Wild Colorado: The science of changing leaves | SummitDaily.com

Wild Colorado: The science of changing leaves

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Summit Daily/Mark Fox

“Welcome to colorful Colorado,” the sign read.

“Where’s the color?” I thought to myself several years ago as I crossed from the green cornfields of Kansas into the vast, sun-burned prairie of eastern Colorado in late summer.

I thought it so ironic that I pulled over, yanked out my black-and-white film camera and carefully framed the sign against the brown, grassy backdrop.

Now, don’t get me wrong. I was headed to Colorado for a reason: All you natives and eager transplants know exactly why you are either still here or why you came in the first place. There’s a wildness and beauty that draws us here. One that has defined the careers of many artists and writers, and one that inspires us to continue our innate tendency to explore and experience.

However, being an East Coast girl, born and raised, the contrast was alarming. Picture clusters of towering green, deciduous trees alongside vibrant garden flowers in the East compared to the High Country in late summer. Nonetheless, I knew Colorado has a beauty all its own – a beauty characteristic of only the West. One that shows its true colors in late spring and early fall.

This is the first High Country fall I’ve experienced in Colorado. I’ve spent recent years in Wyoming, where the colors hang on for mere days before disappearing in the whipping winds. And this year, I came close to missing “colorful Colorado.” I’d gone back East with the hopes of catching the fiery reds, oranges and yellows of the Appalachia.

But Colorado called my name, as places that find a special spot in one’s heart do. My welcome home was dramatic. Even in Denver, where skyscrapers and blocked streets seem to tame the wild western landscape, the sky demanded attention. It emitted flashes of lightning from a cloud that covered all but a sliver of sky. That sliver, way over there in the west, was a gradient of blues and greens silhouetting those jagged peaks.

The next morning, I climbed my way along Interstate 70 back into the mountains. Now, I find myself here in time to enjoy the cool mornings, the sun moving into the southern sky and, of course, the changing aspens.

It’s not hard to see aspens are going into dormancy. According to a US Forest Service Website, as autumn approaches winter, days shorten, triggering the trees to decrease chlorophyll production and essentially hibernate. Chlorophyll is a naturally occurring, green chemical that helps plants produce food.

As chlorophyll disappears from leaves, carotenoids are left. These are what produce pigmentation in plants, such as a cranberry’s red and a carrot’s orange. In aspens, carotenoids are yellow or orange, which seem to paint hillsides and forest drives in shimmering gold. Carotenoids dominate the leaf color until the leaves eventually fall off to frost or wind.

It’s not a process unique to fall, either. Consider bananas from our local Safeway. A picked banana often still contains chlorophyll, leaving a slight green tinge. After it’s picked, though, it stops producing chlorophyll and the remaining chemical begins to break down. As it does, the yellow carotenoids – which have been there all along – show their true colors.

According to the Forest Service information, if we start to see red highlights in the aspens, we’re experiencing a different process: chlorophyll sugar changing form. As a tree ceases producing chlorophyll, chlorophyll sugar is trapped in the leaf. The right combination of bright sunlight during the days and cool, but not freezing, nights turns the glucose into anthocyanin – producing those fiery hues.

Now, as we take to our bikes or the hiking trails before the snow begins to fall, we can know the science behind part of what makes Colorado colorful.

SDN reporter Janice Kurbjun can be contacted at jkurbjun@summitdaily.com or (970) 668-4630.

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