This happens because, in addition to chlorophyll, there are other coloring substances in the leaves. It is especially abundant at the end of September and the first decade of October. 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. By mid-September, birch leaves become ocher-gold and gradually begin to fall off.

For many trees, leaf fall is uneven, that is, it happens at different times. For example, after the first severe frost, leaf fall begins in linden and maples. By this time, birch had already dropped most leaves.

It is difficult to unequivocally answer the question when the time of leaf fall ends. It is noticed that first poplar leaves are lost, then oaks and mountain ash. Dropping leaves from trees serves another purpose - the crown under the snow cover has a significant weight. The branches of trees, especially young ones, are not able to withstand such a load. Thanks to the process of photosynthesis, a large amount of harmful substances accumulate in the leaves by the beginning of autumn, which, with the onset of leaf fall, are removed along with fallen leaves.

Poplar During the period of leaf fall, adult poplar trees lose a third of their leaves in the period from September 15 to 20, in the first ten days of October, up to 10% of foliage remains in the poplar crown. Young poplars remain green longer than old trees, they turn yellow later and shed their leaves. Oak Oak leaves fall off in the first half of September, after about 30 days the trees completely lose their leaves.

Oak leaves immediately acquire a brown color, along with the leaves, ripe acorns fall from the tree. Rowan Autumn rowan as if painted with watercolors, its leaves do not turn yellow, but acquire a pink color, the process of leaf fall begins around the beginning of October, and ends by November 1.

The fall of apple trees begins in the third decade of September and ends in the second half of October. Birch is a genus of deciduous shrubs and trees of the Birch family, which is distributed in almost the entire Northern Hemisphere. Birch is better known to us as a tree up to 45 meters high and with a girth of up to one and a half meters.

Yes, many of us dislike this time of the year because of the constant rains and slush, but without a doubt, early autumn is very beautiful due to the changing color of the trees. For example, the same birch begins to change color around the 20th of August, although this, of course, also depends on the weather.

However, we repeat, it all depends on the weather in the region. If, for some reason, the weather has changed so much that the temperature drops from the usual +20°C to -5°C, then the leaf fall begins almost immediately with the first frost. The remains of the leaves, which can remain on the trees even in the case of active leaf fall, usually fall off after the third or fourth hard frost, and this applies to most trees.

Trees at the time of leaf fall

Reprinting of materials and their use in any form, including in electronic media, is possible only with a back active link to our site, which is not closed from indexing by search engines. The autumn forest is beautiful when the leaf fall begins. The forest clearings are dressed in yellow, and the river valleys are burgundy and pink. In the second half of September, poplars are also multi-colored: some of them become lemon yellow, others almost orange, some golden yellow.

By the end of September, this strong, mighty tree is subdued general laws nature - becomes straw yellow. True, poplar and birch shed their leaves long before the general cold snap. In aspen, leaf fall ends 5-6 days earlier than in birch. By September 15-20, old poplars are bare by a third, and by October 10, no more than 10-12% of the leaves remain on the trees.

Features of leaf fall

The leaf fall of different trees is uneven and sometimes lasts for several weeks. Here are a few aspens, elms, elms, ash and apple trees standing almost naked, and not so far from them - trees of the same age, but with rustling foliage still almost completely preserved.

September - the first signs of the coming autumn are already visible on the trees. The birch is the first to play in the autumn rays of the still warm sun with the yellowness of the leaves, the crowns of the trees are covered with the first noticeable gilding. On August 23, 2016, along the roads in the suburbs of St. Petersburg (specifically Oselki, Leskolovo, Ekaterinovka), I observed crimson maples in their entirety and in separate branches.

Apparently it's a combination of moisture, heat and daylight hours. The summer was very rainy and moderately warm. And by the middle of the month, the forests are bare. In the Leningrad, Pskov and Novgorod regions, the end of leaf fall of birch and mountain ash is observed on average on October 14. In October, the little warblers, warblers, shrikes, and corncrakes fly away from us. In the first days of the month, there is (on average) a mass passage of geese in the Tver and Yaroslavl regions.

Their mass departure is observed in the Tver region on October 18, in the Moscow region - on October 6, in the Vladimir and Oryol regions - on October 8-9. The departure of starlings ends, as a rule, in last decade month. The mallard flies behind the starlings. Some birds stay with us for the winter. And not only rooks winter in our cities.

