Why leaves change color: Science behind fall foliage

Published: Sep. 26, 2023 at 10:09 AM CDT|Updated: Sep. 26, 2023 at 11:43 AM CDT
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DAVENPORT, Iowa (KWQC) - During the growing season, trees produce chlorophyll which gives the leaves its green pigment.

The pigment absorbs light which is then turned into energy that feeds the trees, a process known as photosynthesis.

During the autumn months when there is less daylight and cooler temperatures, the amount of chlorophyll in the leaves decreases. As the chlorophyll breaks down, the leaves begin to change color. Drought can also lead to the loss of chlorophyll.

Yellow leaves appear due to the presence of the chemical, zanthophyll.

Orange leaves are the result of carotene, the orange or red pigments also found in carrots and other plants.

The reds on leaves are from anthocyanins, which are also responsible for the colors blue and purple in other plants.

The brightness of the colors in autumn depend greatly on the weather.

A warm and wet spring, combined with drier weather in the later parts of summer tend to lead to more vibrant colors during the fall, with sunny autumn days and cool night, but not cold enough for frost, which can lead to less vibrant colors.

The amount of moisture in the soil can affect the colors of fall.

Due to the lack of moisture most of the summer, leaves on some QCA trees have changed colors a little earlier than usual. Because of the drought, the colors will be less vibrant.

After the leaves change the stems develop a layer of cells that breaks down the tissues that supports the leaves, leading to the leaves fall off the tree.

During a typical fall, peak fall foliage arrives around the early to middle parts of October.

Click here to learn more about fall colors from the Iowa Department of Natural Resources.

Click here to learn more about fall colors rom the Illinois Department of Natural Resources.