I thought that this story was very interesting and well written. It also talks about the views of Canadians, who just like us and the Mexicans, inhabit this wonderful (in the original sense) continent. There are many different scientists quoted from a variety of perspectives. Well worth reading in its entirety IMHO. One thing that seems to be missing is that the “systems” are so complex that we really have no idea what’s going to happen, even if we spend millions on complicated models and a variety of assumptions. Take home message: new creatures get introduced. The biota changes. Some of the changes may be bad. Some of the changes may be bad, and there’s not much we can do about them at this point.
But what struck me most about it was how the situation illustrates that it is impossible to disentangle the effects of climate change and other activities by Native and Later Americans (I doubt whether North Americans have ever been all Euro). Especially the very mixing that is leading to unprecedented levels of worldwide biotic homogenization. It seems to me like a great policy intervention would be to stop international travel and trade. But our friends in the invasive species world don’t try to do that.. they try to change practices to be more protective. It’s definitely a policy choice to decide to stop things (selling trees on National Forests, producing oil and gas, international travel and trade). The latter would conceivably count double for decreasing carbon emissions as well as reducing threats of invasives. An alternative is to dig down and investigate the practices at the ground level so that they are more environmentally sensitive. We might ask “who in the marketplace of ideas chooses to stop rather than improve practices” and of course, in each unique instance, why did they make that choice? Do certain kinds of people prefer stopping to fixing (disciplines, politics, class)? Why are there groups we all know who are for “keeping oil and gas in the ground”, or “no commercial timber sales on national forests” but none for “no international trade nor travel (I suppose including immigration from other hemispheres?)”. If we think “the cat’s out of the bag” on that, why not on climate change? I’m just exploring some different ways of thinking about how different threats are treated. Anyway, I digress.
Native earthworms disappeared from most of northern North America 10,000 years ago, during the ice age. Now invasive earthworm species from southern Europe — survivors of that frozen epoch, and introduced to this continent by European settlers centuries ago — are making their way through northern forests, their spread hastened by roads, timber and petroleum activity, tire treads, boats, anglers and even gardeners.
In northern Minnesota, the boreal forest has slowly been invaded by earthworms. They have altered not just the depth of the leaf litter but also the types of plants the forest supports, said Adrian Wackett, who studied earthworms in the North American and European boreal forest for his master’s degree at the University of Minnesota in St. Paul.
Endemic species such as the pink and white lady’s slipper — Minnesota’s state flower — as well as ferns, orchids and the saplings of coniferous trees rely on the spongy layer of leaf litter.
As earthworms feast on that layer, they allow nonnative plants such as European buckthorn and grasses to thrive, which in turn push out endemic plants. This process, combined with the effects of warming over time, may slowly transform Minnesota’s boreal forest into prairie, Mr. Wackett said.
If you’re interested in the Minnesota angle, here’s a link about their collaboration with the Fennoscandians.
Their research shows that some of the same earthworm species transforming North American forests have also invaded far northern arctic regions of Norway, Sweden, and Finland (Fennoscandia). They identified numerous locations with active, ongoing earthworm invasions.
These areas were also glaciated, but settlers from southern and central Europe came to farm and brought non-native earthworms with them. Modern gardens, composts, and fishing sites have also helped spread the “unseen invaders.”
“We can identify invasion points pretty easily,” says Wackett. “We target old farm sites or modern cabin lawns, and in many cases observe a radius where the worms have spread out into surrounding birch forests.”