The beginning of autumn - 29 days: from August 26 to September 24. Leaf fall at the birch begins around the first half of September and lasts for another 20 days, that is, this tree completely falls off by the end of September-mid-October.

Leaf fall is a unique phenomenon in the life of trees and shrubs. To answer the question of when the leaf fall begins and ends in mountain ash, birch, aspen, maple or any other plant, several factors must be taken into account. The region of growth of trees and shrubs is very important, the species weather specific time of year and some other features. Leaf fall plays an important role not only in the life of specific plant species, but also in the whole of nature.

The value of leaf fall in nature

Thanks to him, trees and shrubs regulate the evaporation process and the level of moisture consumption. In the cold season root system cannot absorb from the soil the amount of liquid that would provide adequate nutrition for plants. To avoid death in winter, trees are forced to shed their leaves. Since it is this part of the plants that requires the most water.

On branches freed from leaves, in winter there will not be much snow. Under its weight, the branches and trunk will not suffer. Fallen and shrubby, dead parts of herbaceous plants are important elements in the process of soil formation. A large amount accumulates in the leaf plates of plants toxic substances. Liberation from elements harmful to growth and development occurs when the leaves fall.
In mountain ash, birch, aspen, spruce, pine and any other plant, this phenomenon occurs in its own way. Phenological observations provide a wealth of material for studying the deciduous phenomenon.

When does autumn come in the life of a plant?

As you know, the year is divided into four seasons. According to the calendar for autumn, the period from September 1 to November 30 is allotted. I must say that the division is conditional, and in life these deadlines are never met.

This happens for the reason that the replacement periods for each species are set separately. For example, when the leaf fall of the mountain ash ends and it prepares for the conditions of survival in winter, by this time everyone has already completed their growth cycle, without having lived up to the calendar autumn.

in nature

The onset of autumn is marked by certain signs. They can be seen both in living and inanimate nature.

A decrease in the length of the day and a decrease in the average daily air temperature is one of the main indicators that affect the life of representatives of wildlife. The air temperature from plus 15 degrees with a gradual decrease to zero refers to the autumn period. It is with such indicators that changes in the life of most plants begin to occur. So the average daily temperature regime indicates when the leaf fall begins in mountain ash, birch, oak, aspen and other deciduous plants.

Folk omens

On the basis of centuries-old observations of nature, which are carried out by people, signs have been compiled. According to them, you can predict the nature of the upcoming season, the amount of harvest of vegetables, fruits, grain crops. I must say that the reliability of many signs is very high, and today scientists can explain and substantiate their essence. When the leaf fall of the mountain ash ends, bright red berries are very noticeable on its branches. One of the signs says that a rich harvest of mountain ash - for a harsh winter. But the same fact also indicates that when the tree blossomed, the weather was excellent, and nothing prevented the bees from pollinating its flowers.
It is commonly believed among the people that when the leaf fall near the mountain ash, lilac ends, the pre-winter period begins. There are only a few days left before the onset of winter.

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LEAF FALL

Leaf fall is one of the most characteristic phenomena of autumn nature. It most clearly expresses the seasonal periodicity in the development flora our latitudes. Every year it repeats itself, first delighting our eyes with the countless tones and colors that the forest dresses up in, and then inducing involuntary sadness with the dull look of bare trees and the melancholy rustle of fallen leaves. Autumn has long been considered a boring time, a dead season in nature.

Poets compare it with old age, they are sad about its approach. For a naturalist, autumn is the most interesting time of the year, a time of intensive research and observation, when the numerous adaptations of the animal and plant world to the conditions of an unfavorable season are most clearly revealed. At this time, many things can be noticed in nature, many incomprehensible things can be explained. Many manifestations of spring nature will seem mysterious to us without corresponding autumn observations. Spring and autumn are inextricably linked - these are separate stages of a single life cycle of the nature of our temperate latitudes.

