Fall Colors in Nebraska

Beautiful Fall ColorsWhy do leaves turn colors?

Autumn leaf colors are the result of a chemical change in the leaves. The trigger is the onset of cooler temperatures and reduction in day length.

During the growing season, green leaves are green because of the large amounts of chlorophyll they contain. Chlorophyll is the key component in photosynthesis, the process by which leaves use sunlight and carbon dioxide to make the sugars and starches the tree uses for food.

As long as they are growing, trees continually replenish their leaves' supply of chlorophyll. As the days get shorter and cooler, however, growth slows and the tree produces less chlorophyll. As chlorophyll in the leaves breaks down, it isn't replaced, and the other pigments that have been there all along, masked by the green, become apparent.

The intensity of color varies from year to year, depending on the weather. The conditions most favorable for brilliant reds are bright, sunny, warm days and cool nights. The leaves produce more sugar on warm days, and night temperatures below 45 degrees keep those sugars in the leaves. Pigments are formed in those sugars, so the more sugars, the more color.

For more information, read Why Do Leaves Turn Colors in the Fall? by Don Janssen, Extension Educator, University of Nebraska-Lincoln Extension in Lancaster County


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