Causes of leaf color. Why do autumn leaves change color? What makes leaves green
Regional competition research work And creative projects
preschoolers and junior schoolchildren“I am a researcher!”
Municipal budget educational institution
"Average comprehensive school"No. 18"
Engels municipal district
Saratov region
Individual project on the topic of:
"Why leaves
change color in the fall?
Vorfolomeeva Daria
1st grade student
project Manager
Eterevskaya Lyudmila
Vladimirovna
teacher primary classes
MBOU "Secondary School No. 18" EMR
Saratov region
Saratov, 2015
Description of the project…………………………………………………………………………………. With. 3 - 5
Introduction……………………………………………………………………………… p. 3
Project stages and expected results…………………………………... p. 4 - 5
Stage 1: choice of research method, research progress……………… …… p. 4
Stage 2: study of literature on this topic, expected results...p. 4
Stage 3: generalization and systematization of information……………………………p. 4-5
Stage 4: selection of a product of project activity…………………………… p. 5
Conclusions (importance of the project for use in practice)…………… … p. 5
Reflection on project activities…………………………………………….p. 5
Informational – methodological support…………………………………… With. 6
Applications:………………………………………………………………………………………. With. 7 - 9
Why do leaves change color in autumn?
Project Description
Here is a maple leaf on a branch.
Now it's just like new!
All ruddy and golden.
Where are you going, leaf? Wait!
V.D. Berestov
Introduction
Autumn is a wonderful time of year. The change in leaf color is one of the first signs of autumn. Lots of bright colors in the autumn forest! Birches and maples turn yellow, patterned rowan leaves become crimson-red, and aspen leaves turn orange and crimson. At this time of year, I like to walk with my mother in the autumn park or forest, to breathe fresh air, observe nature, collect bouquets from fallen leaves, admiring the yellow, crimson, purple colors.
One autumn, I was collecting beautiful leaves for technology lessons. Looking at them, I wondered: why did the leaves change color? Why did the color change from green to yellow and red? Why does a tree need leaves at all?
I suggested that the leaves change color due to lack of light or cold weather.
To answer these questions, I will conduct research.
Target: Find scientific evidence of the causes of leaf color changes.
Tasks:
study specialized literature;
find out what significance a leaf plays for a tree;
study the reason for the change in leaf color;
answer the question: why some leaves turn red and others turn yellow;
development and design of an information booklet on the project topic
Project type:
by completeness: interdisciplinary
by number of participants: individual
Project stages and expected results
Stage 1 - organizational . The main method of this stage is observing changes in nature. Systematic observation of changes in the color of leaves on trees led to the conclusion that the color of leaves changes in different trees differently.
Observation results V Appendix 1.
I also used the method of surveying classmates. I found out - do they know why the leaves change color in the fall? The results are in Appendix 2.
Stage 2 – theoretical . The main method is studying literature and searching for information on the Internet.
Having studied the article in the encyclopedia for kids “Miracle is everywhere. World of Animals and Plants” by T.D. Nuzhdina, and after reading the articles with my mother on the Internet, I realized:
what role does a leaf play in the life of a tree;
recognized the parts of the sheet;
discovered the reason for the change in leaf color in autumn;
found a lot of interesting additional information on this topic.
Stage 3 – practical. The main method is working with information.
Interest in this topic arose while walking around autumn forest. As a result of observations and studying literature, I learned new concepts and facts:
Leaves work all summer: they feed the tree, extract food from the air with the help of sunlight, protect from sunburn branches and trunk. The leaves that fell in the fall and remained lying under the trees will not be wasted. They will conserve moisture and protect the roots from frost. Then they will decay, fertilize the earth and feed the tree.
During the research I found Interesting Facts about changes in leaf color; picked up folk signs, proverbs, found the author's fairy tale about leaves, took photographs autumn trees, made crafts from fallen leaves for technology lessons.
The information I received formed the basis for my speech, presentation, and information booklet for my classmates.
Stage 4 – final . The main method is to analyze the results of the work performed.
At the beginning of the project, I suggested that the leaves change color due to lack of light or cold weather. My assumptions were not confirmed.
I found out that in the fall, as the activity of the leaf fades, the formation of chlorophyll in it slows down, and then completely stops; The destruction of chlorophyll under the influence of sunlight continues. As a result, the leaf loses its green color and yellow-red pigments appear.
