It’s very likely that when you ask a Wisconsinite what their favorite season is… it’s autumn. And one of the top reasons for that… fall colors! And it is that time of year. The leaves they are a-changin’.
But what role does the weather play in the length of fall colors or the vibrancy of the leaves? Brad Hutnik has the answer for us. He’s a forest ecologist with the Wisconsin DNR. He gives us the ins and outs of why and how leaves change colors in the fall. He says this year, we can expect a good viewing window in most areas.
“I think this year what we can expect is that it’s going to be a little more variable when things start for fall colors,” he says. “It’s been very dry… where it’s been very dry, it’s going to speed up fall colors, and where it’s been a little more moist, it’ll be normal. So, I think in some ways, the colors may be different, but we may have a longer season because of that.”
Hutnik explains that deciduous trees know when to change colors by the length of the days. Shorter periods of light and cool nights tells them to begin shedding their leaves.
As the tree cuts off the leave by forming an incision layer, it signals to the leaf that it no longer needs chlorophyll — the green pigment used for photosynthesis. When the chlorophyll goes away, other pigments in the leaf are revealed: carotenoids show yellow, and the anthocyanins show red.
The Wisconsin Fall Color Map tracks where and when colors are peaking across the state: https://www.travelwisconsin.com/fall-color-report
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