Why do leaves fall off trees?

Answer 1

Deciduous trees lose their leaves every year. In temperate climates, this leaf drop is associated with the onset of autumn weather. Leaf drop is triggered in trees by the longer nights and cool weather. When this happens a corky layer starts to form at the base of the petiole and the leaf begins to “senesce” or grow old and die.

Tree leaves contain different types of pigments. The predominant one is usually green and it comes from the chlorophyll needed for photosynthesis, the process by which the leaf captures sunlight and uses that energy to make sugars out of water and carbon dioxide. In the fall as the leaf begins the process of senescence or dying and falling off the tree, photosynthesis stops and chlorophyll breaks down, revealing the underlying yellow and orange pigments in the leaf. These remaining pigments are carotene (orange-yellow pigment), and xanthophyll (yellow). Red and purple colors come from anthocyanin pigments. Anthocyanins are not masked but actually start to build up in the leaves of certain trees as the chlorophyll breaks down.

Answer 2

Leaves fall of a tree for 2 reasons.
1-In winter the trees drop their leaves so then the damage by frost is minimal
2-When the weather is very hot and the plant is at wilting point,a plant may loose some to reserve some water-less evaporation through the leaves,.

The only other reason is that the plant is dead or diseased.

Answer 3

Trees conserve energy in the winter. They don't need their leaves as they can't photosynthesise as there are less hours of daylight. A chemical reaction turns the leaves brown as the tree draws back the nutrients and subsequently the leaves fall off deciduous trees.

Answer 4

The leaves fall off trees in autumn because the trees nutriants cannot be shared out as much and are needed for its survival.This makes the leaves fall.They are surplus to requirements basically.

Answer 5

Cold weather stops the tree from flowing nutrients to the leaves. There then is a chemical reaction which makes the leaves turn color and fall off. Then you get to go out and rake them up.

Answer 6

cause the tree is too big to fall off the leaves

Answer 7

Because the trees go into a sort of hibernation and so no longer need to photo-synthasise until the spring when the new leaves appear

Answer 8

Because when the leaves fall off,the tree are plant goes dormit.Which means sleeping.So when you sleep,do you sleep with your cloths on.

Answer 9

they fall off the trees so that u have a hobby for the autumn and winter mainly that is raking leaves and unclogging ur drains!

Answer 10

they fall off during autumn because they are coming to the end of their life and must make way for the new leaves to start growing in spring thus continuing the circle of life.