Every October, the Bluegrass State breaks into reds, oranges and yellows as Mother Nature prepares for winter. With the many forests Kentucky has to offer, the state is one of the best places in the nation to observe the transition of summer into autumn.
During the spring and summer months, chlorophyll, the green pigment in leaves, photosynthesizes sunlight and carbon dioxide into sugars that trees need to survive and thrive. This process takes place in numerous cells throughout the leaf and is what gives leaves their green color.
When daylight starts to fade and a chill enters the air during early fall, it is a sign for trees to stop their food making process. Chlorophyll breaks down and the green color diminishes in the plant, revealing the colors which make autumn notable.
“The change is not merely for show; it’s part of a very important ecological process,” said Laurie Thomas, extension forester in the University of Kentucky College of Agriculture, Food and Environment. “Once the green color starts to fade, the oranges, yellows and reds become visible. The pigments which cause these colors — carotenoids, beta carotene and xanthophyll — are present throughout the growing season. However, they are masked by the chlorophyll.”
Carotenoids are responsible for giving the leaves their orange and yellow hues while the anthocyanin pigment is responsible for giving the leaves beautiful red, purple and crimson colors. Anthocyanin production increases dramatically in autumn, especially if the days are warm and sunny followed by cool nights.
Each species of tree provides their own signature colors. Hickories and tulip poplars offer up leaves of yellow. Sugar maples will turn hues of orange, while oak and dogwood trees bring forth shades of red.
Minerals taken into the leaves during the growing season are recycled after the leaves drop to the ground. When the leaves decompose, their nutrients again are available to be taken up by the area’s plant life, and their organic materials nourish the soil.
“Kentucky enjoys a full palette of fall colors because we’re fortunate to have a diverse climate, diverse topography and diverse soil composition,” said Thomas. “This is a great time to get out and enjoy the beauty of a Kentucky autumn.”