The science within the vibrant colors of autumn leaves

SALT LAKE CITY — As autumn temperatures set in, leaves will begin to change into vibrant shades of orange, red, and yellow. Then, they will fall off the trees.  

Why do leaves change color?

According to the United States Forest Service, the color changes are dictated by the onset of longer nights. Coupled with drops in temperature, the longer nights trigger a chemical change in the leaves. The timing of color changes can vary by species. 

Additionally, the University of Utah said that plant genetics determine what color leaves will turn. As leaves slow down on chlorophyll production, they begin to change hues. 

While colors change on the surface, there are also things going on within the leaves. Veins that carry fluids in and out of them begin to shrink, trapping sugars. 

According to the United States Forest Service, once a leaf’s connective tissues are sealed, it is ready to fall from the tree. 

BBC reported that trees release their leaves they use less energy to survive the colder months. 

After autumn leaves fall

After they hit the ground, the leaves begin to play a different role. According to the National Environmental Treasure, insects begin to eat them. 

Per the Forest Service, nutrients from the leaves also re-enter the soil. They become part of the humus layer. According to National Geographic, humus contains important minerals for plants and animals.

Additionally, the United States Department of Agriculture said that the fallen leaves can provide a space for some small animals to live during the winter. 

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