Why do leaves fall in autumn? Why do leaves turn yellow in autumn? Let's find out.

Sasha K. (Belogorsk)

In what period does the leaf fall of linden and birch begin and end?

With the onset of September, the trees gradually begin to change the summer emerald green color of the leaves to autumn yellow. A little more time will pass and all the golden foliage will rush to the ground. Watching nature, people often ask themselves the question - when does the leaf fall end for birch, linden, maple and other favorite yellowing trees? Let's try to answer this question.

When the leaves turn yellow

Foliage begins to change color long before the first frost. As a rule, this happens at the end of August, when the day has already noticeably decreased and it has become a little colder, and lasts for 14-20 days. At first, only single gray-yellow patches are visible on the branches, but day by day there are more and more of them.

autumn birch

By mid-September, birch leaves become ocher-gold and gradually begin to fall off. Maple branches are no less beautiful at this time. The crowns of the tree are covered with foliage of yellow, brick red, red and even purple hues. The foliage of the linden, which is only half yellowed, stands out noticeably.

The beginning of leaf fall

For many trees, leaf fall is uneven, that is, it happens in different time. For example, after the first severe frost, leaf fall begins in linden and maples. By this time, the birch had already dropped most of the leaves. Her leaf fall begins in the first decade of September and lasts 15-20 days.

Important! The beginning of leaf fall depends on the weather. Dry sunny weather and windless days delay the golden decoration of trees.

Leaf fall is especially abundant after the third frost. The leaves fall to the ground very densely, forming a thick bedding on the ground. Birch drops about 30 kg of leaves in autumn. In an adult linden and maple, this amount reaches 40-50 kg.

End of leaf fall

The end of leaf fall, as a rule, is accompanied by a significant cooling, deterioration weather conditions, frequent rain and strong gusts of wind. By October 7-10, lindens and birches lose their last yellow leaves. Maples are exposed much later, only by October 20. Single leaves can be kept on the branches until mid-November, reminding passers-by of the past golden season.

autumn maple

Observations of nature during leaf fall

The period of active leaf fall is accompanied by a significant cooling and the arrival of night frosts. Summer white clouds are replaced by a solid gray veil. It is often foggy in the morning. The first flocks of migratory birds fly into the sky.

The end of leaf fall in lindens and maples is accompanied by gloomy rainy weather, frost on the still green grass and thin ice on the puddles. Rooks gather in flocks and fly south. Gradually the earth cools down and nature falls asleep.

Autumn leaf fall: video

Greetings, my dear explorers!

Today in discussion new project, the material on which can be useful to you for the next speech at the lesson "The world around us". Why do leaves turn yellow in autumn? This question is often of interest to children, especially when they are walking park path, raking the fallen leaves with his foot. But really, why?

Lesson plan:

Which artist paints the leaves?

In summer, the green canopy of trees lives through a process called photosynthesis. Have you heard about this one?

I think it’s not a secret even for preschoolers that the leaves absorb carbon and process it with the help of the sun’s energy into organic substances that they feed on, releasing oxygen back. This magic inside the tree leaf only happens when comfortable conditions: Warmth and sunshine are important to him. What is responsible for the colors?

How do pigment neighbors live in leaves?

I see the question in my eyes: “Why, if all the pigments live together, there are no yellow and orange leaves in summer, but green ones in autumn?”

The thing is that active chlorophyll with its large quantity in warm weather, it masks other dyes, they are simply not visible. With the onset of autumn, when there is little sun and daylight, the green artist begins to develop less and less, not being replenished in such quantities as in summer. That's when other shades begin to shine through.

That is why very often at the very beginning of autumn the leaves on the tree are not painted all at once, but are painted with a bizarre pattern, when green veins are still preserved on a yellow or orange background.

Every day closer to winter, the existing chlorophyll is destroyed, the new one is not replenished due to the lack of conditions for photosynthesis. The veins of the leaves along which they act nutrients, are closed with a dense plug of cells, reducing the amount of juice in the plant.

Here she is: gold autumn at it's peak, green leaves not found on the tree! Moreover, the faster the cold sets in, the sooner the tree “turns off” photosynthesis. A colorful carpet appears under your feet, it's time to make a couple or three.

Why do trees shed their leaves?

Yellow leaves swirl over the city,

With a quiet rustle, they lie under our feet ...

Indeed, they would stand all winter long, delighting us with their bright beauty. But no! Leaves begin to fall at our feet, heralding the change of season. Why?

With the advent of cold weather, the soil begins to freeze, the trees no longer have enough moisture and minerals. Life processes gradually fade, all plants hibernate. And how to sleep if every leaf needs to be fed? You have to save on food, getting rid of unnecessary consumers, which is why trees shed their leaves before winter.

