The many colors you see in fall are actually already present in the leaves. They are in the form of carotenoids and anthocyanins. They are just masked by the chlorophyll in the leaf. Carotenoids, anthocyanins, and chlorophyll, oh my! Don’t worry, I’ll explain.
Chlorophyll is found in the cellular structure of leaves and are responsible for making “food” during the growing season. Chlorophyll is an amazing thing. They take the energy of the sun and use carbon dioxide from the air and the water from the ground to create energy for the tree to grow in the form of sugar and starch. Chlorophyll is very abundant in the leaves and their vibrant green color masks the true color of the leaf that is already there.
Carotenoids are responsible for the orange, yellow, and brown colors that you see in plants, vegetables, and fruits. Think carrots. This makes it easy to remember. The carotenoids are always present during the growing season. You just can’t see them due to the massive amount of chlorophyll being produced by the tree.
Now anthocyanins are produced towards the end of summer. They are responsible for the red and purple colors you see. Not all trees produce anthocyanins, and the production of this chemical is based upon the weather and changes in climate.
As the weather changes towards the fall season, trees change as well. The cooler nights and decreasing amount of sunlight triggers a response from the tree. The trees in your yard and neighborhood start to get ready for the winter ahead. They slowly stop producing chlorophyll until they cease it all together. With that being said, the green color fades from the leaf and reveals the carotenoids and recent production of anthocyanins, based on species.
The vibrancy of the fall colors differ from year to year. The amount of rainfall throughout the year and weather trends towards the end of the season dictate timing and fall color. If a number of warm days followed by cool, but not freezing nights is a trend then you can expect vibrant fall color. This is due to the production of anthocyanin in the leaves. Anthocyanins are produced in greater numbers when more sugars are produced in the leaves (warm sunny days) and slower flow of those sugars happens (cooler nights). Anthocyanins help the tree to recover this energy from the leaves to store for next year. They act as a protection device for the leaves.
So what you are looking for is a warm and moist spring, a summer that is not too hot or dry, and a fall with warm days and cool nights for a great fall color. Seems familiar to the past season, doesn’t it? So grab your favorite beverage and a bowl of popcorn, sit back and enjoy the show! It should be a good one! -By: Jeff Fabian