Forest Regrowth Key to North American CO2 Sink

North American land use has had major impact on global environment

The reforestation of former farmland over the last century has played an important role in reducing the accumulation of greenhouse gasses in the atmosphere, according to Princeton scientists.

The scientists, publishing in the Nov. 10 issue of Science, reported that changes in land use have been critical in allowing North American forests to regrow and soak up large amounts of carbon dioxide. Previous studies had suggested that other factors, such as the fertilizing effects of carbon dioxide, were spurring forests to absorb more carbon dioxide.

"Changes in the way we manage our land have had a real impact on the global environment," said the paper's lead author, John Caspersen.

... Then, in 1996, a Princeton-led group reported that much of this absorption was happening in the United States and neighboring countries - a phenomenon called the "North American carbon sink."

... coming from the recovery of forests on land that had been cleared for agriculture in the 1800s. In a collaboration between scientists at Princeton, the University of New Hampshire and the U.S. Forest Service, the researchers performed a careful analysis of inventory data in five states, comparing recent growth rates to historical growth rates. The analysis showed that forests have been growing at nearly the same rate for most of this century...

The result is also important for scientists developing computer models of ecosystems and climate. Many of these models only take into account physiological processes, such as the supply of nutrients and carbon dioxide, whereas the dominant factor governing carbon uptake in North American forests is historical changes in land use.

[Kyoto gives no credit to CO2 uptake - it couldn't bilk billions from us if the mitigating factor of our reforestation efforts (~1 Million acres a year for the past 40 years} was taken into account - so they don't.]

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