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.

global warming has only recently allowed beetles to flourish in high-elevation whitebark pine forests, where the trees have not evolved strong defenses. Until recently, harsh winters have kept mountain pine beetles (which are the size of a grain of rice) at bay. Warmer temperatures have dramatically increased the beetles’ numbers and allowed them to move upwards to attack the whitebark pines, a number of which have been made more susceptible due to weakening by blister rust. The result is the loss of more than half of historical whitebark stands across their range, with far worse numbers in some areas. In the eastern portion of the Greater Yellowstone Ecosystem, for example, whitebark pine forests have been already functionally lost.

Whitebark pine forests have been hit particularly hard in the Northern Rockies. NRDC and the US Forest Service helped fund an unprecedented aerial survey of the entire 20 million acre Greater Yellowstone Ecosystem to investigate mortality levels of whitebark pine throughout the region. A groundbreaking pairing of airplane overflights with GIS and field-based evaluation techniques have given a new and more detailed understanding of the impact being felt by the region’s whitebark population. The data was brought together by prominent academics leading the research team, to map out the beetle carnage and evaluate the pattern of tree mortality in the region. Released today, the report shows 82% of the Greater Yellowstone whitebark pine forests of Wyoming, Idaho, and Montana dead or dying (high to medium mortality rates). The mundane title, Using the Landscape Assessment System (LAS) to Assess Mountain Pine Beetle-Caused Mortality of Whitebark Pine, Greater Yellowstone Ecosystem, 2009 belies the explosive results, which imply that the problem is far worse than had been previously known. The study was written by prominent experts Wally Macfarlane, Dr. Jesse Logan and Willie Kern. Based on these data, and considering the rapid changes, the report authors believe it is likely that whitebark pine will be functionally extinct in the ecosystem within the next 4-7 years.

The vineyard also escaped the effects of the long, cold winter, he said: “We’ve been very lucky in this corner of the country. With the frosts in April and early May we got down to minus two very close to the buds being frosted off the vines. But not quite.” Now, Mr Barnes said he was hoping the weather stayed dry for the harvest at the end of September. Apples growers have also enjoyed the hot, sunny weather, but said the recent downpours were welcome. Sarah Calcutt, business development manager at Norman Collett, which markets English fruit from its base in Paddock Wood, said the extra light and warmth had been great for Rubens, a new variety of apples. “I’ve been out looking at orchards today with the National Fruit Show president and we’ve been particularly looking at Rubens. “We do not know if it will be a bumper crop yet because they won’t be picked until to September, but from an apple’s perspective the heat and sunshine in particular are great. “Photosynthesis is better with good light because it seeds the tree really well and gives it good energy for feeding themselves next year. A lot of day light hours are wonderful. “We’ve just had rain in time. One of the farmers who has no irrigation system said this bit we’ve just had came just in time for his young trees, which were starting to look a bit stressed. So the recent downpours have been fantastic.” However, organic fruit farmer Mrs Martin said that it had been a bad year for some fruits. “Raspberries are not looking very good this year. It was too hot for them and they were cooking on the plants,” she said. “But a little rain does everything good.” Dr Chris Atkinson, head of science at East Malling Research Centre, which has been collecting climate data since 1913, said the climate was a big determinate when growing fruit because temperature and rainfall had a big impact on crops. The climate data shows that the seasons have been getting longer and the winters are getting milder. “We can even answer sceptics about climate change – no one can argue that climatic data shows it is changing,” he said.

The centre has recorded increasingly milder winters and longer seasons. Dr Atkinson said the changing temperature should be used as an opportunity to explore new crops and spoke about someone who had successfully grown a banana outside in Cornwall.

“Apricots and nectarines on a commercial scale we believe will achieve economic gain in the UK rather than just surviving.” The centre is currently trialling hardy kiwis to see whether they can be grown as a crop.

Speaking about his own cherry trees in his garden, he said that this year they had produced more fruit than over the last 15.

"Fog prevents water loss from Redwoods in summer, and is really important for both the tree and the forest," he said. "If the fog is gone, we might not have the Redwood forests we do now."