A slow-motion invasion has been occurring beneath our feet for the past 300 years. Year after year, a swarm of invasive earthworms has silently burrowed their way through the leaf litter of our forests, grasslands, and private gardens.
Although earthworms are useful for growing food, research indicates that they are causing damage to our forests and may be contributing to climate change. The majority of North America is devoid of earthworms. A massive ice sheet blanketed the northern portion of the North American continent until around 10,000 years ago. According to scientists, it wiped out any earthworms that may have been in the area prior to the previous glacier.
With the arrival of European settlers in the 18th century, earthworms were reintroduced to North America. According to Michael McTavish, a postdoctoral research researcher at the University of Toronto who specializes in the ecology of non-native earthworms, Canada today has more than 30 species of non-native earthworms.
“Earthworms affect everything from the decomposition of organic matter to nutrient cycling, carbon storage, and how water travels through [the soil] by physically modifying the soil environment,” McTavish explained. “They basically have a general impact on everything.”
Although they are commonly thought of as helpful gardeners, they can be a startling destructive force in other areas.