Why do leaves fall in the fall? How do trees drop them?

Leaves fall in the fall because it is a time of year when deciduous trees naturally go through a process of dormancy in order to survive the winter months. As days become shorter and temperatures drop, trees begin to shut down their photosynthesis process and reduce the amount of nutrients and water going to their leaves. This causes the leaves to turn color and eventually drop off the tree.

The process of dropping the leaves is known as abscission. During abscission, cells at the base of the petiole (the stem connecting the leaf to the branch) begin to produce a layer of cork cells, which block the flow of nutrients and water to the leaf. As a result, the leaf begins to die and eventually falls off the tree. This process is beneficial to the tree as it helps to conserve energy and resources during the winter months when photosynthesis is not possible.