As summer fades and autumn is ushered in, the tranquil green palette of summer foliage is transformed into a vivid palette of reds, oranges, golds and browns. Back country roads will soon be lined with Sunday drivers hoping to catch a glimpse of Pennsylvania's autumn splendor.
David Planinsek, a forester with the Department of Conservation and Natural Resources Bureau of Forestry, is predicting an average year for fall foliage across the state. In Pennsylvania, he said "average" translates to spectacular. But a leaf disease in some trees is expected to cause more browning than in some years.
"It's a great time of year for people to get out and enjoy the beautiful forests that Pennsylvania is so fortunate to have," Planinsek said. "We're blessed across Pennsylvania. Our foliage rivals any state in the Northeast."
Planinsek is a forester at Forbes State Forest in Laughlintown. His prediction for peak foliage in southwest Pennsylvania is the week of Oct. 8-15.
When predicting when leaves will turn color, Planinsek said temperature and elevation are the greatest factors to consider. Trees located at higher elevations with cooler temperatures are typically among the first to change color. Those in lowlands and valleys, with warmer temperatures and a longer growing season, are among the last to change.
Leaves of deciduous trees naturally contain yellow and orange pigments called carotenoids. During the growing season, chlorophyll is continually being produced and broken down, overwhelming the carotenoids and making leaves appear green. As hours of daylight grow shorter and nights grow cooler, leaves begin storing food for winter and chlorophyll production slows and eventually stops. As the green chlorophyll disappears from the leaves, the yellow and orange pigments are revealed.
With the right amount of sunlight increasing sugar production in some trees, brilliant red, purple and crimson pigments called anthocyanins are also unveiled.
"The best recipe for beautiful fall foliage is cool days with bright sunlight and chilly nights that remain above freezing," said Planinsek.
He noted that fall spectators will notice more brown pigments in this year's fall colors than in recent years due to an increased prevalence of the leaf disease anthracnose, which was caused by tropical storm Lee and other strong rain events. The disease causes unsightly brown spots on leaves and in severe cases will cause trees to drop their leaves early. The trees most affected by it are ash, black walnut, and maple.
The extra precipitation this year has also lengthened the growing season for trees, but Planinsek said we are right on track for normal viewing opportunities.
Early in the season, Planinsek recommends spectators head to the Laurel Highlands to view spectacular fall displays. One of his favorite viewing areas is atop Mt. Davis, which is the highest point in Pennsylvania. The view from the observation tower affords a spectacular autumn show, but its high elevation means the leaves change two to three weeks ahead of lower lying areas.
The variety of elevations and diverse geography across the state are a benefit to leaf watchers, ensuring that somewhere across Pennsylvania this fall, the leaves are changing.
"That's another reason we're fortunate here," Planinsek said. "If you missed it in one area early in the season, you can continue your viewing season by visiting some of the other counties that tend to peak later."
To help ensure fall foliage spectators don't miss the show, the U.S. Forest Service has established a Fall Colors Hotline that provides audio updates on the best places, dates and routes to take for peak viewing of fall colors in national forests. USFS also launched a website that includes clickable maps that link to forest-by-forest fall color information and to state tourism and fall color websites.
As for the best way to view fall foliage, options include driving tours, canoeing, kayaking and hiking.
"Recreational drivers are some of our most common forms of forest visitors," Planinsek said. "But if you're willing to get out there and get a little bit dirty and exert some energy, hiking is a great way to see it. You can see a little more because you're not going quite as fast."
No matter how you choose to view this season's autumn splendor, Planinsek offers this recommendation.
"Get out and enjoy it because before you know it, the snow will be flying," he said.
For more information, call the U.S. Forest Service Fall Colors Hotline at 800-354-4595 or visit its Fall Colors 2011 website at www.fs.fed.us/fallcolors /. First Published October 9, 2011 4:00 AM