Today is a very rainy Wednesday. I am sitting here in my bay window thinking and realizing that I do some of my best thinking in my bay window. Today is the first time I am really noticing the fall color. This year the fall color won’t be as good as say last year’s fall color because we had a longer drought. I remember that much from college. So what determines fall color, how ‘good’ it will be and how long it might last.
The US Forest Service has an excellent blog about this and I will link to it below. Here are the answers to the questions I asked.
Fall color is determined by these pigments, carotenoids (yellow, orange) and anthocyanin (red). Carotenoids are in the leaf throughout the growing season while anthocyanin is produced when there is an excess of sugar in the leaf. Chlorophyll masks these until it begins to break down, this happens when the nights get longer and the night temperatures get colder. Some trees produce a lot of anthocyanin, like the Red Maple, Black Gum and Sassafras. While others do not produce much if any at all, like Black Walnut, Sycamore and PawPaw. These trees produce more carotenoids and a more yellow color.
There will always be fall color because it is a natural process within the tree to shed leaves and prepare for dormancy in the winter. Some years it is better than others, especially in the Anthocyanin or strong red fall color trees. This compound is produced when there is an excess of sugars in the leaf, therefore if we have had a long drought, color may not be as prominent. As droughts get worse with climate change, fall color may change or lessen. That is something to think about.
How long does the color last? Well the process starts when then nights start getting longer and days shorter. The process comes to an abrupt stop at a hard freeze. Each frost that we get damages leaf tissue and starts breaking down all the compounds in the leaves, including the color compounds. That means it is all up to Mother Nature.
Here is the Forest Service blog: https://www.fs.fed.us/visit/fall-colors/science-of-fall-colors
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