteria, which is below the norm for operating rooms where 500 non-pathogenic microorganisms are allowed. There are even fewer microorganisms in the pine, spruce, and juniper forests.
The oxygen-producing effect of one tree, growing under favorable conditions, is equivalent to the effect of ten room air conditioners, and the amount of oxygen produced is equal to the amount required for breathing by 3 people.
An integral part of atmospheric air is ozone. It prevents the passage of short-wave radiation, which is destructive to living organisms, to the earth's surface. The highest ozone density is at an altitude of 20-25 km. It enters the surface layers of the atmosphere as a result of the movement of air masses, its average density at the earth's surface, depending on the time of day, season - from 10 to 40 μg / m 3. With regard to content ozone contradictory opinions were expressed in the forest air, studies of recent years have confirmed its presence, in particular, in the air of a coniferous forest. Ozone concentration in the forest varies depending on the biological activity of plants, density and age of the stand, weather, season. In a young pine forest, it is 2 times higher than in an old one, in the winter season there is a minimum amount of ozone in the forest, perhaps not at all, in the spring it is the most. The higher the air temperature, the more intensely the plants release volatile substances, the more actively terpenes are oxidized and ozone. Concentration ozone in the forest it rises during lightning discharges, however, this increase is short-term. On the human body ozone at very low concentrations (less than 0.1 mg / m3), it has a beneficial effect - metabolism improves, breathing becomes deeper and more even, and work capacity increases.
Atmospheric air contains positive and negative ions, both of which are subdivided into heavy and light; it is useful for a person to enrich the air with light negative ions. When such air is inhaled, the oxygen content in the blood rises, the level of sugar and phosphorus is greatly reduced, headaches and fatigue are relieved, and the state of health and mood improves.
Forest air differs from any other in increased ionization (it was calculated that a cubic centimeter of forest air contains up to 3 thousand light ions). Ionizing factors are resinous, aromatic substances secreted by plants during the growing season. All of them create a certain biochemical environment and determine a certain composition of the surface air layer.
Everything plant organisms(from bacteria to flowering plants) release into the environment gaseous, liquid, solid, volatile, non-volatile, lifetime, postmortem discharge from damaged and intact organs. These excretions are an important ecological and phytocenotic factor. Those of them that have a detrimental effect on various pathogens are called phytoncides. Oak, juniper, pine, spruce, bird cherry, moss, and walnut are especially rich in phytoncides. On a hot summer day, one hectare of oak forest (oak grove) releases phytoncides up to 15 kg, pine forest - twice as much. The amount of phytoncides released by a juniper forest of the same area is sufficient to destroy all microorganisms in the air of a large city.
Except pine, spruce, oak, juniper and other species , high phytoncidity characteristic of birch, maple, aspen, raspberry, hazel (hazelnut), blueberry. Ash, alder, mountain ash, lilac, honeysuckle, caragana have medium phytoncidal activity.
Caragan plant
The lowest phytoncidal activity is in elm, red elderberry, euonymus, buckthorn. It depends on many factors - on the breed of plants, their age, weather, time of day. The air in a young forest is more saturated with volatile substances, in comparison with an old forest. Such volatile substances are released more on hot days in late spring and early summer, the maximum occurs in the second half of the day, at least at night.
Phytoncides stimulate life processes, improve metabolism. Inhalation of air saturated with pine phytoncides increases blood pressure in patients, and oak phytoncides decreases it. Phytoncides of spruce, balsam poplar, larch inhibit the growth of E. coli. Phytoncides leaves of cherry laurel, bird cherry, black root, herbaceous elderberry are toxic to rats. Bird cherry volatile phytoncides kill a rat in an average of 1.5 hours. The rats leave the places where the dried black root or herbaceous elderberry lie. Small rodents can't stand the smell canufer (balsamic tansy).
Under the influence of volatile substances, not only ozonation of the air and an increase in the amount of light ions in it occur, the radioactive background changes.
Positively affects the human body forest microclimate- calm, cool air and soil, moderate solar radiation. When approaching the forest, the wind speed decreases by 20-50%, in the forest itself - by 80-90%. Under the crowns of trees, depending on the composition, age, density of the stand, as well as the weather, time of day, - the season, the air humidity is 10-20% higher than in open space, the amplitude of humidity fluctuations is less, the minimum humidity is observed at night, on the surface it is higher in the soil than in the crowns of trees, in a pine forest it is lower than in deciduous ones. Illumination under the forest canopy can be 30-70% less than in open space. The total illumination in the summer time in the city is 3-15% less than near the forest, in winter - by 20-30%. There are 2 times less ultraviolet rays here, the wind strength is reduced by 20-30%. But precipitation is 10% more, foggy days - twice, dust - 10 times, carbon monoxide - 25, carbon dioxide - 10, sulfur dioxide - 5 times. A plume of dust from a large city can cause a decrease in solar radiation within a radius of 40 km.
Forest normalizes temperature fluctuations in different seasons, and also neutralizes daily temperature fluctuations.
The average annual temperature in a forest is 1 - 3 ° C higher than in a treeless area. In winter, it is much warmer in the forest than in an open place, for example, in a field, meadow, in summer it is cooler in the forest during the day, and at night it is much warmer. During the day, the crowns are warmest; they are most heated by the sun. In a leafless forest, it is warmer at the soil surface; the forest litter retains heat here. The forest is like a universal, biological, natural air conditioner without side effects on the human body (if it behaves correctly in the forest).
