* Tree, 9,550 years old, aided by global warming
* Unpredictable weather harms other plants as ranges change
* Spruce's survival may offer clues for cash crop pioneers
By Alister Doyle
FULUFJALLET, Sweden, Oct 19 (Reuters) - On a windswept Swedish mountain, a 10,000-year-old spruce with a claim to be the world's oldest tree is getting a new lease of life thanks to global warming, even as many plants are struggling.
Scientists are finding that the drift of growing areas for many plants out toward the poles is moving not in a smooth progression but in fits and starts, causing problems for farmers aiming to adapt and invest in cash crops that are more sensitive to climate than is this ancient conifer known as "Old Tjikko".
At a range of latitudes, but especially in the far north, climate change is bringing bigger than expected swings, putting billions of dollars at stake in a push to develop varieties with resilience to frost and heatwaves, drought or flood.
Understanding those plants which are thriving in such hectic environments - like this ragged Christmas tree on a marshy plateau 900 metres (3,000 feet) above sea level - may yield clues: "It seems to be growing quite well," said researcher Leif Kullman. "That's a result of warming in the past 100 years."
Old Tjikko stands above dead roots that Kullman, from Umea University, says date from 9,550 years ago, just as the Ice Age ended. The spruce regenerates clones when low branches sprout new roots so that, unlike California's Methuselah bristlecone pine whose trunk bears over 4,800 annual growth rings, today's 5-metre tall (16-foot) trunk began growing only about 1940.
Yet the tree's survival in the same spot since the earliest days of agriculture may offer lessons for pioneers trying to take advantage of global warming to push the frontiers for crops further north but finding most plants to be far more sensitive.
"There will be no nice wine from Sweden this year," lamented Lauri Pappinen, one of a handful of new wine producers on the Swedish island of Gotland in the Baltic, where grapes failed to mature after a cool spring followed by mildew in a wet summer.
The failure of Pappinen's 2012 harvest was the first since he started producing a decade ago as an experiment on the same latitude as southern Alaska or Siberia. The Nordic region is aided by the Gulf Stream bringing warm water from the tropics.
GRAPES OF ROT
"Maybe we could collect 300 kg (660 lbs) of grapes. But it's not worth making the machines dirty," he said, adding that his 3.5 hectare (8.6 acre) vineyard can produce up to 10,000 kg. "The starlings are having a big party right now," he said.
Climate unpredictability is especially true further north, in the Arctic, where the extent of ice on the Arctic Ocean shrank to a record low this summer. Less attention has been paid to how the thaw affects growing conditions on land.
"That's been a surprise in the last years. Everyone thought it would be warmer and nice weather. But suddenly it's wetter and colder in some regions," said Lars-Otto Reiersen, head of the Secretariat of the Arctic Monitoring and Assessment Programme.
Many studies show that more carbon dioxide in the atmosphere, the main greenhouse gas, will initially lead to more growth of plants worldwide. But, Reiersen said, not enough study has been made of the downside of increased unpredictability.
Part of the problem for crops at higher latitudes is that the sun still rises and sets at the same times - the light will always be faint in spring and autumn even if the air is warmer.
"There will be extreme weather and that also means risks of frosts in the growing season," said Inger Alsos, a professor at the University of Tromsoe in Norway and a specialist in Arctic ecology. "Frost resistance is a key trait."
Plant breeders and genetic experts were working with a frost-resistant clover, for instance, recently found on Svalbard, a chain of Norwegian islands in the North Atlantic, 1,000 km (600 miles) below the North Pole. It could be developed to help grow animal fodder in the north.
And Kullman from Sweden said experiments show that spruces, for instance, produce a type of anti-freeze letting them survive down to about minus 50 Celsius (minus 60 Fahrenheit). That might also help genetic research into frost resistance.
But for many crops, the expansion of potential growing areas due to climate change may not add to overall production.
"The overall balance will stay as it is," said Hans-Joachim Braun, head of the global wheat programme at the International Maize and Wheat Improvement Center based in Mexico City.
"The losses from climate change will offset the benefits we have expanding in high-latitude areas."
"There will be beneficiaries, such as the United States, Canada, Kazakhstan, Russia," he said, noting that wheat now grows as far north as southern Scandinavia. But many developing nations that now produce wheat will lose out as it gets too hot.
Plant breeders have made huge progress in the past. Maize, for instance, is a tropical crop that has been adapted to grow at lower temperatures and with longer summer daylight hours in places like the United States or Europe, he said.
In the far north, Arctic plants may struggle since they cannot extend their ranges much if the climate warms - there is no land in cooler latitudes, only the Arctic Ocean and icecap.
The northern bilberry, for instance, is likely to gain tiny new areas on the coast of Greenland or on Russian Arctic islands this century as the climate warms. But it will lose big tracts of growing territory to the south, said Alsos at Tromsoe.
"The same is true of many Arctic plants," she added.
Experts disagree about Greenland's potential to provide a fertile new agricultural space as equatorial lands burn up.
Some speak of a new boom in the Danish territory as melting ice opens the Arctic to shipping, mining and oil exploration.
But farming in most of Greenland is a long way off.
Alsos said any thaw in Greenland, shrinking the fringes of an ice sheet that is 3,000 metres, or two miles, thick, will reveal barren ground. "There is no topsoil," she said. That would take decades, or centuries, to form.
"And we are talking about Arctic plants. Agriculture is not really part of it," she said. Southern Greenland, populated, if only sparsely, can now grow more potatoes or carrots and animal fodder, she said. But agriculture will remain marginal.
After past failures, almost 200 nations have agreed to work out a global deal to slow climate change by the end of 2015 that will enter into force in 2020 to help avoid more heatwaves, floods and rising sea levels. While that may be vital to ensure many crops, Old Tjikko can probably cope with the changes.
Kullman said the spruce had survived partly due to factors such as its isolation from other trees on a boggy area with no reindeer. The animals can damage trees with their antlers and isolation means less risk of damage from forest fires.
And he said that, while there would be disruptions to all plants as the climate warmed, their ability to survive should not be underestimated: "All of our species," he said, "Have survived previous inter-glacial periods that were even warmer."
The biggest threat to Old Tjikko is probably not climate change, according to Eduardo Zuniga, a guide who shows occasional visitors the tree on its trackless plateau in Fullufjallet National Park, northwest of Stockholm. Some springy lichen has been trodden flat by sightseers coming to gaze on the "world's oldest tree", threatening to damage its roots.
"We may," he said, "Have to put up a fence."
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