Sunday, October 12, 2008

Changing Leaves

We are lucky here in eastern Tennessee! We live in one of the best places in the U.S. to observe the beautiful fall colors of deciduous trees. Deciduous trees are those that lose their leaves each autumn and the eastern U.S. is the heart of the deciduous forest in this country. The Midwest, southwest, pacific and mountain states don’t have nearly the variety and quantity of colorful deciduous trees that we have between here and Maine.

You will hear people talk about leaf-peeper tours to the New England states, but don’t book that trip yet…Tennessee’s autumn show will rival anyone’s. The Great Smoky Mountains National Park is a prime leaf-lookers destination and October is the second most crowded month in the Park for that reason. The Cumberland Plateau isn’t far behind for autumn beauty.

As you probably remember from grade school, trees are very important for life on earth because they use photosynthesis to convert light and carbon dioxide to oxygen and sugar. The sugar feeds the tree and the oxygen supports life. Chlorophyll in the leaves enables the photosynthesis and gives the tree leaves their green color all summer long.

So then where in the heck do the brilliant reds, oranges and yellow colors come from? As the days become shorter in the fall and the trees prepare for winter, the green chlorophyll production stops and yellow and orange colors in the leaves become visible. Leftover sugars in the leaves produce the red and purple colors once the chlorophyll disappears. The colors were there all along, we just couldn’t see them because of the green chlorophyll.

The exact prime time for autumn leaf-looking varies each year due to several factors. It is not the temperature but rather the amount of daylight that triggers the changes in the leavers. However, the amount of rainfall and temperature also play a part. Warm sunny days, and cool, but not freezing, nights produce excellent fall colors. The best fall colors appear after a warm dry summer and early autumn rains; but, too much wet weather in late fall causes drab autumn colors. The right combinations produce the best autumn viewing.

Sourwood trees are usually the first to show their fall colors; oaks are the last. We have lots of both around here. The best red and orange colors usually come from red maples, sugar maples, sassafras, sumac, blackgum, sweetgum, and dogwood. Hickories, white oak, chestnut oak, and yellow-popular (tulip tree) have the best yellow colors. We have all of these trees in great abundance on the Cumberland Plateau.

The changing of the leaves starts up north and steadily moves south. Mid to late October is generally the prime viewing time in this area. There are maps on the internet updated daily with the progression of the autumn colors, but the Tennessee Forecast Information Line at 800-697-4200 can keep you up to date on the progression of the Tennessee autumn colors.

Lots of leaf-peepers travel hundreds of miles to view the autumn colors. Many travel to Maine or Pennsylvania or some other state. But we don’t need to go anywhere. Sit back and relax. We have front row seats for the best nature show of the year right here in Tennessee. We are lucky!

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