The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council. |
Tuesday, January 29, 2008 - 8:40 AM
Forage, Fire, and Fescue: The Considerations and Challenges of Applying A Patch-Burn Grazing Model on Tall Fescue-Dominated Tallgrass Prairie
Devan Allen McGranahan, Graduate Program in Sustainable Agriculture, Department of Natural Resources Ecology and Management, Iowa State University, 339 Science II, Ames, IA 50010 and David M. Engle, Department of Natural Resources Ecology and Management, Iowa State University, 339 Science II, Ames, IA 50010.
The patch-burn hypothesis has been applied within several grassland systems, often to address specific conservation or management goals unique to each system. An effective patch-burn grazing scheme requires substantial contrast between the most recently burned patch and the surrounding landscape. Thus, three major factors must be considered when determining the proper fire return interval in order to ensure fuel sufficient to create the necessary contrast: rate of litter decomposition/accumulation, stocking rate, and time since previous fire. While patch-burning is often applied to control one or more plant species of management concern, the characteristics of the species may directly affect litter accumulation, either by altering rates of litter decomposition or through increased or decreased grazer selection because of differential palatability. My talk discusses the application of the patch-burn model to fescue-invaded tallgrass prairie pastures in southern Iowa. We hypothesize that patch-burning will increase relative selection of tall fescue in recently burned patches, resulting in a decrease in its abundance over time. Because litter accumulation rate decreases as tall fescue abundance increases, pastures dominated by tall fescue might require longer fire-return intervals to create sufficient contrast between burned and unburned patches, contrast essential to reducing forage selectivity. I discuss data regarding pastures at various stages of fescue invasion, their respective litter accumulation, and the interactive role of stocking rate and past fire history.