Every autumn the leaves change their color, they turn yellow, turn red or purple and gradually fall off, they become dry and brittle. Rustling arises precisely because of these properties. Why do the leaves turn yellow in the fall? Some believe that this is due to frost. It's as if the cold killed the summer beauty, and now the leaves fall to the ground, gradually covering it with a bright rustling carpet. However, this is not at all the case. If you are careful, you will immediately notice that the leaves begin to turn yellow and fall off much earlier than the first frost. Leaf fall is just a seasonal phenomenon, and its causes are hidden in the trees themselves, in their biological mechanism of struggle for survival in severe seasonal conditions.
A small child asks his parents why the leaves turn yellow in the fall? It is very important to correctly answer this question. After all, proceeding from the fact that children are told in their small years, their further worldview develops. If the leaves do not fall off in time, then the plants can suffer or die not from freezing, but from lack of moisture. Cold air can dry no less than hot. The liquid in the soil freezes, and the suction capacity of the roots is suspended, and soon completely freezes. When the inflow of moisture to the leaves stops, the evaporation of water continues through their surface. That is why the leaves turn yellow in autumn. They protect their tree from destruction. If they stayed on the tree, then all the moisture would immediately evaporate from the branches through their surface. Thanks to this protective mechanism, plants are released from a large excess area. And in order for the tree to discard them, you first need to turn the leaves into necrotic ones, which then fall off.
When the leaves turn yellow in autumn, all the processes in the plant stop, life itself freezes. This is one of the irreversible phenomena of nature. When you change the lighting in the street, the leaves of the alarm clock alarm clock, and they begin to change color. This process can be divided into three stages:
- Yellowing of some leaves;
- Coloring of the illuminated sides of the crowns,
- Completion of the process and the first fall.
It is impossible not to notice that all trees do this at different times, and the forest becomes bright unevenly. When do the leaves start to turn yellow? In the autumn. On the illuminated side of the tree, the process is faster, and the shaded leaves are still green for a long time.
From the point of view of the biochemical process, this is due to the fact that they stop producing chlorophyll. In summer, the yellow pigment is also present in leaves, but compared to green, its amount is insignificant. Now it becomes more and more noticeable. And one more interesting feature: the red foliage falls only in a perfectly illuminated and quite cool place. For saturated color anthocyanins together with carotenoids answer.
All this explains why the leaves turn yellow in autumn. However, this does not happen with all trees. Leaves of Ledum, cranberry, juniper, heather and cranberries do not turn yellow, they remain green under snow, because they evaporate very little moisture.