The changing colors of leaves are beautiful to behold and signal the onset of cooler weather, but have you ever wondered why exactly the leaves change color? Keep reading to learn more about this natural phenomenon.
You may remember learning about chlorophyll and photosynthesis in school, but it never hurts to have a refresher. Leaves feed off sunlight to produce chlorophyll which is then turned into energy for the tree and releases oxygen. What you may not know is that there are other pigments in those same leaves: xanthophylls, carotenoids, and anthocyanins. These play a key role in the changing colors we see throughout the seasons.
Shortening Hours of Sunlight
During the summer, tree leaves to absorb the sunlight enabling them to produce more chlorophyll giving us vibrant, green leaves during the summer. The chlorophyll is so plentiful that the other pigments are not visible to us. However, as the days get shorter and there are fewer hours of sunlight, chlorophyll production eventually stops, allowing the other pigments to take over and do their fair share.
These other pigments can absorb the cooler light that chlorophyll cannot but do a similar job of producing energy for the tree. Xanthophylls produce the yellow color we see in leaves. As the weather gets cooler, it too stops producing and then the carotenoids take over where the xanthophylls left off. Carotenoids have the added benefit of being able to turn excess energy into heat, which protects the leaves and allows them to continue supplying energy to the tree.
When the weather cools down even further, the carotenoids then stop producing and anthocyanins get their five minutes of fame. When the weather cools down even further, that signals the leaves that their work is done, and the anthocyanins will taper off. As the tree absorbs the last of the energy from the leaves, they fall to the ground and the tree stores the energy it received to survive the winter.