Recent cold snaps help kick off color change
A dry summer might dim this year’s fall foliage, but the season will be far from dull, a Pennsylvania Department of Conservation and Natural Resources forester has said.
“You don’t really know what it will be like each year, because temperatures, rainfall and frosts all play a role,” DCNR forester Chris Jones said. “But we had a drought throughout a good part of the summer, and that will certainly be a factor in the colors.”
Despite recent rainfall, Blair County’s precipitation is still about a half-inch below average for September and about 1 inch below average for the year, National Weather Service meteorologist Jared Rackley said.
The lack of rainfall, however, could be balanced out by a recent spate of cooler nights and warmer days.
“Last year, the nighttime temps were a little warmer, and you really get the best colors with colder nights,” Jones explained. “So, I think this year will be a little more brilliant than last.”
Why so green?
The green in deciduous trees’ leaves is created by the presence of chlorophyll, which facilitates photosynthesis.
Because chlorophyll does not absorb the green spectrum of light, the substance reflects it, giving leaves their green color, according to an article Jones wrote for the DCNR.
Leaves also contain carotenoid and anthocyanin pigments, but they are masked by the chlorophyll during the growing season. As fall sets in, deciduous trees stop producing chlorophyll, allowing the carotenoids’ and anthocyanins’ many hues to shine through for a few weeks before the leaves fall.
Most conifers, on the other hand, produce chlorophyll throughout the year, earning them the nickname “evergreen.”
“Conifers photosynthesize at a slower rate year-round,” Jones said. “Whereas deciduous trees put a lot of energy into doing it in a shorter period, then shed their leaves.”
Nature and evolution aren’t sticklers for rules, though, so even some conifers, like the American tamarack, shed their needles come fall, he said.
Trees that produce more glucose, a simple sugar, tend to be the stars of the fall season.
In Pennsylvania, those species include sugar maples and red maples, said Marc Abrams, a Penn State University professor of forest ecology and physiology.
“The really famous species, sugar maple and red maple, have been a mixed bag this year,” Abrams said. “But, we’ve seen a lot of early coloration especially in the trees that produce yellow, such as ash, hickory and honey locust.”
Ideally, he said the two groups would change around the same time, creating a tapestry of colors. Instead, it’s now more likely the yellow leaves will be littering lawns by the time maple colors peak closer to mid-October.
“I think this burst of yellow color has been a response to that early cold snap,” Abrams said. “But, it’s hard to pinpoint exactly why that occurs.”
Out and about
Pennsylvania’s fall foliage season can span three to four weeks and typically peaks around mid-October. But with some leaves already changing, Jones said this weekend is a prime time to visit Gallitzin State Forest, about 40 miles southwest of Altoona.
“Areas with higher elevations, like Ebensburg, much of Cambria County and Gallitzin State Forest will be really popping in the next few days,” he said.
With drought conditions worsening north of Altoona, Jones said heading south is a good bet for better colors.
Rather than highlighting a specific location where the colors might be brightest, Abrams encouraged people to hit the road and find their own favorite spots.
“All people need to do is drive through heavily forested areas — whether state forests, game lands or just some of the beautifully wooded back roads in their area,” he said. “Just drive around and try to seek out pockets of these higher producing species, like sugar and red maples.”
For those with commitments in the next few days, there’s still time to plan an outing and catch the best of Pennsylvania’s mosaic season.
“Next week should be about the peak week,” he said. “Then, it should culminate in mid-October.”
Mirror Staff Writer Ike Fredregill is at 946-7458.