Hi,
I have a question regarding the native American earthwormas opposed to the European introduced by the Columbian exchange. Compare a Straight dope link from 2001 to a recent Spiegel magazine review of “1493: Uncovering the New World Columbus Created,” by Charles Mann. Who is correct here? I look forward to your feedback.
davidmich
First off, all of North America was not scraped down to bare rock during the ice ages, and that’s about what it would take to wipe out all the earthworms. It might be fair to say that much of Canada was stripped of its native earthworms last time around, but relatively little of the U.S., and none of Mexico, was affected.
I haven’t read the book yet:
“Extinct in large parts of North America since the Ice Age, earthworms began spreading there once again following Christopher Columbus’ voyage. Wherever this species appeared in American forests, it changed the landscape, aerating the soil, breaking down fallen foliage and accelerating erosion and nutrient exchange.”
“Ninety-nine percent of the populations of native plant species normally found in hardwood forests, including large-flowered trilliums, yellow violets, and Solomon’s seal, are destroyed in affected areas,” said Frelich, a research associate in forest resources. “In many areas, the remaining bare soil is simply eroding away.”
I’ve seen news reports claiming earthworms are invasive too.
That just doesn’t make sense. Any gardener or farmer will tell you earthworms are essential for creating rich soil suitable for plant growth. They eat organic material and turn it into humus. It’s a critical step in producing a rich loamy soil.
I have read them and they make no sense. The reporters assertions are totally unsupported. Unless we’re supposed to believe the soil in North America was basically useless. How did Native Americans farm soil that didn’t have rich humus? Earthworms are essential for that.
Invasive species aren’t limited to animals. Northern Virginia has been waging a losing war against bamboo for years now. It spreads like crazy, grows very fast, is difficult to completely kill (it’ll be back), and no local animals eat it.
I first saw the earthworm invading America theory in reviews of *1493: Uncovering the New World Columbus Created * by Charles Mann. It’s on my list to read.
What you’re saying makes as much sense to me as recommending that what Arizona really needs is some peat moss and water so that we can grow the best cactus possible.
Or like saying that what Venus flytraps really need is some better drainage.
In fact, I’m surprised that you’re not recommending Brawndo.
When a species has adapted to a particular condition, pretty much any change to that condition is bad for that species.
Maybe there is something odd about those Minn trees and they don’t do well in rich garden soil. The expert scientist should know. I concede that.
I’ve gardened and worked flowerbeds since my early teens. Read lots of books on the subject. The earthworm doesn’t take nutrients from the soil. They accelerate the process of turning leaf litter into nutrients that go back into the soil. I gave cites earlier on humus and loamy soil. Loamy soil is something any gardener or organic farmer works very hard to achieve with various soil amendments, earthworms etc.
But, that’s not the natural soil these old growth trees originally adapted too.
The most likely mechanism would be that the Minn trees don’t themselves actually have a problem with rich soil, but that when the soil is rich, they have to compete against other species that like it too, and lose. On the other hand, when the soil is poor enough that only they can tolerate it, they have no competition, and so thrive.