How trees grow in the mountains. Coniferous trees in an urban environment

Phytoncides released by plants have the ability to cleanse the air of bacteria and saturate it with light negative ions. The phytoncidal properties of conifers are especially pronounced. From those growing in middle lane Thuja ranks first in terms of phytoncides, followed by pine, spruce, fir, and juniper.
But in the conditions of modern cities, it is becoming increasingly difficult for plants to demonstrate their protective properties; they already have to fight for their own survival under the pressure of external unfavorable factors, which intensify with the growth of cities upward and deeper and with an increase in traffic flows in them.
The main causes of disease and death of plants in the city, not counting mechanical damage to trunks and roots, are lack of moisture, insufficient lighting, unfavorable soil conditions, salinization and soil contamination with heavy metals and excessive air pollution.
Often mature trees cannot withstand a sudden change in the conditions in which they have grown all their lives, for example, shading due to a high-rise building, or a sharp drop in level groundwater, associated with digging a pit at a distance of 100-200 meters, or with soil compaction from spontaneous car parking that has arisen under the trees. Young specimens tend to adapt better to change.
But when replacing dead plantings, it is necessary first of all to select species that are resistant to urban conditions. This question has been studied, probably, since the first cities arose. And now we know that in the city it is not worth planting the capricious common spruce, which is demanding of soil conditions and moisture and cannot tolerate polluted air. The common pine is also not gas-resistant, although it is undemanding to the soil and is a very frost-resistant species. Near busy highways and in the city center is clearly not its place. The beauties western thuja and prickly spruce tolerate smoke and gas pollution in the urban atmosphere better than other evergreen conifers, they are very frost-resistant, prickly spruce is also drought-resistant, but demanding of light, thuja, on the contrary, is one of the most shade-tolerant species, but does not like the soil to dry out. But the Siberian and European larch is our champion for survival in urban environments. It’s not for nothing that it is the only conifer that survives on permafrost. Its drought and smoke-gas resistance is facilitated by the autumn shedding of needles. Together with the needles, the plant annually partes with the harmful substances accumulated in the tissues of the needles. In evergreen conifers, the accumulation of pollutants in the needles continues for as many years as the needles live. This, of course, has Negative influence for the life of the plant. When choosing a place to plant larch, it is necessary to take into account its exceptional love for light. Junipers are also quite resistant to urban environments, especially Cossack juniper. Common juniper does not tolerate gas pollution well.

and they constantly form new cells, which during the year form what are called annual rings or annual growth rings. These growth rings indicate the amount of wood grown during one growing season. And according to recent research by ecologists, the overall growth rate of most tree species only increases with age. However, regarding the rate of growth in height, a slightly different principle applies. It should be noted that tree growth speed can be increased at proper care, information about this can be found in the article.

Typically, living things, including us, have a period of active growth when they are young, but as they age, growth the body slows down or stops altogether. The growth rate of trees in height has the same character. After a period of active growth in height, the growth rate of the tree decreases, and it begins to gain weight due to the trunk and side shoots. The figure shows the general nature of the relationship between the height of most trees and its age. The schedule is divided into three phases. 1 is the initial phase of slow growth, followed by the phase rapid growth– 2. When the tree approaches a certain height, growth rates fall - phase 3. Of course, time and height values ​​will vary for each individual tree depending on the species and environmental conditions.

The general nature of the dependence of the height of most trees on age

Different types of trees grow from at different speeds. Depending on the growth rate, trees are usually divided into groups. In tables 1 and 2, trees are divided into groups depending on the tree's growth rate per year. Trees gain such growth rates during the active phase (between the ages of 10 and 30 years).

Table 1: Fast and Moderate Growing Trees

Very fast growing	Fast growing		Moderately growing
gain >= 2 m	growth<= 1 м		growth 0.5-0.6 m
	Deciduous	Conifers	Deciduous	Conifers
White acacia Birch warty Gledicia Willow white Willow Babylonian Maple silver Maple ash-leaved Paulownia Poplar black Eucalyptus	Elm small-leaved Elm rough Oak red Catalpa Nut walnut Nut black Tulip tree Mulberry Ash green Ash ordinary Ash Pennsylvanian	Norway spruce European larch Siberian larch Pseudosuga thyssolifolia Weymouth Pine Scots pine	Amur velvet Common hornbeam Sessile oak English oak Large-leaved linden Small-leaved linden Silver linden	Prickly spruce Siberian fir Thuja occidentalis

Table 2: Slow-growing trees

Slow growing		Very slow growing
growth 0.25-0.2 m		growth 0.15 cm
Deciduous	Conifers
Forest pear Pear pear pistachio tree Apple tree Siberian apple tree	Siberian cedar pine Arbor vitae	Dwarf forms of deciduous trees (Dwarf willows) Dwarf forms of conifers (Obtuse cypress) Cedar elfin wood Yew berry

Tree mass growth rate

It was previously thought that large trees were less efficient at sequestering carbon dioxide. However, recently, on January 15, 2014, research data showing the opposite was published in the journal Nature. The study was conducted by a team of international scientists led by Nate L. Stephenson of the Western Ecological Research Center.