The role of green spaces in the purification of the air of cities is great. Plants absorb carbon dioxide and release oxygen. A tree of medium size in 24 hours restores as much oxygen as is necessary for the breathing of three people. In one warm sunny day, a hectare of forest absorbs 220-280 kg of carbon dioxide from the air and releases 180-220 kg of oxygen. 1 hectare of urban green space is released per day up to 200 kg of oxygen.
The results of studying the dust - and gas-retaining role of tree and shrub plantings indicate that the dust content of the air among green spaces is 2-3 times lower than in open areas. The species of trees and shrubs with rough leaves covered with villi (elm, linden, maple, lilac) have the greatest dust-retaining ability.
The gas-protective role of green spaces is due to the ability of plants to capture gases contained in the atmospheric air and their resistance to them. Poplar, Canadian maple, honeysuckle can be classified as the most gas-resistant.
The influence of trees and shrubs on reducing the concentration of harmful gases in the air occurs mainly through the dispersion of these gases into the upper atmosphere by tree crowns, and to some extent through the absorption of gases by leaves through the stomata and cell membrane of leaves. It is known, for example, that green spaces capture sulfur dioxide from the atmospheric air and accumulate it in the form of sulfates in their tissues.
The ability of plants to absorb carbon dioxide and emit oxygen is of great importance in improving the air in populated areas. On average, 1 hectare of green space per hour absorbs 8 liters of carbon dioxide. The intensity of this process depends on the characteristics of photosynthesis of various species of trees and shrubs.
A tree of medium size in 24 hours restores as much oxygen as is necessary for the breathing of three people. In one warm sunny day, a hectare of forest absorbs 220-280 kg of carbon dioxide from the air and releases 180-200 kg of oxygen. Poplar has the highest oxygen productivity.
For 1 ton of birch wood growth, oxygen is supplied: 1335 kg in CO2, 488 kg in H2O, 1823 kg in total. But the wood itself contains 430 kg of oxygen, and the remaining 1393 kg are released into the atmosphere.
It has been established that 1 hectare of a 20-year-old pine plantation, giving an average annual increase in wood of 5 m3 per 1 hectare, absorbs 9.35 tons of CO2 every year and emits 7.25 tons of O2. The most obvious in this respect are middle-aged plantings. So, 1 hectare of a 60-year-old pine forest gives an annual: an average increase of 7.51 m3 per 1 hectare, absorbing during this time 14.44 tons of CO2 and emitting 10.92 g of O2. Photosynthesis is even more active in 40-year-old oak plantations, where the absorption of CO2 per year per 1 ha is 18 g, and the release is 13.98 tons.
One hectare of urban plantings absorb 8 kg of carbon dioxide in 1 hour, which is exhaled by 200 people during the same time. In a city environment, green spaces are a factory of clean air, unsurpassed purifiers and ambulances of the atmosphere. Green spaces absorb not only carbon dioxide from the air, but also purify the atmosphere from carbon monoxide, reduce its concentration to natural - about 0.00001%.
Some plants can absorb the most harmful gases. It has been established that forest communities daily process up to 500 thousand cubic meters of air per hectare of forest with an assimilation apparatus. The total air-cleaning capacity of full-fledged forest stands, forming 4 tons of leaves per 1 hectare, is about 10 tons of toxic gases during the growing season. Only one tree during the growing season is capable of absorbing up to 12 kg of sulfur dioxide.
Students of the Kazakh University, together with scientists from the Botanical Garden of the Republican Academy of Sciences, studied the adaptation process in the city of more than three hundred species of plants. Studies have shown that in an industrial city, the development of green spaces is slowing down, but some individuals are rapidly growing. These are juniper, barberry, hawthorn. The rose belongs to the plant orderlies.
The effect of woody vegetation on the content of harmful chemical compounds in the city air is also manifested in the ability of trees to oxidize, gasoline, kerosene, diesel fuel, acetone, etc. vapors in the city air. Many plants can assimilate aromatic hydrocarbons, carbonyl compounds, ethers and essential oils from the atmosphere. There is information about the absorption of phenols by plants. A large phenol-accumulating ability is possessed by: common lilac, privet, white mulberry. In addition, green spaces are capable of trapping radioactive substances in the air.
Table 1
The best green filters for biological purification of atmospheric air in cities
Studies have shown that poplar is the best "orderly" in the area of strong constant gas pollution. For comparison, over 5 summer months, a 25-year-old oak absorbs 28 kg of carbon dioxide, linden - 16, pine - 10, spruce - 6, and an adult poplar - as much as 44 kg. Small-leaved linden, ash, lilac and honeysuckle also have good absorbing qualities. In the zone of low periodic gas contamination, a greater amount of sulfur is absorbed by the leaves of poplar, ash, lilac, honeysuckle, linden, less - elm, bird cherry, maple.
During the growing season, growing black poplar precipitates 44 kilograms of dust, white poplar - 53 kilograms; white willow and ash-leaved maple, respectively, 34, 30 kilograms. One hectare of spruce forest per year precipitates 32 tons of dust, oak - 54, beech - 68 tons. This function is best performed by trees and shrubs with pubescent, viscous, sticky, rough leaves. Elm, for example, traps 6 times more dust than poplar.
The influence of green spaces on the dustiness of the air and a decrease in the concentration of gases depends on the nature of the plantings: their density, configuration, structure.
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