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Tina Sawyer: Leaf peepers are already making their way to the Upper Peninsula for Autumn's annual tree show. To find out about what makes the trees tick, I recently spoke with Hartwick Pines Park interpreter Craig Kasmer from Grayling. Craig started the conversation by explaining first what a park interpreter does.
Craig Kasmer: My degree is in forestry, so when trees have issues and somebody comes up to me and says, why are my leaves doing this? I can tell you what that tree is saying to me.
TS: How do you tell when they're going to turn color? I mean, do they tell you?
CK: Well, my psychologist tells me that I should stop talking to the tree, but I continue to listen. You know, there are several factors that initiate color change. Number one, of course, is the temperature. But saying that, we can have a cold day in July and the trees are like, nope, they're not ready. It's the amount of daylight sort of triggers them to say, all right, let's stop producing our chlorophyll, which is the green color in the leaves. That chlorophyll absorbs the sunlight, produces sugars, and feeds the tree. Well, our deciduous trees, those broadleaf trees like maples and oaks and aspen and etc. Once they realize that the sunlight is not going to feed those leaves anymore, that chlorophyll starts to go back and recede. And so what we're actually seeing in color change is the true color of the leaf without the green chlorophyll. Kind of interesting.
TS: Wow. I wish it was like that all year round. It'd be beautiful.
CK: I know. Yeah. Well, the issue then would become if those trees had changed color in the summertime, then that leaf will fall off the tree because it's no longer useful.
TS: So I gather the conditions are just right for the western U.P. because they're at peak right now. Now as we start to move farther south in Michigan, is the fall color going to cascade down uniformly across the lower peninsula?
CK: From the coastal areas, whether it's the west side or the east side of the state, the warmer temperatures of the Great Lakes will not facilitate leaf color change as early as we do here in the center of the state because we're not affected by those by the lakes. And so like in Traverse City, Ludington, Petoskey, their color change is going to be different than what you're going to see going down the middle of the state on I-75. And the same thing with Alpena and Harrisville and Rogers City.
TS: Why does it seem that the color changes on the western part of the U.P. first and kind of makes its way downward.
CK: Well, so here in the Gaylord-Grayling area, we are at the 45th parallel. Well, they're farther north, so they have less sunlight earlier than we do, which is why you see so many people in late September heading to the U.P. for the color change. and then early October here in northern Michigan.
TS: Can you give us like a quick estimation where the percentages will be throughout the state as far as color?
CK: I can give you a rough guess because there are several factors, right? So three nights in a row of below freezing temperatures, well, that's going to really accelerate the process. And so if someone wants to travel to the north, look at that weather forecast and go, oh, peak could be on Tuesday. Well, if Saturday, Sunday, Monday of freezing temperatures, peak might be on Sunday then. Wind, of course, is a big factor too. But I would say that because of these warm temperatures, probably next week or the following week would probably be best. We still see a lot of green up here, which is to me is fantastic because now you have the yellows and the browns. and the purples and the reds, but you also have greens, so you almost have a full spectrum.
TS: You work from Hartwick Pines, and so people can probably see that peak, you'd say, within the next couple of weeks.
CK: Yes, in fact, our visitor center is closed for remodeling currently, but the Old Growth Trail is still open. And yes, the Old Growth Trail has the Old Growth forest, but within there is a mixture of beech and maple trees. And most of the park is northern hardwoods. And so the color change at Hartwick Pines is one of the most magnificent that I've seen.
TS: That was Craig Kasmer from Hartwick Pines talking with me about the fall color season in northern Michigan.
