Group items tagged

Scientists see a fingerprint of climate change in the denuded branches, and a pattern of things to come. The effects of climate change, they say, are unlikely to be gradual or predictable. Warming winters will throw into confusion old orders of species, nurturing unexpected predators and weakening age-old relationships that helped form forests.

"They were gross," recalled Barbara Hoffman, 53, with a visible shudder. "You could hear them munching. I said spray 'em." Most trees recovered in the first year; fewer survived the second. But as the bugs struck again in late 2007, an accomplice drought hit the weakened trees, leaving the island now with swaths of stark, barren and lifeless branches.

The islanders fought through clouds of drifting filaments with brooms, brushed off the showers of excrement after they walked under trees, and tiptoed through a maze of half-inch worms on the sidewalks. The local newspapers ran pictures of building sides covered with caterpillars, looking like horror-movie outtakes.

"You can get unexpected dynamics in nature as we generate new combinations with climate change," said David Foster, director of the Harvard Forest, who heads a research group financed by the National Science Foundation to study the Martha's Vineyard die-off

In New England, the majestic hemlocks that were grist for Longfellow and Frost are doomed by the steady advance of a pest in warmer winters. "To see hundreds of acres of dead forest like this in New England is remarkable," said Foster.

Farther north and west in Massachusetts, Foster and others are studying the devastation of the stately hemlocks.  An insect brought from Japan, called the hemlock woolly adelgid, is moving steadily northward into New England. It already has infested much of the US South, bringing what forestry officials call "an ecological disaster" to the iconic Great Smokey Mountains and Blue Ridge Parkway. With warmer temperatures in New England-some studies put the average winter increase at 4 degrees in 40 years-the pest is advancing. "The northward spread is being kept in check by cold winters. As winters warm, which is what is projected, that all falls apart," said Wyatt Oswald, an assistant professor of science at Emerson college who is studying the hemlocks. "At some point, climate change will allow all these hemlock to be wiped out."

Certainly the residents here were perplexed at the caterpillar outbreaks from 2004 to 2007. Although several insects were at work, the prime culprit was eventually identified as a fall cankerworm, a long-time resident of the island that no one recalled having done more than minimal damage. This outbreak was a full-fledged invasion.

"It was disgusting," said Jason Gale, 39. He recalls glancing back at the island from his lobster boat, and being shocked by the stretches of dead trees.