"Our results suggest we need to rethink this," he says. "Rather than there being an intrinsic limit on how much carbon a forest can store, how we use the forest how much we log, how we manage may be more important."
The findings come amid sweeping discussions of international carbon treaties and accounting systems that are designed to reduce CO2 emissions and combat climate change. In the future, for instance, countries might earn credits for maintaining carbon-rich old-growth forests, or replanting trees on lands logged off previously for agriculture.
Areas that once supported large amounts of forest biomass might also be good sites for growing plantations of hybrid poplar and other biofuels crops, says Mladenoff. But, he cautions, any move toward planting more land in trees must be weighed against competing social and economic factors, such as the need for farmland.
"The landscape is full," says Mladenoff. "So if we're going to add something like forests, we're going to need to take something out."
That certainly seems to be true in Wisconsin. Based on historic carbon levels, the researchers' analysis found that much of the best land for growing trees is the north-central region and along northern Lake Michigan. If those lands could be reforested to pre-settlement levels, the scientists estimate they could add 150 teragrams of carbon (150 million metric tons) to the state's current total of approximately 275 teragrams.
The problem, however, is that most of those lands are still being farmed, setting up an interesting dilemma for policy makers: how to weigh the current economic benefit of agriculture against the future environmental benefit of carbon storage.
"Because we often forget the invisible services, like climate regulation, that ecosystems prov
|Contact: David Mladenoff|
University of Wisconsin-Madison