Climate Change

Published on June 18th, 2012 | by James Ayre

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Expansion of Forests Into The Arctic Will Release Carbon Dioxide

June 18th, 2012 by

20120618-104328.jpgThe Arctic is becoming greener as plant growth increases due to warmer temperatures. More plant growth means more carbon stored as biomass, so it had been thought that this would lead to the Arctic removing enough carbon dioxide from the atmosphere to slow warming slightly.

But new research shows that the stimulation of decomposition rates in the Arctic soil outweighs the influence of the increased plant biomass. The researchers found that the expansion of forests into the tundra in northern Sweden will release carbon dioxide into the atmosphere.

Dr Iain Hartley, now at the University of Exeter and lead author of the paper, said: “Determining directly how carbon storage is changing in high-latitude ecosystems is very difficult because the majority of the carbon present is stored below ground in the soils. Our work indicates that greater plant biomass may not always translate into greater carbon storage at the ecosystem level.”

“We need to better understand how the anticipated changes in the distribution of different plant communities in the Arctic affects the decomposition of the large carbon stocks in tundra soils if we are to be able to predict how arctic greening will affect carbon dioxide uptake or release in the future.”

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The researchers measured carbon stocks in vegetation and in soils, in both tundra and neighboring birch forests. They found that “the two-fold greater carbon storage in plant biomass in the forest was more than outweighed by the smaller carbon stocks in forest soils.”

In addition, using a different methodology based on measuring the radiocarbon content of the CO2 being released, the researchers found that the birch trees appeared to be stimulating the decomposition of organic matter in the soil. Which means that birch trees can contribute directly to the release of carbon, from soils, into the atmosphere.

Dr Gareth Phoenix, of the University of Sheffield’s Department Animal and Plant Sciences, said: “It shows that the encroachment of trees onto Arctic tundra caused by the warming may cause large release of carbon to the atmosphere, which would be bad for global warming.”

“This is because tundra soil contains a lot of stored organic matter, due to slow decomposition, but the trees stimulate the decomposition of this material. So, where before we thought trees moving onto tundra would increase carbon storage it seems the opposite may be true. So, more bad news for climate change.”

“The results of the study are in sharp contrast to the predictions of models which expect total carbon storage to increase with the greater plant growth. Rather, this research suggests that colonisation by productive, high-biomass, plant communities in the Arctic may not always result in greater capture of carbon dioxide, but instead net losses of carbon are possible if the decomposition of the large carbon stocks in Arctic soils are stimulated. This is important as Arctic soils currently store more carbon than is present in the atmosphere as carbon dioxide and thus have considerable potential to affect rates of climate change. It is yet to be seen whether this observed pattern is confined to certain soil conditions and colonising tree species, or whether the carbon stocks in the soils of other arctic or alpine ecosystems may be vulnerable to colonisation by new plant communities as the climate continues to warm.”

Source: University of Exeter
Image Credits: Martin Sommerkorn, Svalbard via Shutterstock

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About the Author

's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy. You can follow his work on Google+.



  • Malugssuak

    That is ridiculous!

    Plants inhale carbon dioxide and exhale oxygen. This is basic 8th grade science.

    As the climate warms plants will push north. The taller and denser the plant’s greenery the greater its oxygen-producing potential per square meter of land surface. Oxygen production will thus increase to offset greenhouse gas releases from warming surface temps. This is for the Western Arctic; muskeg and Eastern Arctic forms are far less involved in this transformation due to their land surface neutrality regarding climate change.
    In addition, climate warming will mean that field crops and other farming becomes viable on virgin lands across Siberia and the Western Arctic of North America. This will result in a vast increase in cereals and truck farming crop stores.

    • http://zacharyshahan.com Zachary Shahan

      Sorry, but did you read the article at all? If it doesn’t provide enough detail, check out the actual study. These scientists aren’t morons.

      As far as the last comment, that claim of vast increase in cereals and such doesn’t hold up. Increased drought, fires, flooding, and climate shifts will do more harm to our agricultural systems than good. Please, read up on the science before making such comments.

  • rj

    Solution: cut down all the birch trees.

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