秋に葉が落ちる理由は？木は春から切り離す準備をしています

Why Do Leaves Fall in Autumn?

In autumn, many trees drop their leaves.

Did you know that the leaves do not just fall off by accident?

The tree itself gets ready to let them go.

Trees that lose all their leaves for part of the year are called deciduous trees.

Losing their leaves helps these trees save water and live through the winter.

Bare branches also break much less often in ice storms.

But a tree does not throw its leaves away right away.

First, it takes back useful things from the leaves, such as nitrogen.

It keeps them in its roots and under its bark.

Then the tree cuts each leaf off in a clever way.

At the bottom of each leaf stem, there is a special layer of cells.

This layer is made in spring, while the leaf is young.

In autumn, some cells in this layer grow longer.

This breaks the connection between the cells, and the leaf comes off.

The layer also closes the cut, so the tree does not lose its sap.

Some trees, such as oaks and beeches, sometimes keep their dead leaves on the branches all winter.

This happens when the special layer does not form completely.

Evergreen trees drop leaves too, but not all at once in autumn.

They lose their old leaves little by little all through the year.

Next time you see fallen leaves, remember that the tree started getting ready back in spring.