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Fall foliage – The science behind the colors

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PEORIA, Ill. (WEEK) - Fall foliage is one of the most anticipated parts of the Autumn season for some in Central Illinois. This year, the colors are lagging a little behind the norm and the forecast expectations. Warm temperatures along with the recent rains may result in some muted colors.

The main driver of the fall colors falls in the hands of the day-night cycle. Trees pick up on the lengthening nights and begin the process of going dormant for the winter. The process of changing leaves begins here.

The leaves change color as we head deeper into the Autumn season, however, that is a misconception. The leaves don't "change" color as the colors that begin to pop out are already present in the leaves. What is happening is the lack of chlorophyll production in the leaves, allowing other pigments to shine through.

"Plants start developing an abscission layer at the base of the leaf where it joins the stem, and so now chlorophyll is not being produced and that then reveals the pigments that have been there all along with the carotenoids. So these are the yellows and oranges that we get." Said Dr. Vickie Borowicz, Associate Professor of Plant Ecology at Illinois State University. The yellow and orange colors often come from trees like hickory or beach.

She also discussed the color red, however, it is a little different. The red color present in some trees as Autumn moves in is used by trees to protect from some of the harsher sun rays that may arrive during the season.

Eventually, the leaves fall off the trees and they are dormant until the Spring season.

Austin Evans

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