Fall is all about leaves: the sound of crunching, colorful foliage, and jumping into leaf piles. But did you know that there’s a whole lot of science behind these fall pleasures?
In the summer, leaves get their green color from a chemical called chlorophyll. Chlorophyll helps plants absorb sunlight to make energy. But as summer comes to an end, shorter days and colder weather mean there’s less sunlight. Leaves produce less chlorophyll because they don’t need it. “It’s a sign that trees are getting ready for winter,” says Steve Roberge, a forestry specialist at the University of New Hampshire.
When chlorophyll goes away, new colors come out to play! In the fall, leaves make different chemicals that change their colors. Carotenoids turn leaves yellow, orange, and brown. Anthocyanin turns leaves red. When these chemicals take center stage, trees put on their splendid color display.
Eventually, the show must come to an end as the trees lose their leaves. But that’s not the end for the leaves! Fallen leaves become leaf litter: a layer of leaves, twigs, and other debris on the forest floor. Fungi and bugs feed on the leaf litter. These decomposers break it down into its smallest parts, putting nutrients back into the soil “It’s a pretty amazing thing that happens every year,” says Roberge.