DALY: Fall leaf colors: One of nature's greatest shows

Timothy Daly

Timothy Daly

The brilliant leaf colors of the fall are one of nature’s most fascinating shows. The mountains of North Georgia and other states are popular destinations for observing spectacular displays of color. However, one does not need to go far since the trees in our area can be just as beautiful.

The autumn leaf colors result from several chemical and biological processes caused by the onset of cooler weather and shorter days. The leaves contain several chemical pigments, each having different types of colors. Chlorophyll is the most noticeable one since it is the source of the green color in plants. It absorbs sunlight to be used in photosynthesis, which is the conversion of light energy to food substances in the plant. During the growing season chlorophyll is the pigment present in the highest quantity. In the fall, the plant slows down its production of it, and the other pigments, which have previously been masked by the chlorophyll, begin to become visible. They consist of numerous colors, such as red, orange, purple and yellow, which gives the leaves their colors.

Some species of trees have a higher quantity of one type of pigments in their leaves than others. Hickories have more of the pigments that give their leaves brilliant yellow to brown colors. Other trees, such as dogwoods and sweetgums, have higher levels of the pigment that causes the leaves to turn red and purple. The mixture of two or more of them in similar amounts produces intermediate colors, such as orange.

The leaves on evergreen trees and shrubs stay green throughout the year and do not fall off with the onset of colder weather. Their foliage is covered with a thick wax coating and their cells contain substances that are resistant to freezing. The foliage can persist for several years on the trees, but it will eventually fall off and be replaced by new growth.

Usually the peak time for viewing the leaves in North Georgia is the middle to later part of October. The fall weather has the greatest influence on the intensity of colors. The temperature and moisture are the main influences. Several warm, sunny days and cool crisp, but not freezing nights bring about the most spectacular color displays. Clear days with full sun help enhance the beauty of the leaves. Soil moisture also affects autumn leaves. A late spring or summer drought can set the color changes back a few weeks.

You can plant trees in your yard that produce brilliant fall colors. Red maples, especially the hybrid variety “October Glory” and “Autumn Flame,” produce bright red leaves. Trident maples have yellow to red foliage. Sourwood trees turn a red to maroon color in the fall, and the Gingko tree is famous for its brilliant yellow to gold colors.

The intensity of fall leaf color and times of the change of color will vary each year due to the weather and growing conditions. Again, you can go to the mountains, but there are plenty of opportunities here in our communities and even in our own yards to enjoy one of nature’s greatest shows of beauty.

Timothy Daly is an Agricultural and Natural Resource Extension Agent with Gwinnett County. He can be contacted at 678-377-4010 or tdaly@uga.edu