Hungry Musk-Oxen, Caribou Could Help Warming Arctic

August 19, 2008

Grazing musk-oxen and caribou may help protect the fragile Arctic ecosystem from the effects of global warming, according to a new study.

Large grazers could help the region by feasting on woody shrubs and plants that would otherwise take over as temperatures rise and change the way the Arctic looks and functions.

If shrubs dominated, they would darken Arctic lands and absorb more heat from the sun, enhancing warming due to greenhouse gases.

"Careful management and conservation of existing populations of musk-oxen and caribou, as well as other large herbivores, should be a priority in plans to mitigate the effects of climate change on ecosystems," said study leader and Pennsylvania State University researcher Eric Post.

"Until now, these animals seem to have been regarded more as background noise than as an active component of the ecosystem's response to warming," said Post, a National Geographic grantee. (The National Geographic Society owns National Geographic News.)

Grazing Control

As carbon dioxide levels continue to increase, the Arctic is heating up faster than almost anywhere else.

This additional warmth will likely boost the growth of woody shrubs at the expense of grasses in the Arctic, according to the study published online this week in the journal Proceedings of the National Academy of Sciences.

"Keeping [large grazers] in the picture will help maintain other components of the Arctic as we know it, or at least moderate the effects of global warming," Post said.

Post and Christian Pedersen, also at Penn State, used plots in western Greenland to measure the effects of these grazing animals.

Fences kept several patches free of grazers. Some of these patches were also enclosed by clear plastic walls, which raised temperatures inside by 2.7 to 5.4 degrees Fahrenheit (1.5 to 3 degrees Celsius), simulating future warming.

In the plots off-limits to grazers, shrubs such as dwarf birch spread, crowding out grasses, which make up nearly half of the biomass in western Greenland studied by Post.

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