Dynamic duo: fire, grazing unite for land management

By ANNE LARSON, Special to the Leopold Center

Answers for the future of grazing in Iowa may be found in the historic interaction of fire and grazing on America’s native prairies.

Iowa State University researchers currently are looking at ways to manage Iowa’s private and public grasslands with this “dynamic duo,” thanks to $21,000 from the Leopold Center Ecology Initiative that has leveraged nearly a million dollars worth of support for ongoing study. The Iowa Department of Natural Resources State Wildlife program has provided a $424,400 grant specific to fire and grazing. The U.S. Department of Agriculture’s National Research Initiative has contributed nearly $500,000 focused on related work. The initial project also was supported by the Joint Fire Sciences Program and ISU’s College of Agriculture.

Much like an early American landscape grazed by bison, areas most recently burned offer the most appealing forage for grazing, while those later in the burn cycle are avoided by cattle (see accompanying graphic). By following a three-year cycle to burn three to six areas within a pasture, managers do not need to maintain fences; livestock move from one grazing area to another based on the burn cycle.

New path for grazing
No doubt, it’s a different way to look at grazing. Rather than trying to improve harvest efficiency through minimizing forbs and ungrazed grasses in a pasture, the patchwork, fire-grazing interaction approach focuses on enhancing the presence of native species and expanding the complexity of the grassland make-up. The result, as described by the researchers, is a pasture that has more internal variability within a pasture as well as more stability in a landscape view.

ISU researchers working on this concept are Dave Engle, who leads the ISU Department of Natural Resource Ecology and Management (NREM), colleague James Miller (with a dual appointment in the ISU Department of Landscape Architecture) and Diane Debinski, ISU Department of Ecology and Evolutionary Biology. They recently completed preliminary work that laid the groundwork for research that will show whether using burning in conjunction with grazing (the fire-grazing interaction) can benefit the cattle industry, improve native species habitat, and address wildfire concerns on preserves and privately-owned grazing land.

As described by Miller and Engle, “Grasslands that have not been grazed or burned in several years have a higher probability of fire and lower probability of grazing, and grasslands that have recently been burned have a higher probability of being grazed and lower probability of burning until fuel can accumulate.”

Patterned after Oklahoma work
Research in Oklahoma shows that heavy grazing after a patch-burn has no negative influence on bison, and might be an important tool to enhance nutrient intake during winter. Engle’s earlier research while at Oklahoma State University showed that domestic cattle respond to the patch burning regime by grazing recently burned patches 75 percent of the time. Three separate studies in Oklahoma evaluating performance of domestic stocker cattle and cow-calf pairs indicate livestock performance equivalent to that of traditionally managed pasture.

Grassland bird populations often are used as indicators of ecosystem integrity because of their diverse habitat requirements. Their preferences vary from minimal vegetation cover to areas with dense vegetation and litter. The patch-burning/grazing regimen lends itself to diverse habitats, which in turn can appeal to a variety of species with varying habitat needs. Likewise, invertebrates such as butterflies are attracted to varying vegetation patterns.

Twelve areas in and near Ringgold County in south central Iowa will be targeted in the current study. Since grassland and grazing occupy a great deal of the southern Iowa landscape, this area is ripe for research. The parcels on which the burns will occur include the IDNR Ringgold and Kellerton Wildlife Management areas, on private properties in Ringgold County, and on the Missouri Department of Conservation’s Pawnee Prairie Preserve across the state line in Harrison County, Missouri. Patch burns will begin when snow cover dissipates this spring.

Iowa research begins
Grazed pastures were fenced in 2006 and stocked at a moderate rate (1.25 animal unit months per acre). No fertilizer or herbicide will be used in any of the pastures under study. Baseline surveys of bird populations, vegetation, insects, fuel-loads and cattle trails were made. Measurements will be made against this baseline during the course of the project.

Miller and Engle were intrigued by some results of the initial surveys:

Eight species of birds entirely dependent on grasslands were observed, as well as ten species that use the grasslands as a part of a larger array of habitats.

Pastures, including those that initially appeared devoid of native plants, proved to have many prairie plant species, both grasses and forbs, which are believed to respond well to patch-burn-grassing management.

A surprising number of landowners were open to considering alternative management practices.

Miller and Engle have built a number of partnerships and done considerable outreach during this first year, which holds promise for the future of the project. They also hope to integrate a sociological study on the landowner’s decision-making process regarding adoption of grazing and fire management.

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Dynamic duo: fire, grazing unite for land management