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Autumn: Nature’s last hurrah before sleeping

By Gina Farthing

Published: October 4, 2008

Red, gold, orange, purple, yellow and crimson colors dot nature’s palette as far as the eye can see. To many people, it is the Master Painter’s final brilliant work of a year rich in life and growth. It is autumn.
It is a season associated with harvesting the fruits of one’s labor and allowing the unimportant chaff left behind to whither and die.
But it is really a season of preparation before a time of rest, a season of anticipation. It’s a season of hope for the future.
The jewel-like colors so proudly displayed by nature’s trees are a signal of that hope – that life endures. It continues on.
But there’s more at play in the beauty than mere philosophy. There’s real science behind the foliage displays that delight so many people.
Just as with humans, trees gather the fruits of their labor, sugars that feed them. They store them for the coming winter and eventually spring, when they will need the sustenance and be reborn again.
When the leaves start to lose their green color, it is a sign that they are beginning to convert from food production, known as photosynthesis, to food storage.
“When the chlorophyll, which makes sugars for the tree to feed on, starts to drain out, it is a sign the tree is going dormant,” says Stan Quillen, president of Waynesboro Landscape and Garden Center.
“The trees receive cues to lessen their feeding,” he says.
Signals include shortening of daylight and the lengthening of night, and when temperatures begin to drop from the highs of summer to the lows of winter, indicate to the trees that it has become a time for storage.
When photosynthesis lessens and the chlorophyll, which is a dominant color pigment, drains from the leaves, other color hues become apparent.
“Sugars break down into anthocyanins,” says Jerry Spenger, research coordinator at the University of Virginia’s State Climatology Office. “Anthocyanins are what give apples their red color and produce the reds, maroons and purples in leaves.”
Carotenoids, another by-product of sugar conversion, are evident in the oranges and yellows in carrots, corn and tree leaves, Stenger says. “One of the big factors in overall brilliance is the prevalence of the reds in the leaves.”.
Another criterion for a brilliant foliage display is the amount of moisture a tree receives during the year, mostly just prior to its switch to dormancy.
“Dry conditions near the end of the season will produce less brilliant colors,” Stenger says.
Quillen agrees. “There’ll be better color where they’ve had more rain. Drought situations lessen colors.”
An overabundance of moisture will also detract from nature’s brilliance.
Patti Nylander, a forester for the Virginia Department of Forestry, says, “Sometimes with an excess of moisture, mold spores start forming.
“We’re starting to see some turning now, of walnuts and locust trees,” she says.
Predicting the intensity of a foliage display each year is a gamble.
“Predictions are like those for hurricane season,” says Norm Sprouse, meteorologist for WVIR Channel 29, in Charlottesville.
“They’re not nearly that good,” says Stenger, laughing.
Regardless of the chance, Stenger’s office has offered its opinion on peak foliage in Virginia and has published a state map with estimated time frames online.
The Weather Channel is also tracking peak viewing on its Web site, weather.com. Viewers can select an area of the country to investigate where leaves are at their most brilliant.
As of Wednesday, weather.com’s maps are indicating that the Northeast quadrant of the U.S. is peaking, while the trees in areas below northern Pennsylvania are mostly still green.
“Like in all things, moderation is key. Optimum conditions for producing a great display would be some rainy or overcast days and cooler temperatures, but not below freezing,” says Vivian Brown, of the The Weather Channel.
Based upon this year’s moisture levels, Brown says, “Fall is coming inline with the climatology and the coming cooler temperatures. It looks to be a colorful display.
Nylander, too, predicts the Valley will have a nice season.
“It should be toward the end of October, the beginning of November for the most peak times for viewing,” she says.
Quillen says that this past season has been a little warmer than previous years.
“Last year, it was the third or fourth week in October when the foliage peaked.”
Stenger’s online map is backing up those estimates.
“My best guess,” Stenger says, “is that we’re headed for a particularly good display.”