Photo: Photo by Alissa Kennedy

PARK CITY, Utah — The Wasatch is starting to shimmer as quaking aspens shift from green to gold, marking the arrival of fall in Utah’s high country.

According to the U.S. Forest Service, the transformation begins when shorter days signal trees to stop producing chlorophyll, the pigment responsible for green leaves. As chlorophyll breaks down, the yellow pigments known as carotenoids become visible, giving aspens their golden glow.

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The Forest Service notes that weather influences the intensity of color. Warm, sunny days followed by cool, frost-free nights create the most vibrant displays, while drought stress and early freezes can dull or shorten the season.

Aspens themselves are remarkable beyond their color. The Forest Service explains that the quaking aspen (Populus tremuloides) often grows in large colonies connected by a single root system. Aspens reproduce both by seed and by root sprouting, but sprouting is by far the more common and successful method. New shoots, or “suckers,” rise from the tree’s lateral roots, forming clusters of genetically identical trees known as clones.

The Forest Service also notes that these clones share a root system and can span from less than an acre to more than 100 acres in size. One of the most remarkable examples is the “Pando” clone in Fishlake National Forest, Utah, which stretches over 100 acres and is considered one of the oldest living organisms on Earth, with estimates as high as 80,000 years.

In the Wasatch, higher elevations typically turn first, with lower stands following later in the season. For now, the first hints of yellow are a reminder that the mountain landscape is on the cusp of autumn’s full show.