Fall foliage is revealed

By JEFF THOMPSON
Area Forester

Fall colors reach their peak during mid to late October in the Upper Cumberland Region, as is evident here now.

A wide variety of colors can be found in the woods, including:

• Dogwood, sumac, red/“soft” maple, scarlet oak, and silver maple (a common yard tree that is native to the northeastern U.S.) are robed in scarlet and purple;

• Sugar/“hard” maple, white ash, yellow-poplar, black walnut, pignut hickory, elm, and American beech glow with a clear yellow radiance;

• Sassafras and persimmon often have exotic shades of orange and pink;

• American sycamore, understory beech, and most of the oaks add warm yellow-brown colors to the landscape; and

• Sweetgum supports a kaleidoscope of hues.

Thin leafed species such as blackgum, black walnut, black willow, dogwood, yellow buckeye, ash, and maple are usually the first species to change color.

Thicker leafed species, such as the oaks, turn yellow browns and dark reddish browns a couple of weeks later.

Fall colors emerge when trees begin the process of shedding their leaves.  Cut off from their nutrient supply, leaves start to die and stop producing the green colored pigment chlorophyll.

As the chlorophyll breaks down the pigments previously covered up by it begin to emerge.  All the varieties of color seen in the fall are due to just three pigments found in the leaves of trees: orange carotene, yellow xanthophyll, and blue anthocyanin.

The ideal weather conditions for long lasting fall colors include a dry late summer, followed by periodic and gentle rains, gradually cooling sunny days, and frost-free nights.

Frost simply kills leaves, causing them to turn brown and fall off sooner.

The timing of leaf fall (and their emergence in the spring) is determined by day length, temperature, moisture, and genetics.  Fallen leaves contain nutrients that help fertilize the soil.

Evergreen trees, such as pine, holly, and southern magnolia, keep their leaves in the winter, because their leaves contain chemicals that act similarly to antifreeze in cars’ radiators.