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DALY: Fall leaf colors brighten the landscape

The brilliant leaf colors in autumn 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 onset of cooler weather and shorter days initiate several chemical and biological processes that cause the leaves to change colors. 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. Chlorophyll is the one present in the highest quantity during the growing season. In the fall, the plant reduces chlorophyll production. The other pigments, which have previously been masked by the chlorophyll, become visible. They consist of numerous colors, such as red, orange, purple and yellow, which gives the leaves their fall colors.

Some species of trees have a higher quantity of one pigment in their leaves than others. Hickories have more of the type that gives their leaves the 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. Their cells contain substances that are resistant to freezing.

Temperature and moisture have the greatest influence on the intensity of colors. Several warm, sunny days and cool nights, but not freezing ones, allow for 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 varieties 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 locally 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.