The scientists reviewed records from studies conducted on six continents, collected over the past 80-plus years, and based their conclusions on repeated measurements of 673,046 individual trees.

“Large, old trees act not just as aging carbon reservoirs, but also actively sequester large amounts of carbon compared to small trees... In some situations, one large tree can add as much carbon to the forest mass in a year as is contained in an entire medium-sized tree "

The main problem is the perception of scale. Stevenson says it's difficult to see a large tree grow because it's already huge. Thickness with age the tree gains less, but the larger the diameter, the more surface area it grows. A tree can grow in height for many years, but at a certain point it reaches its peak and then begins to increase in trunk diameter, increasing the number of branches and leaves.

The researchers write:
“It is likely that rapid growth of giant trees is the global norm and can exceed 600 kg per year in the largest specimens.”

Stevenson also says that if people grew at this rate, they could weigh half a ton at middle age, and well over a ton by retirement.

The figure shows the general nature of the dependence of the growth rate of tree mass on the decimal logarithm of tree mass, given in the materials of the article.

As a result of human activity and other reasons, huge areas of ancient forests are being destroyed. . Trees play a very important role in existing ecosystems, so it is vital for us to protect forests from destruction.

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Ecological problems of the ocean. 5 threats to the future Deforestation is one of the environmental problems in Russia

Let's get acquainted in detail only with the mountains of the Western Caucasus.
The lower belt of vegetation here is formed by broad-leaved forests. At the very foot of the mountains there are oak forests, and higher up there are beech forests. Oak forests are formed by several types of oak - pedunculate, sessile, large-fruited, Georgian and others. In appearance they are all quite similar to each other. The abundance of oak species in the forests under consideration differs from the oak forests of the central European part of the country, where only one species of oak is found. Oak forests in the Caucasus Mountains develop in a somewhat drier climate than the following beech forests. The latter are formed by only one species beech - eastern(Fagus orientalis). Characteristic features of beech are an ash-gray smooth trunk, oval leaves, pointed at the ends, and at the same time with a completely smooth edge. Beech fruits are also unique. An individual nut-like fruit resembles a greatly enlarged grain of buckwheat. Two or three of these nuts are collected together and covered with a strong woody shell, forming small shaggy balls. The surface of the ball is covered with needle-like processes, but completely soft and non-prickly.
In beech forests, the grass cover is usually poorly developed. In early spring, ephemeral plants bloom here, most often white snowdrops (galanthus), but by summer all these plants dry out. Only a few types of grass remain green. Often there are no plants at all under the beech forest canopy due to extremely strong shading. The soil is covered only with a layer of dry fallen leaves.
Following the beech forests comes a belt of dark coniferous forests. From a distance, it stands out well on the mountain slopes with its thick black-green color. The replacement of broad-leaved forests with coniferous forests is due to the fact that as you rise into the mountains, the climate becomes colder and summers become shorter. During the short, cool summer, heat-loving broad-leaved trees do not have time to sufficiently prepare for winter. Their shoots, which appear in the spring, do not ripen by autumn and therefore cannot withstand winter frosts. In these conditions, coniferous trees prepare for winter quite normally; they do not need a large amount of heat to ripen young shoots.
In the belt of dark coniferous forests of the Caucasus, Caucasian fir and eastern spruce reign supreme. Both of these trees are quite similar in appearance. They have dense, dense crowns, tall, completely straight trunks. In the mountain coniferous forest there is always deep shadow, dampness and coolness. The whole situation is very reminiscent of our northern spruce forests on the plain.
Eastern spruce(Picea orientalis) is similar to Norway spruce. It has the same single needles, densely covering the branches, the same cones hanging down, the same thick needles. The trunk is also similar, covered with rough, large-scaled dark gray bark. However, the needles are much shorter and at the same time soft, non-prickly. Both trees are very shade tolerant. But only the spruce growing in the Caucasus is more thermophilic than its northern relative; it does not tolerate severe frosts. Wood is quite demanding when it comes to humidity.
Caucasian fir(Abies nordrnanniana) although similar in appearance to spruce, is very different from it in the details of its structure. Fir needles are not needles, but very narrow plates, rounded at the end. On the underside of the needle, two white longitudinal stripes are clearly visible. This is where the stomata are located.
Fir also differs from spruce in its cones. The difference lies primarily in the fact that fir cones do not hang like those of spruce, but are directed upward. They are located on the branches of a tree, like candles on a Christmas tree. A mature cone crumbles into pieces, scales and seeds fall to the ground. All that remains of the cone on the tree is a thin, sharp rod sticking up.
Finally, the bark of fir is also not the same as that of spruce, it is completely smooth, without any cracks. Its color is greyish, quite light. Fir can be easily distinguished from spruce by its smooth ash-gray trunk. Caucasian fir is one of our tallest trees. In dense mountain forests you can find huge old specimens, the height of which reaches 70 m.

