Fish Lake Aspens in Autumn

October 25, 2021

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Photographer: Ray Boren

Summary Author: Ray Boren

When fall sweeps through central Utah’s high aspen forests, Fishlake National Forest pops with bright colors, as shown in the photographs above from October 3, 2021. The forest’s namesake— the beautiful Fish Lake— is seen in the foreground of the first image. As the name implies, the lake is teeming with trout, perch, and other fish species. Surrounding the lake are vibrantly colored quaking aspen trees (Populus tremuloides), which is Utah’s state tree.

As temperatures drop and nights grow longer in late September and early October, the aspen leaves stop photosynthesizing and producing chlorophyll, which makes them green. This process reveals previously hidden carotenoid shades of yellow, gold, orange and red. Interestingly, the aspens’ distinctive white-bark trunks continue the process of photosynthesis throughout winter, producing life-sustaining sugars during a time other deciduous trees have gone dormant. Pando, an aspen forest southwest of Fish Lake, is a 100-acre grove of clones — some 50,000 stems rise from a shared root system — making it one of the largest known organisms on Earth.

The Fish Lake Plateau is a geologic transition zone where the Colorado Plateau, to the east, and the Basin and Range Province, to the west, converge. The Geological Society of America notes that the plateau is characterized by graben of various sizes. Fish Lake sits atop one such graben. The plateau is composed of Tertiary volcanic rocks, including basal andesite, trachyite and Osiris Tuff. In a second photo taken on the same day, a field of such lava-born boulders is fringed by colorful aspen trees on a steep slope above Johnson Valley, north of Fish Lake.

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