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Why are trees throw off foliage and why leaves yellow? Probably, this question sooner or later arises not only in children, but also adults. Let's figure it out, why do the trees throw foliage in the fall, and why the autumn leaves change their color?

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As you know, chlorophyll is responsible for the green color of the leaves. It is also necessary to launch photosynthesis - the process of converting the energy of sunlight into oxygen. But plant leaves contain other coloring pigments, such as:

  • Carotene . Gives orange shades leaves
  • Xanthophil . Color leaves in yellow.
  • Anthocian . Pigment, coloring leaves in red. It helps the leaves longer to hold on the tree before falling to transfer the last nutrients to the tree. And also protects the leaves during freezing and the overaction of dangerous solar radiation.

All these pigments are constantly kept in the leaves, but they become visible only when decreasing the production of chlorophyll, that is, in the fall, when the trees reduce its development as a consequence of lack of light and decrease the temperature.

Between the tree and leaves throughout the summer there is a mutual exchange: the leaves supply wood with useful substances, such as sucrose. It is sucrose that makes our favorite fruits with such juicy and sweet. And the trees nourish the leaves of moisture, the reserves of which in the cold season are significantly depleted.

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Thus, in the fall, in the premonition of the onset of cold weather, the trees cease to produce chlorophyll and begin to scar the places of fastening of the leaves, thereby stopping fluids to them.

Chlorophyll, leaving the leaves, makes the rest of the coloring pigments that hide behind it throughout the summer season. Depending on the individual characteristics of each tree and his lifestyle, falling leaves may have a completely diverse color palette, which annually stains our lives in bright yellow-red shades and gives a unique lyrical, "autumn" mood that inspired to create global works by no generation poets, artists and composers.

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A B. This article You will find out where oxygen is taken in winter.

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Why fall on the trees yellow and fall leaves?

Summer leaves

For the emerald foliage of any plant meets a special substance chlorophyll - Pigment, giving green color leaves. It not only gives fresh herbal color, but also feeds plants, participating in the process of forming glucose and other nutrients.

This pigment is produced thanks to the photosynthesis process. The leaves are absorbed by carbon, and oxygen isolated. It happens in comfortable conditions - in the presence of heat and the sun. In addition to oxygen, the chlorophyll known to us is produced at photosynthesis.

With the onset of the cold season, a sunny day is shortened: the weather is no longer happy, the light becomes less. Chlorophyll ceases to be actively produced, and other pigments come to replace it.

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Autumn foliage paints are obliged to special pigment substances. Carotine is responsible for orange. Such a pigment can be found not only on the autumn crowns of trees, but also in conventional carrots. Yellow leaves appear thanks to Xanthofila, and red - Anthocian.

The conditions for developing pigments are different. If chlorophyll need a lot of heat and sun, then xanthofila and carotine is quite warm and a little light. But to get a lot of crimson leaves, you need cold weather and bright sun. Frost and the abundance of light are the conditions for the appearance of a large number of Anthocian in foliage.

Leaves yellow over the city spin

Autumn sometimes trees first please us with bright colors, but with the approach of winter pores begin to get rid of the leaves. Why and why is it going on?

With the arrival of the cold season, the soil begins to freeze. Trees cease to receive the desired amount of moisture and nutrients. The vital processes begin to stop, the plants go into a hibernation. In order not to spend power on food, plants are forced to get rid of excess cargo - and dump the foliage.

At the base of the sticker (narrow part of the sheet, the place of attachment of the sheet plate to the stalk) is formed a special separation cork layer, blocking the "delivery" of nutrients from the tree. Excessive leaves are becoming more difficult to stay on the branches and gradually they begin to fall. As with the appearance of a multi-colored crown, and when leaf foliages, all processes do not proceed instantly. That is why we first see the dimensional shift of the colors of foliage, and then slow deliverance of trees from its bright outfit.

The leaf fall is a prerequisite for the existence of trees that helps them annually update their foliage. With the arrival of spring through the roots of the trees again begin to receive the required amount of water from the fatal soil and revive their magnificent crown.


But why the coniferous trees do not drop their "greens", because the needles are also a type of leaves too?

The whole thing in the structure of the needles. The upper cellular layer is a dense shell coated with a thin wax layer. Thanks to such a rigid "equipment", the coniferous trees are not afraid of cold. A special form of chewing provides a smaller degree of surface area, therefore needles evaporate moisture significantly less than ordinary leaves.

Naturally, the needles also agrees and fall. However, it happens not at one moment, but gradually throughout the year or even several years, therefore the change of needles flows not as noticeable as deciduous trees.

But among the coniferous trees there are exceptions, for example, larch. It grows in harsh conditions and cannot evaporate moisture in the winter. Therefore, as deciduous trees, also with the approach of winter discharges their cheva.

