What is the name of the phenomenon when the leaves change their color?

In preparation for winter, perennial plants store nutrients. When this process is completed, the process of photosynthesis in the leaves of the plant slows down and then stops altogether. As a result, the color of the leaves changes from green to yellow and red. After that, the leaves die off and fall off. This process is called leaf fall, since the tree no longer needs to produce organic matter, and low temperatures in winter will not allow this, so the tree is forced to shed excess organs, that is, leaves.