I found scientific evidence of the reasons for the change in leaf color, that is, my goal was achieved.
conclusions
Working on this project gave me the opportunity to read interesting material about nature, I acquired new knowledge - I learned what chlorophyll is and what it is needed for, trained my powers of observation, learned to work independently, tried my hand at working on a computer and creative work with dry leaves. I applied the knowledge I gained in lessons about the surrounding world and technology. I spoke in front of my classmates and presented the results of my work.
Reflection
While working on the project, I learned to work with various sources information, evaluate the quality of my work, which I consider good, work in collaboration with my mother and teacher, and draw conclusions based on the data received. Also, working on the project helped develop my personal interest in studying nature and natural phenomena.
I think that I achieved my goal.
Information and methodological support:
T.D. Need E encyclopedia for kids “Miracle is everywhere. World of Animals and Plants", Yaroslavl Academy Holding 2003
Annex 1
Results of monitoring changes in foliage color
Appendix 2
Classmate survey results
Appendix 3
Fairy tale
Why do leaves change color in autumn?
Autumn has come. The leaves on the trees began to turn yellow and fall.
Once Marinka was sitting under an oak tree, looking at the yellowed leaves and thinking:
The leaves turn yellow from the cold. They tremble, cower, and the wind blows - and leaves fall from the branches and fly away. Only the oak tree still had leaves, but even on it there were fewer and fewer of them every day.
One day Marinka, a kind soul, couldn’t stand it: she took glue and threads from home and ran to her beloved old oak tree. I started tying and gluing the last leaves to the branches so that the wind wouldn’t tear them off. Maybe the girl tied and glued 20 leaves, or maybe all 30. And she would have saved them, but her hands were completely frozen. Marinka sat down, put her hands to her mouth, breathing into her fists: first one, then the other. Then the wind flew in again - and suddenly it seemed to Marinka that the leaves above her head began to whisper and rustle. Then the oak seemed to stretch with a creak, yawned and said quietly:
What are you doing here, you idiot? Why are you disturbing me from sleeping?
“I didn’t want to wake you up,” Marinka was embarrassed. - I’ll paste the leaves for you, otherwise you’ll sleep through the last ones.
Eh, baby! I've finished my chores, it's time to rest. Look what acorns I grew, beautiful! Perhaps new oak trees will grow. But that’s later, and now the days are getting shorter, the light is getting less and less, which means it’s time for the trees to sleep. In the leaves, tiny green grains, living plants, disappeared and dissolved like sugar in water. There were no green seeds, and the leaves turned yellow.
But why yellow and not white or transparent? - Marinka was surprised.
Because besides green grains in the leaves there are also others - yellow ones. While the green seed grains were working in the leaves, no yellow ones were visible, but the green grains dissolved - and only yellow ones remained. The leaves have turned yellow. And then they dry up and fall off.
But how can this be? ! - the girl became worried. - What will you do without these little plants, without leaves? Who will feed you all winter?
“But I don’t want to eat or drink,” the oak tree whispered and yawned long. - It makes me sleepy. In winter, sleeping like this is a blessing. In winter, we trees do not grow or bloom. - Oak sighed and fell silent.
Hey! - Marinka quietly tapped on the wrinkled bark. -
I want to ask: maybe it would still be better if the leaves remained? Although they are dry and yellow, the tree is much more beautiful with them.
No, - the oak tree yawned. - We have no time for beauty in winter. We trees shed our own leaves. If you leave all the leaves, in winter such snowdrifts will grow on the branches that they will not be able to stand it and will break from the weight.
And I thought that the wind was tearing off the leaves.
“It’s possible without the wind,” the oak tree whispered. - We specially build up a thin partition between the petiole of the leaf and the branch, which does not allow juice or water to pass through. A septum grows and separates the leaf from the branch. As soon as the leaf has nothing to hold on to, it will break off and fly. The leaves will fall to the ground and the roots will be protected from the frost... Eh-he-he...
The girl wanted to ask the oak tree about its bark, buds, and acorns, but then the wind blew again, and it seemed to her that the old tree was quietly snoring.
Pupils of 3rd grade (Kolnik A. Fursova E)
Autumn wanders through the woods.
She seems a little sad.
Then he will cry early in the morning,
The sky will be covered with clouds,
It will sparkle in the sun
More beautiful than the fabulous firebird,
That autumn Ball will arrange
Cover the earth with leaves
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Preview:
MBOU "Bykovskaya basic secondary school of the Yakovlevsky district of the Belgorod region"
Research paper on the topic
“Why are the leaves colored in autumn? different colors?»
Kolnik Arina,
Peremyshlev Mikhail
3rd grade students
Supervisor:
Peremyshleva T.I.
primary teacher
Classes
Bykovka 2012 -2013 academic year
Autumn wanders through the woods.
