October 16, 2008
Fall Color in Alabama--Guest Blogger: Danny Cain
This week, Backyard Wisdom welcomes its first guest blogger, Danny Cain. Danny is both a friend and a colleague. He is the county Extension coordinator in Walker County, which is in northwest Alabama.
Fall Color in Alabama
I recently had the opportunity to observe some of the best natural scenery that I have ever seen while riding with a couple county agent buddies of mine in the hill country between Lake Guntersville and Monte Sano State Park. The sun was shining down through the valleys and almost seemed to make the maple trees, which are numerous in North Alabama, glow red. To top it off we were treated to a rainbow that seemed to reach from the mountaintops to the maple trees. People travel near and far to see such scenery, and we have it right here in Alabama. I have always said that we live in one of the most beautiful states. Anyway, that experience got me to thinking a little bit about fall colors and where they come from.
Here is a little bit of fun fall trivia for your enjoyment. Do you know what a ripening banana has in common with fall leaves? The green color in bananas when you buy them at the grocery store is actually chlorophyll, the same pigment that gives leaves their green color. As bananas ripen, the chlorophyll breaks down and disappears allowing the yellow color, which has been there all along, to show through. The potential for the yellows and oranges of fall leaves have likewise been there all summer long and have been covered up by the green chlorophyll.
The cool mornings and changing of leaf color from green to reds, yellows, and oranges can only mean that fall has arrived. Another reminder is the fact that there is now a constant supply of freshly dropped leaves on the ground. The tremendous variety and mixing of the reds, yellows, orange, and even purples for some plant species mixed with the greenery of our pines really makes a wonderful display that comes and goes fairly quickly in our part of the country.
Now you know that the leaves do not actually “change” colors by magic in response to frost but rather because of chemical processes in the plant that cause chlorophyll (and the green color) to break down. Photosynthesis, the food-making process in the plant, takes place in the green, chlorophyll-containing leaves.
In addition to chlorophyll, leaves contain yellow, orange, and often other color pigments such as carotene (the pigment that gives carrots their orange color). For most of the year, the yellows and oranges are hidden or have not been expressed ,but as daylight hours shorten and temperatures drop….you guessed it, we get the first hint of fall colors.
While all this is going on inside the plant, other changes are going on as well. Other chemical changes cause yellow or red or even purple pigments to form. This is what gives plants such as dogwoods, sumacs, sweet gums, and other trees their red to purple fall colors. Other trees have colors that easily distinguish them as well. Sugar maples take on a fiery orange color, hickories show only yellow colors, while oaks are primarily reddish brown to brown.
Warm sunny days with nighttime temperatures below 45 degrees tend to raise the level of red coloration. The cool nighttime temperatures trap the sugars produced during the daytime inside the leaves. Common trees with red fall color include red and silver maples, flowering dogwoods, sweet gums, black gums, red oaks, and scarlet oaks.
The interesting thing about fall color is that it can vary from tree to tree because of things such as genetics or physical location. The color can even vary on the same tree. For example, leaves directly exposed to the sun may turn brilliant red while those on the shady side of the tree may turn yellow or may even simply turn brown and shed off. Trees of the same species and the same location can vary in fall color from year to year depending upon weather conditions.
As the leaves “change” color, other things are happening to them. At the base of the leaf where it attaches to the branch or limb, the leaf gradually separates from the tree, and the result is the all too familiar fall leaf drop. At the same time, scar tissue forms on the twig to seal the scar left where the leaf was attached. And you thought that all leaves did in fall was simply change colors and fall!
Posted by lawremc at October 16, 2008 03:40 PM | TrackBack