Patch Burn-Grazing to Promote Environmental Sustainability

Patch-burn grazing, continuous grazing and rotational grazing treatments were applied in spring 2008 and 2009 on five participating ranches in eastern South Dakota. Vegetation data was collected to evaluate forage quality, diversity, and structure. Analyses validated the ability of patch burn-grazing to create more heterogeneity than rotational or continuous grazing. Concern was noted by producers regarding forbs (specifically goldenrod species) was increasing under patch-burn grazing. This concern was raised by producers on field tours. Calf weights were measured between patch-burn grazing and continuous grazing, and no differences were found. Patch-burn grazing may need to be conducted at moderate stocking rates to ensure appropriate fuel loading for next year’s burn compared to rotational or continuous grazing. Heavier stocking rates on pastures that are continuous or rotationally grazed would produce more beef per acre than patch-burn grazing. Tours were held on several research sites and were attended by professional grassland managers represented by state, federal, and non-governmental agency personnel as well as rancher participants. We also had additional tours for ranchers and grassland managers demonstrating the pluses and minuses of patch-burn grazing. Keen interest exists by ranchers to conduct prescribed fires. A rancher workshop was held on how to conduct prescribed burns in August 2010. Patch-burn grazing in the north central U.S. works to create more structural heterogeneity than traditional grazing systems but it does come at higher cost to the producer.

Introduction:

During the last 30 years, scientific scrutiny of standard grazing practices designed to optimize livestock production on grasslands of the Great Plains has led to observations that other ecosystem services that grasslands provide are constrained. In addition to livestock production, grasslands provide habitat for wildlife, sequester carbon, improve water quality, and are a refuge for maintaining native plant diversity. Strong profit motives are likely responsible for decisions to apply high stocking rates that often result in a landscape dominated by shorter, more grazing resistant plant communities. It’s easy to place blame on this practice because of the striking impacts overstocking has on wildlife, water quality, and plant diversity. Yet, some more sophisticated techniques of rotational grazing often result in a uniform vegetation structure across the landscape, albeit not as short as heavy, continuous grazing.
Recent investigations suggest that age-old management tools aimed at improving grazing distribution have resulted in a predictable habitat structure that may actually reduce plant and animal diversity across a managed landscape. Grassland bird diversity has become the focal illustration to prove this point. Proponents of a multiple-use concept, meaning grasslands could be managed for both ecosystem goods (livestock production) and services (habitat, carbon sequestration, diversity, etc.), argue for a change in how we manage livestock grazing. Historically and still to this date, rest-rotation and deferred rotation grazing strategies have been effective tools at providing contrasting vegetation structure that have benefited wildlife. In the last 10 years, a new strategy called “patch-burn grazing” has been proposed as an alternative to conventional rotational grazing techniques (Fig. 1).

The concept behind patch-burn grazing is to reintroduce an ecosystem processes that once dominated the Great Plains. Historical evidence suggests that fire and large ungulate grazing co-existed for a long time in the Great Plains such that these ecosystem processes created a shifting mosaic of vegetation structure across the landscape. This mosaic of vegetation structure created a tight evolutionary bond between plants and animals and maximized regional diversity. Patch-burn grazing offers several intriguing benefits to the landscape and the land manager. First and most obvious, patch-burn grazing brings back fire as a management tool to the landscape. Fire has been suppressed in the Great Plains for the last 100+ years. There are unique places such as the Flint Hills of Kansas or the Osage Hills of Oklahoma where fire is still a consistent part of the land management process. However, for the most part fire is quite rare, especially in the northern Great Plains states of Nebraska, South Dakota, and North Dakota. Secondly, no rest period is required after fire. Cattle can be placed in the pasture immediately after the burn or can even be in the pasture when the burn occurs. Thirdly, no fences or additional water developments are needed. The desired outcome of patch-burn grazing is to increase the structural heterogeneity across the landscape and hopefully result in increases in plant and animal diversity; “if you build it, it will come”. Several recent publications from the southern Great Plains have provided evidence that plant and animal diversity is increased through patch-burn grazing. Traditional grassland management has shown fewer forbs, insect species, and grassland birds compared to patch-burn grazing.
This patch burn-graze strategy has been tested in the tallgrass prairie ecoregion of Oklahoma and Kansas where the predominant native grass species are warm-season and late-spring burns are effective in controlling exotic cool-season species. In addition, these experiments have been carried out on large tracts (>4,000 acres) in a region where grassland fragmentation is less severe. In the northern tallgrass prairie region of the US, landscapes are highly fragmented, tract sizes are smaller, and dominant plant species are quite different which makes them vulnerable to invasive species, and reduces environmental quality.