Science behind Prescribed Grazing as a Conservation Practice.

Conservation Practice Standard 528 of the Natural Resource Conservation Service (NRCS) defines prescribed grazing as “managing the harvest of vegetation with grazing and/or browsing animals”. Prescribed grazing or browsing incorporates a variety of management actions. For the purposes of this presentation the actions have been termed management “strategies”. The management strategies include choices of grazing intensity, grazing method, season of grazing, type and class of livestock, and livestock distribution in the landscape. It is presumed that appropriate prescribed grazing choices 1) protect grazing land ecosystems, 2) prevent soil erosion, 3) maintain or enhance soil quality, 4) sustain forage and livestock production, 5) improve water yield and quality, 6) allow diverse wildlife habitat, 7) enhance aesthetics and open space, and 8) provide quality recreational opportunities. We reviewed the scientific literature to assess whether these benefits were occurring and to address whether managing the harvest of vegetation using these particular strategies allows the purposes of Prescribed Grazing Practice Standard 528 to be achieved. This talk will focus on the effects of only two of the five strategies, grazing intensity and grazing method, on plant, animal, soil, and water responses. A large body of literature describes the effects of these two strategies on plant and animal responses, and there is growing awareness of plant-animal interaction effects on the broader ecosystem. This is leading to increasing research emphasis and publication on soil and water issues. This presentation will highlight responses to prescribed grazing that apply across environments; however, in some cases the complexity of grassland environments makes it impossible to develop overarching generalizations. The review process has confirmed that research results may not always match perceived patterns of response, especially across the diversity of pasture environments in the USA, and these discrepancies will be identified and discussed.