Oriental beech (separately plush and nuts) and Caucasian fir

The coniferous forests of the Caucasus Mountains are in many ways reminiscent of northern spruce forests. There is the same twilight, the same layer of dry fallen pine needles on the soil, the same emerald green moss carpet. Grayish tufts of lichens, resembling a beard, hang down from tree branches. The grass cover contains many plants common to the spruce forests of the North - wood sorrel, mynika, sedmichnik, alpine circea, etc. Blueberries are very abundant, forming thickets over large areas. Among the green mosses growing on the soil, there are many that can be found in spruce forests. There are, of course, purely Caucasian plants that are absent in the North. One of them - Caucasian blueberry(Vaccinium arctostaphylos), which is very different in size from its northern relative. It grows as a fairly large shrub, reaching a meter in height. Otherwise, both plants have many similarities. Flowers and fruits are especially similar. The leaves of the Caucasian blueberry are much larger than those of the northern blueberry, but the shape is the same. They fall off in the winter.

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In boreal forests, mainly different types of fir, spruce and pine grow. Where there is less moisture, and primarily in Siberia, larches predominate.

Species diversity in boreal forests is low, and although mixed forest grows here and there, much more often vast spaces are occupied by trees of a single species. Such monotony is a hallmark of boreal forests.

Coniferous trees grow much denser than broad-leaved trees. On 100 m2, for example, up to 14-15 spruce trees can grow. Because of such cramped conditions, the shadow there is very thick - there is practically no light left for other plants. Nothing usually grows in the forest floor of a spruce forest. But in the pine forests the shade is not so thick, and many herbs grow there.

Hardy deciduous trees are also found in boreal forests. They grow around lakes and clearings. But conifers eventually choke out and displace them.

Altitudinal zone

When climbing a high mountain, the air temperature will drop by approximately 6°C with each kilometer. Therefore, even near the equator, where the climate is hot, it is cold in the mountains. And on the slopes of the mountains several natural zones can be distinguished. The tops of the mountains are covered with snow and ice - it is too cold for plants there. Below, where it is warmer and there is more moisture, grasses and shrubs begin to appear. Coniferous forests usually grow high on the slopes, and below them they are replaced by broad-leaved forests. Where persistent cloudiness creates a cold and wet climate, montane cloud forests grow.

Altitudinal zones in the mountains are found not only in the tropics. In the Rocky Mountains of North America, coniferous forests extend much further south than in neighboring valleys.

Coastal forests

A narrow strip of mangrove swamps stretches along the tropical and subtropical coasts. Mangrove trees can grow in salt water, and some species grow in tidal zones. Thanks to their breathing and stilt roots, these trees survive in swamps. Further from the seashore, where the water of the swamps is no longer so salty, there are other trees.

3. ANGIOSPERMS

Flowering plants or angiosperms have much more diverse trees than conifers. There are tall and multi-stemmed trees. The former have a well-defined main trunk, which branches at a certain height to form a crown. The main trunk lives for tens (and in some cases hundreds and thousands) of years, without stopping growth. In multi-trunked trees, after some time, the growth of the main shoot slows down, and additional shoots develop from dormant buds at the base of the trunk.

Such trees are characteristic of tropical and subtropical regions.

Trees growing in the tropics are characterized by the presence of above-ground roots - supports, stilted and plank-shaped roots, which give the trees a very bizarre appearance. Thus, representatives of the tropical genus Ficus form a large number of support roots, adventitious roots on the lateral branches, which, upon reaching the ground, take root and form peculiar “trunks”. This form is called banyan.

Trees are the predominant life form in the humid tropical regions of the planet. It is there, under the most favorable growing conditions, that trees reach their maximum size. In the temperate zone there are already much more herbaceous plants than woody plants. In places where the climate is warm but dry, or, conversely, humid but cold, tree forms transform into a lower-growing shrub form.

4. CONIFEROUS TREES – SURVIVAL STRATEGY

Coniferous trees have to withstand very harsh winters. The temperature there is below 0°C, and often drops below - 40°C. Winters bring severe drought as the groundwater freezes completely. The snow lies for a very long time, only a thin layer of soil thaws in the summer, and there is little water available to plants.

Conifers are evergreen, so even in winter their needles continue to produce nutrients. The surface area of ​​one needle (their “leaf”) is very small, and it is also covered with a layer of wax. This delays evaporation and helps conserve water. In addition, the needles produce a substance that prevents them from freezing and dying from frost.

In the coldest, driest areas, larches shed their needles to keep water loss to a minimum.

