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Maples are among the many hardwood species expected to display brilliant colors this season. Photo courtesy of the UT Institute of Agriculture. Download this image (727 KB)

Yellow feathers, rusty stars, red and maroon hearts – what makes a canopy of colorful shapes drift onto autumn lawns? The University of Tennessee Forest Resources Research and Education Center offers virtual visitors a guide through fall's magic.

The Web site http://forestry.tennessee.edu/fallguide.htm explains how sunlight, moisture and temperature combine to create each year's unique palette. Center Director Richard Evans says the site sheds some light on the chemistry of the season in an easy-to-read format.

"Each fall as the chlorophyll in the leaves drops, current weather conditions help determine how vibrant the hues become," Evans said. However, the forestry expert explained that weather conditions throughout the growing season also influence each autumn's display. For example, a late summer drought delays fall color, and rainy days during peak coloration decrease intensity. Moderate, cool temperatures translate into the brightest color, while frost browns the landscape. "Colors are determined by the sugars trapped in the leaves as the chlorophyll levels drop," Evans said. "How fast the transformation occurs is up to Mother Nature."

Changing Colors of Leaves, a UT Extension publication by Wayne Clatterbuck, associate professor of forestry, provides further details. It can be downloaded for free from http://www.utextension.utk.edu/publications/spfiles/SP529.pdf.

In addition to some simple science lessons, the Research and Education Center Web site also features a guide to leaf colors by species and a link to the state of Tennessee's fall color Web site, which predicts where and when fall colors will be most intense.

Evans invites the public to view some of East Tennessee's finest fall colors at the UT Arboretum in Oak Ridge. The 250-acre Arboretum features more than four miles of walking trails of various lengths. As a research and education facility, it maintains more than 800 native and exotic woody plant species, varieties, and cultivars.

A project of the UT Agricultural Experiment Station, the Arboretum is free and open to the public during daylight hours. For more information or directions visit: http://forestry.tennessee.edu

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Contact:

Richard Evans, (865) 483-3571

Student editorial assistant Terri Friedman contributed to this article.