"We might get really severe drought, and we might get major outbreaks of insects or really severe weather impacts," Foster said. "Unexpected events will lead to unexpected and rapid changes."
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.
Timothy Boland, head of the Polly Hill Arboretum on the island, was thrust into the middle of a growing community debate about whether to attempt wide-spread spraying. The pesticide, Conserve, is a bacterial substance considered greener than most insecticides, but it is very expensive. And it can be toxic to aquatic life and bees. Boland urged patience.
"Typically, in the second year population, the moths can't sustain themselves and the population crashes," he said. "But it did not happen." He ordered the spraying of the most valuable trees on his 70-acre arboretum, advised residents to spray their favorite trees, and let the rest go.
"It was a funny position for me as a tree man to argue that we should let these trees die," he said.
Jeremiah Brown, 39, is a burly landscaper and elected tree warden of West Tisbury, an island community of 2600 year-round residents. He has healthy, stately oaks next to his shaded home. He sprayed them. Next door, his neighbor did not. The trees there are dead fingers reaching leafless to the sky.
"People were looking to me to save the day," he said ruefully. "They said I should have a helicopter over town spraying everything."
Town officials in several communities on the island voted emergency funds for limited spraying. In West Tisbury, Brown said he sprayed about 150 of the most critical trees on public grounds. As other trees died, they began to rot in 18 months, and communities have had to pay to remove trees threatening roads.
"I don't want to cut trees down," said Brown. "I'd like to, naturally, plant a few things and have the town be proud of me in 100 years. But all I do now is cut down trees because of those darned caterpillars."
The worst stretches of dead trees are on the elevated moraines of the island away from the roads. The suddenly open sky has created new opportunities. A profusion of beech, now free from the oak shade, is sprouting. Blackberry and blueberry shrubs are promising bumper crops. Foster, Boland, and other scientists are fascinated to watch the progression of a forest as the oaks are replaced. Residents see the dead trunks as fodder for their wood stoves. Not everyone has taken the same lesson from the die-off.
"I don't believe in climate change. I think it's just the way the world is. That's nature," said Judy Jahries, 70, emerging from a West Tisbury grocery.
"It's a sign we are out of balance," countered Jackie Clason, 56. "If a person is sick, they are open to diseases. It's the same with the planet and trees."
This article originally appeared at The Daily Climate, the climate change news source published by Environmental Health Sciences, a nonprofit media company.