The roots of coniferous trees are shallow and highly branched in order to collect moisture from a larger area. And such a root system allows it to absorb nutrients even in early spring, when the soil thaws only a few centimeters from the surface.

The high density of trees helps them retain heat. The air captured by the needles and branches forms a kind of insulating layer around each tree. And the conical shape of the trees does not allow snow to linger on the branches, and they do not break under its weight.

In winter, conifers make the most of sunlight. Their shape is such that the sun's rays reach every tree. The heat reflected by the snow is trapped between the trees.

5. NEEDLES AND SOIL

Dying needles fall to the ground all year round. Over time, they accumulate in a thick layer on the surface. In cold climates they rot very slowly. In addition, the acids contained in the needles repel decomposers (bacteria and other organisms that decompose organic matter).

Dead needles are low in nutrients. Because of its acidity, earthworms and insects do not mix the needles with the soil. As a result, infertile acidic soils are formed that are not suitable for other plants. By creating such soils, conifers increase the territory of their distribution.

Coniferous trees could not exist so successfully in such conditions without “helpers”. They thrive through symbiosis with fungal mycelium. Myceliums supply the roots of trees with necessary minerals, receiving nutrients in return.

The soils of coniferous forests are infertile. The shallow root system allows trees to absorb water from soil that thaws in the spring.

6 .

HOW TREES GROW

Like all living things, trees require food to grow. How does the tree get it? The plant receives water and mineral salts from the soil. From the air - carbon dioxide, and the green leaves of the tree convert solar energy into starch, sugar and cellulose. This releases oxygen into the atmosphere. That is, a chemical process occurs that ensures the growth and development of the tree.

Between the wood and the tree bark there is a thin layer of cells called the cambium. New cells are created in this layer. Those that arise on the inner part of the cambium form wood, and those on the outer part form bark.

The diameter of the tree increases constantly, but this does not happen with the bark.

The leaves and roots of some trees, for example, bird cherry, spruce, pine, oak, emit substances that inhibit the growth of their neighbors. That is why pine forests and oak groves are so transparent, the undergrowth is not at all dense.

7 .

WHY DO TREES HAVE RINGS?
If you look at a cross section of a tree trunk or branch, you can easily see the so-called growth rings. Why are they formed? The fact is that the trunk and branches consist mainly of wood - a mixture of cellulose and lignin, that is, organic substances of a complex structure from the class of hydrocarbons, the main property of which is to be solid, to form, as it were, the skeleton of a plant. But the trunks and branches must grow annually. Why? But because the leaves of trees, even evergreen ones, are not at all eternal and are replaced with new ones over time.

New ones are also appearing

Firstly, another layer is deposited on top of the previous layer of wood, and secondly, this cylinder turns out to be heterogeneous: its inner part is formed by large cells, and the outer part is formed by small ones. Next spring, everything repeats again, and as a result, a layer with large cells begins to be deposited on top of the wood of small cells. The boundary between two such layers is clearly visible in the section. So, one such ring is deposited per year, which means that by counting all the rings, you can determine how old a branch or trunk is. It was precisely such calculations that made it possible to determine how many years some trees live: oak - 2000 years, sequoia (mammoth tree) - 5000 years, some cycads are even up to 10,000 years old! However, most trees have a much shorter lifespan. Bad weather, storms, fires, environmental disturbances greatly shorten their lifespan, and the age of 500 years for our lindens and oaks is quite respectable. For birches it is the limit.

Birches and aspens at 100 years old are already old plants, and poplars rarely live to that age. The reason for the unequal longevity of trees lies in the varying degrees of strength of their wood and its tendency to rot.

8 The fact is that as new layers grow, that is, new rings, wood, the old ones are gradually buried in the depths of the trunk and lose their viability. Living protoplasm leaves them, and only lignified (lignin) cell walls remain. If air and water enter the trunk, the wood may begin to rot. And it’s quite easy to gain access to air and water if, for example, a branch or twig of a tree is broken, or the bark is damaged. This is how a hollow begins to form.

True, it happens that the trunk inside is completely rotten, but the tree, nevertheless, remains alive. However, then the trunk becomes gnarled, the branches quickly dry out, and the top of the tree also dries out.. WHAT IS BARK The trunk of any tree is formed by a layer of living cells - the cambium. Cambium (from Late Latin " cambium" - exchange, change) - a single-row layer of plant tissue cells, in which wood (secondary xylem) is subsequently formed in the process of division inward, and in the process of division outward - phloem (secondary phloem). Phloem (from the Greek " " - felled tree) - water-conducting plant tissue that forms wood, the different growth rates of which form annual rings.

During the process of cell division, wood is deposited inside the trunk, and phloem is deposited outside. Bast is the inner, living part of the bark of any tree or shrub. Living means filled with protoplasm and juices that move from top to bottom, from leaves to roots. And in wood, along its outer edge, where the youngest tree rings are deposited, water moves from bottom to top, from roots to leaves.

