Boreal forest fires important source of emissions
mongabay.com
October 31, 2007




Forest fires in the boreal forests of Canada are an important source of greenhouse gas emissions reports a new study published in the journal Nature.

University of Wisconsin-Madison forest ecology professor Tom Gower, and colleagues write that fires trigger the release of large amounts of carbon dioxide through mechanisms in addition to burning. The loss of tree canopy following a fire can allow more sunlight to reach the forest floor, leading to increased decomposition and rates of carbon emissions. Warming can melt underlying permafrost, releasing even more stored carbon.

Gower adds that climate change is creating warmer and drier conditions conducive to forest fires.

"All it takes is a low snowpack year and a dry summer," he said. "With a few lightning strikes, it's a tinderbox."

Gower and colleagues say their model suggests that boreal forests are becoming less effective as a carbon sink and that they could soon become a carbon source, contributing to climate change.

"The soil is the major source, the plants are the major sink, and how those two interplay over the life of a stand really determines whether the boreal forest is a sink or a source of carbon," said Gower. "Based on our current understanding, fire was a more important driver (of the carbon balance) than climate was in the last 50 years. But if carbon dioxide concentration really doubles in the next 50 years and the temperature increases 4 to 8 degrees Celsius, all bets may be off."

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Boreal forest fires important source of emissions.

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