Forests are supposed to reduce carbon dioxide levels, but new research shows that the increase in fires and their tendency to burn larger areas of forest are converting forests into generators of carbon.
“Since the proliferation of black spruce, Alaskan soils have acted as huge carbon sinks,” says Evan Kane, a research assistant professor in Michigan Technological University’s School of Forest Resources and Environmental Science. “But with more frequent and more extensive burning in recent decades, these forests now lose more carbon in any fire event than they have historically been able to take up between fires.”
American and Canadian researchers, of which Kane was one, collected data on the depth of ground-layer combustion I 31 Alaskan black spruce forest and peatland fires to find that with increased fires more trees and layers of moss, peat and leaf litter are burned, releasing the carbon that is stored in each.
The research was published in the recent edition of the journal Nature Geoscience.
Not only does the burning of these ground layers cause an initial release of carbon into the atmosphere, but their removal goes on to affect other natural processes, such as regulation of soil climate, maintenance of permafrost, and the kids of trees that can grow back; new forests are weaker carbon sinks than the original black spruce forests were.
Showing a trend towards increased carbon loss, the researchers found that the annual carbon losses from forests fires between 2000 and 2009 were more than double the amount of carbon lost during the previous five decades.
Adding to the worries in the already fragile Arctic is the fact that an increase in fires will only hasten the loss of the already diminishing permafrost, thus minimizing the reflectivity of the area and as a result increasing the negative effects of climate change.