Aspen and the greater Roaring Fork Valley is listed as one of the places in the U.S. to view fall colors. It’s easy to see why, with the backdrop of golden aspens against the Maroon Bells or along the Fryingpan River in the sunlight. Some may have noticed the leaves are late to change this year, and there’s a reason for it.
During the spring and summer, the leaves of trees are responsible for making food, which contain chlorophyll. This is what makes leaves green as well. Carotenes and xanthophyll are other pigments which exist in leaves and that are responsible for more orange and yellow hues – like the color of a carrot. For most of the year, these colors are masked by the chlorophyll. In the fall, though, when there is a change in temperature and the amount of daylight, the food process stops and the chlorophyll breaks down, allowing those other pigments to break through.
Temperature, light and water influence the duration of fall and the trees’ colors. Low temperatures above freezing will favor anthocyanin, producing bright reds, but early frost will weaken the brilliant red color. This year, with the wet, late spring and higher temperatures for September, it hasn’t quite been cool enough for the leaves to begin changing. They’re coming soon, though!