The phloem contains layers of living cells similar to cambium, that is, capable of actively dividing and producing other cells. They are needed just to create a protective layer on the outside for the phloem cells. Otherwise, the barrel would be damaged by any touch. Plants protected themselves with armor, but not from metal, but from bark. The wood of the trunk is composed of cellulose and lignin, and the outer crust is made of a substance called suberin (from the word "suber" - "cork").

Cork (phellema ) - the outer part of the secondary integumentary tissue of plants. It develops on trunks, branches, roots, sometimes on bud scales, fruits (in pears), rhizomes, and tubers (in potatoes). Cork protects plant organs from excessive evaporation and penetration of microorganisms into them.

Well, what kind of material this is - cork - is well known to everyone. Corks are used to seal the necks of bottles. The best corks are made from the bark of the cork oak tree, which is specially bred for this purpose in many Mediterranean countries.

So, in the outer layers of the bast there are layers of living, dividing cells that form cork protective tissue. But these layers do not form either a continuous ring or a cylinder, but are located in separate pockets and work inconsistently, since, pushed aside by the wood growing from within and the inner layers of bast, they gradually lose their viability and stop working. From inside the phloem layer they are replaced by other cells.

Birch has an outer bark, the familiar birch bark on which our distant ancestors wrote letters, instead of suberin, it is impregnated with a similar composition, but still a slightly different substance - betulin, which colors it white and not brown.

Now, perhaps, it is clear why the bark on old trees is so cracked. Because both wood and bast continue to grow (thanks to the cambium), and the dead, outer part of the bark

What thickness the bark was initially, when the tree was smaller in diameter, remains so, and its inner layers seem to be bursting. Let's imagine what will happen, for example, to a balloon if it is inflated to infinity? It will burst. So the outer layer eventually bursts here and there.

So, the outer layer of bark (crust) consists of dead phloem tissue and a layer of cork.

In central Russia, all trees have very thick bark, or rather the outer dead layer. It protects the tree well from frost. But do trees need such protection in countries with mild winters? Wouldn't it be better to do without the outer crust altogether? And, imagine, they get by. For example, eucalyptus trees. On the Black Sea coast of the Caucasus in the fall (in September - October, which corresponds to spring in the southern hemisphere), you can see huge, rolled-up rags of old peel hanging from the trunks and branches of eucalyptus trees. In this tree, apparently, the layer of cells separating the bast from the bark is as continuous as the cambium. However, here too, the outer crust cracks longitudinally under pressure from the inside, since the eucalyptus trunks are thicker from below than from above, therefore, the cracks go from bottom to top.

On the outside of the eucalyptus trunk there is again smooth, crack-free bark, formed mainly by bast with a thin but durable layer of protective cork tissue.

9 Every year, therefore, some other trees, such as the strawberry tree, change their bark. The old and new bark of this cute tree are very different from each other: one is red, the other is greenish-yellow. And in plane trees (plane trees), each layer of bark lives a little more than a year. The bark of this tree does not change immediately, but gradually, in small areas.

.

HOW TO DETERMINE THE AGE OF A TREE

An old or diseased tree quickly deteriorates. Very soon he is attacked by microscopic fungi. Woodlice and slugs inhabit the wood; Spiders and centipedes hunt for prey.

After one year, the bark begins to fall off in some places. The reason for this is parasitic fungi that live on its trunk, and insects that sharpen its wood, etc. lay their eggs in it,

After 3-5 years, the bark completely disappears. In the resulting depressions, various phrases begin to grow (for example, oxalis), and ivy appears here and there. Gradually, bark beetles, slugs and other inhabitants of the tree leave it. The wood becomes rotten and finally crumbles.

11 .

WHY DO YOU NEED LEAF FALL?

How beautiful the forest is at the end of September! Against the background of the still green hazel tree, the leaves of a young birch tree are already turning yellow. And maple and oak stand elegantly decorated in green and red. Why do leaves turn different colors in autumn?

Let's remember that they owe their green color to the presence of a green pigment - chlorophyll. But there are other substances in the leaves. For example, the substance xanthoyl consists of carbon, hydrogen and oxygen and gives leaves their yellow color. Carotenoids are also present in the leaf. (Carrots are especially rich in carotene.) Anticyanite pigments impart bright red, crimson shades to maple and oak leaves.

In summer these pigments are not visible, we only see green chlorophyll. With the onset of cold weather, nutrients collected in tree leaves enter the branches and trunk. Since nutrient production stops in winter, chlorophyll decomposes. With its disappearance, other pigments that were always present in the leaf become visible.

And we enjoy the variety of tree colors.

By autumn, a thin layer of easily separated cells forms at the base of each leaf. A gust of wind tears off the leaves. A scar remains on the shoot, indicating the former location of the leaf. Most evergreen trees do not shed their entire cover as cold weather approaches. This happens gradually throughout the year, so they always remain green.

