In their neverending battle against invasive plants, personnel at Glacial Ridge National Wildlife Refuge in northwestern Minnesota have pulled out some heavy hitters:
Thats heavy, as in cattle200 cow/calf pairs, to be precise.
The refuge last spring launched a fouryear study to measure the effectiveness of a grazingandburning technique to keep invasive plants such as thistle, sweet clover and hybrid cattails at bay, according to Glacial Ridge Refuge manager Dave Bennett.
Weve used every technique we can think of to try and remove some invasives and give the upper hand to our lands seeded thereand all for the benefit of tallgrass prairie and wildlife fauna that would naturally occur, Bennett said.
This year, being that its very wet, I would say the invasives have had the upper hand.
Thats where the cattle come into play.
Bennett said the technique, known as patchburn grazing, relies on cattle coupled with prescribed burns to target invasive plants while stimulating native vegetation such as prairie forbs.
Bennett said Glacial Ridge Refuge, which was established in 2004, has implemented the technique on a 2,100acre unit.
The idea, Bennett said, is that burning promotes green vegetation, which in turn attracts the cattle. Crews then burn another site, drawing cattle to the new area once it turns green.
Other sites are left untreated, Bennett said, leaving a patchwork of varyingheight grasses and forbs that provide niches for different wildlife species. Species expected to benefit from this specialized management tool include upland sandpipers, marbled godwits, Wilsons phalaropes, greater prairie chickens, Richardson ground squirrels and numerous grassland songbirds.
It allows us to give a second dose of treatment to invasives and to give some advantage to prairie forbs that are having a hard time surviving when vegetation gets real dense, Bennett said. Its a doublewhammyburning with grazing behind it.
Bennett said the U.S. Fish and Wildlife Service started the process with a public meeting at which local ranchers were invited to apply for the grazing program. Six ranchers applied, he said, and the Service awarded the permit to one from nearby Fertile, MN.
Before the cattle could be introduced, refuge crews had to fence the site, Bennett said. Cattle were released on May 20 and stayed on the refuge until late September.
Cattle will be on the land for the next three summers, and the refuge plans to burn onefourth of the 2,100acre area every year, Bennett said. He said the area is divided into 60 study plots, which refuge biologists are monitoring to see whats growing and whether the technique is reducing invasive plants.
Our purpose at the refuge is to manage for the benefit of plant species and wildlife that are indigenous to our area, Bennett said, so we have to show or prove that the techniqueswhether burning, mowing, grazing or a combination of thoseare in fact favoring the desired species.
Bennett said patchburn grazing has been used quite extensively on federal lands in Kansas and Oklahoma and on a smaller scale in southern Minnesota. In northwestern Minnesota, though, the technique is fairly new.
Its kind of an exciting tool to look at, Bennett said. I know other people are watching over our shoulders, in the Fish and Wildlife Service and other agencies, to see the results.
Brad Dokken is a reporter for the Grand Forks (ND) Herald, in which this article originally appeared on Aug. 14, 2011.