She seems a little sad.
Then he will cry early in the morning,
The sky will be covered with clouds,
It will sparkle in the sun,
More beautiful than the fabulous firebird,
Then he will arrange an autumn ball,
Cover the earth with leaves...
Autumn is a very important time for observations. All living things are preparing for change. Autumn has the following periods: early autumn, Golden autumn, deep or late autumn and pre-winter. Each period has its own main features. But we are more interested in the second period - the golden autumn.
The object of our researchis a school park
Subject of study: autumn leaves different trees.
Purpose of the study: to know, Why do leaves change color in autumn?
And they fall off?
Research objectives:
- how long does a leaf live?
- why in autumn the leaves are painted different colors;
- what benefits does the plant receive from shedding its leaves for the winter;
- what is contained in fallen leaves;
- causes of leaf fall;
- characteristics of leaf fall in some trees and shrubs
Research methods:
Research;
Practical;
Collection and analysis of various sources of information;
Questioning of classmates and elementary school students;
Studying literature on the research topic;
Searching for information on the Internet.
Hypothesis:
- perhaps the leaves contain dyes;
Coloring is affected by weather conditions;
Leaf fall is a biological phenomenon caused by the life of the plant or caused by other reasons.
Practical significance:
Using the material in lessons about the surrounding world;
Creating a slide presentation for wide use;
Decor creative works from leaves.
Stages of work:
- Preparing for the study.
- Conducting research.
1). Questioning classmates and elementary school students
2). Excursion to the school park.
3). Excursion to the children's library.
4). Conducting observations.
3. Design of research work.
4. Preparation and defense of work.
2. Main part .
2.1 How long do leaves last?
Looking through the literature, children's encyclopedia, and Internet materials, we realized that the leaf is an important part of the plant. This is a "multi-story factory." The main purpose of leaves is to capture and transform the energy of sunlight. Thanks to continuous work, the leaf feeds, releases water vapor, and breathes. One square meter The leaf blade releases up to four liters of oxygen every hour and takes the same amount of carbon dioxide from the air.
How long does a leaf live? The leaves of our trees live from spring to autumn. If the leaf is green, it means it is alive. As soon as they turned yellow and red, it means they grew old and died.
Conclusion:
Plants are our friends! Millions of years ago, it was the leaves of fossil plants that made the atmosphere of our planet suitable for habitation.
2.2 Why do the leaves turn different colors and fall off in the fall?
We conducted a survey among primary school students to find out if they know why a tree needs leaves, and why the leaves change color and fall off in the fall. After analysis, we concluded:
- Why do trees need leaves?
__10_____students answered correctly, __4____ people answered incorrectly, did not think about it at all ___-______
- Why do leaves change color?
__10_____students answered correctly, ____3___people answered incorrectly, did not think about it at all ___1______
- Why do the leaves fall?
___7___students answered correctly, ____7___people answered incorrectly, ____-_____ didn’t think about it at all.
- Which trees are the first to shed their leaves and why?
__5_____students answered correctly, __2____ people answered incorrectly, they didn’t think about it at all ___7______
- Why is it harmful for trees to have leaves in winter?
___4____students answered correctly, ___7____ people answered incorrectly, did not think about it at all ___3______
- Which tree doesn't last longsheds its leaves and stands in its autumn attire throughout the winter?
___2____students answered correctly, ____10___people answered incorrectly, did not think about it at all __2_______
Analyzing the results of the survey, we found that most students do not know the reasons for the change in color of autumn leaves and the reasons for their falling.
2.3 Who painted the trees? What is contained in fallen leaves?
Emerald green is replaced by golden-orange, orange, and fiery red tones. Why does the replacement happen? color palette trees? Who is guilty?
Studying this problem in encyclopedic and reference literature, as well as we turned to Internet materials and realized thatplants seem green to us large quantity tiny chlorophyll grains located in the cells of leaves and stems. Chlorophyll grains are not eternal; they are destroyed under the influence of light and are reborn again only in the light. However, chlorophyll is not the only coloring agent in plant tissues. There are in the leaves yellow pigments- carotenoids, and red-violet - anthocyanins.
These pigments begin to quickly appear on the outer part of the leaf and stem only when the air temperature drops, and chlorophyll grains, on the contrary, collapse and disappear. And the forests dress, as Pushkin said, in “crimson and gold”
Conclusion:
When the air temperature drops in clear sunny days chlorophyll grains are destroyed.As a result, the leaf loses its green color, and yellow pigments, previously invisible, suddenly appear and color the leaf.
