Worms are on the move and people are tense.
This is because they have taken over lands in the far north that have been worm-free since the last Ice Age. Scientists say expansion will inevitably alter northern ecosystems, with ramifications for the entire planet, in ways we don’t fully understand and probably can’t undo.
“We have to be careful about an organism that comes in and is really difficult to remove,” said Jonatan Klaminder, a professor of ecology at Umeå University in Sweden who studies earthworms. “We should really, really carefully study the effects of this organism.”
In much of the temperate world, shoveling a clump of earth infested with common earthworms is a sign of Healthy soil full of good plants, fungi, and bacteria. Earthworms actively contribute to soil health by chewing on decomposing organic matter and defecation from nutrient-rich fertilizer.
But this means that worms also have the potential to alter the natural balance of ecosystems in the Arctic and sub-Arctic regions. For example, by encouraging the growth of some plants at the expense of others, Changing entire food webs And Eliminate rare native plants already threatened by climate change.
Earthworms, at least locally More powerful in changing vegetation said Dr. Clamender.
They can also be fired Bacterial activity that can help open as powerful greenhouse gases Carbon DioxideThe methane and nitrogen stored in the soil.
The worms didn’t make it this far north on their own. Research has shown that Humans have brought it on intentionally and unintentionallyIt has been introduced to remote places above the Arctic Circle and into sub-Arctic regions since at least the mid-19th century by importing soil for lawns and gardens and using it as fishing bait. Recently Increases in travel to these areas It can also contribute to invasion. Worms go where humans go.
Now, as human-caused climate change raises temperatures and melts permafrost, Worms gain a foothold. Only without feet. Once established in the soil, they don’t even need to find a partner of the opposite sex to reproduce. Earthworms are hermaphrodites, which means they have both male and female reproductive organs. So, anyone will do.
Because of changes in the Earth’s chemistry and physics, grasses and shrubby plants tend to thrive, displacing tundra mosses and lichens. This is good news for rodents and mice that prefer such plants, according to Hannah Johnson, an ecology researcher at Umeå University. But it is probably not so good for other herbivores who may not adapt easily to the change in available food.
Importantly, these changes could reduce the amount of snow cover that reflects the sun’s heat back into space from above the globe. This means that the earth can Doubly absorbs heat.
Something similar is happening in the temperate and boreal forests of North America, from Indiana to Alberta, where the worms are Grasses and weeds help take the lands from Pines, spruces, and pine trees, according to Dylan Craven, a plant ecologist at the Universidad Mayor in Santiago, Chile.
This leads to a complex global picture, and scientists are still not entirely sure how these earthworm infestations will affect the planet’s ecosystems and greenhouse gas levels in general.
“You get into a situation where there are so many different influences that it’s hard to predict the outcome,” Freilich, director of the Center for Forest Ecology at the University of Minnesota, told me. “The effects can really vary greatly and it seems contradictory, but they can actually do opposite things depending on the context.”
Preliminary research by Dr. Claminder and Ms. Johnson suggests that, By type of vegetation, the overall impact on the planet’s carbon balance could be zero or even a net reduction. This is because any release of carbon dioxide from decomposing organic matter caused by worms can be offset by the growth of plants that can absorb some carbon from the air.
Other experts, including Dr. Freilich and Dr. Craven, say any such beneficial effect on the carbon balance could be canceled out by the decline in tree growth in North American forests. And any kind of CO2 sequestration that earthworms can do in the long term will be too little, too late.
“The world has a problem with too much carbon dioxide in the atmosphere right now,” said Dr Freilich.
What the scientists agree on is that the worm-related changes are definitely important. They are happening very quickly in a region that is warming much faster than the rest of the planet and hosts some of the world’s last untouched ecosystems and some of the most endangered species of plants and animals.
Perhaps the changes will be irreversible, because it is very difficult to eradicate earthworms. And it is very likely that we will see settlements expand as the farther north becomes warmer and more generous.
“The first step from an Arctic perspective is to actually get a good estimate of the scale of the problem,” said Dr. Claminder. “Because the Arctic, as I see it now, is one of the last pristine regions where human settlements have not spread all over the landscape.”