Study links C02 to demise of grazing lands

Rising levels of carbon dioxide in the atmosphere may be contributing to the conversion of the world's grasslands -- crucial for livestock grazing -- into a landscape of useless woody shrubs, according to a study released today.

By artificially doubling carbon dioxide levels over enclosed sections of the Colorado prairie, researchers created a dramatic rise in Artemisia frigida, commonly known as fringed sage.

The study paints a harsh picture of what grazing lands could look like in 2100, when some project carbon dioxide levels will be double today's.

"To the extent that CO2 is driving this conversion, this suggests the problem is going to become more intractable in the future," said Jack Morgan, a plant physiologist at the U.S. Department of Agriculture and lead author of the study, published in the Proceedings of the National Academy of Sciences.

Scientists believe the degradation of range lands, which cover about 40% of Earth's land surface, is mostly because of overgrazing and the modern practice of putting out fires rather than letting them burn, which destroys woody vegetation. But researchers have long suspected that rising carbon dioxide levels also play a role.

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