2.4 . Causes of leaf fall.What benefits does the plant receive from shedding its leaves for the winter?
A leaf is not only an organ in which nutrients and mineral salts are created, but also water evaporates through the leaves. By shedding their colorful outfit, deciduous trees, which need a lot of moisture, are saved from winter drought. A large birch tree, for example, evaporates 7 tons of water during the warm months, but in winter you can’t pull that much out of the soil. The second reason. In the pulp of the leaf, under a microscope, you can find dead cells clogged with salt crystals. And if in May beech leaves contain 5% mineral salts, then by October they become 11%. The leaves become overloaded with unnecessary substances and the tree sheds its leaves, thereby freeing itself from the excess minerals. The leaves are prepared to fall off in advance: between their petiole and the branch a layer of special cells with thick walls is formed - the so-called plug. The cork does not allow water and juices to pass through. The leaves cannot feed and become weaker. Now all it takes is a light breeze, a few drops of dew andeven its own weight, so that the leaf would separate from the native branch on which it was held so tightly. We are watching the leaves fall.
Conclusion:
Leaf fall is preparation for winter, not only the cold, but most importantly, the dry season.If our deciduous trees remained in their greenery for the winter, they would inevitably die as a result of 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.
2.5 Features of leaf fall in some trees and shrubs. Why are conifers able to overwinter in greenery?
The importance of leaf fall in the life of our deciduous trees is especially noticeable when comparing them with conifers. Conifers - spruce and especially pine - are drought-resistant plants. Their needles evaporate many times less water than the foliage of our hardwoods. Thanks to this, they are able to overwinter in a green form. This ability to save moisture is achieved by our conifers due to the special structure of their needles. The needles have a number of drought-resistant adaptations: a thick skin surrounding the needles on all sides, and a bluish waxy coating, which also reduces evaporation; great importance It also has stomata located in special recesses. In contrast, 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 draw attention to the fact that by shedding leaves, they thereby protect themselves from mechanical damage under the weight of snow. Often in winter you can observe how, even in a leafless state, large branches of trees break under the pressure of snow; wide leaf surfacewhich would allow a lot of snow to settle would make this phenomenon catastrophic.
While observing the deciduous trees and shrubs in our school park, we compiled a table. What trees, and in what order do they take off their outfit? How long does leaf fall last?
When the days become shorter and the sun no longer generously shares its warmth with the earth, one of the most beautiful times of the year begins - autumn. She, like a mysterious sorceress, changes the world around her and fills it with rich and unusual colors. These miracles occur most noticeably with plants and shrubs. They are one of the first to respond to weather changes and the onset of autumn. They have three whole months ahead to prepare for winter and part with their main decorations - leaves. However, first, the trees will certainly delight everyone around with the play of color and the madness of colors, and the fallen leaves will carefully cover the earth with their blanket and protect its smallest inhabitants from severe frosts.
Autumn changes in trees and shrubs, the reasons for these phenomena
In autumn, one of the most important changes in the life of trees and shrubs occurs: a change in the color of foliage and leaf fall. Each of these phenomena helps them prepare for winter and survive such a harsh time of year.
For deciduous trees and shrubs, one of the main problems in winter time year is a 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 leaves evaporate liquid very strongly, which is very wasteful in winter. Coniferous trees, in turn, can afford to show off their needles even in the cold season, since the evaporation of liquid from them occurs very slowly.
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 be able to withstand such a heavy load.
In addition, over time, a lot of harmful substances, which can only be gotten rid of when leaves fall.
One of the recently uncovered mysteries is the fact that deciduous trees that are placed in a warm environment, and therefore do not need to prepare 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 life cycle 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 unusual colors. At the same time, each tree has its own set of pigments - “paints”. These changes occur because the leaves contain a special substance, chlorophyll, which converts light into nutrients and gives the foliage its 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 weather conditions. If the weather is sunny and relatively warm, the autumn leaves will be bright and variegated, and if it rains often, they will be 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 color of the leaves is purplish. Maple and aspen boast a crimson color. These trees are very beautiful in autumn.
The leaves of birch become light yellow, and those of oak, ash, linden, hornbeam and hazel become brownish-yellow.
Hazel (hazel)
The poplar quickly sheds its foliage; it just begins to turn yellow and has already fallen off.
Shrubs also delight with the variety and brightness of colors. Their foliage turns yellow, purple or red. Grape leaves(grapes - shrubs) acquire a unique dark purple color.
The leaves of barberry and cherry stand out against the general background with a crimson-red hue.
Barberry
Rowan leaves can be yellow to red in autumn.
