Alanna Mitchell reports for the New York Times
Cindy Shaw, a carbon-research scientist with the Canadian Forest Service, studies the boreal forest — the world’s most northerly forest, which circles the top of the globe like a ring of hair around a balding head.
A few years ago, while conducting a study in northern Alberta to see how the forest floor was recovering after oil and gas activity, she saw something she had never seen there before: earthworms.
“I was amazed,” she said. “At the very first plot, there was a lot of evidence of earthworm activity.”
Native earthworms disappeared from most of northern North America 10,000 years ago, during the ice age. Now invasive earthworm species from southern Europe — survivors of that frozen epoch, and introduced to this continent by European settlers centuries ago — are making their way through northern forests, their spread hastened by roads, timber and petroleum activity, tire treads, boats, anglers and even gardeners.
As the worms feed, they release into the atmosphere much of the carbon stored in the forest floor. Climate scientists are worried.
“Earthworms are yet another factor that can affect the carbon balance,” Werner Kurz, a researcher with the Canadian Forest Service in Victoria, British Columbia, wrote in an email. His fear is that the growing incursion of earthworms — not just in North America, but also in northern Europe and Russia — could convert the boreal forest, now a powerful global carbon sponge, into a carbon spout.
Like this? Click to receive free updates