CAUSES OF LEAF FALL

What are the causes of leaf fall? What causes our deciduous trees and shrubs to shed their leaves every year in order to be clothed with them again at the end of a harsh winter? To answer this question, it is necessary first of all to find out whether leaf fall is a biological phenomenon due to the vital activity of the plant, or whether it is caused by a drop in temperature and the onset of autumn bad weather. If we transplant some young tree, for example, an oak or a maple, into a pot with earth in the summer or - even better - from the spring, and put it in a room or in a greenhouse, in the fall it will inevitably shed its leaves, despite the best care. Autumn bad weather does not penetrate into the room or behind the glass of the greenhouse, there are no frosts here, nevertheless, leaf fall will appear here with sufficient regularity. This indicates to us that the autumn shedding of leaves is not a direct consequence of the onset of adverse conditions. It, together with the winter period of rest, is included in the very cycle of plant development. There is another way to make sure that leaf fall is a biological process. At the end of summer, a cut is made through the base of the leaf petiole of a tree in the place where the petiole is attached to the stem, forming the so-called "leaf pad". Under a microscope on a cut, it is easy to see the formation of a special separating (cork) layer.

The cells of this layer have smooth walls and are easily isolated from each other. By the beginning of leaf fall, the connection between them is broken in some place, and the leaf remains hanging on the tree only thanks to the vascular bundles, which, like the smallest "water pipes", connect the leaf with the rest of the plant. Vascular bundles can be easily seen with the naked eye on leaf scars in the form of three, five or more large dots. They serve to conduct water and mineral salts from the root to the leaves (ascending current) and nutrients - carbohydrates produced by the leaves in the process of assimilation (descending current). However, there comes a point when this last connection between the petiole and the mother plant is also broken. Often the slightest gust of wind is enough for this, sometimes the leaves fall even in completely calm weather as a result of sharp fluctuations in temperature, freezing or thawing, or directly under the influence of the gravity of the leaf blade, weighed down by settled dew. Have you ever been in the forest in the midst of leaf fall, when in clear weather it gets very cold in the evening, but there is complete calm? At this time, the uninterrupted rustle of falling leaves is surprisingly quiet and distinctly heard in the forest. The formation of a cork layer in the leaf petioles indicates to us that the leaf fall is preceded by a long preparation in the plant.

WHAT GIVES THE PLANT DISCHARGE OF LEAVES FOR THE WINTER

Leaf fall is an adaptation of plants to the conditions of winter - not only the cold, but also the dry season. If our deciduous trees remained for the winter in their green cover, they would inevitably die as a result of a lack of moisture, since the evaporation of water by their leaves would not stop, and the flow of water into the plant could almost completely stop. In many tropical and subtropical countries, where temperatures during all year round is quite high, but the humidity is subject to strong fluctuations; annually, when a drought sets in, the trees shed their foliage. Thus, the trees of the African savannas are exposed for several months, the grasses of which are also burned out by the sun, until heavy rains again revive the vegetation of the savannahs. The significance of leaf fall in the life of our deciduous trees is especially noticeable when compared with conifers. Conifers - spruce and especially pine - are drought-resistant plants. Their needles evaporate many times less water than the foliage of our hardwoods. Because of this, they are able to overwinter in a green form. It is believed that under conditions of poor water supply, the amount of moisture evaporated by conifers is related to the amount of moisture evaporated by deciduous species as 1:10, while under conditions of increased water supply, as 1:6. Oak per 100 g of dry matter of leaves evaporates 54.6 kg of water over the summer, birches - 81.4 kg, ash - 85.6 kg, pine is only 9.4 kg. It is interesting to note that larch in this respect behaves like hardwood and evaporates moisture 10 times more than pine, and five times more than spruce. This ability to save moisture is achieved by our conifers by the special structure of their needles. Not to mention the much smaller surface, the needles have a number of drought-resistant adaptations: a thick skin that surrounds the needles on all sides, and a bluish wax coating, which also reduces evaporation; great importance also has an arrangement of stomata in special depressions. After all, stomata are pores, a kind of vents through which gas exchange occurs in the plant and moisture transpiration occurs; immersing them in leaf tissue significantly reduces transpiration. On the contrary, the leaves of our deciduous trees lack any special drought-resistant adaptations. They have a wide surface and thin skin. Speaking here about the importance of leaf fall in the life of our trees, one cannot help but pay attention to the fact that by shedding foliage, they thereby protect themselves from mechanical damage under the weight of snow. Often in winter one can observe how, even in a leafless state, large branches of trees break under the pressure of snow; a wide leaf surface, on which a lot of snow would settle, would make this phenomenon catastrophic. The above is far from limited to the biological significance of leaf fall. It also plays another role in the life of trees. It helps to remove waste, various mineral salts, a large amount of which accumulates in the leaves in the fall and becomes harmful to the plant.

