From: Wendy Plump, Princeton Environmental Institute
Published September 18, 2014 01:55 PM

Fall foliage may be delayed, but will last longer

The fall foliage season that prompts millions of Americans to undertake jaunts into the countryside each year could come much later and possibly last a little longer within a century, according to new research.

Climate change could postpone fall leaf peeping in some areas of the United States as summer temperatures linger later into the year, Princeton University researchers report in the journal Global Ecology and Biogeography. For instance, the paper birch — a popular foliage tree that is the state tree of New Hampshire — could change color one to three weeks later by the end of the century, the researchers found. Although some trees will be less susceptible to the ongoing heat than the paper birch, the more southern the region, the more likely there is to be a greater overall delay in leaf coloration, the researchers found.

Trees need daily temperatures to be low enough and daylight hours to be short enough to produce the vivid vistas of fall, explained senior author David Medvigy, an assistant professor of geosciences and associated faculty member at the Princeton Environmental Institute. He and first author Su-Jong Jeong, a former Princeton postdoctoral student now at NASA, found that daily temperature and daylight hours can not only be used to predict the timing of leaf coloration, but that the influence of these factors depends on the individual tree species and the specific geographic area.

"We're really interested in understanding how these systems will change as we experience global warming or climate change," Medvigy said. "What these results are suggesting is that different locations will change in different ways, and that these differences are actually going to be quite interesting."

Aside from fall foliage and its economic importance to many areas, the research has broad implications for predicting growing seasons, agricultural productivity and ecosystem productivity, Medvigy said. In particular, a delay in when leaves change color could affect how much carbon an ecosystem removes from the atmosphere, which would partially combat the climate change that caused the delay in the first place, he said.

"When plants have green leaves, they're doing photosynthesis and taking carbon out of the atmosphere," Medvigy said. "The longer you have green leaves, the more carbon dioxide you can take out of the atmosphere. At least, that's how the current thinking goes. So, figuring this out could potentially be important for understanding the impacts of climate change."

Continue reading at Princeton University.

Fall foliage image via Shutterstock.

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