Huffpost Science

Ancient Antarctica's Forests Featured Weird Trees, Wood Fossils Show

Posted: Updated:
ANTARCTIC FORESTS
A fossilized tree trunk protrudes through ice near Antarctica's Mount Achernar. | Patricia Ryberg

DENVER — Strange forests with some features of today's tropical trees once grew in Antarctica, new research finds.

Some 250 million years ago, during the late Permian and early Triassic, the world was a greenhouse, much hotter than it is today. Forests carpeted a non-icy Antarctic. But Antarctica was still at a high latitude, meaning that just as today, the land is bathed in round-the-clock darkness during winter and 24/7 light in the summer.

The question, said Patricia Ryberg, a postdoctoral researcher at the University of Kansas Biodiversity Institute, is how plants coped with photosynthesizing constantly for part of the year and then not at all when the winter sun set.

"The trees are the best way to figure this out, because trees record physiological responses" in their rings, Ryberg told LiveScience.

A forest mystery

Fossilized wood and leaf impressions record a history of the Antarctic forests. The leaf impressions appear to show mats of leaves, as if the trees had all shed at once — a sign of a deciduous forest.

To confirm this, Ryberg and her colleagues gathered samples of fossil wood and examined the tree rings. Wood cells in the rings reveal how the trees grew: Early wood is produced when the tree is growing upward and outward. Late wood is produced when the tree is preparing to go dormant. At that point, the tree stops growing and starts storing carbon in its cells. Late wood is denser than early wood, and has thicker cell walls.

Deciduous and evergreen trees have different patterns of late and early wood. Ryberg and her colleagues examined the Antarctic fossils and found that they looked evergreen. [Image Gallery: Life at the South Pole]

"Now we have leaves that suggest a deciduous habit and fossil wood that is suggesting an evergreen habit, so we have a bit of a contradiction going on," Ryberg said here Wednesday (Oct. 30) at the annual meeting of the Geological Society of America.

antarctic trees
A microscopic look at Antarctic wood from the Triassic period, when forests carpeted this now-icy continent.

Mixed results

Follow-up studies analyzing carbon molecules in the fossil wood also gives both deciduous and evergreen answers, Ryberg said. The implication is that ancient Antarctic forests may have been a mix of deciduous and evergreen.

"It's not one or the other," she said. "It's actually both."

Much of the ring structure looks tropical, Ryberg added. Tropical trees that are not exposed to seasons experience a sort of short-term dormancy that echoes what is seen in the Antarctic wood.

"But they weren't growing in the tropics, so obviously it's two different environmental characteristics," Ryberg said.

Ryberg is now investigating how much plant matter these strange Antarctic forests produced. It's not yet clear whether the forests grew more densely than those seen in modern forests.

Follow Stephanie Pappas on Twitter and Google+. Follow OurAmazingPlanet @OAPlanet, Facebook and Google+. Original article at LiveScience's OurAmazingPlanet.

Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Also on HuffPost:

Close
Yuka Woolly Mammoth Baby
of
Share
Tweet
Advertisement
Share this
close
Current Slide

Suggest a correction

Around the Web

Weird Forests Once Sprouted in Antarctica - Yahoo News

BBC News - Secrets of Antarctica's fossilised forests

Antarctica was once home to rain forest - Mother Nature Network

Why so cold? The last refuge of Antarctica's forests | Ars Technica

Forests in Antarctica After the Flood? - Answers in Genesis

Just 12 million years ago, there were forests on Antarctica - io9

AFP: Drilling discovers ancient Antarctic rainforest - Google

Fossils from Antarctica reveal evidence of lush vegetation | Natural ...

Antarctica Was Once Home To Rainforest, Say Scientists

Antarctica harboured strange forests 250 million years ago?

Weird Forests Once Sprouted in Antarctica