The viburnum leaves turn red along with the berries.
Euonymus dresses in purple clothes.
The red and purple shades of foliage are determined by the pigment anthocyanin. An interesting fact is that it is completely absent from 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 pine, spruce and cedar. To the south the number of such plants is even greater. Among them are trees and shrubs: juniper, myrtle, thuja, barberry, cypress, boxwood, mountain laurel, abelia.
Evergreen tree - spruce
Some deciduous shrubs They also don’t part with their emerald clothes. These include cranberries and lingonberries. In the Far East there is interesting plant wild rosemary, the leaves of which do not change color in the fall, but curl up into a tube in the fall 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 and also accumulate mineral components. However, in winter, when it occurs acute shortage light, and, therefore, nutrition, 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, which act as leaves. The needles are perfectly adapted to cold weather. The needles contain a lot of chlorophyll pigment, which converts nutrients from light. In addition, they have a small area, which significantly reduces evaporation from their surface so necessary in winter moisture. The needles are protected from cold weather by a special wax coating, and thanks to the substance they contain, they do not freeze even in very coldy. The air that the needles capture creates a kind of insulating layer around the tree.
The only one coniferous plant The tree that leaves its needles for the winter is larch. It appeared in ancient times, when summers were very hot and winters incredibly frosty. This climate feature led to the fact that the larch began to shed its needles and there was no need to protect them from the cold.
Leaf fall, as a seasonal phenomenon, occurs in each plant at its own time. certain period. It depends on the type of tree, its age and climate conditions.
Poplar and oak are the first to part with their leaves, then the time comes for rowan. The apple tree is one of the last to shed its leaves, and even in winter, there may still be a few leaves left on it.
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.
The oak begins to lose its leaves at the beginning of September and after a month it completely loses its crown. If frosts start earlier, leaf fall occurs much faster. Along with the oak leaves, acorns also begin to fall off.
Rowan begins its leaf fall in early October and continues to delight with its leaves until November 1st. pink leaves. It is believed that after the rowan leaves its last leaves, dank, chilly days begin.
The leaves on the apple tree begin to turn golden by September 20th. By the end of this month, leaf fall begins. The last leaves fall from the apple tree in the second half of October.
Evergreen plants and shrubs do not lose their foliage even with the onset of cold weather, as ordinary ones do hardwoods. Permanent foliage cover allows them to survive any weather conditions and maintain maximum reserves. 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 continuous nutrition of the trunk and roots. Most often, evergreen trees and shrubs grow in areas with mild and warm climates, where the weather is warm even in winter, however, they are also found in harsh climates. climatic conditions. These plants are most common in tropical rainforests.
Evergreen plants such as cypresses, spruce trees, eucalyptus trees, some types of evergreen oaks, and rhodendron can be found over 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 its unusual appearance and height of more than 3 meters.
One more evergreen shrub is gardenia jasmine. Its homeland is China.
Autumn is one of the most beautiful and vibrant times of the year. Flashes of purple and golden leaves preparing to cover the ground with a colorful 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.
The world is beautiful in its diversity. There are a lot of plants and trees on the planet. When we think about nature, we imagine a walk through a deciduous forest or clearing. In summer, the natural spaces are surrounded by greenery. And in the fall, the trees take on a solemn appearance, donning multi-colored outfits. Let's try to figure out why the leaves turn yellow?
Every green leaf, even the smallest one, contains a pigment - a substance that absorbs light and forms the color of the plant and is responsible for its color. This substance is called chlorophyll. Thanks to it, a blade of grass or a leaf breathes, develops, and grows.
When trees and shrubs begin to prepare for winter, necessary substances move to the roots and core of the trunk. They will feed the living organism until spring. After all, food supplies are cold period are needed not only by animals, but also by plants. The remaining energy will be used to produce new shoots.
When beneficial elements leave the leaves, chlorophyll production stops. Its remains disintegrate, forming pigments of other colors. One of them is carotene - carrots are rich in it, so it orange color. And another pigment is responsible for the purple, red color - anthocyanin. As in a radish or a scarlet rose. So the leaves acquire different shades of yellow, orange and red. It all depends on which substance is more.
Why do trees shed their leaves?
The leaf is connected to the tree by a stalk, in which there is a cluster of small vessels. They carry water and nutrients. But by winter, trees need to save water. And the leaves no longer serve any practical function. Therefore, in order to save water, bushes and trees get rid of their leaves and they fall off. And we enjoy the beauty of the golden autumn, so that in the spring we can again enjoy the blossoming buds.
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