why do autumn leaves fall?
970397
Leaves fall from trees in the autumn to protect the plant from the harsh environmental conditions of the winter, primarily the cold temperatures.  By dropping their leaves the plants are able to seal off their internal tissues, that contain water, from the outside environment and this prevents the water in the plant tissues from freezing in the cold winter.
943391
Leaves are nature's food factories. Plants take water from the ground through their roots. They take a gas called carbon dioxide from the air. Plants use sunlight to turn water and carbon dioxide into glucose. Glucose is a kind of sugar. Plants use glucose as food for energy and as a building block for growing. The way plants turn water and carbon dioxide into sugar is called photosynthesis. That means "putting together with light." A chemical called chlorophyll helps make photosynthesis happen. Chlorophyll is what gives plants their green color. \n\n\nAs summer ends and autumn comes, the days get shorter and shorter. This is how the trees "know" to begin getting ready for winter. \n\nDuring winter, there is not enough light or water for photosynthesis. The trees will rest, and live off the food they stored during the summer. They begin to shut down their food-making factories. The green chlorophyll disappears from the leaves. As the bright green fades away, we begin to see yellow and orange colors. Small amounts of these colors have been in the leaves all along. We just can't see them in the summer, because they are covered up by the green chlorophyll. \n\nThe bright reds and purples we see in leaves are made mostly in the fall. In some trees, like maples, glucose is trapped in the leaves after photosynthesis stops. Sunlight and the cool nights of autumn cause the leaves turn this glucose into a red color. The brown color of trees like oaks is made from wastes left in the leaves. \n\nIt is the combination of all these things that make the beautiful colors we enjoy in the fall.
310693
All spring and summer there is a lot of water to keep the trees well watered.  They use their leaves to convert sunlight into energy, but this uses up a lot of their water, so they have to keep drinking a lot from their roots.  In the winter it is too cold outside for the trees to drink because the ground is frozen and so is all of the water.  Therefore the trees go into a kind of hibernation, just like bears do.  The shed their leaves because they don't have the resources to hold onto them all winter.  \n\nThe trees also move all of the energy that they have gathered all summer from the sun and the extra water they gathered into their roots.  They take all of the nutrients from their leaves, so they change color, and they move them to their roots.  This way the tree's food is safe all winter.  Then because the trees no longer have any use for their leaves (which used to gather energy from the sun), they let them go.  That leaves all of us with leaves to make into piles and play in!
205443
The "tree line" on any mountain top is the point at which no tree can grow above this line.  It is usually due to cold as the chlorophy cannot run in a tree under cold conditions. (thats why leaves change color, die and fall off)  In the souther part of the US mountain tops do not get cold enough like the ones in the north east.
1085073
As summer ends and autumn comes, the days get shorter and shorter. This is how the trees "know" to begin getting ready for winter.\n\nDuring winter, there is not enough light or water for photosynthesis. The trees will rest, and live off the food they stored during the summer. They begin to shut down their food-making factories. The green chlorophyll disappears from the leaves. As the bright green fades away, we begin to see yellow and orange colors. Small amounts of these colors have been in the leaves all along. We just can't see them in the summer, because they are covered up by the green chlorophyll.\n\nThe bright reds and purples we see in leaves are made mostly in the fall. In some trees, like maples, glucose is trapped in the leaves after photosynthesis stops. Sunlight and the cool nights of autumn cause the leaves turn this glucose into a red color. The brown color of trees like oaks is made from wastes left in the leaves.\n\nIt is the combination of all these things that make the beautiful colors we enjoy in the fall.
427340
Indoor plants are fooled as to season because of lighting inside. Length of uninterupted night compared to day light is usually what triggers cycles in outdoor plants, not frost, etc.
104677
Autumn. I absolutely love the fall season with the changing colors of the leaves and the crispness in the air. And, my favorite place to be in the fall is either in New England or Yosemite.
448071
Because of it's position. If it's vertical. it would fall faster. If it's horizontal, there is more space for the air to push it up. It would fall slower because air molecules pushes it up as the leaf pushes air down. Have you heard of "Action-Reaction". All objects exert force to one another. Hope that helps.
409172
Of course, many trees shed their leaves in the fall and winter, but the tree is still living....
522653
It could get confused, but only for one season.\n\nTrees drop there leaves based on declining day length, and it takes many weeks of exposure for them to be able to 'read' the time correctly. If you took a tree across the equator it could well suffer from the seasonal change.\n\nHowever if it survived then the following year it would have no problem at all. It would drop its leaves when the days started drawing in in Autumn just like it did back home.\n\n\nTrees don't have some mystic link with the place where they germinated. They just read the signals from the place where they are growing.
429953
thats cause thats when the leaves fall. so its called fall season. seriously.
759633
This month. I love how everything smells like fall and snow is right around the corner. The leaves haven't fallen and they are the brightest colors. Plus Thanksgiving is one of my favorite holidays.
263278
It stops plant growth, meaning at times like winter, a plant has to stop growth, conserving its energy and making it more useful at a better time like spring. (Give me best answer :))
977858
Yes, deciduous trees like oaks and maples will lose their leaves in winter, even if the winter season is very, very short. Palm trees keep their leaves year round, so it could be considered an evergreen too even if it's not a pine or cedar.
628771
Your Maple tree is suffering from the physiological disorder called SCORCH.The causal factors of the disease are drought and heat stress.Symptoms usually develop after periods of hot, dry weather in July and August. Leaves appear curled at the edges and cupped; they may develop brown, necrotic or dead margins. Leaves also shrivel and drop prematurely. Since the symptoms can be confused with those associated with anthracnose, careful examination is necessary for accurate diagnosis.Although the weather can’t be controlled and there are no "cures" once the damage is done, there are steps that can minimize the effects of scorch. These include maintaining optimum growth and vigor by watering during periods of drought, fertilizing at the proper time to avoid growth late in the season that may not harden-off properly for the winter, and pruning to remove dead twigs or branches to minimize secondary invaders or opportunistic pests.
565716
originally because labor day marks the beginning of the fall season for fasion designers.. fall means winter is comming winter means snow in new york..winter clothes need to be dark to retain heat..
564661
Forest and the trees perform a lot of functions to receive more rains. There is always evaporation of water vapour from the leaves which will become clouds and then precipitate into rain during the night or at cool climate.  The climate becomes almost cool during night time and cause the rain.  All passing clouds are interrupted by the tall trees and cause rainfall because of the cool climate there.\nThe humidity in the air in forest areas also cause more clouds and also cool climate.  It is almost cyclical. The soil becomes more fertile because of the leaves, animals and insects and helps more plants.