One of the most reliable signs of autumn is the leaves turning from green to orange, red, and brown and falling to the ground. Autumn is one of the four temperate seasons and is the transition from the hot, sunny days of summer to the cold, windy days of winter.
The reason why leaves fall in autumn is this; as the weather gets colder, plant resources such as water and mineral salts become sparse. This means that trees find it harder to support every part and shed their leaves to reduce the burden on their resources.
The falling of leaves in autumn ensures that the plant can survive the winter with the least amount of water and food. When spring arrives, and plant resources are replenished, the leaves grow back greener and healthier.
In autumn, it is not uncommon to see piles of leaves that have fallen from trees. These leaves fall in autumn for various reasons:
1. For survival
The main aim of living things is to survive, and plants are no exception. With a scarcity of plant resources, the leaves are cut off to preserve the root and stems. When these resources are replenished, the leaves grow back.
2. For health
Leaves fall in autumn because of health issues. After four seasons, many of the leaves are damaged and no longer function as usual. When the leaves fall, they create space for newer and healthier leaves to grow.
3. Breakdown of chlorophyll
In autumn, a chemical change occurs and leaves no longer produce enough chlorophyll, which is necessary to produce food for the plants. This is why the leaves turn orange, yellow, and any variation in between.
When do the leaves stop falling?
4. Temperature
The leaves falling in autumn is an inevitable act that occurs every year. However, the exact time the leaves begin falling and finally stop can differ based on the temperature of your location and the amount of moisture in the atmosphere. Trees need a temperature of 32 to 45 degrees Fahrenheit for the necessary pigments and the ascorbic acid to develop.
What is it called when leaves fall off trees?
Leaves fall from trees in the autumn season in preparation for winter. This phenomenon of leaves falling from their trees is known as abscission. The trees that undergo abscission, that is, trees where leaves fall in autumn, are known as deciduous trees.
Leaf abscission includes not only the process of leaves falling from trees due to the high amount of ascorbic acid at the petiole but the color change the leaves undergo before they fall, which is due to plant pigments like carotenoids etc.
When do leaves begin and stop falling in autumn?
Generally, leaves will begin falling by September. In some areas, the leaves will start changing colors as early as the first week of September and begin to fall by mid-September. It can take a duration of four to six weeks before the leaves of a mature tree are done falling. By the end of October and the beginning of mid-November, the leaves of trees are done falling, and the tree is bare and ready for winter.
Why do leaves change color in autumn?
The leaves of plants are usually green, and this green color is caused by the pigment chlorophyll, which is very important in the synthesis of sunlight and carbon dioxide to produce food for the plant. The plant contains other minor pigments, but chlorophyll dominates the leaves.
However, in autumn, the leaves turn different colors, particularly orange, yellow, red, and brown, with some having mixed patches with different colors. The change of color that leaves undergo in autumn is due to the drastic reduction of the chlorophyll pigments and an increase in pigments like flavonols, carotenoids, and anthocyanins.
These pigments give rise to different coloring depending on the amount present in the leaves and in which area a certain pigment is more concentrated. Flavanols produce leaves with yellow coloring, carotenoids produce leaves with orange-to-red coloring, and anthocyanins produce leaves with red-to-purple coloring.
Why do the leaves of some trees not fall in autumn?
In some cases, the leaves of certain trees do not fall in the winter. This can be caused by various reasons, including:
1. Evergreen trees
Evergreen trees are trees whose leaves remain green throughout their lifetime. These trees do not lose their leaves during winter and the leaves remain green throughout. If you have an evergreen tree then you don’t have to worry about its leaves falling off unless it is diseased.
2. Drastic temperature change during autumn
The right temperature is extremely necessary for the production of the necessary pigments and the ascorbic acid that cause leaves to fall in autumn. A drastic change in temperature during the autumn can cause the weather to drop significantly which can kill the leaves immediately.
Since the necessary pigments and elements are not present, the leaves hang on to the tree until a new leaf comes in spring to push them off.
3. Unusually warm winters
With the increasing climate change happening worldwide, more and more areas are experiencing warmer winters. Since the trees need a cooler temperature of 32 to 45 degrees Fahrenheit for the leaves to begin falling, warmer winters can interrupt the process, and the leaves just hang on.
What happens to leaves after they fall?
After the leaves of the deciduous tree fall, they drop to the ground and die. After a few days, the leaves will begin to break down and decompose. They serve as an organic manure for the trees and return any minerals to the trees. These decomposed leaves serve as a layer of protection against frost in the winter. When the leaves have decayed completely, they provide water and carbon dioxide to the trees.
For homeowners, to prevent the leaves from flying all over the lawn, you can pack them in a garden container and let them decompose before spreading them at the tree’s root to serve as organic fertilizer.
