As summer draws to an end, nature is barraging us with signs of the changing season. Goldenrods in full bloom, wooly bear caterpillars marching, and swallows flocking in mass are a few of the tell-tale signs that fall is upon us. The more obvious but equally exciting signs of autumn are the crisp cool mornings and seeing the first colorful leaves on the forest floor. This edition of the Nine Minute Naturalist will break down the Wintergreen fall foliage.

The primary trigger for the signs of autumn we see around us is photoperiod, which is the duration of an organism’s daily exposure to light. This along with fluctuation in local weather patterns will determine when chlorophyll production ceases in plants. When chlorophyll begins to break down, the green color disappears giving rise to our beloved red, yellow, and orange colors we see in our fall foliage. The Wintergreen forest offers some of the most striking color spectrums in the mid-Atlantic region due to our great diversity of trees.

My favorite color to appear in our forest is the deep reds common amongst the black gum, sassafras and red maple. These brilliant foliage producers tend to change early in the season to make for stark contrast amongst the still green oaks and hickories. The reds and purples produced by these species and others, such as dogwood, are a result of a pigment called anthocyanin. They are most vivid after weather periods with warm, sunny days and below 45-degree nights. Unlike chlorophyll, anthocyanins are not always present in a leaf but are produced in late summer when other environmental changes begin occurring.

The yellow, orange and brown colors come from pigments called carotenoids. This color is most common among our hickories, birch, and maples. The oak trees stay green the longest and turn mostly brown late into the season. When carotenoids combine with anthocyanin, they produce a fiery red, orange or bronze color seen among sumacs and sugar maples. All the colors seen across our landscape are due to the mixing of pigments with varying amounts of chlorophyll still present in the leaf.

Weather greatly affects the intensity of color each autumn. Low temperatures above freeze produce brilliant reds while early freezing temperatures reduce the red color. Rainy weather tends to increase fall color. Stress factors such as drought, disease or insects may cause fall color to come on early but with less coloration. An abrupt hard freeze can cause leaves to drop prematurely as well.

This is the best time of the year to be traversing the wilds of Wintergreen. For a short period of time we get to enjoy perfect hiking weather amongst our changing leaves. Get out onto a trail today to enjoy the uniqueness our mountain has to offer.