Which trees experience leaf fall? Main autumn seasons. What's in fallen leaves?
Leaf fall is one of the most characteristic phenomena of autumn nature. It most clearly expresses the seasonal periodicity in development flora our latitudes. Every year it repeats itself, first delighting our eyes with the countless tones and colors in which the forest is dressed up, and then inducing involuntary sadness with the dull appearance of naked trees and the melancholic rustle of fallen leaves. Autumn has long been considered a boring time, a dead season in nature. Poets compare it with old age and 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, it is possible to notice a lot in nature, to explain a lot of incomprehensible things. 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 nature in our temperate latitudes.
The main decision is to choose The best way express and present what you have discovered about changes in your trees. Do you want to create a mural or scale models of trees, tell a story about changes in trees, write poetry, create music, create a dance, play a game about the animals that live in trees? Children can also decide whether they want to prepare an exhibit where others can observe their work, or instead plan a less complex end-activity such as creating a book to share with families.
Probably everyone has at least once admired colorful leaves flying in the wind. But not everyone knows that leaf fall is not just the end of the summer season, but a vital process for plants. Leaves fall even from trees growing in warm countries where there is no frost.
In temperate climates, trees shed their leaves at approximately the same time - in the fall. In southern latitudes, this process extends throughout the year or occurs before the dry season. Why do leaves fall on the eve of difficult periods in the life of a tree?
The teacher may meet with small groups to discuss the children's decisions. Ask children questions such as: ¨What do you particularly want others to know about your study of tree changes? ¨What do you think is most interesting to you? ¨ Teach children about time, space, and monetary constraints that may affect what they do as a culminating activity. Help children set and stick to deadlines to complete their performances.
- Serve as a consultant when groups encounter difficulties.
- Provide materials requested by groups.
- Let the children do this work.
Why do we need leaf fall?
Why do plants get rid of the organs that provide them with daily nutrition? After all, it is in green leaves that photosynthesis occurs - the conversion of carbon dioxide into nutrients under the influence of the sun.
The reasons for leaf fall can be different:
- annual weather changes, the onset of cold weather or drought;
- internal cycle of tree development, accompanied by growth, renewal or lignification of branches;
- damage by viral diseases, pests;
- bad ecology;
- root damage or lack of nutrients in the soil.
If the cause of leaf fall lies in poor external conditions, the tree may stop growing and even die. But leaf fall caused by natural natural factors, useful and necessary for plants.
Interact with families during Phase 3
The teacher can reinforce their creative work during Phase 3. Family members often see what the children have done and learned during the project. As the tree exploration ends, the class can develop several ways to expose their work for their families. Here are some ways to help teachers.
Have children create invitations for family members to come and view the exhibits. Offer family members the opportunity to volunteer for culminating activities. Invite parents to think about their children's participation in the project. . It is important to keep in mind that children themselves will likely find many correct ways to explore changes in trees. In fact, while children pursue what interests them, any given project may turn out to be very different from what was originally expected. Changes in Trees may be just a small part of another subject that stimulates the minds of many children in the class.
Harsh winter is a test for trees
In winter frosts upper layer The soil freezes and the water in it turns into ice. The roots receive neither moisture nor the microelements contained in it. If the tree does not shed its leaves early, it will continue to evaporate water and dehydration will soon occur. This is why leaves fall from trees in the fall.
Children's books related to trees
Thanks to Barry Gullick and Lisa Lee for reviewing the documents. Many teachers like to start a project by sharing well-written, accurate informational books with children. During stages 1 and 2, it is especially important to have reliable factual information, whether text or images.
Children's direct experience with trees may help them respond better to the descriptive language of poetry about trees during the phase. Magic elements folk tales and fantasies related to trees may awaken the imagination of some children during the phase. Throughout the project, children can also observe how book illustrators represent changes in trees.
In addition, wet snow and ice are too heavy even for bare branches - in winter they become brittle and quickly break after heavy snowstorms. A tree, dressed in lush foliage, will collect whole snowdrifts on itself, bend under their weight and may collapse, unable to withstand the load.
Another important reason why leaves fall from trees is to get rid of accumulated summer season toxins and excess nutrients. In preparation for winter sleep, plants slow down their development and seem to freeze in anticipation of frost, snowfall and blizzards. They don’t need extra food this season.
Information books
The following reading lists for children are not comprehensive, and teachers may be aware of additional books that may be helpful to children during a tree modification project. Some of the books on the list may be too advanced for preschool-aged children, but may contain some text or some photographs that may be useful for children.
Realistic fantasy illustrated books about trees
Debbie Miller. McMillan. Tree Flowers Millicent Selsam. Betsy Maestro. Illustrated by Loretta Krupinski. Collins, we're going on a leaf hunt with Steve Metzger.
- It may still be the Allan Fowler tree.
- Board books.
- Gordon Morrison Oak.
- Small, brown, are there trees?
The natural phenomenon of leaf fall is a very wise decision; it allows plants to gain strength for the next season. In the southern regions, during drought, the situation is similar - plants have nowhere to get water, which is evaporated by foliage every day in a hot climate.
