Potential to amass more carbon in eastern North American forests

Science Daily: With climate change looming, the hunt for places that can soak up carbon dioxide from the atmosphere is on. Obvious "sinks" for the greenhouse gas include the oceans and the enormous trees of tropical rainforests. But temperate forests also play a role, and new research now suggests they can store more carbon than previously thought.

In a study that drew on both historical and present-day datasets, Jeanine Rhemtulla of McGill University and David Mladenoff and Murray Clayton of University of Wisconsin-Madison quantified and compared the above-ground carbon held in the forest trees of Wisconsin just prior to European settlement and widespread logging, and the total carbon they contain today.

Writing in the current issue of the Proceedings of the National Academy of Sciences, the researchers report that despite decades of forest recovery, Wisconsin's woodlands still only hold about two-thirds the carbon of pre-settlement times — suggesting substantial room for them to accumulate more. "There's probably more potential (to store carbon) than people were considering," says Mladenoff. "There's still a big difference between what was once there and what's there now."

He adds that the true storage potential is probably at least two-fold higher than what he and Rhemtulla calculated, since they factored in only the live, above-ground biomass of tree trunks and crowns, and not the carbon stored in roots and soil.

The results have implications not only for Wisconsin, but also for regions across eastern North America where forests were leveled historically to make room for agriculture, and then grew up again as settlers abandoned their farms and headed west. In Wisconsin, for example, forest biomass and carbon have been steadily recovering since the peak of agricultural clearing in the 1930s, while those in the northeastern U.S. have been rebounding for about 125 years….

Forest Hill House, Franconia, New Hampshore, 1909