The Appalachian mountains that stretch from Georgia to New York are known for brilliant color changes in the fall. It's a defining feature of many rural mountain communities, but those colors may become less vibrant as climate change continues to warm the planet and reduce rainfall, Robynne Boyd of Scientific American reports. (Photo by Ivy Brashear, 2010: Fern Lake on the Kentucky-Tennessee border)
There was a "desynchronization in leaf color changes" this year, Appalachian State University leaf specialist and biologist Howard Neufeld told Boyd. Basically, some trees turned colors before others. Dogwoods and some maples turned in early August, but oaks didn't start turning until the middle of October. The U.S. Department of Agriculture says this schedule of change appears to be genetic. "Trees of the same species turn in unison whether on high or low [altitude] if located within the same latitude," Boyd reports.
Temperature and precipitation seem to have the biggest impact on leaf color, said Neufeld, who publishes an annual fall color report. "Conditions leading up to the fall were ripe for good fall color -- sunny, cool, no severe drought," he told Boyd. "But they didn't develop. I don't know why that is." But he does provide a theory: trees produce volatile organic compounds, which reflect the sun's radiation back into space. This "VOC armor" will not stay strong forever, Boyd writes. "It will weaken as the climate warms, and will one day demonstrate the same higher temperatures as most of the rest of the country."
Plants are cooled by evaporating water through their leaves, but "many tree leaves were were damaged as a result of the inability of root systems to supply sufficient water to leaves that experienced high temperatures" this year, Cornell University plant biologist Karl Niklas told Boyd. "The damage to leaves earlier in the season meant that many leaves could not color up or simply died while still attached." (Read more)
Temperature and precipitation seem to have the biggest impact on leaf color, said Neufeld, who publishes an annual fall color report. "Conditions leading up to the fall were ripe for good fall color -- sunny, cool, no severe drought," he told Boyd. "But they didn't develop. I don't know why that is." But he does provide a theory: trees produce volatile organic compounds, which reflect the sun's radiation back into space. This "VOC armor" will not stay strong forever, Boyd writes. "It will weaken as the climate warms, and will one day demonstrate the same higher temperatures as most of the rest of the country."
Plants are cooled by evaporating water through their leaves, but "many tree leaves were were damaged as a result of the inability of root systems to supply sufficient water to leaves that experienced high temperatures" this year, Cornell University plant biologist Karl Niklas told Boyd. "The damage to leaves earlier in the season meant that many leaves could not color up or simply died while still attached." (Read more)
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