Earthworms have long been considered a friend to farmers and home gardeners, playing a vital role in soil quality. However, recent studies have shown that glaciated forests in North America—forests that evolved without native earthworms–now face the invasion of European earthworms from agriculture and fishing.
This underground invasion has compounding impacts on the capacity of the soil to provide nutrients and sequester carbon—an important role as the world faces global climate change.
Prior to colonization, the glaciated areas of North America were devoid of native earthworms. European earthworms were first introduced to U.S. soils when immigrants brought crops from their native lands, harboring earthworm cocoons. Worms made their way to the edges of farmlands and to the forests.
“Gardeners and farmers all appreciate the beneficial effect of earthworms,” says Yoo, “However, there were systems where worms didn’t exist before and, as we have seen with other non-native invasions, there are ecosystem implications…”
Recent studies have shown that forest composition, with earthworm invasion, can change in as little as 30 to 40 years. As early as the 1940s, researchers studied the impact of invasive earthworms on soils, in terms of the soil chemistry and physics; however, it has only been within the last decade that the focus has shifted to the impacts on the entire ecosystem.
No doubt this will amuse those of you who haven’t followed my musings for a long spell; but, this is a favorite topic of mine. Generally, I don’t succeed in convincing people that earthworms are an imported replacement – even though the logic of life underground generally having ceased during glaciation is easily understood.
The topic is fascinating and, honestly, I wonder where this study will lead? Personally, my guess is that forests will accommodate the wiggly additions to the woodscape. They probably did so between previous Ice Ages is my guess.
Now, of course, I have to wander off to investigate that, as well. 🙂