Why Trees Lose Their Leaves

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  • Post published:November 30, 2020
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Some trees lose their leaves in the winter. These trees are called deciduous trees. It is common in many areas to see these leaves change colors before they fall off. We are going to go over why the trees lose their leaves, and why we love it. 

The deciduous trees have a lot of green foliage in the summertime. If you ever look through a thick deciduous forest in the summer it is much different than looking through it in the winter. In the summer you will notice that you can not see very far because of all of the green leaves. In the winter these leaves are gone and here is why. 

The reason that the leaves are green is due to a substance you probably learned about in 7th grade science class. That is chlorophyll. Here is a little refresher on Chlorophyll. It takes in sunlight and turns it into energy through a process known as photosynthesis. So when the sun is at its strongest season, the summer, it takes all that sunlight and turns it into energy to keep growing. All through the summer the tree continues to produce enough chlorophyll for the leaves to keep the green color, however once the sunlight gets weaker and the days get shorter changes start to take place. 

In the fall as the days get shorter, and the sunlight isn’t as strong the tree starts to go into a hibernation phase. It makes less chlorophyll and doesn’t grow near as much. The color of the leaves actually do not change. The leaves simply show their true colors due to the chlorophyll not being present in large amounts. All this time you thought leaves were green didn’t you? They are but only because of the chlorophyll, and when it leaves (no pun intended) the leaves change colors. The tree doesn’t grow nearly as much without the chlorophyll present. 

Once enough chlorophyll is gone from the leaf the energy for the leaf stops growing. The leaves become more and more lifeless. Without chlorophyll the leaves can not live. Therefore, they die. As they die the connection they have to the tree becomes more and more dried out. To the point where they break at the bottom of the stem and fall to the ground. Don’t worry it doesn’t hurt the tree. It is simply part of the natural process that each tree goes through in it’s own season. 

Once the days start getting longer the tree comes out of the hibernation period. It starts to produce more chlorophyll and the tree buds. The buds eventually open up into pretty green leaves and the cycle goes on and on. To sum it up it goes spring new buds turn to leaves, summertime they stay green due to chlorophyll, fall the chlorophyll leaves allowing leaves to change colors until the leaves fall off because they become lifeless and brittle.


Now you know why trees lose their leaves in the winter. It has everything to do with the sun and the chlorophyll it produces. 

Thank you for reading another article from Tree Trimming Albany.

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