If you take the leaves of a tree and examine how much ash they contain in spring, in the middle of summer and in autumn, before leaf fall, then the result will be a sharp increase in ash with the age of the leaves. At the end of May, beech leaves contain 4.6% ash relative to dry weight, at the end of July - 7.4%, and at the end of October - 10.8%, i.e. more than twice as many as in spring. How does the accumulation of such a significant amount of minerals in the leaves occur during the summer? The fact is that the leaf evaporates water intensively throughout its life. To replace this evaporated moisture, a new one continuously enters it, which is sucked in by the roots from the soil. However, as we know, the plant receives from the soil not clean water, and solutions of various salts. These salts, passing along with water through the whole plant, also enter the leaves. Part of them goes to feed the plant, while the part that remains unused is deposited in the cells of the leaf. As a result, by autumn, the leaves become, as it were, mineralized, abundantly saturated with salts, the deposits of which in some cases can even be seen under a microscope. A large amount of mineral salts deposited in the leaves by autumn disrupts their normal operation and becomes harmful to the plant; therefore, dropping old leaves is a necessary condition for its normal functioning. Since the deposition of mineral salts in the leaves is the result of evaporation, it is clear that the more moisture the leaves are able to evaporate, the more they mineralize by autumn. This is especially clearly seen when comparing the amount of ash deposited in the leaves of pine and larch. Pine, which, as we know, evaporates very little moisture during the summer, contains in autumn only about 1.5% ash in its needles, while larch, which approaches hardwood in terms of evaporation, accumulates up to 2.5% in soft needles. % mineral salts. The need to get rid of harmful waste accumulated in the leaves causes leaf fall in trees in a humid tropical climate. At first it was believed that in tropical regions, where the climate remains more or less uniform throughout the year, leaf fall does not exist at all. However, more careful observations made on the island of Java in the famous tropical botanical garden at Buthenzorg and in India showed that leaf fall is a common occurrence in the tropics as well. True, the fall of leaves in different trees does not occur here simultaneously, and even different specimens of the same species have leaf fall in different ways. time. As a result, the period of dormancy in a humid tropical climate often lasts for a tree or part of a tree for only a few days. The plant discards the old leaves that have become unnecessary ballast for it and immediately puts on a new green outfit. These facts indicate that leaf fall depends not only on external, but also on internal causes, that is, it becomes necessary as a result of the vital activity of the plant itself.

WHAT IS FALLEN LEAVES

Analyzes of fallen leaves showed that, in addition to a certain percentage of ash, they contain a significant amount of carbohydrates - organic substances containing carbon and produced by the leaf as a result of its absorption of carbon dioxide from the air. Remarkably, fallen leaves are much richer in carbohydrates than young ones. Thus, the plant, by shedding foliage every year, is deprived of a certain amount of nutrients that do not have time to completely pass into the stem. However, such extravagance does not bring much harm to the plant. Carbohydrates are substances that can be obtained by a plant from the air in any quantity. Plants absorb nitrogen only from the soil in the form of dissolved salts. And nitrogen is often not enough for the plant. Therefore, it turns out that before leaf fall, nitrogenous substances move in significant quantities to the trunk, where they overwinter or are consumed by the plant during the winter; together with nitrogenous substances, other mineral salts valuable for the plant are also removed from the leaves; nevertheless, it has been established that a significant part of them still remains in the falling leaves.

Fallen leaves are a very valuable fertilizer. Thanks to them, the soil in the forest is annually enriched with humus, acquiring a number of important properties. We know, for example, that the soil of a broad-leaved forest does not freeze in winter due to its significant humus content, and this makes it possible for spring plants to develop under the snow. One hectare of oak forest receives more than 5000 kg of waste (dry weight of leaves, brushwood, etc.), which yields approximately 520 kg of ash. From this it is clear that the collection of fallen leaves and the general removal of forest litter in the forest adversely affect the life of trees. So, for example, in one experimental German forestry, where the collection of forest litter was practiced for a number of years, the increase in planting fell by 11%. The leaves of some trees contain tannins. They are found in small quantities in oak leaves, but they are especially abundant in the leaves of the noble chestnut, a tree that is widespread in Western Transcaucasia. Fresh fallen leaves in chestnut forests contain up to 12% tannins, so collecting them to obtain tannic extract can be of industrial importance.

