PERHAPS THE CREATURE the gardener is aware of greatest is the earthworm, however how deep does that data go? Recently readers have been emailing me sensational headlines about “unhealthy” earthworms, asking: Aren’t all earthworms “good”? To get an earthworm 101, I invited Ryan Hueffmeier, an environmental scientist on the College of Minnesota-Duluth and Director of Nice Lakes Worm Watch, to affix me on the radio (October 2013). Our Q&A consists of some surprises:
First, some background: Nice Lakes Worm Watch is a citizen-science outreach group, working to map the state of the earthworms—and the habitats they’re residing in.
“We need to know the place earthworms are throughout the panorama,” says Ryan—and meaning even past the Nice Lakes space, the place the undertaking started. (There’s a Canada Worm Watch, too, for these throughout the border; researchers on the College of Vermont, on the Cary Institute in Millbrook, New York, and elsewhere are likewise learning earthworm invasion.)
People, colleges or backyard teams can signal on assist acquire knowledge on what worms are discovered when and the place. That final bit—the habitat, or “the place” facet–is vital, as a result of earthworms are neither good nor unhealthy. The function they play, and whether or not it’s useful or dangerous, is determined by the setting they make their approach into.
ROUGHLY SPEAKING, there are two totally different lessons of ecosystems, Ryan defined in our chat:
In artifical environments, reminiscent of farms and gardens, worms have confirmed to be useful as soil-aerators and as detritivores, super-efficient recyclers who break down natural materials and return it to the loosened-up soil.
Pure habitats, such because the hardwood forests of the Northeast and higher Midwest, have been traditionally earthworm-free by design—which means no native earthworm species and never meant to have earthworms, as an alternative counting on tiny fungi and micro organism to do the recycling duties.
“The fungus and micro organism do this job actually, actually slowly,” Ryan explains. “However when earthworms come into such an setting [as they did with the European settlers hundreds of years ago] they do it a lot, a lot quicker.” They speed up the order of issues—and never in a great way.
The forest flooring is supposed to be a thick, spongy natural “duff” layer, gradual to interrupt down. Not solely do earthworms make issues decompose too quick, however their castings make forest soil extra compacted and dense–and extra mineral-rich. The altered medium is inhospitable to tree seedlings and herbaceous crops that used to thrive. Pure forest succession is interrupted, and the range of the plant neighborhood threatened.
The forest flooring may even drop, so what was a tree root might immediately discover itself above soil grade—a root not, however a department.
“Researchers have coined the time period ‘tree root gingivitis’,” says Ryan, who can inform instantly when he enters a woodland whether or not it has been invaded. Huge timber nonetheless tower up above, maybe, however on the bottom: possibly sedges (Carex species) or not a lot in any respect. When the large timber die, what’s going to occur, since there are not any saplings in the neighborhood?
LATELY, the story of invasive earthworms who can change environments has gotten extra difficult—therefore headlines reminiscent of “The Darkish Aspect of Earthworms” and “Invasion of the Earthworms.”
Asian species within the genus Amynthas (above) have made turn out to be extra widespread in American soils, together with giant parts of the East Coast, and these days into the Nice Lakes space, with pockets in Minnesota, Ohio and Wisconsin. With assist from citizen researchers, Nice Lakes Worm Watch is making an attempt to trace, and assist cease, their march. Why?
“These could possibly be a gamechanger on the subject of earthworms,” says Ryan, referring to potential impression of unchecked unfold. “They’re very aggressive, and may dwell in actually excessive densities,” consuming a number of natural supplies in a really brief time. “Some researchers have coined it ‘Nothing Grows Right here Syndrome’ the place these worms have been.”
extra earthworm 101
Q. Why have been there principally no earthworms right here to greet settlers a whole lot of years in the past in a lot of the nation?
A. Within the final Ice Age, glaciers “scraped proper right down to the bedrock,” says Ryan. Within the northern tier of the nation notably, and in Canada: no native earthworms the final 11,000ish years, which is about when the final glacial interval ended.
Q. How did European earthworms attain the USA?
A. “The earthworms we have now recognized and grown up with usually are not initially from North America, they’re from Europe,” says Ryan.
Researchers assume they got here as a facet impact with ballast in ships—soil and rocks have been utilized in ships after which unloaded. Plus European plant species introduced with settlers, reminiscent of lilacs or buckthorn amongst many, most likely had earthworms of their rootballs. Settlers—noticing the Northern U.S. didn’t have earthworms–might also deliberately have introduced them alongside for soil enchancment of farms and gardens.
At this time human exercise–from soil in tire treads to improperly disposed-of fishing bait and extra–continues to unfold worms the place they don’t belong. The worms offered for composting (learn GLWW’s pdf), as an example, typically embody the aggressive Asian species.
Q. How can I be taught to ID earthworms?
A. Earthworms match into three basic ecological teams (get images and particulars)—which means their have three ways in which they feed and burrow:
- Epigeic sorts (small, reddish brown species residing within the leaf litter);
- Endogeic sorts (small to giant, with no precise pores and skin pigmentation however showing gray-blue, yellowish, pink or whitish and even with a greenish solid, and residing and feeding within the mineral layer of the soil);
- Anecic species (very large-sized deep soil burrowers who might feed up within the litter; reddish-brown). Nightcrawlers are our solely anecic species to date.
There are keys to additional worm ID on this web page of Nice Lake Worm Watch’s web site.
Use grownup worms to do your ID’ing, as it may be much more complicated in any other case. Easy methods to inform if a worm’s an grownup? Adults have a collar-like clitellum near the entrance of their our bodies. Fundamental earthworm-anatomy diagrams.
Q. How can I assist Nice Lake Worm Watch as a citizen scientist (and the right way to I get the worms to come back as much as the floor and be counted, anyhow)?
A. Discover ways to be part of the crew (an incredible undertaking for a backyard group, faculty class, scout troop, and many others. within the coming rising season), and likewise learn to report worm observations, beginning right here.
As for the right way to persuade these burrowing worms to come back up and be counted? On the Nice Lakes Worm Watch, Ryan says they use a recipe of mustard powder and water to annoy the worms and get them to floor, like this.
(All illustrations from Nice Lakes Worm Watch.)