Why do leaves change colors and fall off trees?

Answer 1

Chlorophyll is not a very stable compound; bright sunlight causes it to decompose. To maintain the amount of chlorophyll in their leaves, plants continuously synthesize it. The synthesis of chlorophyll in plants requires sunlight and warm temperatures. Therefore, during summer chlorophyll is continuously broken down and regenerated in the leaves of trees.

During summer, the leaves of trees are factories producing sugar from carbon dioxide and water by the action of light on chlorophyll. Chlorophyll causes the leaves to appear green. (The leaves of some trees, such as birches and cottonwoods, also contain carotene; these leaves appear brighter green, because carotene absorbs blue-green light.) Water and nutrients flow from the roots, through the branches, and into the leaves. The sugars produced by photosynthesis flow from the leaves to other parts of the tree, where some of the chemical energy is used for growth and some is stored. The shortening days and cool nights of autumn trigger changes in the tree. One of these changes is the growth of a corky membrane between the branch and the leaf stem. This membrane interferes with the flow of nutrients into the leaf. Because the nutrient flow is interrupted, the production of chlorophyll in the leaf declines, and the green color of the leaf fades. If the leaf contains carotene, as do the leaves of birch and hickory, it will change from green to bright yellow as the chlorophyll disappears. In some trees, as the concentration of sugar in the leaf increases, the sugar reacts to form anthocyanins. These pigments cause the yellowing leaves to turn red. Red maples, red oaks, and sumac produce anthocyanins in abundance and display the brightest reds and purples in the autumn landscape.
Sugar Maple
The range and intensity of autumn colors is greatly influenced by the weather. Low temperatures destroy chlorophyll, and if they stay above freezing, promote the formation of anthocyanins. Bright sunshine also destroys chlorophyll and enhances anthocyanin production. Dry weather, by increasing sugar concentration in sap, also increases the amount of anthocyanin. So the brightest autumn colors are produced when dry, sunny days are followed by cool, dry nights.

As the bottom cells in the separation layer form a seal between leaf and tree, the cells in the top of the separation layer begin to disintegrate. They form a tear-line, and eventually the leaf is blown away or simply falls from the tree.

Answer 2

trees have hormonal changes in their vascular system which is driven by the DNA of the tree. The DNA dictates what the tree is to do. During changes of season, The DNA of the Tree instructs it to slow growth and production during fall and have all the leaves fall die. in the process the leaves wither and turn from a lively green to amber and brown color. The green part of the leaf is chlorophyll (solar energy capturing part of the leaf). During winter the tree needs to protect itself from the harsh temperatures. So it drops its leaves, in by doing so reduces the metabolic demands of the tree and goes into a low energy stasis all winter. sort of like hibernation.

Answer 3

The short answer is the trees are getting ready for winter. The tree stops sending "food" to the leaves to conserve "food" for the whole tree, so it can survive the winter. Less sunlight in the winter means less chemical reation for the tree, so the tree goes into a kinda hybernation. Hope this helps.

Answer 4

Three factors influence autumn leaf color-leaf pigments, length of night, and weather, but not quite in the way we think. The timing of color change and leaf fall are primarily regulated by the calendar, that is, the increasing length of night. None of the other environmental influences-temperature, rainfall, food supply, and so on-are as unvarying as the steadily increasing length of night during autumn. As days grow shorter, and nights grow longer and cooler, biochemical processes in the leaf begin to paint the landscape with Nature's autumn palette.

Answer 5

if you hung from a tree all winter, you would change color and fall off too

Answer 6

The loss in colour and eventual dropping of the leaves is termed leaf senescence. In training for the iciness months that are incorrect for advance the plant leaves die, first dropping their chlorophyll (which makes them turn from eco-friendly to yellow/orange/purple) and then different photograph-pigments if modern-day (making them turn brown). In iciness many flowers enter a level of dormancy-truly hibernating-with the intention to stay to tell the tale the lean months. flowers are waiting to stumble upon the quantity of photograph voltaic (technically the quantity of darkness), it is on the subject remember of the lean of the earth and the seasons. the mild detection means is extensively utilized whilst flowers flower Evergreen leaves are many times in basic terms ever eco-friendly (alive) or brown (lifeless). They drop there leaves in basic terms no longer without warning.

Answer 7

To furtilize the ground around them properly for the next season

Answer 8

A change of weather patterns.

Answer 9

They die, making way for new growth the following year

Answer 10

bcos human change ang grow old too