Colors are really starting to pop across the mountain ranges of Southern Tennessee and Northern Alabama. This weekend is when fall foliage typically peaks and the colors this year are particularly vibrant!
For the brightest and most intense colors we need a few good soaking rains early in the season and a few ‘cold’ nights. We’ve had both this year, so plan a hike or a picnic this weekend to enjoy the colors!
Why do leaves change colors?
During the spring and summer, trees and plants produce new leaves and experience significant growth in size as well as foliage.
From spring into summertime, a compound located within the leaves allows trees and other plants to produce food.
This compound, known as chlorophyll, reacts with sunshine as well as carbon dioxide to create glucose, a type of sugar that serves as the plants’ energy source.
Chlorophyll is the color green, and so much of it is produced in the spring and summer that the overwhelming color from trees and plants is the ubiquitous shade of green. With that said, other compounds are still present in the leaves, it’s just that the amount of chlorophyll present overwhelms the other compounds, which produces the predominantly green hue.
In the fall, the decreasing amount of daylight as well as changing solar angle signal to the trees and plants that winter is coming. Leaves contain a great amount of water content, and if these were to freeze during the winter, it would cause a large amount of stress to the plant. As a result, the trees and plants gradually halt production of chlorophyll as well as divert water resources from the leaves to the trunk or branches. As the chlorophyll fades away, other compounds present in the leaves produce the vibrant colors that we see every autumn.
As the leaves become sufficiently dry, they are no longer able to remain attached to the tree or plant, and they fall to the ground during the season.
Different compounds within leaves produce different fall colors
Depending on the tree or plant, various compounds will produce the varying fall hues that we enjoy every autumn. These compounds include carotenoids, flavonoids, and anthocyanins. An in depth analysis of these compounds are available on the chemistry infographic site Compound Interest.
- Carotenoids and flavonoids produce yellows and oranges, and they break down at a slower rate than chlorophyll. According to Compound Interest, notable carotenoids seen within the leaves include beta-carotene (the same compound that makes carrots orange); lutein (the same yellow compound found in egg yolks); and lycopene (the same compound that makes tomatoes red). Carotenoids
- Anthocyanins are a type of flavonoids that aren’t usually present in the leaf in the spring/summer. Instead, they are generated in the fall as the sugars in the leaves concentrate (due to the decreasing amount of moisture as fall creeps into winter). Anthocyanins produce the vivid red, purple and magenta shades.