Leaf fall in evergreens
Among tropical trees, leaf fall as a natural phenomenon is also necessary, but it occurs in all plants in different time. Renewal of the cover can take several weeks or months, and the crown is never completely exposed. After old leaves are shed, new ones grow quickly, so rainforests and appear evergreen.
Illustrated books of fantasy and folk tales
Joanne Ryder.
- “When Sofia gets angry, she really gets angry” by Molly Bang.
- Red Leaf, Yellow Leaf by Lois Ehlert.
- Illustrated by Pamela Zagarenski.
- Houghton Mifflin, List Man Lois Ehlert.
Duluth Advisory Committee on Indian Education, Nanabosho and Woodpecker by Joseph McLellan. Illustrated by Ryan Brynjolson. Pemmican, First Fire by Marijo Moore. Illustrated by Anthony Chi Emerson. “Nuts for you!” Lois Ehlert. . The following resources, including field guides and related books, activity books and curriculums, articles on trees and other plant projects, online resources related to trees and others, may be useful during a tree change project .
In our latitudes there are also evergreens. These include not only conifers, but also low shrubs - lingonberries, heather, hoofed grass. In winter, they are hidden under snow, so they do not evaporate excess moisture and do not break. Coniferous trees thanks to the resin, they retain the flexibility of the branches even with a significant drop in temperature, so they do not break under the thickness of the snowdrifts. Evergreen trees and bushes also change leaves, but they do it gradually, and fresh greenery immediately grows in place of the fallen ones.
Guides and related books
Department natural resources Illinois National Tree Gazetteer North America Keith Rushforth and Charles Hollis. National Geographic Society.
- What kind of tree is this?
- Arbor Foundation.
- Molenbrock and the Department of Natural Resources.
Artificial plants and plants
Chichester.
- Environmental experiences for early childhood education.
- American Forest Foundation.
- Discovering Nature with Young Children by Ingrid Chalufour and Karen Worth.
- A book about the nature of nature in the family.
- Reggio Children of Wood by Andy Goldsworthy.
How does the leaf fall process occur?
There are still a few weeks until the leaves begin to swirl in a yellow-red dance, but nature is already preparing for what happens to the trees in the fall. At the end of summer, the active exchange of moisture between the stem and leaf slows down. At the base of the petiole a cork layer is formed - a kind of partition that prevents the passage of juices. Gradually it coarsens and becomes waterproof.
Besides the importance of answering an intriguing question about nature, studying seasonal leaf senescence could be very important for people, especially in agriculture. Accompanying the process of cell death, the color change of these leaves is something truly remarkable. But does leaf color change only due to the process of cellular aging? The so-called “autumn colors” are the result of a mixture of three pigments: chlorophyll, carotenoids and anthocyanin. Both chlorophyll and carotenoids are produced throughout the year, but due to the high production of the main photosynthetic pigment, the yellow-orange colors are masked.
The fastening of the sheet in this place becomes weak, and with gusts of wind it easily comes off. U different types The fall of leaves occurs unevenly: some trees are distinguished by early and friendly leaf fall, other plants fly off only before the onset of frost.
How leaf fall occurs depends on the shape of the crown, the flexibility of the branches, and the location of growth. Shrubs with easily bending low shoots shed their leaves later than brittle tall poplars, blown by all the winds. Leaves with a hard, glossy structure fly off later - water evaporates from them more slowly.
Red pigments are specially produced in the fall, shortly before the leaves fall. Thus, the red coloration of leaves in autumn is not a side effect of seasonal senescence, which makes the active production of this pigment in autumn ecologically interesting.
The predominance of red, yellow and brown colors on the leaves. Brown usually indicates cell death. The oldest and most proven explanation for the function of the red pigment is protection against abiotic factors, especially solar radiation. Anthocyanins would alleviate this photo-oxidative stress, functioning as a true “sunscreen.” But why relieve this stress on leaves that are dying anyway? Here we come into the role of a very important mechanism, nutrient reabsorption. Healthier leaves can increase the efficiency of nutrient reabsorption to the rest of the plant.
Why do leaves change color
Yellow and crimson leaves of all shapes, with intricate patterns of veins, pleasantly rustling underfoot, make autumn elegant and festive. Why do trees change color before it even starts? a natural phenomenon leaf fall?
The leaves acquire a pleasant green color due to the chlorophyll cells in which photosynthesis occurs. Carbon dioxide, combining with water, turns into carbohydrates, while chlorophyll is destroyed and re-formed, already in more. This is how the leaf plate grows.
This mechanism is well dispersed in plants that are of great competitive importance in nutrient-deprived environments. In addition to abiotic explanations, another group of explanations for active fall anthocyanin production by senescing leaves involves interactions with plant insects. Coevolution, seed dispersion, direct defense, camouflage, anti-camouflage, tritrophic reciprocity are hypotheses associated with this type of interaction. Of all these biotic possibilities, the most studied, for happiness, is coevolution.
