by Greg Hoch
In the early 1900s, naturalist John Muir described livestock in the alpine meadows of the Sierra Mountains of California as "hoofed locusts." Later in the century, wilderness advocate Edward Abbey called cattle in the desert Southwest "a pest and a plague." Blaming cattle for environmental ills has long been a popular point of view of conservationists.
However, prairie plants evolved with and are well adapted to grazing by bison, deer, elk, and uncountable numbers of grasshoppers. The growing parts of many prairie grasses, the meristems, are at the soil surface, protected from both teeth and flame. In this landscape, a new and growing practice called conservation grazing returns hooved animals to their historic place in the prairie ecosystem.
Land managers with the Department of Natural Resources, the U.S. Fish and Wildlife Service, and The Nature Conservancy are learning that it isn't always enough to protect and preserve acres of land. We also need to return ecological processes to those acres. Fire, grazing, and climate variability are three processes that control the diversity and productivity of tallgrass prairie. We can't do much to control annual climate variability, but we can use prescribed fire and conservation grazing to limit trees and other invasive plants, increase native species richness, and improve the overall structure of grasslands.
Room for Diversity. By reducing the height and density of grasses, conservation grazing creates room for dozens of wildflower species, especially shorter species such as pasque flower, prairie smoke, and bird's foot violet. With no grazing, grasses crowd out some wildflowers, decreasing diversity. However, with too much grazing, invasive plant species such as leafy spurge and spotted knapweed can increase. By controlling the number of cattle, timing, and duration of grazing, land managers can increase wildflower diversity without harming grazing-sensitive native species or allowing invasive plants to take over.
Historically, grazers such as bison would have grazed an area, moved on, and not revisited that area for months or years. Thus, the prairie had a pulse of ecological disturbance followed by a period of recovery. Conservation grazing seeks to mimic these pulses by grazing a particular area for a short time or grazing the area only once every few years.
Since agencies don't necessarily want to get into the livestock business themselves, they rely on local ranchers to provide the cattle. This benefits ranchers who are looking for pasture to rent for grazing cattle, at a time when more land is being put into crop production due to high prices of corn and other commodities.
"Allowing conservation grazing of our wildlife grasslands gives our livestock farmers an opportunity to maintain their herds," says Don Baloun, state conservationist for the U.S. Department of Agriculture's Natural Resources Conservation Service. "We get the benefit of grazing to enhance the cover, and they get quality grasslands to maintain their herds."
Jim Wulf, a rancher in west-central Minnesota, points to additional benefits: "By moving cattle across different pastures, ranchers are able to break disease and parasite cycles."
Patch-Burn Grazing. One type of conservation grazing is patch-burn grazing, which relies on the natural feeding behavior of the animals to guide where they graze. One of the reasons American Indians burned prairies was to attract bison herds to the succulent regrowth after fire.
DNR prescribed-fire crews recently burned a 500-acre patch of land at the DNR's Lac qui Parle Wildlife Management Area and The Nature Conservancy's Chippewa Prairie. The patch is within a 2,770-acre pasture, which has been fenced from the area's much larger conservation lands. The spring fire removed the insulating layer of thatch and deposited black ash, which absorbs sunlight that rapidly warms the soil. The grass in these burned areas emerges earlier in spring and grows faster than do grasses in adjacent unburned areas.
More than 300 cattle from a nearby privately owned herd graze this pasture over the summer. Although the cattle can go anywhere within the fenced land, they spend the majority of their time in this burned patch. Because the cattle are attracted to the lush grasses there, no fencing is needed to contain them. Next year, fire crews will burn different acres, and the cattle will move there. DNR biologists are tracking responses of plant communities, insects, small mammals, and snakes to the fire and grazing.
Glacial Ridge National Wildlife Refuge in Polk County has a similar 2,100-acre patch-burn project and monitoring program, also using local private livestock herds. These two projects will help managers fine-tune techniques for Minnesota's grasslands and prairie remnants.
Patch-burn grazing has been used successfully in the hotter, drier prairies of Oklahoma and Kansas. Success can be measured in various ways. First, plant diversity increases. More important, the variety of plant heights increases. (Ungrazed prairies with frequent fires form tall, uniform stands of grass.) With conservation grazing, livestock gain weight as well as or better than cattle do in traditional grazing systems.