WHY THE LEAVES TURN YELLOW IN AUTUMN

Plants appear green to us from a large number of tiny chlorophyll grains located in the cells of leaves and stems. We know that in the chlorophyll grain, the process of decomposition of carbon dioxide takes place, as a result of which organic substances, carbohydrates, are created in the plant from inorganic compounds. The chlorophyll grain does not remain unchanged in the plant. It is short lived. Capturing the solar energy necessary for the assimilation process, chlorophyll is destroyed under the influence of light and re-created in the plant, and its formation can also occur only in the light. However, chlorophyll is not the only coloring principle in plant tissues. Along with it, special pigments are constantly present, known as xanthophyll and carotene. The first one is pure yellow color, the second has an orange tint; carotene is responsible for the characteristic color of the carrot root, where it is found in a very in large numbers. Yellow pigments are always present in the green of the plant, but in summer they are completely invisible, as they are masked by the intense green color of chlorophyll; nevertheless, they are very easy to distinguish with the help of the following simple experiment. Everyone probably knows that the green parts of plants, if thrown into strong alcohol, begin to turn pale, while alcohol, on the contrary, quickly turns green. This process of leaf discoloration is caused by the chlorophyll dissolving in the alcohol, and especially quickly when the alcohol is heated or even gently boiled in a water tank.

A strong alcohol extract from green leaves, when viewed in transmitted light, looks emerald green, but in reflected light it fluoresces (shines) with a cherry red tint. Together with chlorophyll, yellow pigments also pass into alcohol. To separate them, pour a little gasoline into the hood. After shaking the mixture, after a while, you can notice that gasoline, as it is lighter, will float to the top, while the layer of alcohol will remain at the bottom. In this case, gasoline will have an emerald color, while alcohol will take on a golden yellow color from the yellow pigments of the leaf remaining in it - xanthophylls and carotenes. The separation of chlorophyll from yellow pigments is based on the fact that it has a greater solubility in gasoline than in alcohol. In autumn, as the activity of the leaf fades due to the formation of a separating layer in its petiole, the formation of chlorophyll in it slows down and, in the end, completely stops; the destruction of chlorophyll under the influence of sunlight continues. As a result, the leaf loses its green color, and yellow pigments, imperceptible until this time, are suddenly revealed. Therefore, however, it must be added that not only xanthophylls and carotenes cause the yellow color of leaves in autumn; at present, other yellow pigments have also been found that are absent in the living tissues of the leaf and appear only when they die off at the time of leaf fall. Since the destruction of chlorophyll proceeds more rapidly in bright light in sunny weather, it becomes clear why in cloudy rainy autumn the leaves retain their green color longer and why, two or three clear sunny days, which have replaced the bad weather that has been standing so far, immediately decorate the crowns of trees in the bright golden colors of autumn.

PURPLE TREE COLOR

The autumn coloring of the leaves is especially attractive with its crimson tones. However, these tones are not found in all trees. Crowns of maples and aspens are removed in crimson; an elegant, pinkish color is taken by the foliage of the euonymus; garlands of wild grapes turn dark purple. Along with this, lindens, oaks and birches are devoid of red shades, they are cast only in various yellow and golden tones. What causes the red color of autumn leaves? It is caused by a special coloring matter, anthocyanin, which is extremely widespread in plants. Unlike chlorophyll, anthocyanin is not associated with plastic formations inside the cell. It is dissolved in cell sap and rarely occurs as small crystals. Anthocyanins are very easy to extract from any red or blue parts of the plant. If you boil a certain amount of beets or red cabbage, then the water turns from anthocyanin into a lilac or dirty red color. It is enough to add a few drops of some acid, for example, acetic acid, to this solution, and it will immediately take on an intense red color. Anthocyanin also causes blue and pinkish flowers. The numerous colors of roses, the fiery color of poppies, the sky-blue shades of forget-me-nots, the purple color of violets and bluebells - all this is the result of the presence of anthocyanin in cell sap. The fact is that anthocyanin, depending on the environment in which it is located - in acidic or alkaline, is able to quickly change its shade. Like litmus paper, it has a pinkish color when it is acidic, and turns blue when it is alkaline. In this regard, some plants have a remarkable ability to change the color of their flowers with age. We have already mentioned this phenomenon in the flowers of the lungwort, which at the time of flowering have a pinkish corolla, which later acquires a purple and then a blue color. The same is observed in the inflorescences of another inhabitant of the broad-leaved forest - the nomadic. In its graceful racemes, the lower, older flowers are blue in color, the upper, younger ones are pinkish. A similar change in color with age can be seen on forget-me-nots. The flowers of all these plants are initially very rich in acids, then they gradually lose their acidity, and the anthocyanin dissolved in the cell sap turns blue. Using this property of anthocyanin, it is possible to arbitrarily change the color of some flowers without much difficulty.

