The Joplin Globe, Joplin, MO

Local News

October 17, 2011

An off-color autumn

Dry summer takes toll on leaves; studies cite climate factors in delaying change

CARTHAGE, Mo. — One of the hottest and driest summers on record will mean lackluster fall colors in the area, but that’s not all that’s affecting the change.

Several recent studies have noted a delay in the arrival of fall colors, and some scientists think it could be linked to global climate change.

“Foresters are predicting dull colors because of the (summer) drought,” said Jon Skinner, forester with the Missouri Department of Conservation in Joplin.

Despite the overall drabness, some hot spots have surprised him.

“Virginia creepers are still bright,” Skinner said. “Maples are coming into color now, especially sugar maples in Carthage.

“Sumacs are hit-and-miss. There are a lot of oranges and some reds in sassafras. They are probably at their peak.”

Skinner said leaves on oak trees are mainly just turning from green to brown, and he categorizes fall’s display this year as average to below average.

Brady Murphy, a horticulture professor at the University of Arkansas in Fayetteville, said that considering the heat and drought of the summer, he doesn’t expect much.

“The conditions have been so abnormal,” Murphy said.

He said stress may result in leaves dying without changing colors, but sometimes that can generate leaves with brighter colors.

“It’s a tossup,” he said.

Delayed autumn

Although predicting fall colors is not an exact science, some scientists say there is evidence that global climate change is resulting in delays of autumn brilliance.

Richard Primack, a biology professor at Boston University, wrote one of the studies, using data from Japan.

“It’s very clear that in Japan, the fall colors and fall leaf drop is happening about a week later, on average,” Primack said by phone. “The temperature over time is getting warmer in Japan. Autumn is getting delayed.”

He said the phenomenon is probably because of global climate change. He also said his main area of study is spring flowering time, and he said that is coming earlier.

Researchers at the NASA Goddard Space Flight Center and at Seoul National University in South Korea used satellites to show that the end of the growing season for trees was delayed by 61⁄2 days from 1982 to 2008 in the Northern Hemisphere. And leaves are changing about three days later than they were two decades ago at Harvard Forest in Massachusetts, 65 miles west of Boston, according to data collected by retired Harvard professor John O’Keefe.

State foresters studying sugar maples at the Proctor Maple Research Center in Underhill, Vt., found that the growing season ended later than the statistical average in seven of the past 10 years.

In New Hampshire, data collected at the federal Hubbard Brook Experimental Forest in Woodstock suggests that sugar maples are going dormant two to five days later than they were two decades ago.

But not everyone is convinced.

William Ostrofsky, a forest pathologist with the Maine Forest Service, is skeptical about whether there’s a proven link between fall foliage and climate change.

“I just don’t know that there’s any evidence to indicate there’s a trend one way or the other,” said Ostrofsky, who said year-to-year fluctuations make it difficult to discern long-term trends. “I really don’t think we’ve seen any long-term trend, as far as I can tell.”

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