Conservation grazing creates some patches that are heavily grazed, some that are lightly grazed, and some that aren't grazed at all. This produces a greater variety of habitat for more species. Pheasants, mallards, and Henslow's sparrows nest in taller, ungrazed grasses. Blue-winged teal, chestnut-collared longspurs, and upland sandpipers prefer to nest in grass that has been lightly grazed. Prairie chickens and sharp-tailed grouse prefer ungrazed grasslands for roosting in winter, grazed areas for their spring leks, lightly grazed areas for nesting, and patchy grazed areas for brood rearing. Some mammals such as Richardson's ground squirrels also prefer grazed areas.
In summer, grasses and wildflowers are waist-high across much of Two Rivers WMA in Redwood County. The land has numerous trails where cattle have grazed or trampled vegetation. These trails make it easier for pheasant hens and chicks to move through the grass, foraging along grazed paths while remaining concealed from predators and protected from hot sun or driving rain.
Grazing has even been shown to improve wetlands for ducks. Many wetland edges or margins in the prairie pothole region are solid walls of cattails. Cattle break up these walls, creating a more heterogeneous habitat. Adults and ducklings of canvasbacks, mallards, blue-winged teal, and gadwalls have all been shown to prefer wetlands where cattle are present.
"Conservation grazing helps us better manage grasslands and build local support for conservation lands," says Tom Landwehr, DNR commissioner. "We need to make sure we don't negatively impact recreational uses of WMAs and other conservation lands, but I think sound grazing planning can accomplish both ecological and recreational goals."
Grassland Restored. In 2010 a number of government agencies and conservation organizations came together to develop the Minnesota Prairie Conservation Plan, a 25-year project to restore, enhance, and protect native prairie and grasslands across western Minnesota. A key component is to take a working-lands approach to grassland and wildlife conservation, integrating traditional agricultural practices such as grazing and haying with wildlife conservation. The working-lands approach shows how public lands can benefit from privately owned livestock herds and how livestock producers can benefit from grazing these grasslands.
Private pastures can also boost local wildlife populations. "Grazing can be beneficial to many species of migratory grassland birds in Minnesota," says Jim Leach, wildlife refuge supervisor for the U.S. Fish and Wildlife Service. "By resting private pasture when cattle graze public lands, wildlife populations on these acres should also increase." Resting private pastures is called grassland banking.
Grazing can achieve specific habitat goals "by getting animals to the right place at the right time for the right reasons," says Richard Olsen, DNR assistant area wildlife manager in Glenwood.
J.B. Bright, wildlife refuge specialist for the U.S. Fish and Wildlife Service in Morris, also notes an advantage of conservation grazing. "With fire, conditions may not be right for several years and the management objective may have missed its window of effectiveness," he says. "With grazing, I can count on it to occur when I want to apply it."
Like any type of management, grazing isn't always suitable everywhere. The staffs of the DNR Minnesota Biological Survey and the DNR Prairie Habitat Team are working with managers to identify native plant species and natural areas such as fens that could be harmed by grazing.
Cattle heavily grazed 182 acres of Brandon WMA in Douglas County during spring and early summer of 2012. While this might have lowered nesting success for grassland birds such as mallards that season, the long-term benefits are clear. Nonnative brome grass is only ankle high and has no seed heads. Native bluestem and Indiangrass are almost chest-high with heavy seed heads. The managers used cattle to stress undesirable nonnative plants, then removed the cattle just as desirable native plants started to grow. In another couple of years of careful management and overseeding with local seed, this WMA can be converted from a near monoculture of brome grass to a diverse stand of native grasses and wildflowers.
Common Goals. Too often people mistakenly assume that wildlife conservation and agriculture production have little in common. "Corn and soybeans will always be the largest part of western Minnesota's agricultural economy," says Wayne Monsen, grazing specialist for the Department of Agriculture and a DNR contractor. "However, livestock grazing can help diversify the agricultural economy while increasing wildlife-habitat diversity."
Ranchers raise not just cattle but also the grass that provides forage for the cattle. Similarly, wildlife managers manage prairies and grasslands to provide the best possible habitat for pheasants, mallards, and songbirds.
This focus on healthy, productive native plant communities—whether called forage or habitat—is where livestock production and wildlife management can meet and work for the benefit of both.