Tuesday, February 8, 2011

Secrets of Antarctica's fossilised forests

Peter Trusler (written permission obtained by HF-L)It may be hard to believe, but Antarctica was once covered in towering forests.

One hundred million years ago, the Earth was in the grip of an extreme Greenhouse Effect.

The polar ice caps had all but melted; in the south, rainforests inhabited by dinosaurs existed in their place.

These Antarctic ecosystems were adapted to the long months of winter darkness that occur at the poles, and were truly bizarre. ...

Possibly the weirdest and most baffling feature of the polar forests was their adaptation to the Antarctic "light regime". Near the pole, night reigns all winter long while in the summer, the sun shines even at midnight.

Professor David Beerling of the University of Sheffield, and author of Emerald Planet, explained the challenge that Antarctic trees must have faced in this unusual environment: "During prolonged periods of warm winter darkness, trees consume their food store," he said. And if this goes on for too long, they will eventually "starve".

To understand how trees survived against the odds, Professor Beerling has been investigating the kinds of plants that once grew on Antarctica. These include trees like the Ginkgo, a living fossil.

"What we did was grow seedlings of these trees in blacked-out greenhouses where we could simulate Antarctic light conditions", he told the BBC.

"We also raised temperature and CO2 concentration to match ancient growing conditions."

His experiments showed that trees could cope remarkably well with the strange environment. Although they used up food stores in the winter, they more than made up for this by their ability to photosynthesise 24 hours per day in the summer. ...

via BBC News - Secrets of Antarctica's fossilised forests.

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