BRULE — Some goats were watching a big, black nanny goat as she struggled to push over a tall bush of buckthorn.

But when the bush got down to their level, they pounced. It was a goat stampede to get to the lush leaves that had been out of their reach before.

“They absolutely love buckthorn. They’ll eat that first before anything else. ... And that's why this idea might just work,’’ said Dan Kephart, Wisconsin Department of Natural Resources property manager for the Brule River State Forest.

Kephart was watching as 32 goats from local goat herders Regenerative Ruminants were doing their thing, chewing away at highly invasive buckthorn on a 5-acre patch of the state forest about 40 miles east of Duluth.

Buckthorn has been here for decades, maybe a century or more, and it keeps spreading. The import from Europe grows fast and tall, and then shades out the native, local plants that are slower to grow each spring.

“We chose this pine plantation because it’s well defined and because just about everything growing under the big red pines now is buckthorn. Nothing else can compete with it,’’ Kephart said.

When the DNR is ready to harvest the red pines here, if the buckthorn is still growing below, this part of the forest could become mostly a buckthorn plantation. The goats are an experiment to see if they are an effective way to get rid of buckthorn. They are now in their third rotation this summer grazing this spot, brought back every few weeks to chew any new leaves that sprout.

Buckthorn is an incredibly hardy plant and can survive being cut right down to the ground, only to sprout again. Its seeds also can sit for years in the soil, then sprout.

There are other ways to get rid of it — namely chemical brush killing compounds and hand or mechanical removal. But both are expensive. The goat project will cost the DNR forestry department about $7,500 over two seasons.

“We’re always being asked to reduce the amount of pesticides that we use,” said Mary Bartkowiak, a forest health specialist for the DNR overseeing the goat project. “We want the forest to be able to regenerate our native species. … If the invasives out-compete all of the native vegetation, we won't have the sugar maples, red pines or the white pines because they would be overtopped by the invasives. … So goat grazing is one more tool in our toolbox.”

If the buckthorn doesn’t have green leaves for most of two growing seasons, that should be enough to kill it for good. Kephart said it will probably take another summer season of goat grazing at this plot to evaluate how effective the goats are compared to mechanical removal and other efforts. A plot next to the goat’s area has been mowed to compare.

The goats are in a solar-powered electric fence pen that is moved often to fresh plots of buckthorn. The fence keeps the goats in and any wolves out. Rhubus, a burly guard dog, also is on watch for predators.

Jake and Brigid Williams operate Regenerative Ruminants out of land they purchased this summer near Poplar. This is the third season they have been professionally operating the goat grazing business. The grazing service is time consuming but both Williams also work off the farm.

“We started on our little homestead (near Washburn) with a couple of our own goats and people kept asking if we ever rented them out. So we started adding more of them,’’ Jake Williams said. “We saw what they were able to do on our land, with tansy and goldenrod and other brush, so we know they can do the job.”

In addition to the herd of 32 goats, Regenerative Ruminants also has a herd of 20 sheep for other jobs. Most of their work so far has been for private landowners.

“We can tailor our herd size to fit the customer’s needs,’’ Williams said. “It’s a process. … it’s not a miracle solution. We’ll have to come back in for a second season and go after it again. But they’ll keep eating.”

Brigid Williams once had a job removing invasive species on Madeline Island, but saw how pesticides also killed native plants and animals.

“She said never again,’’ Jake noted.

Similar goat efforts have been used by Douglas County to remove invasive species at Lucius Woods Park near Solon Springs.

More information about invasive species in Wisconsin is available on the DNR website at dnr.wisconsin.gov/topic/Invasives . More information about Regenerative Ruminants and using goats and sheep to remove invasive species can be found at washburngoats.com .

Buckthorn is a nonnative woody shrub/tree that grows up to 20 feet tall. Also known as Common buckthorn, European buckthorn, Hart's thorn and European waythorn, the plant was introduced to North America in the 1800s apparently for either medicinal purposes or as a landscape plant, or both. Buckthorn has spread across North America, particularly in the Midwest and parts of Canada. There are two native buckthorns in the U.S. that resemble it which are smaller and don’t spread as fast.

Buckthorn became popular for landscaping because it matures fast and makes an attractive hedge. But its seeds quickly spread into wild areas. The bush produces many berries that are eaten and then spread by birds and rodents. The seeds are hardy so they can survive years in the soil. Buckthorn can grow in many soils and climates, but likes damper soils (not standing water) in the Northland.

The problem is that, other than goats, buckthorn is a poor food source for most wild animals. The high nitrogen component of the leaves changes the soil, also impacting native plants. But mostly it grows so fast and tall that it shades out and kills the native trees and plants that are part of the natural ecosystem.

Researchers at the University of Minnesota are trying to determine if buckthorn can be thwarted by planting even faster-growing native plants to shade out the buckthorn. But it takes a lot of shade, reducing sunlight to just 3-4%, to keep buckthorn at bay.

Getting rid of buckthorn isn’t just as easy as cutting it down. The seeds may sprout years later, so land managers, whether it’s a backyard or a state forest, have to keep going back year after year.

Experts from the University of Minnesota and Minnesota Department of Natural Resources say to start removing the berry-producing plants first and then return to remove the smaller plants.

Herbicides, such as Ortho Brush-B-Gone and Roundup, work when sprayed on a cut stump of buckthorn to kill the root. Products that contain Triclopyr amine, Triclopyr ester and Glyphosate will kill buckthorn roots, but they also kill just about everything else they touch.