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Why leaves yellow in autumn?Incredible facts

For many years, scientists studied the leaves and how they change their color in the fall. Molecules responsible for bright shades of yellow and orange, are no longer a mystery, and why the leaves acquire a red color while remains a mystery.

Responding to Air temperature shift and fewer daylight, leaves cease to produce chlorophyll (which gives green), absorbing blue and partially red light emitted by the sun.

Since chlorophyl is sensitive to cold, some Changes in the weather Such as early frosts, "turn off" its developing is faster than usual.

Why yellow and fall leaves

At this time, orange and yellow pigments called Carotenoids (which can also be found in carrots) and Xantofilla Shoot through the leaves that have no green left.

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"Yellow color is present in the leaves all summer, but it is not visible until the green will not disappear," says Paul Shaberg (Paul Schaberg), physiologist of plants from the US Forest Service.

But scientists have little information about red color, which appears in some leaves in autumn.

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It is known that the red color comes from Anthocyanids which, unlike carotenoids, are produced only in autumn. Anthocyanids also give the color of strawberries, red apples and plums.

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Trees produce anthocyanids when they feel shifted in the environment - Frost, ultraviolet radiation, drought and / or fungus .

But the red leaves are also Sign of illness Tree. If you notice that the leaves of the tree before the usual (at the end of August) became red, most likely the tree suffers from the fungus, or it was damaged by man somewhere.


Why does the tree spend its energy to work out new anthocyanids in a sheet when this sheet is about to fall?

Paul Shaberg believes that if the anthocyanids help the leaves remain on the tree longer, they can help the tree to absorb more useful substances before the leaves fall. A tree can use soaring resources to flourish next season.


The theme of the anthocyanin is a little more difficult for study, rather than the remaining components of the trees. Despite the fact that all trees contain chlorophyll, carotene and xantophylls, not all produce anthocyanins. Even those trees that have anthocyanins produce them only under certain conditions.

Before the tree get rid of their leaves, it tries to absorb as More nutrients Of these, [leaves], and at that moment an anthocianin is entered into the role.


Scientists have several answers to the question why some trees produce this substance, and the leaves change their color.

The most common theory It suggests that anthocyanins protect the leaves from the oversupply of sunlight, while allowing the wood to absorb useful substances stored in the leaves.

On the tree these pigments Play the role of sunscreen , Blocking the dangerous radiation and the protection of the leaves from the overaffect of light. They also protect the cells from rapid freezing. Their favor can be compared with the benefit of antioxidants.

Large amount of sunlight, dry weather, frosty weather, low nutrient level and other stress factors Increase sugar concentration in wood juice . This launches the mechanism for generating a large number of anthocyanins, in the last attempt to accumulate energy to survive the winter.

Scientists believe that the study of anthocyanids will help to understand the level of the disease Each tree. This, in turn, will give a more understandable picture of environmental issues.

As the character of the book and cartoon said Lorax: "The color of the trees will once be able to tell us that the tree feels at the moment."

Why leaves dry and fall

With the arrival of winter, part of the globe receives Less sunlight And the air becomes colder. When such changes occur, trees are preparing for the winter.


Trees who discard their leaves, clog the places of fastening the leaves . It does not allow liquids with useful substances to reach the leaves, because of which the leaves change their color and fall.

Leaffall symbolizes not only the change of season, this process is also helps wood survive cold , dry winter air.

In winter, trees are lacking liquid to "Keep" leaves . If they did not clog the places where the leaves begin to grow, the trees would just died.

When spring brings warm air and water, trees start growing new leaves.

Why are coniferous trees do not reset the leaves?

Undergrowth in autumn
Why yellow leaves on trees: pixabay

The world around the world is so habitant that it often becomes a small-billing background for some important, according to individual, events and affairs. However, when autumn occurs, the period comes with it, ignore which is impossible - leaf fall. In this beautiful, singing by poets, many children (and often adults) are beginning to be interested, and why yellow leaves? In the article, we will tell what the peculiarity of this phenomenon is for what reason the leaves fall from the trees in the fall, and also for which they are generally needed by plants.

Why yellow leaves in autumn?

First of all, we will deal with the foliage itself, or rather, with its tint. She, by the way, happens depending on the surrounding conditions:

  • green;
  • orange;
  • red;
  • yellow.

Why is this happening? It's all about the accumulated pigments (these are such natural coloring substances). So, in particular name:

  • green - chlorophyll;
  • Punchov - Anthocian;
  • Orange - carotene;
  • Yellow - Xantofil.

