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[at-l] Earthworm Controversy
I don't know if red wrigglers are native species or not, but here's an article form the September 5 New York Times which addresses the "ecological problems" created by non-native earthworm species:
Sam Hooper Samuels NEW YORK
ANGLERS TAKE note: the night crawler at the end of your hook is an invader. According to recent research by an earthworm ecologist, you could dig up approximately the upper half of the North American continent and almost never find an earthworm of true North American descent.
"Basically, anything you can buy in a bait store in most of the country is European," says ecologist Sam James, a professor of life sciences at Maharishi University of Management in Fairfield, Iowa.
Biologists have a term for the many species that wander into non-native territory and prosper: weeds. The area in question, which includes all of Canada, New England, some mid-Atlantic states, and much of the upper Midwest, is entirely populated by weed earthworms. The rest of the continent contains a mixture of weeds and native earthworm species.
The dividing line begins on the east coast in New Jersey, at about 40 degrees latitude, then snakes its way westward, dipping a few degrees south in the Midwest, then rising to just below 50 degrees latitude as it makes its way to the Pacific in Washington.
"Look along that line," says James. "That's where the last glaciation stopped, the furthest advance of the ice in the last glacial period, which was 15,000 to 20,000 years ago. To the north of it, you generally don't find native earthworm species. To the south, you can find them."
During that last period of glaciation, when areas that are now temperate were covered with vast sheets of ice, earthworms were among many of the creatures that were wiped out, he explains. For some distance below that line, permafrost set in and pushed the earthworms even farther south. In the 150 to 200 centuries that followed, they simply have not made their way back again.
"Earthworms have been very slowly diffusing over the north," James says. " They aren't like an organism that can look over the rise of the next hill. They can't disperse like trees. They are way, way behind."
James found support for his earthworm findings, which have not been published, in a Dutch study that measured the speed at which earthworm populations enlarge their territory. The Dutch researchers placed earthworm colonies in a field that was free of worms. After one year, the colonies had radiated outward by about 10 metres in each direction. The worms were a European variety, and especially good colonizers.
"If you take 10 metres per year as a high-speed earthworm infiltration, and multiply that by 20,000 years, it's not very much," James says. "It's 200 kilometres."
That means it has taken the native earthworms of North America more than the entire duration of human history to expand their territory by the length of a small state.
Yet there are earthworms north of the line, and James has identified them as European and Asian immigrants. These were brought inadvertently by humans.
"It was the horticultural trade," says James. "People moved trees, probably in the colonial period, by bringing tubs of trees with them. Plants were moved in their soil: apples, rosebushes, any woody plant. Lilacs were probably brought over in pots."
And along with the soil came earthworms.
While scientists have long known that invader species of earthworms exist in North America, James is the first to find that native worms were absent north of the line of glaciation.
Diane Debinski, an associate professor of animal ecology at Iowa State University who specializes in biodiversity studies of vertebrates and invertebrates, says: "This is news because there are so few people who study invertebrates that are not pest species. There are a lot of taxonomic groups that are not studied because they are not perceived as being of value to humans. So I'm not surprised that we didn't know this before."
Worms are such poor travellers that their presence or absence in an area can be used to tell geological history. "They're indicators of plate tectonic movement," James says.
Remarkably, worms can be used as markers to track the excruciatingly slow drift of land masses. Geologists know, for example, that the island of Puerto Rico was once in the Pacific and passed between North and South America en route to its present location in the Caribbean. James is confident that the island touched what is now Colombia along its way, because of the similarity of Puerto Rican earthworms to Colombian earthworms.
"This group of earthworms on Puerto Rico must have arrived on ancient Puerto Rico by ancient Puerto Rico coming into contact with ancient Colombia," James says.
In the grand scheme of things, what difference does it make whether alien worms are on American soil? A lot, scientists say.
For one thing, the invasion is still in progress. There are still some areas that have no earthworms. And there, the gradual penetration of alien worms is having a profound effect on the soil structure.
In a wooded area with worms, the ground is covered by a thin layer of the previous year's fallen leaves. Below that is a potting-soil-like mixture left behind by worms that have eaten those leaves and passed finely broken-down organic matter. But in worm-free zones, like those in Michigan or Minnesota, that layer of leaf litter is much deeper.
"It's probably a good four inches thick, and it gets progressively older as you get deeper," James says. "If you walk out to where the earthworms haven't penetrated and you kick aside leaves, you just find more leaves."
On 9/25/2000 at 11:15 AM John O wrote:
>By Brigitte Ruthman
>© 2000 Republican-American
> KENT — When the Appalachian Mountain Club went digging for an answer to
>the problem of overused privies, it turned to science.
> Now, red worms will be helping hikers.
> The worms have an appetite for human waste — one that accelerates the
>natural process of decomposition. The worms chow down, then relieve
>themselves, leaving ”waste“ that is, essentially, compost and free of
>the bacteria and odor of its origin.
> In test areas, the hungry wigglers have turned waste that threatened
>underground water supplies into fertile compost.
> That’s handy along the 53-mile Connecticut stretch of the Appalachian
>Trail from Kent to Salisbury, which has 23 privies, the rough equivalent
>of old-fashioned wooden outhouses. The growing popularity of hiking has
>dramatically increased the use of privies, most of which are near remote
>campsites and maintained by volunteers from the Appalachian Mountain
> Volunteers used to dig new, four-foot holes and move the outhouses as
>they filled every few years. Lately, they have been running out of space
>to dig the holes, which have been filling as quickly as a single summer
> ”We needed some new kind of privy technology,“ said Elaine LaBella, the
>club’s liaison with the Cornwall-based Housatonic Valley Association, a
>land preservation organization. ”It’s a lot of holes.“
> The concern, LaBella said, is contamination.
> ”We are really concerned about running out of places to put these pits
>without infiltrating groundwater,“ she said.
> A number of options was studied, including electrically operated
>composting privies that speed the composting process with heat. A
>labor-intensive process of adding wood chips, called Batch Bin, was
>rejected because of the time and effort required to mix them in, LaBella
> Then the club learned of the Green Mountain Club’s use of moldering red
>worm privies in Vermont. The method presented a more environmentally
>friendly, time-saving and relatively inexpensive alternative, LaBella
> Unlike other varieties, the red worms accelerate the natural process of
>decomposition even in cool temperatures, as long as they are near the
>surface, she said.
> The worm privies are made of the top halves of existing privies, which
>are then set on platforms over side-by-side pairs of 15-inch deep
>”bins.“ The privy is reached by short steps. When one bin fills, its
>clean-smelling compost is removed while the other bin is used.
> ”The only other option was packing waste out as they do in some areas
>of the national parks lands out West,“ said David Boone, member of the
>club’s Trails Committee.
> Worms were installed in a privy at Upper Goose Pond in Massachusetts.
>In August they were added to the privy at the Stewart Hollow shelter and
>camping area off Skiff Mountain Road in Kent. So far the results are
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