For many people who live on the spacious prairies of Minnesota, Iowa and Wisconsin planting a tree can be a personal statement about their conservation ethic. On this sweeping landscape dominated by active farms, rural developments and the stubby grass and woody overgrowth of farms long-dormant, trees can provide an aesthetically pleasing contrast, as well as a nesting perch and habitat for all manner of migratory birds.
So trees are a good thing, right?
Not all of them, say federal land managers and wildlife biologists who are working to restore native prairie and the valuable nesting habitat it provides for ducks, pheasants, and a number of non-game migratory birds. It’s a job that requires some trees to be removed, particularly the scattered, non-native trees that have become established in valuable tallgrass prairie stands. “We’re not anti-trees,” said Jim Leach, area supervisor for National Wildlife Refuges in Minnesota and Wisconsin. “Trees in the right places are desirable, but when trees negatively impact wildlife by encroaching upon, or taking over prairie grasslands we need to remove them.”
For several years, the U.S. Fish and Wildlife Service has been working in concert with the both the Minnesota and Wisconsin Departments of Natural Resources, The Nature Conservancy and other government and non-government partners to restore and protect the vanishing native prairie in Minnesota, Iowa and Wisconsin.
When the first European settlers arrived in west central Wisconsin, in what is now St. Croix and Polk counties, they found more than 200,000 acres of tallgrass prairie and oak savanna. This complex of prairie, wetlands and oak savanna was very productive, both for wildlife and agriculture. Many of the local communities, such as Star Prairie and Erin Prairie, have names reflecting the surrounding prairie landscape. Today, only a small percentage of the original tallgrass prairie still exists, making it one of the rarest and most fragmented ecosystems in America. Along with the loss of the prairie grasslands, many species of wildlife also began to disappear or decline.
Wildlife biologists and land managers with the U.S. Fish and Wildlife Service are aggressively removing scattered trees and woody vegetation that are threatening to overtake tracts of tallgrass prairie habitat on Waterfowl Production Areas in western Wisconsin. The scattered non-native trees, mostly Russian olive, Siberian elm and buckthorn, as well as trees native to North America like green ash, box elder and cottonwood, and scattered pine plantations combine with other woody species to provide cover for predators that threaten nesting waterfowl, pheasants and numerous non-game bird species that depend on large open grasslands to thrive.
Following tree removal, these pieces of land are planted with native prairie grass and forb species. The original seed source for these species was collected locally so these seeds are adapted to local growing conditions and represent some of the species found on the original prairie in west central Wisconsin.
“Tree nesters and edge species such as robins and blue jays are doing OK, but grassland nesting birds – including waterfowl- are not doing as well as we would like,” said Tom Kerr, project leader for the Service’s St. Croix Wetland Management District in New Richmond, Wis. “Grassland nesting birds need all the help that we can provide, including removing trees and other woody cover for predators that feed on them.” Many species of grassland birds such as meadowlarks, bobolinks, blue winged teal and Henslow’s sparrows need large tracts of prairie grassland to survive.
In addition to restoring this vanishing habitat, wildlife biologists are being confronted by a new challenge: educating the public on why removing trees from a prairie landscape can actually be good for wildlife.
“Over the years, we have learned more about creating and restoring habitat that is valuable for ducks and other wetland and grassland dependent wildlife,” Kerr said. “Much of the management we do is not only good for ducks but also for many other species of grass nesting birds.”
Research into the effects of woody vegetation on grassland nesting birds such as ducks, pheasants and many non-game species supports the strategy for removing many, but not all, trees and shrubs from the prairie’s grassy landscape. For example, researchers in Missouri have found that prairie chicken nesting success is directly related to the distance the nests are from woody cover. A study in western South Dakota found that trees along pond edges decreased use of the pond by mallard broods. During a typical South Dakota winter, cattail wetlands, tall grass and food plots ranked highest in pheasant hen use. Nesting success was found to be lower in shelterbelts in South Dakota and Colorado.
Despite the scientific evidence supporting removal of trees on prairie grasslands, some people oppose removing trees. Federal and state wildlife biologists agree that educating the public on where trees are beneficial and where they are not is an important component of their wildlife and prairie restorations efforts.
“The trees that we are removing are on federally managed waterfowl production areas,” said Kerr “and like the name implies, we want to make these places attractive to waterfowl.”
“Many people associate trees with conservation and wildlife, and we will be leaving many of the native oaks that are an important part of the oak savannas scattered across the prairie,” said Kerr. “Without the removal of trees and active management of these prairie plantings, these grassland dependent birds will continue to disappear from the landscape.”
The U.S. Fish and Wildlife Service is the principal federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The Service manages the 95-million-acre National Wildlife Refuge System, which encompasses 544 national wildlife refuges, thousands of small wetlands and other special management areas. It also operates 69 national fish hatcheries, 64 fishery resources offices and 81 ecological services field stations. The agency enforces federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign and Native American tribal governments with their conservation efforts. It also oversees the Federal Assistance program, which distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state fish and wildlife agencies.
