Rangelands provide many human benefits such as food production, income for rural families and communities, recreation, wildlife habitat, soil carbon sequestration, plant and animal biodiversity, and water filtration. Grazing is often assumed to negatively impact the natural ecosystem and that removal of grazing would result in more pristine rangelands. The largest driver of forage and animal productivity, and economic return is proper stocking rate, and rotational or deferred grazing do not enhance these responses. But, management intensive grazing practices allow forages to store reserves during times of abundant precipitation, increase water-holding capacity, provide wildlife habitat at critical times of rearing young, and create a shifting mosaic with both old and new growth vegetation all the while maintaining animal productivity and income for ranchers. Therefore, several management factors such as stocking rate, grazing management, and fire regime can impact the human benefits received from rangelands.
Optimum rangeland management practices may differ depending on the ecosystems, and a recent analysis evaluated the interaction of ecosystem and rangeland management system at sites across the Great Plains. A computer simulation model capable of simulating plant growth and soil processes in response to stocking rate, grazing management, and fire regime was used for this analysis.
Increasing stocking rate resulted in increased soil erosion at Kansas and Wyoming sites, but not at Montana, South Dakota, and Nebraska sites. Additionally, timed rotational grazing increased soil erosion at Kansas sites. Annual burning of rangelands in the spring increased soil erosion at all sites except Nebraska due to less ground cover to protect the soil; however, the computer simulation was not designed to evaluate changes in the population of invasive plant species that might occur without spring burning. In contrast, timed rotational grazing decreased nitrogen losses from runoff, leaching, and volatization at all sites, but nitrogen loss was not affected by stocking rate or annual spring burning at any site.
Soil carbon deposition among rangeland management practices was highly dependent upon site. Rotational grazing had no effect on soil carbon deposition at Kansas and South Dakota sites, increased soil carbon deposition at Wyoming site, and decreased soil carbon deposition at Montana and Nebraska sites. In general, soil carbon deposition decreased with increasing stocking rate, but was somewhat dependent upon grazing management and site. Annual spring burning drastically decreased soil carbon deposition at all sites due to the fact that the previous year’s forage residue was no longer available to enter the soil.The results of the analysis confirmed that ecosystem effects the response to rangeland management practices such that there is no one-size-fits-all management system. The optimum rangeland management system will need to be developed locally. Additionally, there will be tradeoffs that will need to be evaluated by each rancher to meet their sustainability goals.
