EDEN — The cooler air and shorter days that come as summer fades into fall serve as the catalyst for a display that draws people from all over to Utah’s mountains and valleys to witness nature’s paintbrush in full effect.
While it may not have the cachet or notoriety of New England or the Great Smoky Mountains when it comes to fall foliage, Utah’s rugged terrain provides a dramatic backdrop for a variety of reds, yellows, oranges and golds as the state’s deciduous trees prepare to shed their leaves and hole up for the winter.
The process starts at higher elevations and moves down into the valleys as temperatures grow colder.
As early as August, aspens in the high country can be found tinged with yellow and gold. By early September, maples and oaks at lower elevations begin turning a stunning array of colors from creamsicle orange to deep crimson.
The display generally peaks in late September or early October. By then, trees in the lower valleys of the Wasatch Front have begun to mimick their mountain-dwelling counterparts, and before we know it, it’s time to start raking leaves.
The two major branches of science that explain the phenomenon of fall foliage are weather and biology.
Ideally, the best foliage occurs when autumn days are mild and the evenings are cool and crisp, but not below freezing. However, if daytime temperatures are too warm for a relatively long period of time in the fall, the colors may be less intense. The foliage season may also last one to two weeks longer. Frost tends to inhibit the production of a pigment that produces shades of red. This is why having temperatures above freezing is advantageous.
The temperature during the spring can also have an impact on the fall foliage. A late spring may delay the color change by a week or two.
Annual precipitation, which provides moisture for soil and plant life, also plays a role in the foliage. A late spring, which delays the release of moisture through snow melt, may push back the color change by a nearly a week, sometimes longer in extreme cases. Severe drought often causes the leaves of young and distressed trees to turn brown and drop early.
The third weather-related factor, wind, has a rather obvious impact on the fall foliage. Very windy conditions, like those observed during and after storms, cause the leaves to drop, sometimes before full color has been reached. Calm winds during the foliage season help preserve the display.
Ideal foliage is produced by a warm and wet spring, typical summer conditions, and mild, sunny autumn days with cool evenings that stay above freezing.
The leaves are responsible for producing food and nutrients through photosynthesis for the trees and shrubs. Deciduous trees produce enough nutrients, which are stored by the tree in the trunk and roots, to last throughout the winter. The leaves also allow the trees and shrubs to release excess moisture.
To use the sunlight from which they draw their energy, the trees must have a mechanism for absorbing the light. Plants use chlorophyll and carotenoids, both chemical pigments, to absorb light.
The light spectrum consists of red, orange, yellow, green, blue, indigo, and violet. The green light portion of the spectrum is not effectively absorbed by chlorophyll in plants. The green light is either reflected by or passed through the leaf. This is why leaves generally appear green.
So often, people talk about the “changing of the leaves”. It may be more accurate to say that the leaves are actually losing their color. Leaves always contain the pigments that come out in the fall, but are overshadowed during the spring and summer by an abundance of green chlorophyll.
As autumn approaches, the amount of available sunlight decreases. This signals the tree that winter is approaching and that it is time to begin the process of shedding its leaves. As a result, the production of chlorophyll ceases and breaks down. Because of this, the green color of the leaf disappears, allowing the other pigments to show off their hues.
Autumn colors can be seen in many areas throughout the United States, and the world for that matter. However, it is certain areas of the United States, including the Northeast corridor, Southeast U.S. along the Appalachian Mountain chain, and much of the Midwest that produces the most striking and vibrant colors. This is attributed to mild autumn days coupled with cool, crisp, but not freezing evenings.
As one of the driest state’s in the nation, Utah just doesn’t have the sheer volume of deciduous trees that these more famous fall destinations have. The strength of Utah’s color show lies more in its contrasts — brilliant hues set against dark evergreens and mountain cliffs.
That’s not to say that people aren’t aware of the show the state puts on every year. In recent years, has been mentioned in national media outlets (the Ogden area was recently named one of the top 10 places in the nation for viewing fall foliage by msn.com).
This potential isn’t lost on local tourism officials. The Ogden Valley Business Association is plugging the fall color display as a tourist attraction. The group has even started a website and “Leaf Peepers” blog highlighting different areas where the colors are on full display at specific times throughout the season.
Individuals can submit photos from their own leaf-watching adventures in the area to be posted for others to see. It’s a great way to stay up to date on which local areas have the most impressive displays at any given time.
I would encourage anyone looking for a fall foliage adventure in the Top of Utah to visit the blog at www.utahfallcolors.com before heading out to experience this unique show of natural beauty.
Jeff DeMoss is the outdoors editor for the Standard-Examiner. He can be reached at firstname.lastname@example.org or (801) 625-4263.