If you hold on for a while blue flowers forget-me-nots or violets in an atmosphere of tobacco smoke, they soon begin to turn green under the influence of alkali, which is contained in tobacco smoke. The same result is obtained with the action of ammonia. If you place the flowers of the plant under a glass cap with fuming hydrochloric or acetic acid, they quickly turn pink. Anthocyanin is widely distributed in young growing parts of the plant. We indicated above that it colors female alder catkins and stigmas of female hazel flowers in purple and pink color. Here it can play the role of some additional heat ray trap, absorbing the green and blue parts of the spectrum. What is the significance of anthocyanin in dying leaves? The appearance of anthocyanin in plant tissues depends to a certain extent on external conditions. With a decrease in temperature, the amount of anthocyanin in the cell sap increases in the same way as in bright light. At the same time, the formation of anthocyanin is also stimulated by the stop or delay in the foliage of nutrients received by the plant as a result of assimilation. This is especially noticeable with various wounds of plants. Carbohydrates accumulate above the cut site, and then the corresponding part of the plant takes on an intense anthocyanin color. Prof. Molisz, who first drew attention to this, describes such a case.

While walking through a vineyard one day, he was struck by the fact that on some branches of the vines the leaves were red, while others had normal foliage. Intrigued by the cause of this phenomenon, he began to carefully examine the reddened parts of the branches and found that they were all damaged in such a way that the movement of juices was hindered, but not stopped. In order to finally make sure that it was the defeat and the resulting stagnation of nutrients that played a role here, he made numerous cuts on other bushes up to two-thirds of the wood. After two or three weeks, all the affected parts of the branches above the incision took on a bright anthocyanin color. It can be assumed that in autumn leaves, where damage easily occurs in the vascular system, the flow of carbohydrates is inhibited, which contributes to the formation of anthocyanin. Thus, the crimson shades in which the trees are painted during leaf fall are not some special adaptation. They testify only to the ongoing attenuation of vital activity in the leaves in connection with the preparation of plants for winter period rest.

FEATURES OF LEAF FALL IN TREES AND SHRUBS

Autumn coloring of leaves is not observed in all trees. Alder leaves retain their green color during leaf fall and turn black only after frost. In the same way, lilac leaves do not change their color at all: they remain green on the branches until the snow falls, despite the fact that they have long been killed by frost. In aspen, leaf fall begins when the leaves are still green, while autumn coloring comes later, when part of the tree is already exposed. The duration of leaf fall in different trees, as well as the period of yellowing of foliage, is extremely different. Of our trees, leaf fall seems to be the longest in birch: it lasts about two months, while linden has time to shed its foliage in two weeks. It is not so easy to establish the timing of leaf fall in any tree species, since in different specimens of the same species it does not begin and end at the same time. It is interesting to note that the cause of this phenomenon does not always lie in external conditions. Often two trees growing in the neighborhood differ for a whole week in the time of yellowing and falling of their leaves, and these features of the leaf fall of individual trees are repeated annually. Of particular interest are some specimens of oak, which do not shed their leaves for a very long time and stand in their autumn dress throughout the winter. Despite the fact that the leaves on such oaks have been dead for a long time, they hang firmly on the branches, withstanding winter blizzards and snowstorms, and fall off only at the beginning of spring, shortly before the development of young leaves begins. These peculiar trees are a special form of oak, known as "late oak", while specimens that normally shed their leaves are early oak. Both of these forms seem to be hereditary, although this still needs to be verified.