In addition, the leaf contains other pigments: carotene, which gives it a yellow color, and xanthophyll, which makes plants turn red. These elements are also found in green leaves, but they are perfectly masked by the green color of chlorophyll.
Leaf fall is a natural phenomenon that begins with a change in the color of trees. When a plug forms at the base of the leaf, the flow of water into the leaf is impaired and soon the process of photosynthesis becomes impossible. Chlorophyll cells gradually die off, the green color of the leaves fades, and red and yellow pigments appear more and more brightly.
According to this hypothesis, the red coloration would be a warning sign for herbivorous insects. This indicates high level chemical protection, poor nutritional quality or impending leaf fall, which is of no interest to insects. Because fall migration is a crucial stage in the life cycle of several insects, the selective pressure to produce a quality leaf to lay eggs on is quite strong. Already the plant would benefit from both a lower rate of herbivory in the leaves and a lower rate of infection by viruses, bacteria and fungi caused by insects.
Some plant species contain too many red pigments in their vacuoles, so they acquire a crimson color long before the leaves fall, in early or mid-summer. These include some types of hazel, euonymus, and virgin grapes.
In rainy and cloudy autumn, the leaves change color slowly and evenly. But as soon as the clear September sun warms up, the plants begin to evaporate the remaining water in them. The destruction of chlorophyll occurs faster and faster, and forests and parks instantly turn red and gold.
Thus, insect selection of leaves and fall colors could continue, as in an arms race. Plants with reddish-colored leaves would be selected because they had a lower rate of herbivores, and insects that searched for leaves in different shades of red would be selected because they found better substrates.
Well, the hole is a little lower. The study, which analyzed 262 tree species, found that the species that present "autumn color" are those that represent the evolutionary history associated with insects that migrate in the fall. Aphids do seem to prefer green leaves over reddish leaves, but how do they differentiate between green and red? Many insects do not have photoreceptors for red and therefore will not see what we see as red. One possibility would be that aphids would not be attracted or reflected by color, but rather by volatile chemical factors related to leaf quality.
The foliage of poplar, birch and linden acquires a yellow color; aspen, rowan and elderberry turn purple. Maples delight with the whole range of shades from gold and red to red and fancy patterns. Nature celebrates the end of the summer season in a bright and colorful way.
What is rich in a fallen leaf?
What defoliation is and why it occurs can be easily understood by considering the life cycle of plants. Is fallen leaves good for a tree? As always, the answer is easy to find by contacting wildlife which does nothing in vain.
Thus, they would have an indirect indication of leaf color, which is consistent with the coevolution hypothesis. But this does not fully support the hypothesis because it does not show that red coloration is a signal that guides leaf selection by aphids.
The hypotheses that try to explain the adaptive value of "autumn flowers" are so great that a review of the current level of the topic was published in the corresponding periodical "Oikos" this year. In total, Marco Archetti raised 16 different hypotheses in his paper and concluded by showing that we still have a great path ahead: “We have no evidence for any hypothesis.”
What happens to leaf litter in forests? It lies on the ground and covers it with a soft thick carpet, accumulating year after year and gradually rotting. The soil, covered with a layer of rotten leaves, is always characterized by excellent fertility, freezes less and is not subject to erosion. What is so rich about a fallen leaf?
It has already been mentioned that over the summer nutrients, carbohydrates and microelements accumulate in the foliage. Having fallen to the ground, they are processed with the help of microorganisms into a water-soluble form convenient for absorption by plants - this produces useful humus with a high content of nitrogen, potassium and phosphorus compounds. This is the best fertilizer for trees.
In addition, small rodents, reptiles and insects overwinter in the thick layer of fallen leaves. Loose and soft soil under the forest floor - perfect place for dry and warm mink. In nature, everything is interconnected; there are no unnecessary or unnecessary processes. This is why leaf fall occurs.
Why are leaves removed from city parks and gardens?
Why rake and transport such useful and necessary fertilizer? Wouldn't it be better to leave it on the lawns? Gardeners have asked this question more than once, and a definite answer has not yet been found.
On the one hand, leaf litter is useful for protecting roots from frost and creating a nutrient medium. On the other hand, not only beneficial insects, but also ardent pests of fruit and ornamental trees can overwinter in it. And lawns strewn with rotten leaves don’t look decorative at all next year.
In addition, in urban areas, leaves actively accumulate toxins from exhaust gases and other chemical compounds, and with litter they fall into the ground, poisoning the trees. Therefore, the foliage is raked and taken away, and the plants are fed with ready-made fertilizers.
Is it possible to burn leaves?
Removing leaves is a costly and troublesome task; sometimes it seems that it would be easier to burn it. However, in cities, landscaping rules strictly prohibit this, and not only for fire safety reasons. The fact is that when leaves burn, volatile compounds are released containing carbon dioxide, sulfur dioxide, soot and heavy metal salts accumulated over the summer.
Smoke from fires is extremely harmful to breathing and has a poisonous effect. It especially affects the health of allergy and asthma sufferers, children and the elderly, causing runny nose, cough and more serious consequences. Carcinogens contained in leaf smoke can even cause cancer and autoimmune diseases.