While the air has warmed up again as October begins, the annual fall color change is still starting to intensify locally. According to the Iowa DNR, peak viewing is still a few weeks away, although many typical early showing varieties are starting to turn.
Central College Professor of Biology Paul Weihe says there are two primary drivers in the annual changing of the leaves.
“One of those would be sort of the yellows, oranges, and golds, and those really are pigments that were present in the plant all along, but those were masked by the green, and that’s what most of us were taught about how color change works,” he says. “But there’s the whole category of colors which are the reds, purples, and some of those really vibrant ones–those are actually produced in response to the changing conditions as we enter the autumn, so those are really acting as a sunscreen to protect the tissues within the leaf, while the tree is recovering some of those materials that the leaf is made out of for recycling and use the following year.”