With little rain in the long-term weather forecast, a worsening drought in much of the Northeast portends trouble for Pennsylvania’s vaunted fall foliage display, according to a Penn State professor. At least in parts of the state.
“The drought is fairly extensive throughout the Northeast, but not in eastern Pennsylvania and southern New York,” said Marc Abrams, professor of forest ecology and physiology in Penn State’s College of Agricultural Sciences. “If this continues, there will be continued early coloration of trees, browning and leaf fall.”
The Pennsylvania Department of Environmental Protection on Aug. 21 declared a drought watch for 16 counties in the state: Armstrong, Blair, Butler, Cambria, Cameron, Centre, Clearfield, Clinton, Fayette, Huntingdon, Indiana, Juniata, McKean, Mifflin, Perry, and Potter.
“It is hard to be optimistic for great fall coloration in the areas now under extreme drought because it has persisted for so long,” Abrams said.
Abrams said trees that are having early color and dropping leaves now will not be foliated in mid-October, the normal peak color season. And there is a tree physiology aspect of the current situation that will detract from the display, as well.
“Some of the drought-tolerant trees — such as oaks — that are seemingly handling the drought OK are not among the great color producers,” he said. “One of the most famous trees for fall color is sugar maple, but unfortunately it is a drought-sensitive tree. That spells more trouble, especially in northern Pennsylvania, northern New York and New England. Even the fairly drought-hardy red maple is starting to color early and losing leaves in places.”
Each fall, according to Abrams, cooler temperatures signal deciduous trees to stop producing chlorophyll, the green pigment responsible for photosynthesis. The chlorophyll breaks down and disappears, unmasking other leaf pigments. These other pigments — called xanthophylls and carotenes — are what create the yellows and oranges seen in the leaves of yellow poplar, hickory, sycamore, honey locust, birch, beech and certain maples.
After chlorophyll production stops, trees also produce another pigment in their leaves called anthocyanin, Abrams said. The anthocyanins create the brilliant reds and purples seen in maple, sassafras, sumac, blackgum and scarlet oak.
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