Secrets of Antarctica`s fossilised forests
Baku, February 8 (AZERTAC). 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 and 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. But if global warming continues unabated, could these ancient forests be a taste of things to come? One of the first people to uncover evidence for a once greener Antarctic was none other than the explorer, Robert Falcon Scott. Toiling back from South Pole in 1912, he stumbled over fossil plants on the Beardmore Glacier at 82 degrees south. The extra weight of these specimens may have been a factor in his untimely demise. Yet his fossil discoveries also opened up a whole new window on Antarctica`s sub-tropical past. Professor Jane Francis of the University of Leeds is an intrepid explorer who has followed in Scott`s footsteps. She has spent 10 field seasons in Antarctica collecting fossil plants and received the Polar Medal from the Queen in 2002.
"I still find the idea that Antarctica was once forested absolutely mind-boggling", she told the BBC.
"We take it for granted that Antarctica has always been a frozen wilderness, but the ice caps only appeared relatively recently in geological history." One of her most amazing fossil discoveries to date was made in the Transantarctic Mountains, not far from where Scott made his own finds.
She recalled: "We were high up on glaciated peaks when we found a sedimentary layer packed full of fragile leaves and twigs." These fossils proved to be remains of stunted bushes of beech. At only three to five million years old, they were some of the last plants to have lived on the continent before the deep freeze set in. However, other fossils show that truly subtropical forests existed on Antarctica during even earlier times. This was during the "age of the dinosaurs" when much higher CO2 levels triggered a phase of extreme global warming. "Go back 100 million years ago and Antarctica was covered in lush rainforests similar to those that exist in New Zealand today," said Dr Vanessa Bowman who works with Francis at the University of Leeds. "We commonly find whole fossilised logs that must have come from really big trees." Professor Francis has been polishing thin slices of these logs to reveal the "annual rings" in the wood. Studying these tree-rings sheds light on ancient climate.
Dark secrets
Possibly the weirdest and most baffling feature of the polar forests was their adaption 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.
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