Continental Changer: Earthworms were re-introduced to the Americas after a gap of 10,000 years by colonists from Europe
We all know that Christopher Columbus and European pioneers brought back potatoes, tobacco and rubber from the New World in the wake of his voyage of 1492, but a new book examines the overlooked impact of the Old World on the newly discovered Americas.
In fact so great was one import from Europe that its impact is still being felt today after having undermined the entire ecosystem of North America. And that illegal alien is the lowly earthworm.
Wiped out in North America since the Ice Age, the re-introduction of the earthworm by the British colonists of Jamestown caused the landscape that had formed for 10,000 years to radically alter and not for the better.
Earthworms eat fallen foliage, the problem is that northern trees and shrubs beneath the forest canopy depend on that litter for food too.
In its absence, water washes away the nutrients stored in the fallen foliage and without this food plants die and the forest becomes more open and dry - losing much of its firmness and fertility.
In short, a forest with worms is vastly different to a forest without them and that means, that as forests across North America's East Coast become re-infested with earthworms the continent began to change.