Wildfire drives carbon levels in northe...( MADISON - Far removed from streams o...)

MADISON - Far removed from streams of gas-thirsty cars and pollution-belching factories lies another key player in global climate change. Circling the northern hemisphere, the conifer-dominated boreal forests - one of the largest ecosystems on earth - act as a vast natural regulator of atmospheric carbon levels.

Forest ecologists at the University of Wisconsin-Madison are studying how environmental factors such as forest fires and climate influence carbon levels in this forest system. Their most recent findings, reported in the Nov. 1 issue of the journal Nature, offer insight into the balance of carbon uptake and release that contribute to atmospheric carbon dioxide levels worldwide.

Second in size among forests only to the tropical rainforests, the boreal forests form a massive green band spanning the higher latitudes of Canada, Alaska, Siberia, China, and Scandinavia. Their sheer size, coupled with the fact that they are expected to experience the greatest warming of any forest biome as global temperatures rise, means that climate-related changes here are likely to resonate well beyond the forest boundaries, says S. Tom Gower, UW-Madison professor of forest ecology and management and primary investigator of the project.

In the new study, Gower and his colleagues used a computer model to simulate the carbon balance of one million square kilometers of the Canadian forest over the past 60 years, to determine the relative impacts of climate and disturbance by wildfire.

The group found that the effects of carbon dioxide and climate - temperature and precipitation - varied from year to year but generally balanced out over time and area. Instead, forest fires during the 60-year period had the greatest direct impact on carbon emissions from the system.

However, "because fire frequency and fire intensity are directly controlled by climate change, it doesn't mean that we shouldn't be focusing on climate change," Gow
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