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Did Metra Accidentally Unleash Nasty Invasive Vine Near Nature Sanctuary?

By Sam Cholke | June 7, 2016 8:27am | Updated on June 10, 2016 11:54am
 An invasive vine that's ravaged forests in Canada is now a block from 40-acres of nature sanctuary.
Burnham Nature Sanctuary
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KENWOOD — Metra chopped down a stand of trees along Lake Park Avenue in Kenwood last week and may have inadvertently imperiled more than 40 acres of bird and butterfly sanctuaries on the south lakefront in the process.

When I went over to take a look at the area being trimmed, I found a weed that has ravaged forests in the Northeast had accidentally been given the perfect habitat to spread to the Burnham Nature Sanctuary, which starts less than a block away on the eastern side of the tracks on the north side of 47th Street.

Neighbors are focusing their complaints on the appearance.

“It’s horrendous and it makes it look pathetic,” said Claudia Traudt, who tipped me off about the tree trimming. “It’s heartbreakingly ugly.”

Sam Cholke on the vine that could wreak havoc at the Burnham Sanctuary.

I went over to check it out last week, hoping that I wouldn’t find black swallow wort — a nasty vine Canadians call dog-strangling vine, which has already made my nearby garden plot nearly unworkable.

Black swallow wort is an invasive vine from areas of Spain and France, and in North America it has mutated into this vicious infiltrator that is very effective at killing butterflies, ruining bird nests and destroying forests.

Once it gets established, it forms a dense mat over the bushes and grasses shading them out until they die and destroying or choking nesting sites for birds. Monarch butterflies mistake it for milkweed and lay their eggs on the plant, and the larvae die within 48 hours of being born unable to eat the vine. It also climbs trees to find a nice breeze to spread its little wispy seeds farther along.

Black swallow wort can’t be dug out. It can’t be burned. Nothing will eat it. And herbicides are largely ineffective, except for the ones that obliterate everything.

No one wants to see something like that get into a nature sanctuary.

Morel mushrooms have been found in an area now threatened by invasive black swallow wort vines.

The Burnham Nature Sanctuary is a rare slice of wilderness in the city extending between the train tracks and Lake Shore Drive. It’s been getting a lot of attention in the past three years, with $1.1 million spent by the park district on removing invasive plants and drafting an army of volunteers to plant 125,000 saplings. The savvy forager can find black currants, wild onions and even the elusive and highly coveted morel mushrooms and, of course, a glorious array of species of migrating birds and butterflies in the middle of the city.

There was definitely a sinking feeling in my chest when the black swallow wort was, of course, there along the tracks near 47th Street and Lake Park Avenue with all competition cleared away, the tree canopy opened up for plenty of sunshine and a nice bed of mulched woodchips put down from the felled trees.

The conditions are now ideal for it to spread this fall across the tracks to the 40 acres of oak savannah the Chicago Park District spent $1.1 million to restore in Burnham Nature Sanctuary.

Metra has accidentally created the ideal conditions for an invasive vine to spread and take over a neighboring nature area.

When I talked to researchers Monday, they said once it’s in the nature sanctuary, it is never coming out and it will become a choice between a handful of expensive and labor-intensive control methods.

“The conditions are just perfect — it’s a very light-loving species,” said Antonio DiTommaso, a professor at Cornell University who has spent the past 10 years studying black swallow wort.

He said the plant has choked vast swathes of undergrowth in forests in Ontario and the vine is so dense there that it now looks like its snowing when it releases its seeds in August. He said there is nothing stopping the same thing happening in the bird and butterfly sanctuary on the South Side.

“It could be disastrous,” DiTommaso said.

I described for DiTommaso the area where I’ve found the vine both on the eastern and western sides of the railroad tracks just south of 47th Street and the nearby nature sanctuary.

He said the oak savannah is an ideal habitat for the vine and the nearby train tracks would allow it to spread quickly and smother the 125,000 saplings the Chicago Park District has planted there.

When I reached out Metra, Michael Gillis, a spokesman, knew about the community’s concerns about the looks, but not the invasive vine.

He said the work was done to remove trees that were close to the power lines between 47th and 51st streets and said Metra believed it looks better now with fewer trees, but it will continue to work to make it look nicer.

“Metra plans to work closely with the community in the days to come to learn if they are interested in working with us on landscaping enhancements,” Gillis said. “In fact, Metra is working on a program to work with local communities on proposals for enhancement projects, including art installations and landscaping projects on the railroad property.”

He said Metra may have a little money available to help with beautification projects, but it was largely relying on community groups to come up with the funding.

DiTommaso recommended planting grass or clover now to keep pressure on the black swallow wort and to keep the area clear for mowing — because it’s going to need to be mowed a lot.

He recommended mowing at least four times a year to keep the plants from seeding, but was careful to warn that more would need to be done to kill the vines.

He said lab tests have suggested that if the plants are mowed every two weeks for six years it could exhaust the plants reserves and kill it, but all the seeds still in the soil would also need to be killed.

Black swallow wort’s seeds stay viable in the soil for two years, with each seed able to produce two plants.

Some rough math then means the area would need to be mowed every two weeks for the next eight years to knock down this invasive intruder, and so far that seems to be the cheapest and fastest option.

DiTommaso said digging up the plants could slow the spread, but only if all of the roots are meticulously pulled. The plant can reproduce from small sections of the root crown left in the soil and DiTommaso said inevitably there would be survivors that would still need to be mowed down.

He said herbicides can work in the short term, but they usually very quickly become too expensive because it takes years of applications to finally kill the plant and have the unfortunate side-effect of killing the plants that are trying to be encouraged in places like a nature sanctuary.

DiTommaso said Metra could smother the plants, but only if it's willing to cover the existing plants with at least a foot of infill, and it would have to be denser than woodchips, which black swallow wort can easily push up through from as much as a foot underground.

I reached out to the Chicago Park District as well, which owns the areas where I found the plant on the eastern side of the tracks. A spokeswoman for the park district was not able to provide a staff member to comment.

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