At the place of attachment of the petiole of the leaf, a special cork layer is formed, which closes the influx of nutrients from the tree. The leaves are getting weaker every day and gradually fall off. As when changing color, they do not all leave the tree at once. Some will linger longer, fluttering in the wind, some fall among the first, lining the golden paths.

Therefore, leaf fall is a condition for the continuation of the life of a tree, necessary so that with the advent of spring we can again enjoy young green leaves.

So briefly, today we have found the answer to the question posed. To make the report interesting, I propose a rebus on the autumn theme. Catch! And I say goodbye to you until we meet again on projects.

"To the stream, pockmarked and motley,

Poem - "Before the rain"

Evgenia Klimkovich.

The leaves on fruit trees in the garden turn yellow at the height of summer. The gardener understands that this is certainly an abnormal phenomenon, so he tries to find ways to restore fruit trees. In today's article, we will look at why the leaves on the trees turn yellow in the summer and what to do to restore them.

Determine the reason why the leaves on the trees turn yellow in summer will help detailed description yellowing or symptoms of disorders and diseases:

Nutrient imbalance

The main nutrients needed for the development of a tree:

• Magnesium;
• Potassium;
• Phosphorus;

Magnesium may be lacking in sandy and sandy soils. Often its imbalance manifests itself in wet weather, with frequent watering - magnesium is quickly washed out.

Potassium there are not enough leaves if, in addition to yellowness, a red rim is noticeable on sheet plate. The lack of potassium is accompanied by a simultaneous lack of phosphorus.

Phosphorus starvation manifests itself in the appearance of a bronze hue and the leaves dry up, covering the entire surface of the leaf.

top dressing soil mixture missing ingredients will solve the problem.

Waterlogging of the soil

close occurrence ground water and waterlogging of the soil due to frequent watering will affect the stagnant water, the breakdown of oxygen. Fruit trees in the garden will not only begin to turn yellow, but also dry up, wither, it is possible that root system will rot. Soil drainage, raising the level of planting, and normalizing care will help solve the problem.

Chlorosis of fruit trees

With the development of chlorosis, the leaves of fruit trees become dull, pale, turn yellow, as if there is no sun in the garden. Chlorosis can appear for many reasons:

• Exceeding the level of lime in the soil;
• Excessive amount of fresh manure;
• Lack of iron salts (chlorophyll is not formed);
• Root freezing;
• Oxygen starvation (due to waterlogging);

If chlorosis did not have time to cover the entire crown of the tree, then it is necessary to restore the gap in care that caused chlorosis, and also feed it with a solution iron sulphate (2%).

Pests and diseases of fruit trees

When aphids or mites appear, the leaves not only turn yellow in the summer near the trees in the garden - deformed shoots appear. Similar symptoms can occur with the development of fungal diseases. In order to garden trees were healthy, it is necessary to carry out prevention by spraying with solutions before flowering and after it ends.

Damage to the bark of garden trees in summer

In summer, garden trees begin to turn yellow if their bark or root system was previously mechanically damaged. This could happen when transplanting, loosening the soil, pruning or processing. Due to the violation of the vital activity of the tissues of the tree, a general wilting occurs. It is difficult to determine the problem in this case. Reestablish fruit tree in the garden in the summer, either top dressing or the use of biological preparations to cover wounds will help.

DO YOU KNOW...

WHY DO THE LEAVES TURN YELLOW? Green color leaves give a special substance - chlorophyll. Chlorophyll in a living leaf is constantly destroyed and re-formed. But it only happens in the light.

In summer the sun shines for a long time. Chlorophyll is destroyed and immediately restored. Therefore, the leaf remains green all the time.

Yellow paint is always in the leaves. Only in summer yellow invisible. He clogs with a stronger one - green.

Autumn is coming, the nights are getting longer. Plants receive less light. Chlorophyll is destroyed, and does not have time to recover. The green color in the leaf decreases, and yellow becomes noticeable - the leaf turns yellow.

Leaves fall green from alder and lilac. In their leaves, except for chlorophyll, there are no other coloring substances.

According to G. Graubin

WHY ARE THE LEAVES ON ONE ASPEN YELLOW AND THE OTHER IS RED?

It turns out that the substance that gives the red color to the leaves is formed in those plants that have stored more sugar. Plants that failed to do so have yellow leaves.

WHY DO LEAVES FLY FROM PLANTS?

AT winter cold plant roots can hardly get water from the ground.

In autumn there is a lot of water, but it is cold. Therefore, plant roots cannot absorb it.

Leaves constantly evaporate water. So plants have to drop them so as not to dry out in winter.

In winter, the leaves would only damage the plant. Piles of snow that piled on them would break branches and branches. In addition, in the leaves during spring and summer accumulate harmful substances. Dropping foliage, the plant is cleared of them.

How does spruce get rid of unnecessary substances?

