OUTDOOR CORNER: FALL CREATES COLORFUL LEAVES, STORIES

As summer gives way to autumn, we observe a number of changes in the natural world that surrounds us. The amount of sunlight (photoperiod) decreases by a few minutes each day and temperatures fall. The leaves of trees and other plants change from the greens of summer to sometimes brilliant shades of red, yellow, orange and purple.

For centuries, humans have given a variety of explanations for the changing colors of the October woodlands. One Native American legend told of spirit hunters who slew the Great Bear in the autumn. The bear's blood, dripping on the trees, turned some leaves red. Other leaves turned yellow from the bear fat that splattered out of the kettle as the hunters cooked the meat.

Even today, many people credit Jack Frost or Mother Nature's paintbrush for the vivid colors we see. While such notions are romantic, and most definitely have their place, the truth is that the changes in leaf color are the result of chemical processes which take place in the trees as they prepare for winter.

Throughout the spring and summer growing season, the leaves manufacture food for the tree's growth. Each leave contains chlorophyll, a green-colored chemical, that absorbs energy from sunlight and uses it to transform carbon dioxide and water into sugars and starches. The chlorophyll gives the leaf its green color.

The leaf also contains yellow and orange pigments called carotenoids. These are the same pigments that give carrots, corn and bananas their color. Most of the year these yellowish colors are covered by the green-colored chlorophyll. The shorter days and cooler temperatures of fall cause the leaves to stop making food. As the chlorophyll breaks down, the green color disappears and the orange and yellow colors, that were there all summer, become visible.

The red and purple colors are not present in the leaf throughout the growing season. They develop in late summer and depend on the amount of sugar the leaf has manufactured and the weather conditions. Warm, sunny days promote the sugar production and cold nights prevent it from moving out of the leaves and down to the roots of the tree. The brighter the light during this period, the more brilliant the red colors.

The degree of leaf color will vary from tree to tree. Leaves directly exposed to the sun may turn red, while those on the shady side of the same tree may be yellow.

Rainfall is an important factor in the fall color display. Well distributed rainfall during the summer and early fall will result in more brilliant colors while trees under stress from drought often drop their leaves without showing much color. Most areas of southeast Missouri did not receive a great deal of rainfall this summer and consequently it will be difficult to see vast expanses of trees showing brilliant colors. However, if you will take the time to look at individual trees, you will still be able to enjoy the splendor of Missouri's woodlands.

In most of Missouri, the fall colors peak between Oct. 15 and Oct. 21. The National Forest Service provides a toll-free telephone number (1-800-898-8895) from now to the end of the color season so that callers can keep track of changing conditions for Missouri and northern Arkansas. The recorded information is updated each Thursday.

~Gene Myers is a Missouri Conservation Agent in Cape Girardeau County.