Invading earthworms pose climate threat

Abstract

Invasive earthworms are spreading into the northern forests of Canada and the US, disturbing the soil and transforming ecosystems, researchers reported at the American Geophysical Union Fall Meeting in San Francisco in December. This “global worming” could contribute to climate change by potentially unleashing the large stocks of carbon stored in northern soils. The boreal forests—large expanses of wild lands in the planet’s northern latitudes—are Earth’s largest terrestrial carbon sink. Their soils hold an estimated 200 billion metric tons (t) of carbon, 60 billion t of it in Canada alone. Until about 20 years ago, scientists didn’t think it was possible for earthworms to survive in the relatively cold, acidic soils of the Canadian boreal forests. But these days researchers find the worms just about everywhere they look, says Justine Lejoly, a researcher in the lab of University of Alberta soil biogeochemist Sylvie Quideau. People spread the critters when they