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Last Updated: Friday, 15 June 2007, 07:50 GMT 08:50 UK
Arctic ice no barrier for plants
Mountain avens (Image: Bjorn Erik Sandbakk)
Arctic plant species can travel vast distances, researchers suggest
Arctic plants are able to migrate the distances needed to survive changes to the climate, scientists have suggested.

Habitats are expected to shift further north as the planet warms, and plants' inability to move quickly enough has been a cause for concern.

But researchers, writing in the journal Science, suggest seeds can be carried vast distances by the wind and sea ice.

The biggest challenge, they added, was likely to be their ability to establish themselves in the new habitat.

Researchers from Norway and France analysed more than 4,000 samples of nine flowering plant species found on the remote Svalbard islands inside the Arctic Circle.

By analysing the genetic fingerprints of the plants, the team reconstructed past plant colonisation and decline in the area.

They found evidence that seeds from plants from various sources, including Russia and Greenland, had repeatedly colonised the islands over the past 20,000 years when climatic conditions allowed.

Likewise, when the islands cooled, the plants died out because they were unable to survive under blankets of ice.

Seeds of hope

Climatologists project the polar regions are going to experience the largest degree of climate change over the coming century, risking the long-term stability of ecosystems.

Map showing location of Svalbard (Image: BBC)
"Climate change is expected to cause the distribution area of many plant species to shift northwards in the Northern Hemisphere," the researchers wrote in their paper.

"The composition of future ecosystems will critically depend on the long-distance dispersal capabilities of individual species."

It had been assumed that long-distance dispersal of seeds happened rarely and randomly, making the chance of colonisation unlikely.

Yet, the team said, the study suggested it was more common than previously thought.

"Probable dispersal vectors are wind, drift wood and drifting sea ice, birds and mammals.

"North-western Russia and Greenland are frequently connected to Svalbard by way of sea ice during the winter.

"Bank erosion along the Russian rivers routinely results in logs and other debris finding their way on to drifting sea ice, which reaches Svalbard by means of surface currents."

They suggested the main limiting factor was the plants' ability to establish themselves through "germination, survival and local reproduction".

"This interpretation is supported by our observation that 80-90% of the most cold-adapted species that occur in the potential source zones are currently present in Svalbard," the team wrote.

Whereas, they added, only 40-60% of the species limited to zones where summer temperatures of 6-7C (43-45F) were found on the islands.

The findings suggest future studies should have greater confidence that seeds can travel long distances, and place more emphasis on whether there is suitable habitat to sustain the plant species.




SEE ALSO
Climate threat has plants quivering
20 Apr 07 |  Science/Nature
New crops needed to avoid famines
03 Dec 06 |  Science/Nature
Climate response risks to nature
03 Nov 05 |  Science/Nature
Earth's species feel the squeeze
21 May 05 |  Science/Nature

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