Seeds with wings are formed in plants that live in open places. Anemone seeds are completely covered with hairs. In willow and poplar, small seeds are equipped with a tuft of fine hairs. And poplar fluff is well known to us. The fruit of hazel, birch, alder and hornbeam is a small nut with two wings. One wing each for maple and ash fruits. That's why they spin when they fall.

13 .

INFLUENCE OF CLIMATE ON TREES

Climate is one of the most significant factors determining the nature of forest vegetation and the evolution of tree species over geological time. The current distribution of most of these species on the globe is due to relatively recent climate changes. The trees, in turn, have allowed modern science to reconstruct the climatic conditions of prehistory, down to the direction of the prevailing winds that carried their seeds.

The ancestors of all our trees were tropical plants. In the tropics, seasonal temperature changes are usually small; only the amount of precipitation varies from one season to another.

Most tropical trees are evergreens and can grow either continuously or in periods when sufficient moisture is available. Special areas in the tropics are mountainous zones, such as the equatorial Andes or Mount Kenya and Mount Kilimanjaro in Africa, where temperatures decrease with altitude and the upper slopes and mountain meadows are characterized by low-growing, oddly shaped alpine plants.

Temperate trees are well adapted to the changing seasons. They are called winter-hardy because they are able to withstand long periods of frost and sudden temperature fluctuations.

14. HOW TREES PROTECT FROM FROST

If clouds or tree canopies hold a layer of warm air near the ground's surface, heat cannot escape into the atmosphere and frost is less likely to occur (A). On a cloudless night (B), the earth freely loses heat. and the soil temperature drops below the air temperature (B). The soil takes heat from the ground layer of air, resulting in radiation frost.

Plowing up new lands, building cities, dams on rivers, people for many centuries carelessly and frivolously took from nature everything they wanted. And in the second half XX V. It turned out that some once common plants and animals, especially useful or very beautiful, began to disappear. There are no longer thickets of water chestnut, or chilim, on the lakes, it is almost impossible to find ginseng root in the taiga, lily of the valley has completely disappeared from the forests near Moscow, yellow roses of swimsuits in coastal thickets and beautiful water lilies in forest ponds have become rare. Now these are rare, or endemic, plants.

Long-lived plants can also be called endemic. The landscape surrounding them has changed, new plant species have appeared and disappeared on the planet, and they have been greeting and seeing off for centuries. There is only a small grove of Lebanese cedars left on the planet. Centuries-old American sequoias are given their own names. The Seychelles palm grows only in the Seychelles and nowhere else. Among the endemics there are also predator plants. There are still plants on the planet that are endemic due to their geographical location. The granite Seychelles Islands can be called one of the wonders of the world. They exist in isolation for a very long time.

It is believed that this is a fragment of the ancient single continent of Gondwana, which later “broke up”, forming all the modern continents. There are more than 70 endemic plant species and genera in the Seychelles.

16. WHAT ARE VYTONCIDES

In spring, the bird cherry bush or tree is strewn with snow-white clusters of flowers. And even if you didn’t notice flowering plants in the forest and walked past them, you will still feel a strong, intoxicating smell. Bird cherry smells very pleasant, but we do not recommend keeping a large bouquet of these beautiful, fragrant branches at home. The smell of bird cherry can cause a severe headache. Why? The fact is that bird cherry produces strong phytoncides containing poisonous hydrocyanic acid. Phytoncides are volatile substances released by a plant. They kill microorganisms that usually fill the air. That’s why it’s so easy to breathe in the forest.

Bird cherry phytoncides are so strong that they kill flies, mosquitoes, horseflies, and mold fungi if they are placed in a jar with flowers and crushed bird cherry leaves. The Colorado potato beetle really dislikes calendula (or marigolds) - the worst enemy of potatoes.

A pine forest releases 5 kg of phytoncides per hectare per day, a larch forest - about 2 kg, a juniper forest - up to 30 kg.

Many plants secrete phytoncides. We usually smell their scent, strong or weak. Phytoncides from fir, oak, and poplar leaves kill diphtheria bacilli. Pine phytoncides have a detrimental effect on tuberculosis pathogens.

Phytoncides are also released by microorganisms and lower fungi. They are called antibiotics. Many potent medicines are prepared on their basis.

Wood is the main material for making paper.

Wood is the main material for paper production. Nature also uses paper, or, more precisely, papier-mâché.

Just as bees build their hexagonal honeycombs from wax, so wasps build their honeycombs from a papery substance. The hexagonal design saves space (more than 100 combs can be placed in the palm of your hand for larvae or honey storage). Wasps scrape dry wood with their jaws, significantly increase its volume with saliva and stick the fibrous substance in layers.

