Fall, the fabulous time of year when baseball pennant predictions, politician picks and fall foliage forecasts dominate coffee shop conversations around the region. I'll politely defer the two former topics to a more qualified soothsayer. The latter topic however, now there's something everyone has an opinion about.

Each fall, as surely as the days will shorten and cool air comes down from the north, people ask me about the fall color forecast. As a forester, I have a professional obligation to respond with scientific reason and educated logic. That is why I tell those who ask, I'm as qualified to predict leaf coloration, as is a meteorologist to predict the weather, a stockbroker to pick stocks, or a pollster to pick politicians. My accuracy of predicting fall colorations rivals the respective predictions of those folks.

Actually, predicting fall coloration of leaves can be a bit more subjective than the objective side of my brain would like. Sure we forester types know all of the scientific mumbo jumbo that explains why leaves change color. But whenever asked, "Will this be a colorful fall and what date will the peak color appear?" then the science of leaf physiology gives way to the art of reading tea leaves and Tarot cards.

Historically and scientifically, deciduous trees (those who shed their leaves) located in our region of the temperate zone (between the tropics and the polar circles) have been changing color every fall ever since deciduous trees evolved millions of years ago when the North American plate of the Earth's crust crossed the Tropic of Cancer. Deciduous trees south of the Tropic of Cancer are not exposed to the changing of the four seasons and thus do not undergo fall coloration. The fact remains, leaves in our neck of the woods will undoubtedly, positively change color every fall. It is the degree or magnitude of this transition from green to brown that is debatable or somewhat subjective.

Before I commit my yearly fall color forecast to stone, let's first review a little Fall Color 101. Sorry, the scientific side of my brain sometimes dominates my artistic side.

Why do leaves change color? No, Jack Frost is not the culprit. Some leaves change color weeks before the first icy nights. What's really going on is a bit more complex.

Tree leaves contain cells that create food for the whole tree. Those cells use chlorophyll, which gives leaves their green color. The chlorophyll absorbs energy from the sun to turn water and carbon dioxide into sugars and starches-food for the tree.

Even though green is what you see during the growing season, there also are hidden colors in the leaves. Those are carotenoids. They're the same pigments that give yellow and orange to plants such as carrots, corn and daffodils.

In the fall, shorter days and cooler nights means there's less energy for food-making. The chlorophyll starts to break down. The green disappears and the yellow carotenoids can finally be seen in such trees as hickory, ash, birch, maple, sycamore, cottonwood and sassafras.

The red and purple colors, though, aren't hiding in the leaves. They're newly created in the fall when sugars are made during warm days, then trapped in the leaves during cool nights. The trapped sugars change chemically into anthocyanins, which appear red and purple.

The more sunshine during the day, the more red color is created. That's why shaded leaves will be less red than those that get lots of sun. If the weather is cloudy and the nights stay warm, there won't be as much vivid red in such trees as maple, sweetgum, oak and dogwood.

Other factors, in addition to contrasting temperatures, also affect fall color. Trees that don't get enough water during the growing season may just drop their leaves quickly before they color. And if it gets very cold, that kills the leaves, too, before they have time for a fall display.

In good seasons, Missouri's fall color may slowly change from mid-September to a peak in mid-October. By late October, the colors fade and the incredible show is gone.

Now for the moment you've been waiting for, Forester Hayes' fall forecast. My objective forcast calls for coloration to be a five on a scale of one to 10, with the peak of color climaxing on Oct. 21. My subjective forecast calls for another beautiful fall peaking sometime around mid to late October. Of course my disclaimer statement is that my predictions are dependent upon consultation with area meteorologists and this year's Farmer's Almanac. A good forecaster must always be able to place the blame on someone else if need be.

For more information on this year's fall color forecast, contact you local forester by calling the Missouri Department of Conservation at 290-5730, or by contacting any member of the Missouri Urban And Community Forestry Advisory Council (MUCFAC). Anyone interested about fall colors or trees in general is welcome to attend the next MUCFAC meeting held at the Cape Girardeau Department of Conservation office beginning at 7 p.m. on Thursday, Oct. 10.

~Rocky Hayes in a urban forester for the Missouri Department of Conservation.