Why are trees losing their leaves now?
Why do trees lose their leaves in autumn?
Trees shed their leaves to protect themselves from drying out.
© Source: Sina Schuldt/dpa
Hanover. Nature has its very own tricks to prepare for winter. Deciduous trees, for example, shed their leaves – taking them off instead of covering them, so to speak. This protects the trees from drying out in winter. A lot of water is lost through the leaves as it evaporates. This is usually not a problem in spring and summer, but in winter the trees cannot absorb water as well. On the one hand, because it is often dry in winter. And on the other hand, because the ground is sometimes frozen. If the tree were still full of leaves in winter, it would slowly dry up. Therefore, he throws them off in time.
Before discarding: replenish and store nutrients
But before that happens, the trees draw all the important nutrients from the leaves. For example sugar and minerals. These are stored in the branches and twigs, in the trunk and in the roots. In this way, the trees collect important reserves for the coming spring.
A substance called chlorophyll is also extracted from the leaves. This is what gives them their green color. When it’s absent, other pigments appear: red, yellow, and orange, for example. Until then, these were covered by chlorophyll. For this reason, the leaves of the maple trees, for example, turn yellow and the leaves of the oak red.
Foliage is like a “warming blanket” for the ground
In order for the leaves to finally fall off, the tree cuts the line to them, so to speak. For this purpose, a separating tissue is formed between the branch and the leaf style. If a strong gust of wind comes, it blows the leaf away. And the nuts of the horse chestnut also fall to the ground in autumn. For many garden owners, a tiresome task is then on the list: collecting leaves. But in some places in the garden you can save yourself the work – because leaves insulate the soil against frost.
The Naturschutzbund Deutschland (Nabu) compares the layer of leaves with a warming blanket. In the cold, sensitive trees and shrubs such as shallow-rooted currants and gooseberries can really use this protection.
Animals also benefit from piles of leaves during the cold winter months. Hedgehogs or mice, but also insects can hide there. In spring, the pile of leaves turns into humus, which is good for the soil. Lawns, however, should not be covered with leaves in winter – because the lawn needs light and must be able to “breathe”.
RND/dpa
