Why do tree leaves turn red in fall?Posted: September 29, 2011
Here in North Texas, we don’t start to see the leaves change (usually) until well into late October and November. But changing leaves are a key indicator to students of the changing seasons. The folks at Earth & Sky address the science behind the color change:
Bill Hoch is a plant physiologist at the University of Wisconsin. He’s especially interested in red leaves. He said:
Nature is very efficient, and doesn’t just do something for no reason. So we figured there had to be some purpose for the production of these pigments in autumn.
For much of the year, green leaves help convert sunlight into food. In the fall, trees break down the green pigments and nutrients stored in the leaves. As the leaves of the tree begin to change, nutrients are shuttled into the roots for reuse in the spring. Hoch suspected that some trees produce red pigments as a kind of sunscreen, protecting leaves from sunlight while the tree stores nutrients.