It turns out that spruce is also falling leaves. But its leaves do not fall all at once, but little by little and constantly. New ones grow in their place. Some fall, others grow. This happens imperceptibly to our eyes, and it seems to us that the spruce always has the same needle leaves.

WHY DOES THE FIR DO NOT SHUT LEAVES FOR THE WINTER?

Leaves-needles ate small, hard, resinous. They evaporate less water than ordinary leaves. Winter drought spruce is not terrible.

The branches of the Christmas tree do not break off and why under the weight of snow? Because they grow obliquely down and springy. Snow easily slides off the branches from the slightest push, a breath of wind, from the excessive weight of wet snow. In addition, due to the wax coating of the needles, snow does not firmly stick to them.

WHY ARE THERE NO WOUNDS ON THE BRANCHES FROM FALLEN LEAVES?

The thing is that the leaves do not break off the branches, but fall off in a strictly defined place - where the petiole is attached.

In summer, the petioles of the leaves are firmly connected to the branches. In autumn, amazing changes take place in the petioles.

In the place where the petiole is attached to the branch, a special cork layer gradually grows. He, like a partition, separates the petiole from the branch.

Now the leaf with the branch is connected by several thin fibers. The weight of the leaf itself, the impact of a raindrop, the breath of a breeze is enough for the leaf to easily separate from the plant.

LEAF FALL

Linden, birch and elm leaves are the first to lose.

In linden and poplar, the leaves of the large lower branches fall first, then the middle is exposed, and the crown of the tree is the last to fly around. But in elm, hazel, ash, leaf fall begins with the upper branches. The foliage gradually melts, revealing dark trunk tree.

Aspen leaves fall with the first frosts, then maple leaves. Only alder and willow along the banks of the rivers stand thick and green until the first snow. And then the frozen, blackened, crispy leaves fall off.

According to V. Korabelnikov

Adults, plunging into everyday problems, stop paying attention to the world, while children are surprised by its features every day. And how does it work? And why? What for? Is it necessary? What just does not interest these little whys! And if you wear the proud title of mom or dad, then sooner or later you will definitely hear the question: “Why do the leaves turn yellow in the fall?” It seems that the question itself is not very complicated, this is one of, but it will certainly entail a number of additional ones that need to be answered in detail and clearly. Well, let's try to do it!

Why are the leaves turning yellow?

In spring and summer, the pigment chlorophyll lives in each leaflet, which has green coloring. Exactly a large number of Chlorophyll makes the leaves on trees green. The tree needs this pigment not just for beauty, but for tasty nutrition, since chlorophyll can transform with the help of daylight carbon dioxide and water into nutrients. So thanks to its spring-summer green color, the tree grows and develops. But there comes a season when nature prepares for winter, when its vital activity stops, when the leaves turn yellow - this happens in autumn. Everything goes to the leaves less water, chlorophyll is gradually destroyed, and the plants lose their green color. An interesting fact is that chlorophyll is more actively destroyed under the influence of the sun, so the period when the leaves begin to turn yellow in autumn does not always occur at the same time. In a dry, clear autumn, the leaves change color faster, and in a rainy autumn, they remain green for a long time.

Why are these yellow and those red?

An attentive kid will definitely ask why some leaves on the trees turn yellow, others turn red, and still others turn brown. The answer is simple enough. The fact is that in addition to chlorophyll, plant leaves contain other pigments, but because of the predominant green, they are simply not visible. As the green chlorophyll recedes, other colors become visible:

• yellow leaves get their color as a result of the "work" of the plant pigment xanthophyll;
• orange leaves put on their autumn outfit when the carotene pigment becomes visible, which, by the way, is familiar to everyone from the bright orange color of carrots;
• red leaves get this unexpected color thanks to anthocyanin pigments;
• brown leaves- this is no longer the color of pigments, but the color of the cell walls of the leaf, it appears when other visible coloring pigments are absent.

If we talk about the process of leaf fall itself, then the mechanism is quite clear - in the fall, when the leaves turn yellow in plants, a thin separating layer of cells appears at the base of the leaf, the so-called cork layer. Gradually, this partition breaks the connection between the tree and the leaf. It remains to wait for the wind to blow and the leaf is on the ground. A small scar remains on the branch at the place where the leaf is torn off, which is overgrown with a protective cork layer, which means that this is a completely painless period for the tree. If you wonder why the leaves turn yellow and fall, in a global sense, it can be understood that this defense mechanism, which nature came up with for the survival of trees in the cold season. Most All plants get their nutrition from the water that comes from the soil, but in winter the water freezes. That is, if the leaves remained on the trees, they would need to eat, but the frozen water could not bring the necessary nutrition with it, so the leaves would draw substances from the roots, trunk and branches. Most likely, having lost vitality, the tree organism would die. So the fall of the leaves is an opportunity to endure the winter steadfastly, and in the spring to dissolve the buds again.