Why fall yellow leaves? This is primarily due to the change of seasons. The fact is that:

  1. The entire spring-summer period deciduous trees are assembled in their fabrics nutrients and minerals, that is, make reserves for the winter.
  2. This requires a chlorophyll pigment, since it is impossible to carry out photosynthesis without it (a process that helps turn carbon dioxide and light into a nutrient organic).
  3. When it becomes cold, that is, in the fall, the leaves on the trees are yellow and fall. They are due to the reduced light day can no longer serve as a source of nutrients. On the contrary, the leaves begin to spend reserves strongly.
  4. The trees are activated by the mechanism that contributes to the elimination of such an important mineral from the foliage cells as magnesium. Without it, chlorophyll loses stability and disintegrate, and therefore the green shade is lost.

The leaves of the trees in the fall, having lost the emerald pigment, do not become colorless, as they contain other coloring substances that are stated above. So why leaves yellow, blush or become orange? It depends on the predominance of some specific pigment in them.

Explaining why the leaves are yellowing, it is notable to tell about the reasons forcing them to become brown-brown. This shade occurs only when all sheet pigments are destroyed. As a result, only cell membranes remain, and they, in fact, are painted in brown.

Infographics telling, why yellow leaves
Why yellow leaves in autumn on the trees:

What are the leaves for?

From the above section, it becomes clear that the foliage of trees is extremely important. Without it, the plant is not able to fully eat, but, remaining with it at a certain point, can die. However, about everything in order:

What is the purpose of the leaves?

It is twofold. Leaves:

  • Call photons (that is, particles) of light, because they have the ideal form for this - wide and as flat as possible.
  • A carbon dioxide is absorbed, completely unnecessary (and even harmful) to other creatures inhabiting our planet.

While the foliage is engaged in photosynthesis, the root tree of the tree supplies the assembled in the ground:

All this on special channels is sent to the leaves, where there is a combination of water and microelements with carbon dioxide and sunlight.

A nutritious solution prepared so complicated way is further spent on the development of wood, its growth and fruiting. In the process still stands out (as a byproduct) oxygen, without which the person and animals cannot exist.

Why leave the leaves?

When trees are flying, it suggests that they are not able to maintain their processes of life in normal mode. Falling leaves appear not only with the onset of cold weather, but also often during a strong drought. The reason in both cases is the same - the need to save resources.

Only some trees have learned in the process of evolution to save the crown, despite the extreme weather conditions. For example, eucalyptus unfold their leaves sideways to the Sun, which protects them from moisture loss.

This process is always initiated by wood. This is the case:

  • At the base of the sheet, the sheet begins to increase the layer of special cells, referred to as cork;
  • It interrupts the connection between the tree and the sheet and repels the last to the side;
  • As a result, the sheet plate is broken.

The described process is universal: so falls out of almost all trees.

Why not yellow fir?

Why yellow and shrink leaves from ordinary trees, it is clear. And what are special conifers? Fir, pines and other representatives of conifers, like all trees, are also discharged by foliage (needles - this is leists). However, this process is sluggish, constantly and regardless of the season. Therefore, he is not striking. They don't need to turn yellow, because the needles almost do not evaporate moisture.

Autumn Park
Why yellow leaves on trees in autumn: pixabay

It is not difficult to understand why yellow leaves and fall behind it. The importance of this process for the tree is impossible to overestimate. Do not have a plant of the ability to get rid of the leaves, it would certainly died.

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Many written poems, drawn pictures about the golden autumn. Autumn is really very beautiful when all trees in yellow leaves, we admire a golden leaf fall and walk along the rustling foliage. But many of you will be able to answer why the leaves are changed in the fall and fall out?

Why leaves fall yellow?

Green leaves in plants due to chlorophyll pigment, and its reserves are replenished while there is light and heat. With the onset of autumn, climatic conditions are changing. Light day becomes short, nights become longer and cold. Since trees and bushes are less and less sunshine, the process of photosynthesis is slowed down, all the processes of vital activity slow down in plants. Chlorophyll, giving green leaves, is destroyed, and instead of it other painting pigments are activated - Anthocian, Karotin, Xantofil. They paint leaves in yellow, crimson and orange.

Why leaves fall fall in the fall?

Yellow leaves on earth

As a result, the above-described climatic changes through leaves are less and less nutrients. The leaves become unnecessary wood and gradually weaken the relationship between the tree and leaves. The leaves are worse and begin to fly even from a small impulse of the wind. The autumn leaves begins.

During the life of the leaves, various harmful substances accumulate in them and, dropping them, the tree gets rid of pollution. And spring will grow new and healthy leaves.

In winter, snow accumulates at the branches of trees, and if they remained and the leaves are on them. The dropping of leaves in the fall prevents breakdown branches under the weight of snow on the leaves.

Yellow leaves in water

In winter, the tree due to weather conditions gets less moisture and nutrition. The leaves take a large amount of fluid, and the natural leaffall helps the bushes and trees save their resources.

From fallen leaves there is a huge use - in winter they are overloaded and form a layer of fertilizers that feeds plants.

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