Why do trees lose their leaves after autumn?

Reasons why the tree loses its leaves after autumn:Lack of moisture, the air gradually becomes dry in autumn, the water loss in the soil becomes faster, the water absorbed by the roots of the tree decreases, the tree cannot provide sufficient water to the branches and branches, the water of the leaves is evaporated, it begins to wither and yellow, the base of the petiole is fragile, and the leaves fall off naturally.

Nutrients are insufficient, the temperature drops in autumn, many plants enter the dormant period, the growth rate is slow, some plants stop growing, and leaf drop can reduce the consumption of nutrients, so that plants can retain nutrients, and wait for the temperature to rise to enter the growth period.

The sunshine decreases, and the sunshine time gradually shortens after the autumn equinox, and the plants are transpired by time constant subtraction.

It can produce a large amount of chlorophyll in the same way as in spring and summer.

The leaves turn yellow and then fall off.

Abscisic acid, a plant hormone, is produced in the leaves. When the abscisic acid in the leaf is transported to the base of the petiole, a layer of very small parenchyma cells with a very thin cell wall will be formed at the base of the petiole, which is separated from the layer, and the formation of the separation layer makes it impossible to transport water to the leaf normally.

Under the action of abscisic acid, a natural fracture surface is formed around the separation layer. Due to the lack of sufficient water**, the leaves will gradually dry up, and the natural fracture surface will become more and more obvious. When the autumn wind blows, the leaves will fall, and if there is no wind, they will automatically drift away.

Due to the sensitivity of various trees to the length of sunlight and the need for water, the time of defoliation is also different. Even if the same tree is located in a different environment, the defoliation time will be different.

Extended Materials. 1. Autumn defoliation is to reduce the metabolism of plants, which is equivalent to the hibernation of animals.

2. If the leaves will strengthen transpiration, it is not conducive to water retention, and it will also accelerate the consumption of organic substances. At this time, the leaves are a kind of burden, and the leaves can be dropped.

The autumn wind is up, the weather is getting cooler, the flowers are gone, the grass is withering, and the leaves are falling from the trees one after another, why do trees lose their leaves in autumn?

It turns out that autumn has arrived, the temperature has dropped significantly, the rain has rarely returned, the ability of the roots of trees to absorb water has also decreased, and the efficiency of photosynthesis has been greatly reduced. In order to retain water and nutrients and maintain the life of the trees, the tree reeds have to lose many leaves.

Another reason why trees lose their leaves in autumn is that some of the cells in the leaves are rounded and separated from each other, so that the force of the leaves and branches is slowly weakened, and finally, as soon as the autumn wind blows, the leaves fall.

In autumn, the chlorophyll is destroyed by low temperatures and strong light, and the leaves gradually turn yellow and fade. At the same time, the ability of tree roots to absorb nutrients from groundwater is weakened. In order to have enough nutrients to resist the cold winter, the trunk and branches form a "separation layer" between the leaves and branches, cutting off the water source, so that the leaves fall down.

The shortening of daylight in autumn is a sign that a harsh winter is coming, and when mature leaves sense the signal as receptors, growth hormone decreases, and substances such as abscisic acid and ethyl gradually increase, and finally defoliation occurs. Defoliated trees reduce water and nutrient depletion and transport nutrients to roots, stems and shoots for storage, which can then go into dormancy to survive the cold winters.

Do all trees lose their leaves in the fall?

Whether the leaves fall or not is determined by the conditions and the environment. Broad-leaved trees that live in temperate and cold temperate zones have leaves that fall off in order to adapt to the dry and cold climate of winter because of their wide leaves, evaporating water and consuming more nutrients. Conifers such as pine and cedar live in temperate and cold zones, and their needle-shaped leaves evaporate little water and consume less nutrients, so they can survive the winter without losing leaves.

Larch, which is also in the Pinaceae family, lives in extremely cold areas, and in autumn, it also loses its leaves. However, broad-leaved trees that live in the tropics do not lose their leaves because they have summer and no autumn all year round.

Why do leaves turn yellow or red before they fall?

The chlorophyll in the leaves usually breaks down in autumn, and the nutrients in the leaves are redistributed to the trunk and roots to help the trees survive the sun-scarcity winters. When leaves lose chlorophyll, the yellow carotenoids or anthocyanins that are already present are revealed, which is why the leaves of some trees turn yellow or red in the fall.

Why do trees fall late next to street lamps?

Plants or some branches next to street lamps continue to be irradiated by street lamp lights after sunset, which interferes with the influence of short day conditions, so the leaves fall late or even do not fall at all. This phenomenon is harmful to the plants themselves. Because if you don't lose your leaves, you can't go into hibernation, and the leaves continue to lose water due to transpiration, and at the same time, the roots of the tree have difficulty absorbing water in winter, which will cause branches to wither and even die.

Autumn is coming, and with the autumn wind, the yellow leaves are quietly falling, and you may feel sorry for the falling leaves, but have you ever thought that the fallen leaves are precisely the self-protection of the trees?

Because autumn means the advent of winter, trees need to be dormant in order to protect themselves, and overwintering dormant trees themselves also need nutrients, in order to regulate their own homeostasis, many trees need to fall leaves, reduce the loss of water's nutrients, and save energy until the conditions are suitable before germinating;Some trees such as pines and cypresses can remain evergreen because their leaves are like needle tips and have very little water loss.

People often use the phrase "autumn wind sweeping away the leaves" to describe the autumn scenery in temperate regions. When autumn arrives, the leaves of broad-leaved trees such as poplars and locust trees gradually age, and with the autumn wind, the yellow leaves quietly fall. You may feel sorry for the falling leaves, but have you ever thought that falling leaves are precisely the self-protection of trees?

When it was cold, people lit stoves and put on cotton clothes. But what about the trees? They can only survive the winter safely by stripping their leaves to minimize water transpiration.

Otherwise, it is already difficult for the roots to absorb water, but the transpiration of the leaves continues as usual. Think about it, what awaits the trees but death?

The petioles originally grew stiffly on the branches. In autumn, as the temperature drops, several layers of fragile parenchyma cells form at the base of the petioles. Because these cells are easily separated from each other, they are called delamination.

When the separation layer is formed, it breaks if it is blown by a slight breeze, and the leaves fall down.

Leaves are broad-leaved trees in temperate regions, reducing transpiration and preparing for a safe winter.