Buckthorn Invasive Shrub Unnoticed In Montana For Years
Edit 3/4/20: A previous version of this article stated that chokecherry is an invasive. It is, in fact, a native plant to Montana and the article has been corrected to reflect this. Additionally, the photo displayed with the article was not buckthorn, and this has also been corrected.
In October 2019, a team from Billings attended a national urban forest workshop where they presented on an invasive shrub that has escaped notice in Montana for years.
Buckthorn is now pushing out native vegetation by the Yellowstone River in southeastern Montana.
It’s a snowy day at a popular park in Billings. City forester Steve McConnell leads the way down a forested trail towards the Yellowstone River.
McConnell shows where buckthorn, a resilient, thorny shrub with black berries inedible for humans, has filled in the open spaces and overtaken the cottonwood trees. Essentially, everywhere in this section of Riverfront Park.
“The understory here is all buckthorn. You can see it’s all ten, 12, 14-foot-tall, really dense shrubs," McConnell says.
McConnell says this area should be an open savannah with plenty of distance between trees.
“Eventually we would end up with basically a 20-foot-tall, dense shrub layer rather than the kind of iconic Yellowstone River cottonwood forest that we have currently,” McConnell says.
McConnell says they took their first crack at clearing the infestation last fall, and it cost around $4,000 in man hours and supplies to treat an acre. Billings Parks estimates it needs to treat about 80 to 100 acres in Riverside. Buckthorn has already decimated about a third of the area.
He’s concerned that if left alone, this insidious invasive could overtake the entire park.
Not only can buckthorn berries stay viable in the earth for five years and sprout new growths, but stumps can sprout multiple plants if chopped down and left untreated.
Buckthorn is drawn to wetter areas. Like here, by the undammed Yellowstone River, where flooding usually maintains the ecosystem of the native cottonwood forests. That is, unless buckthorn blocks the growth.
While buckthorn is a well known issue in states like Minnesota and Wisconsin, it has a fairly low profile in Montana and looks kind of like another common plant, the chokecherry, which is native to Montana. That’s partly why it wasn’t noticed until recent years.
City of Missoula Parks and Recreation Department Conservation Lands Manager Morgan Valiant was part of the push to add buckthorn to the state noxious weed list in 2017.
He says buckthorn first came to Montana as an intentionally introduced decorative hedge bush at the beginning of the 20th century and remained popular up until the 1970s or '80s.
“And the majority of it spread now is from birds,” Valiant says.
After recognizing it as a problem, Valiant says he and his colleagues made the effort in 2016 to pinpoint centers of large, breeding populations that were established and encroaching on native ecosystems.
He says they eventually narrowed it down to Missoula, Helena, Bozeman and Billings.
“Our online survey was sent out to a bunch of other land managers that we work with, kinda plant geeks that we know across the state, and so it was not a large, statistically valid survey or a survey of the entire state to try find the distribution of the plant. It was really just to help us fine tune where we would set up our research," Valiant says.
Billings City Forester McConnell says the approach they’ve taken is to cut the buckthorn down to a stump and apply herbicide.
“It’s a complicated thing. The stumps apparently seal over quickly, so you need to cut it and treat it within 20 minutes. The people in Missoula recommended five,” McConnell says.
Billings Parks and Recreation will see if this past year’s treatment paid off when the buckthorn leaf in the spring.