In addition to the features of leaf fall, late oak differs from early oak in later flowering and bud break, which is 2-3 weeks late. In spring, such oaks are still completely bare, while their neighbors are already covered with a green haze of young foliage. Despite such a sharp difference in development, both oaks do not differ significantly in the shape and size of their leaves and acorns. True, some authors point out that the early form of oak, which is generally more common with us, is characterized by a wider spreading crown, less regular trunk and lighter wood, while late oak has a more compressed crown, full-wooded trunk and heavier wood; it is interesting that both forms of oaks are distinguished by the local population: the early oak is called the "summer oak", or simply "oak", and the late - "winter oak", or "oak". At present, most authors believe that the late, or winter, oak is more adapted to our climatic conditions, and therefore, over time, it should gain wider distribution. The fact is that young oak shoots are often damaged by spring frosts. In this regard, the late form of oak is in more favorable conditions. If this is true, then from this we can conclude that our climate has now deteriorated compared to the past, which, however, is confirmed by some other data. Let us recall, for example, the wider distribution of broad-leaved forests in our past, the remnant of which is the oak anemone, which currently lives under a canopy alien to it. spruce forest. Despite the great scientific and silvicultural interest that the early and late forms of oak represent, they are far from being studied enough. It is interesting to conduct more detailed observations of them under different conditions and in different years and find out whether any form is associated with certain habitats. It is also very interesting to establish whether any other tree species of this kind have early and late forms. We have already pointed out the ability of larch under certain conditions to retain its needles for a very long time; late forms of beech and chestnut are often found in the Caucasus, but they have not yet been studied in this respect.

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.

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 at different times. 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, worsening weather conditions, frequent rains 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.

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

When the days become shorter, and the sun no longer generously shares its warmth with the earth, one of the most beautiful seasons of the year comes - autumn. She, like a mysterious sorceress, changes the world around and fills it with rich and unusual colors. Most notably, these miracles occur with plants and shrubs. They are among the first to respond to weather changes and the onset of autumn. They have three whole months ahead of them to prepare for winter and part with their main decorations - leaves. However, at first, the trees will certainly please everyone around with tints of color and frenzy of colors, and the fallen leaves will carefully cover the earth with their veil and protect its smallest inhabitants from severe frosts.

Autumn changes with trees and shrubs, the causes of these phenomena

In autumn, one of the most important changes in the life of trees and shrubs occurs: a change in the color of the foliage and leaf fall. Each of these phenomena helps them prepare for winter and survive such a harsh season.

For deciduous trees and shrubs, one of the main problems in the winter season is the lack of moisture, so in the fall all useful substances begin to accumulate in the roots and core, and the leaves fall off. Leaf fall helps not only to increase moisture reserves, but also to save them. The fact is that the leaves evaporate the liquid very strongly, which is very wasteful in winter. Coniferous trees, in turn, can afford to show off with needles in the cold season, since the evaporation of liquid from them is very slow.

Another reason for leaf fall is the high risk for branches to be broken under the pressure of a snow cap. If fluffy snow fell not only on the branches themselves, but also on their leaves, they would not withstand such a heavy burden.

In addition, many harmful substances accumulate in the leaves over time, which can only be eliminated during leaf fall.

One of the recently uncovered mysteries is the fact that deciduous trees placed in a warm environment, and therefore not in need of preparation for cold weather, also shed their leaves. This suggests that leaf fall is not so much associated with the change of seasons and preparation for winter, but is an important part of the life cycle of trees and shrubs.

Why do leaves change color in autumn?

With the onset of autumn, trees and shrubs decide to change the emerald color of their leaves to brighter and more unusual colors. At the same time, each tree has its own set of pigments - "paints". These changes are due to the fact that the leaves contain a special substance, chlorophyll, which converts light into nutrients and gives the foliage a green color. When a tree or shrub begins to store moisture, and it no longer reaches the emerald leaves, and the sunny day becomes much shorter, chlorophyll begins to break down into other pigments, which give the autumn world crimson and golden tones.

The brightness of autumn colors depends on the weather conditions. If the weather is sunny and relatively warm outside, then autumn leaves will be bright and colorful, and if it often rains, then brown or dull yellow.

How the leaves of different trees and shrubs change color in autumn

Autumn owes its riot of colors and their unearthly beauty to the fact that the foliage of all trees has different combinations of colors and shades. The most common purple color of the leaves. Maple and aspen can boast of crimson color. These trees are very beautiful in autumn.

Birch leaves become light yellow, and oak, ash, linden, hornbeam and hazel - brownish yellow.

Hazel (hazel)

Poplar quickly sheds its foliage, it is just beginning to gain yellowness and has already fallen.

Shrubs also delight with the variety and brightness of colors. Their foliage turns yellow, purple or red. Grape leaves (grape - shrub) acquire a unique dark purple color.

The leaves of barberry and cherry stand out against the general background with a crimson-red tint.

Barberry

From yellow to red, rowan leaves can be in autumn.

