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Fall's change of colors an amazing process

By Ed Helmick

Looking up the mountain, we see splashes of red from the canyon maple (Acer grandidentatum) leaves, which are the first fall colors of the season. The aspen trees (Populus tremuloides) with their brilliant yellow leaves will be next. It is commonly understood the fall colors arrive as a result of shorter days and cooler temperatures. However, the changing of the leaves appears to have started earlier this year. Utah State Regional Horticulturist Jay Dee Gunnell believes this may be due to the drought the region has experienced this year. By the time you read this in early October, the fall colors in Utah County may have peaked for this year.

The colors we see in the transition from the warm growing season to the dormant plant life of winter are a wonderful story of the creator’s design when you think about it. Amazing chemistry takes place in the leaves of trees during the warm growth season. The green chlorophyll in the leaves absorbs sunlight energy and transforms carbon dioxide and water into carbohydrates for the tree’s growth. With the reduced daylight and temperatures of the fall season, the leaves stop their food-making process and the chlorophyll breaks down, which results in the green color fading away. This allows the red, yellow and orange colors to become visible and produce the colors of fall season.

Now there is more to this amazing story. As the leaves are changing color, another change is taking place as a layer of cells develops where the stem of the leaf is attached to the tree. This growth of a cork-like material eventually severs the leaf from the tree and seals the wound where the leaf stem had been attached to the tree. This occurs so tree sap does not leak out. The leaf falls off or blows off the tree. This is tree survival; the tree cannot afford to support the leaf system during the winter months. When you think about the rest of the story of the fall colors, it is an incredible adaptation to the coming season.

The photo at the top of this article was taken up Pole Heaven Road, which is a dirt road off the Left Fork of Hobble Creek. This road becomes very rocky after the first mile and is suitable for high-ground-clearance vehicles only. This eventually leads to Camel Pass and a dramatic view looking down Little Rock Canyon toward Mapleton and Springville. Following the road north will eventually connect you with Squaw Peak Road and Provo Canyon Highway, Highway 189. This is a spectacular fall color drive if you have an off-road vehicle.