Higher plants in the Arctic warmer

Shrubs, grasses and other lowland plants growing in the Arctic are becoming larger.

The results come from scientists who analyzed three decades of measurements.

These data, collected in Alaska, Canada, Iceland, Scandinavia and Russia, indicate that global warming is driving change.

The team of 180 researchers said that increasing the height could eventually raise the temperature.

The international group reports its work in the journal Nature.

Isla Myers-Smith, co-author of the University of Edinburgh, UK, predicted that Arctic flora, which measured several inches in height, could double as much as one year ago. here the end of the century.

"It does not seem to be a very dramatic increase, but if you compare it to the ecosystems around your house, like the nearby forest, if you imagine that this forest would become twice as big, it changes dramatically." .

The plants must be robust to thrive in the extreme north or in the high alpine mountains.

The cold and short growing season prevents trees. Instead, the tundra landscape is populated by small species that cling to the ground. But the Arctic is undergoing rapid changes.

The last decades have seen the region experience one of the fastest warming rates on the planet. It's not just that existing plants have increased their stature, although this is the case; it is more than larger species now invading areas where they never grew in large numbers.

For example, common-odor hay, which is common in lowland Europe, has now entered the research plots in Iceland and Sweden, where long-term monitoring is undertaken.

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Why is height important?

The reconfiguration of plant communities is important because it could alter the functioning of the tundra ecosystem.

The taller Arctic plants will capture more snow around them, insulating the soil from very cold air and preventing it from freezing so hard. This facilitates defrosting of generally rocky soils in summer and releases their carbon into the atmosphere. That would add to the warming.

Higher plants could also have the same result because, by placing their heads above the snow, they would present a darker surface, which would allow the ecosystem to trap more heat from the sun.

"While there are still many uncertainties, higher tundra plants could fuel climate change, in the Arctic and for the planet," said Anne Bjorkman, co-principal investigator. of the Biodiversity and Climate Research Center of Senckenberg. Germany.

How does this study stand out?

It's remarkable by its magnitude. It integrates more than 60,000 observations of data from hundreds of sites in the Arctic and in the European Alps and the American Rockies.

The information goes back several decades and can reliably detect real trends.

Scientists will come back to specific places to take the same steps again and again. These measures cover everything from plant height and leaf area to wood density, seed size, leaf chemistry, and so on.

The researchers who initiated the first data collection would never have known exactly how their persistence would ultimately bear fruit. They would have simply recognized that long series of observations are invaluable.

"One of the goals of our project was to make this database publicly available so that future researchers can ask questions that we can not anticipate at the moment," said Dr. Myers-Smith.

UK funding for this project comes from the Natural Environment Research Council. You can find out more about the Team Shrub and Arctic Above websites.

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