It’s hard to imagine a fall without colorful trees and crunchy piles of leaves. But why do leaves change color and fall to the ground?
To answer that question, let’s start by taking a look at why spring leaves are green. The substance that makes leaves green is chlorophyll, a pigment that helps trees absorb sunlight and convert it into energy. This process is known as photosynthesis!
At the beginning of fall, the temperature drops and the nights get longer. This signals to trees that it’s almost winter and resources are becoming scarce. To conserve energy, trees stop producing chlorophyll, and the chlorophyll in their leaves begins to break down.
When the chlorophyll is depleted, other pigments in the leaves (such as yellow or orange carotenoid pigments and red or purple anthocyanin pigments) take center stage. These new pigments make our eyes perceive the leaves as yellow, orange, or red!
Since chlorophyll produces the energy leaves need to stay alive, leaves slowly weaken without it. Throughout the fall season, they gradually separate from the tree until they fall to the ground.
While this process might seem sad, it’s a completely natural part of a leaf’s life. It’s actually a positive thing for nature as a whole! Rather than using up much-needed energy from trees, fallen leaves are able to serve as food for animals or fertilizer for the soil. And loosing leaves helps the tree survive through the chilly winter and so it can sprout new leaves the next year!
Learning about why tree leaves change colors is awesome, but going outside to see this beautiful process in action is even better! Which leaf color are you most excited to spot this fall? Click the blue button below to vote! 👓