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Re-Awakened Plants

Re-Awakened Plants Revived bryophytes from the Arctic Circle.
Photo Credit: Catherine LaFarge/University of Alberta

Plants that were frozen in glaciers 400 years ago are growing again as those glaciers melt away.


Transcript

Plants wake up from a deep freeze. I’m Bob Hirshon and this is Science Update.

On Ellesmere Island, in the Arctic Circle, mossy plants have been frozen in glaciers for centuries. Now, the glaciers are retreating, and some of those thawed-out plants are actually growing again. University of Alberta biologist Catherine La Farge and her colleagues recently confirmed this. She says it was already known that viruses, bacteria, and fungi could survive and even grow in glaciers.

La Farge:
But we never would have thought that you could have land plants, actually being able to be regenerated.

In the field, La Farge’s team saw signs of growth in the exposed mosses. Using radiocarbon dating, they confirmed that the plants were 400 to 600 years old. And several samples were able to grow in the lab. La Farge notes that these re-emerging plants could affect the entire ecosystem, by re-introducing genes that have long since disappeared. I’m Bob Hirshon for AAAS, the Science Society.


Making Sense of the Research

From about 1550 to 1850, the Northern Hemisphere (and possibly the entire planet) went through a period called the “Little Ice Age.” While it wasn't a true Ice Age, it was a period of cooler temperatures, colder winters, and advancing glaciers, compared with the Medieval period that came before it. Now, not only has the Little Ice Age naturally ended, but human activities have caused the planet to warm up even more, and glaciers the world over are melting away.

As these glaciers melt, they expose some of the material they covered up when they originally froze. These include mossy plants called bryophytes. As far back as the 1960's, scientists on Baffin Island (which, like Ellesmere, is within the Arctic Circle, north of mainland Canada) noticed signs of regrowth in these exposed bryophytes. However, they assumed the growth was actually new material from spores that had recently landed on the exposed plants and mixed in with them. In other words, they thought the old plants couldn't actually be growing themselves.

This assumption stood for a long time. But when La Farge's team visited Ellesmere Island, they found the re-exposed bryophytes not only showed signs of new growth, but also looked perfectly healthy. So they decided to take a closer look. They took samples from the bryophytes back to the lab, and used radiocarbon dating (a widely accepted scientific tool) to confirm that the samples were 400 to 600 years old.

Then came the big test. They ground up pure samples of the centuries-old bryophytes, and attempted to grow them in lab cultures and regular potting soil. In a number of cases, growth occurred. That shows that plant material that's been buried in ice for centuries can, in fact, start growing again.

It's not clear how common this is. In many parts of the world, glaciers advance and retreat in cycles, and La Farge doubts that bryophytes would be able to withstand repeated freezing, thawing, and re-freezing. But in places like Ellesmere Island, which have been consistently cold for centuries, some plants may be seeing the light of day for the first time since Europeans began exploring North America. These plants may be better preserved in their original condition, and more capable of regrowth.

One concern La Farge mentions is the effect these re-awakened plants might have on the local ecosystem. There's a good chance that some of the genes contained within these plants have been functionally extinct for centuries. Now, they could mix into the contemporary gene pool. It remains to be seen whether this would have a serious effect on newer plants.

Now try and answer these questions:

  1. What are bryophytes?
  2. Why are the bryophytes on Ellesmere Island being exposed after 400 years?
  3. How did the researchers confirm that old plants, originally buried centuries ago, can regrow?
  4. Would you expect this to happen more and more in the future? Why or why not?
You may want to check out these related podcasts:
 

In Pumpkin Planet, find out why melting glaciers are actually changing the shape of the Earth.

To learn more about the consequences of melting ice, listen to the podcast Siberian Permafrost.

In the Science Update Thoreau's Plants, learn how scientists are using Henry David Thoreau's journals from the mid-19th century (the end of the Little Ice Age) to track the effects of climate change around Walden Pond in Massachusetts.


Going Further


For Educators

In Pumpkin Planet, find out why melting glaciers are actually changing the shape of the Earth.

To learn more about the consequences of melting ice, listen to the podcast Siberian Permafrost.

In the Science Update Thoreau's Plants, learn how scientists are using Henry David Thoreau's journals from the mid-19th century (the end of the Little Ice Age) to track the effects of climate change around Walden Pond in Massachusetts.


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