The leaves of the viburnum turn red along with the berries.

Euonymus dresses in purple clothes.

Red and purple shades of foliage determines the pigment anthocyanin. An interesting fact is that it is completely absent in the composition of the leaves and can only be formed under the influence of cold. This means that the colder the days, the more crimson the surrounding leafy world will be.

However, there are plants that, not only in autumn, but also in winter, retain their foliage and remain green. Thanks to such trees and shrubs, the winter landscape comes to life, and many animals and birds find their home in them. In the northern regions, such trees include trees: pine, spruce and cedar. To the south, the number of such plants is even greater. Among them, trees and shrubs are distinguished: juniper, myrtle, thuja, barberry, cypress, boxwood, mountain laurel, abelia.

Evergreen tree - spruce

Some deciduous shrubs also do not part with their emerald clothes. These include cranberries and cranberries. On Far East There is an interesting wild rosemary plant, the leaves of which do not change color in autumn, but curl up into a tube in autumn and fall off.

Why do the leaves fall, but there are no needles?

Leaves play an important role in the life of trees and shrubs. They help create and store nutrients, as well as accumulate mineral components. However, in winter, when there is an acute shortage of light, and, therefore, nutrition, the leaves only increase the consumption of useful components and cause excessive evaporation of moisture.

Coniferous plants, which most often grow in areas with a rather harsh climate, are in great need of nutrition, so they do not shed their needles that act as leaves. The needles are perfectly adapted to the cold. The needles contain a lot of chlorophyll pigment, which converts nutrients from light. In addition, they have a small area, which significantly reduces the evaporation from their surface of much-needed moisture in winter. From the cold, the needles are protected by a special wax coating, and thanks to the substance they contain, they do not freeze even in severe frosts. The air that the needles capture creates a kind of insulating layer around the tree.

The only coniferous plant that leaves its needles for the winter is larch. It appeared in ancient times, when summers were very hot and winters were incredibly frosty. This feature of the climate led to the fact that the larch began to shed its needles and it was not necessary to protect them from the cold.

Leaf fall, as a seasonal phenomenon, occurs for each plant at its own specific time. It depends on the type of tree, its age and climate.

First of all, poplar and oak part with their leaves, then the time of mountain ash comes. The apple tree is one of the last to shed its leaves, and even in winter, it may still have a few leaves.

Poplar leaf fall begins at the end of September, and by mid-October it completely ends. Young trees retain their foliage longer and turn yellow later.

Oak begins to lose its leaves in early September and completely loses its crown in a month. If frosts begin earlier, then leaf fall occurs much faster. Along with oak leaves, acorns also begin to crumble.

Mountain ash begins its leaf fall in early October and continues to delight with its pink leaves until November 1. It is believed that after the mountain ash parted with the last leaves, dank chilly days begin.

The leaves on the apple tree begin to turn golden by September 20. By the end of this month, leaf fall begins. The last leaves fall from the apple tree in the second half of October.

Evergreens and shrubs do not lose their foliage even with the onset of cold weather, as ordinary hardwoods do. Permanent leaf cover allows them to survive any weather conditions and retain the maximum supply of nutrients. Of course, such trees and shrubs renew their leaves, but this process occurs gradually and almost imperceptibly.

Evergreens do not shed all their leaves at once for several reasons. Firstly, then they do not have to spend large reserves of nutrients and energy to grow young leaves in the spring, and secondly, their constant presence ensures uninterrupted nutrition of the trunk and roots. Most often, evergreen trees and shrubs grow in areas with a mild and warm climate, where the weather is warm even in winter, however, they are also found in harsh climatic conditions. These plants are most common in tropical rainforests.

Evergreens such as cypresses, spruces, eucalyptus, some types of evergreen oaks, rhodendron can be found in a wide area from harsh Siberia to the forests of South America.

One of the most beautiful evergreens is the blue fan palm, which is native to California.

The Mediterranean oleander shrub is distinguished by an unusual appearance and a height of more than 3 meters.

Another evergreen shrub is the jasmine gardenia. Her homeland is China.

Autumn is one of the most beautiful and colorful seasons. Flashes of purple and golden leaves, preparing to cover the ground with a multi-colored carpet, coniferous trees piercing the first snow with their thin needles and evergreens, always pleasing to the eye, make the autumn world even more delightful and unforgettable. Nature is gradually preparing for winter and does not even suspect how fascinating these preparations are to the eye.