Science News checks out yet another disaster, though one on a smaller scale and a bit closer to the ground than most, as armies of Asian jumping worms are suddenly exploding across America’s forests“:
Endemic to Japan and the Korean Peninsula, three invasive species of these worms — Amynthas agrestis, A. tokioensis and Metaphire hilgendorfi — have been in the United States for over a century. But just in the past 15 years, they’ve begun to spread widely. Collectively known as Asian jumping worms, crazy worms, snake worms or Alabama jumpers, they’ve become well established across the South and Mid-Atlantic and have reached parts of the Northeast, Upper Midwest and West.
Jumping worms are often sold as compost worms or fishing bait. And that, says soil ecologist Nick Henshue of the University at Buffalo in New York, is partially how they’re spreading. Fishers like them because the worms wriggle and thrash like angry snakes, which lures fish, says Henshue. They’re also marketed as compost worms because they gobble up food scraps far faster than other earthworms, such as nightcrawlers and other Lumbricus species.
To date, scientists have worried most about the worms’ effects on ground cover. Prior to a jumping worm invasion, the soft layer of decomposing leaves, bark and sticks covering the forest floor might be more than a dozen centimeters thick. What’s left afterward is bare soil with a different structure and mineral content, says Sam Chan, an invasive species specialist with Oregon Sea Grant at Oregon State University in Corvallis. Worms can reduce leaf litter by 95 percent in a single season, he says.
That in turn can reduce or remove the forest understory, providing less nutrients or protection for the creatures that live there or for seedlings to grow. Eventually, different plants come in, usually invasive, nonnative species, says Bradley Herrick, an ecologist and research program manager at the University of Wisconsin–Madison Arboretum. And now, new research shows the worms are also changing the soil chemistry and the fungi, bacteria and microbes that live in the soils.
You can read some worm research in Soil Biology and Biochemistry.