Nontarget Benefit

To be successful, using grazing or browsing to control weeds requires a clear understanding of how both target and non-target plants respond to grazing, how plant communities can be modified by grazing pressure, and how grazing integrates with other management activities. It is relatively easy to suppress invasive annual grasses where they form nearly pure stands (i.e., monocultures) that exclude most other plants. On these sites, prescribed livestock grazing can be applied to achieve maximum damage to annual grasses with little concern for non-target plants. Grazing intensity can be high (residual stubble height less than 3 inches) and grazing relatively uniform if a site is largely dominated by invasive annual grasses. The specific stubble height or utilization level is less important than selecting a grazing intensity heavy enough to prevent annual grasses from developing viable seeds.

A clear understanding of the palatability and susceptibility of all plants in the community is needed to design a grazing strategy that will compromise the target plants and benefit the desirable plants. Plants grazed more heavily are at a competitive disadvantage compared with those grazed less severely. In simplest terms, grazing should be applied when the target plant is most palatable to livestock and most susceptible to damage through defoliation. Likewise, grazing should be applied when associated or desired plants are more tolerant to grazing. Such efforts can be enhanced by selecting animals that favor the plants targeted for control. It may be difficult for livestock producers or land managers to concentrate grazing during specific short periods when undesirable plants are most susceptible to damage, especially on vast rangelands where intensive management is more difficult.

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