Earthworm Invasion

    It's worming its unwanted way into Alberta's boreal forest

    By Lucas Habib, ’06 MSc on January 24, 2011

    Worm
    The lowly worm is just one of the creatures making its way to Alberta’s boreal forest... where it doesn’t belong

    The environmental impact of Alberta’s oil, gas and forestry industries on Alberta’s boreal forest is well-documented. But behind the litany of headline-grabbing issues are other less well-understood effects of human encroachment on this sensitive ecosystem. A group of researchers from the U of A’s Department of Biological Sciences has been quietly working with industry players, the provincial government and other concerned groups to shed a light on what some of those effects are.

    U of A biological sciences professor Stan Boutin, ’77 BSc, holds the chair in Integrated Landscape Management (ILM), that — for almost a decade now — has been coordinating research to assess the total environmental cost of development in Alberta. In collaboration with U of A biology pro- ­­fessor Erin Bayne — and a small army of assistants — Boutin has been working on creating an ecologically-informed land-use plan for northern Alberta and, by extension, the boreal forest across Canada.

    One of ILM’s early finds was that by reducing the size of seismic lines — the three- to 12-metre wide swaths cut through the forest for energy exploration — to less than two metres wide, their cumulative ecological footprint can be reduced. This width has since become the industry standard.

    In the course of their research, Boutin and Bayne also discovered some troubling trends. New mammals, birds, worms and plants that didn’t belong there were all showing up in northern Alberta, with possible catastrophic effects for native species. This kick-started a new direction for the ILM team — examining how human activities in the boreal forest are helping invasive species encroach on this area and how this might change the forest.

      Robin

    An American robin eating an earthworm.

    One invasive species Boutin and Bayne hadn’t initially planned to study was earthworms. Earthworms were wiped out in Canada during the Ice Age over 20,000 years ago and were likely reintroduced to North America when settlers brought plants and soil from Europe or when ships dumped soil used for ballast on shore. In the early 1980s, two new earthworm species found their way into Alberta, and while that may be good news for gardeners and fishermen, earthworms are the kind of under-the-radar species that can have a huge impact on boreal forests by changing the layers in the soil, altering the way nutrients are distributed, and determining the makeup of plant communities.

    None other than naturalist Charles Darwin — who studied worms for some time — came to the conclusion that, “it may be doubted if there are any other animals which have played such an important part in the history of the world as these lowly creatures.”

    One study has shown that each year on an average acre of cultivated land, 7,200 kg of soil can pass through earthworms and be deposited atop the ground — almost double that amount can be moved in really wormy soil.

    “They’re one of the few things that can cause a huge transition in the ecosystem,” says Boutin about earthworms. “Over time they can cause a major change in the whole plant community, and this isn’t recognized at all.”

    Boutin and Bayne recruited PhD candidate and 2009 Vanier Scholar­ship winner Erin Cameron, ’05 BSc, ’08

     Poster

    Poster promoting Erin Cameron’s earthworm campaign.

    MSc, to help them investigate the effects earthworms are having in Alberta’s boreal forest. And despite all the snickers she got for taking on the un-charismatic earthworm as a research subject, Cameron expanded the project into a major undertaking, complete with a public relations campaign (worms.biology.ualberta.ca).

    Cameron began her research by looking at the mechanisms of earthworm introduction to the boreal forest and found that they were more likely to be present at boat launches and near roads. “At the boat launches,” says Cameron, “the species found are ones commonly used for fishing bait, which suggests that fishermen are leaving them behind.” Cameron has developed models showing that in the next 50 years half of Alberta’s boreal forest will suffer some form of an earthworm invasion, which could lead to major changes in insect, invertebrate and small plant communities that could cascade upwards to affect tree and vertebrate communities as well.

    A more conspicuous invasive species that historically has never been in the boreal forest is the white-tailed deer. Their arrival could have devastating effects on the woodland caribou population as wolf populations could rise due to the increase in prey putting a further strain on the threatened caribou that traditionally were the only ungulates living in the boreal forest.

    PhD candidate Kim Dawe is working with the ILM team to study the mechanisms behind deer expansion in the boreal forest, which she theorizes is either due to cut blocks and seismic line clearings providing good growing grounds for the grass the deer like to feed on or to climate change. As for which one it is, the jury’s still out, but Dawe suspects that both play a role. “If it’s a climate change issue, there’s probably not much we can do at this point,” she says. “But if it’s a land-use issue we may be able to take some management actions to help caribou.”

      Cameron and group

    Erin Cameron (background) and her crew prepare to head into the bush to catalogue one of the invasive species that has taken up residence in Northern Alberta.

    Besides worms and white-tailed deer there are other species infiltrating the boreal forest, including the brown-headed cowbird and the coyote. “Coyotes have now reached Kluane Lake in the Yukon, and the first ones were just seen in Yellowknife,” Boutin says. “The pattern of their expansion is almost exactly the same as for deer.” Coyotes will be one of the major research focuses of the ILM group going forward.

    Ultimately, both Boutin and Bayne reinforce the importance of gathering accurate scientific information and applying that knowledge to large-scale land-use planning initiatives. “What we might have expected about something is not necessarily what’s actually happening,” says Bayne. And he’s got ILM’s earthworm research to back that statement up.

    Visit Integrated Landscape Management's website to learn more about them.