This is how paper honeycombs are built. Field wasps build their nests from one or more free-hanging honeycombs. Some species of wasps that live under the roofs of houses wrap their honeycombs in bell-shaped paper formations. They are impregnated with a special substance and are therefore waterproof. When it rains, water flows off them.

Elongated tree cell Paper multifunctional systems.

Large colony wasps build nests as a multi-component system that performs different functions. Wasps use a paper-like material, but use air-filled hollow spaces. This entire structure also acts as a thermal insulator. Thus, with the help of one material, nature achieves different goals. This paper nest on the eaves is almost the size of a football.

Anyone who wants to know what cellulose feels like should pick up a cotton swab

A stick. Its head consists of almost pure cellulose fibers

22. PRELIMINARY PREPARATION AND DEVELOPMENT

Development means change, growth. So, for example, a flower appears, already born in a bud. The principle of preliminary preparation is familiar to technology.In a bud, the flower elements are folded into a narrow space. Due to increased pressure and growth processes, the petals of the bud shell diverge, revealing a flower, which then blooms and often becomes so large that one could not guess its size in advance. Sometimes it is difficult to imagine how a flower could fit in a small bud. The principle of nature is this: preliminary placement in the narrowest space is combined with an increase in size as the flower blooms.

The same rule applies to leaves. Sometimes both flowers and leaves are born in one bud, as, for example, in chestnut.Replacement boards.

To an increasing extent, technology uses the principle of preliminary preparation, borrowed from nature. Devices are often constructed in this way: whole groups of components are prepared in advance, which are then placed in intermediate warehouses awaiting assembly. For example, replacement boards with ready-made circuits for computers and televisions are produced. When an element fails, the old board is removed and a new one is inserted.

23. PEOPLE AGAINST TREES

Farmers have a very ambivalent attitude towards trees. They often think that on lands occupied by trees they could grow crops and raise cows and sheep.

Trees have served humans for a long time. After all, wood is an excellent building material. It can be used to make strong bridge supports and elegant carved legs of tables and chairs. Man has discovered other ways to use wood, and one of the most important is to make paper. Newspapers and magazines, notebooks and envelopes - much of what we use today is made of wood.

In addition, forests still remain an important source of fuel. Billions of people continue to use wood to heat their homes or cook dinner.

Today, only 50% of the forests that once covered the earth have survived. In their place are now fields and cities.

About 10,000 years ago, the natural distribution zone of forests - taiga, broadleaf and tropical rainforests - occupied vast areas of land.

The second period of forest destruction began about 2000 years ago.

Metal processing became widespread, requiring huge amounts of charcoal. Other branches of handicraft production also needed wood. Thus, many oak forests in England were destroyed when wooden ships were built for the Royal Navy. In Europe to the beginning XIX

centuries, the area of ​​deciduous forests has significantly decreased. Soon a similar fate befell the forests of North America and Australia. In the last 80 years alone, about half of the forests have been destroyed.

Forests were cut down with stone tools and burned. Grains were sown in the vacated spaces. This farming system was called slash-and-burn. As metal tools, plows, and the use of draft animals spread, peasants began clearing even larger tracts of land from the forest.

24. HOW FOREST DEATH OCCURS

Forest destruction is currently causing alarm throughout the world. Every eight minutes, 259 hectares of tropical rainforest are cut down. In many countries, the use of forests is now strictly controlled, but in many cases irreparable damage has already been done. Logging, oil and other mineral extraction, agriculture, city and road construction and many other human activities are a real disaster for the tropical rainforest.

In the subtropics and savannas, prolonged droughts and human demand for fuel threaten the few remaining forests with complete destruction. In Southeast Asia, mangrove forests are being brutally cut down to make chopsticks.

The effects of deforestation are greatest in mountainous tropical areas. Rainfall washes away the soil left unprotected by trees from the mountain slopes, leaving bare cliffs and deep ravines.

Water carries soil into rivers. And there it clogs the riverbed, clogs irrigation canals and causes crops to suffocate under a layer of silt.

However, it is much easier to prohibit destruction than to restore lost forests. In many areas, soil erosion has gone so far that giant trees can no longer grow on such soils. Even under favorable conditions, forest restoration is a long process. It can take up to 600 years for the tropical rainforest to return to its original state.

In temperate zones, vast areas of cleared deciduous forests are being replanted with fast-growing coniferous trees. Although they are a renewable source of wood, they are not the best choice. Coniferous trees increase soil acidity and can disrupt soil drainage. If they are foreign to the region, they will be of no use.

25. HOW THE FOREST IS RESTORED

The first to invade the fields were wild grasses, weeds familiar to all of us.

