Up and autumn: Fall color here early

Some aspen trees starting their show

Aspens are beginning to show off their autumn color on the top of Grand Mesa.

Autumn is coming.

The calendar says so, but so do the mornings around 6 a.m., when the sun’s not far below the horizon and the temperature’s not far below 60. Still: Brrr… A jacket wouldn’t be a bad idea.

So, the chilly mornings hint at approaching autumn, and so do the leaves. A surprising number of them are yellow already.

Perhaps because of the continuing drought and perhaps a continuation of an unusual year that saw warm temperatures leading to an early spring, “there are some patches of what seems like early color,” said Kelly Rogers, a district forester with the Colorado State Forest Service in Grand Junction. “Particularly in oak brush, we’re seeing fairly early color change on the Uncompahgre Plateau and Grand Mesa. It seems like it’s stepped up a little early this year.”

Though it’s impossible to determine an exact cause for this, fingers could point at the ongoing drought.

“It’s hard to say what the higher temperatures (in summer) and lack of water will do to stress the trees,” said Lee Ann Loupe, public affairs officer for the Grand Mesa, Uncompahgre and Gunnison national forests.

“What I suspect is that trees and shrubs are, because of drought stress, being forced into early dormancy as a kind of survival mechanism,” Rogers said. “I guess we’re two or three weeks early. There are some little patches of pretty bright color on the mesa, but a lot of the color we’re seeing is at lower elevation and in dryer areas.”

According to the U.S. Forest Service, dry weather increases the sugar concentration in sap, which leads to an increase in anthocyanins. Anthocyanins are a class of pigment that absorbs blue, blue-green and green light, so the light reflected by leaves containing them looks red. Add to that the normal cycle of low night temperatures and bright sunlight breaking down chlorophyll—the pigment compound that makes leaves appear green—and fall colors bloom and leaves fall off the trees.

“Even in residential areas and parks and stuff, people are saying the trees are starting to lose their leaves already,” said Ken Hahn, a visitor information specialist for the Aspen-Sopris Ranger District of the White River National Forest.

Early color change isn’t widespread, said Jason Pooler, a visitor information specialist for the Rifle Ranger District of the White River National Forest, making the red and yellow leaves already visible among the green even more noticeable—“normally, they’re not turning until mid-September,” he said.

It seems to be another happening in a year that saw early snowmelt, early leaf-out and early high temperatures, Rogers said. Area farmers have reported crops ripening as much as two weeks ahead of normal years.

However, just because the colors are starting early doesn’t mean there won’t be any left by Color Sunday, scheduled for Sept. 30.

“One of the things we have noticed is there’s not a lot of leaf blight in the aspen this year,” Rogers said. “In fairly wet years, like last year and the year before, aspen can be affected by the marssonina fungus, which causes not only early color change but early leaf drop. We’re not seeing that this year, so we may be having an early color change but it may last longer.”


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