Beyond ecology, invasive species pose threat to health of humans

Provide Lyme disease tick habitat, consume water

Joshua Vissers/Daily Mining Gazette Purple loosestrife, seen here at the Sturgeon River Sloughs boat ramp, consume huge amounts of water and form dense growths which choke out native species.

Sigrid Resh, coordinator of the Keweenaw Invasive Species Management Area (KISMA), would like you to think twice when planning landscaping: Some plant species that are still being sold by local nurseries are invasive species, and they might even be enabling the spread of Lyme disease. Japanese Barberry in particular provides a habit not usually available for small rodents that carry the disease.

“That encourages the Lyme disease-carrying tick,” said Resh, a research assistant professor at the Michigan Technological University (MTU) School of Forest Resources and Environmental Science.

If it was only present in landscaping, it might not be an issue, but like other invasive species, the barberry can reproduce in its adopted environment, choking out native plants and changing the local ecology, according to Resh. The plant chokes out other species by altering the soil pH balance, he said.

KISMA is a coalition of 22 partners who share information about the location of invasive species in an effort to better understand and manage their spread.

Other local invasive plant species include autumn olive, buckthorn, certain honeysuckles, spotted knapweed, giant knotweed and purple loosestrife, which is currently blooming and spreading thousands of seeds from each flower stalk.

Purple loosestrife thrives in swampy areas, and it consumes so much water it can lower the water level, harming fish and other plant species.

One of the more destructive and difficult to exterminate species is giant knotweed.

“It grows into foundations,” Resh said.

She said people will tear it out of landscaping near their house and throw it into a compost pile, only to have it spring back to life both near the house and in the compost.

“They’re incredibly hard to kill,” Resh said.

The plants grow a complex root system that allows them to spread and regrow quickly.

To stop the plants, Resh said early detection is key.

Once found, an invasive species should be reported to KISMA at its website or by phone. Then the plants can be treated manually or chemically.

KISMA is not licensed to use chemicals, which is just as well to Resh, who prefers manual treatments.

“I feel like we’ve put enough junk into our environment,” she said.

Either method requires repeated treatment through the course of multiple seasons to eliminate knotweed.

TOMORROW: The Keweenaw Bay Indian Community is working in partnership with KISMA in fighting invasive species on tribal land.