The seeds of trees and shrubs took root under their cover. Creeping plants - rose hips, blackberries, ivy - covered the entire ground. And after 25 years, young broad-leaved trees were already growing there. Seasonal life cycle of a tree. 1) Spring: leaves are growing. 2) Summer: dense foliage on the trees. 3) Throughout history, people have cut down huge tracts of trees for crops and pastures. When the lands ceased to be cultivated, natural vegetation was restored. Scientists were able to trace how different plant species gradually conquered the former fields until a specific plant community was established there. Autumn: leaves dry out and fall off. 4) Winter: the trees are bare.

Leaves falling on the forest floor increase the nutrient content of the soil. They are then absorbed by tree roots.

Dropping leaves is a great way to store nutrients until next year. Low temperatures in winter slow down the decay process, and nutrients are retained until the beginning of the growing season (until spring).

Earthworms and insects mix rotted leaves into the soil.

Due to the shade cast by the trees, many plants bloom in early spring.

Scilla, like other primroses, manages to complete the annual development cycle: bloom, bloom and produce seeds before the tree crowns close.

In autumn, the ground in the forest is covered with a carpet of fallen leaves. Their layer compacts and rots, turning into humus and soil.

26 As tree roots penetrate deeper into the parent rock, breaking it down, deciduous forests develop fertile, well-mixed soil. Many tree species grow in such forests: from oak to horse chestnut and sycamore.

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TREES IN FAIRY TALES AND MYTHS

Trees existed on our planet long before the appearance of humans.

Many of them now live much longer than people. The oldest giant and long-lived trees are now more than 2000 years old. But in ancient times people treated trees with much more respect than they do today.

In ancient times, people considered the forest a mysterious and scary place. Their imagination populated the dark forest thickets with bloodthirsty monsters, evil trolls and other evil spirits. In many myths, legends and stories, the strangest and unexpected things happen in the forests. But forest dwellers, on the contrary, treated trees and animals as their own kind, endowing them with souls.

The Green Man is the pagan god of spring,

To which the celebration of the first of May was dedicated.

In ancient India, peasants often deified a tree. While everything was fine in the village, they worshiped the tree and brought gifts to it.

But as soon as luck ran out, they forgot about the tree, leaving it to the mercy of fate.

The tribes of ancient Europe had many beliefs associated with trees. Trees were often planted in sacred rings, alleys or groves where only priests and priestesses could enter. In North America, Indians of many tribes tried not to cut down living trees so as not to cause them pain.

27. Carving from a church in Norway

For many years, “greens” have been calling for people to refuse to buy a live Christmas tree, so as not to destroy a living tree for the sake of momentary joy. And this does not mean at all that on New Year’s Eve you should be left without the magical smell of the forest!

Imagine that in your apartment there are correctly cut down (one from the tree and not from its top) or correctly purchased (the merchant had a forestry invoice) spruce branches. How to make them even more magical?

An example of a “correct” bouquet is a traditional asymmetrical triangle. On the right in the vase, a large spruce branch is directed upward, the remaining branches from its center lean down to the left. From above the bouquet looks like an elongated oval, from the side it looks like a chair with a back on the right.

The shape of the bouquet is “seated man”. And in the place where the backrest meets the seat, you need to place an accent - a ball or a candle. For bouquets in a vase, the ratio of the height of the vase to the bouquet should be equal to the classic Japanese proportion - 3:5.

To store a bouquet in a basket, fill a bag with wet sand, tie it tightly, turn it over and place it tightly in the basket. The branches are stuck into the bag, but their location cannot be changed, the sand will spill out through the empty holes, and the life of the bouquet on the wall can also be extended. Place a potato on a cut branch, disguising it with a toy or bow. Or you can first hold the branches in water for two hours, and then wrap the ends with tape. Needles usually do not fall off for a long time if the branches are not near the battery and have access to moisture.

The colors for New Year's compositions are red, white, crimson, but blue against the background of pine needles is not advantageous. A bouquet looks beautiful if only one color is used in its decoration. For example, silver-white: silver tinsel, white packing tape, silver bells. You shouldn't use more than 4 colors at all.

An unusual decoration is made on the basis of a hoop. Two big branches
having crossed at the bottom, they are launched from the bottom up. To avoid resemblance to a funeral wreath, in no case should they be tied to the hoop with a red ribbon, just something colorless! The rest of the hoop is wrapped in tinsel, and two balls are hung on top at different heights on packing tapes.

One small branch can magically change an apartment if you wrap it to the edge of a wicker stand, starting from the bottom, just to the left of the middle, wrap the rest of the edge with tinsel, and attach a bow on top.

And in the summer you can prepare material for a most unusual Christmas tree - from pine cones. True, you will need a large supply of spruce or pine cones. Think about it this summer! The base of this unusual Christmas tree is a pear-shaped cover made of fabric and stuffed with cotton wool. To ensure stability, it is strengthened on a fairly massive stand. Using threads and glue, cones are attached to the base. And then they decorate the Christmas tree with garlands of light bulbs and small toys - as your imagination dictates. Try it - it will be an interesting activity for the children, and one less cut down Christmas tree.