Invasive Species
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This synthesis describes what is known about the cumulative impacts of historic livestock grazing patterns and short-term effects of livestock grazing on fuels and fire in sagebrush ecosystems. Over years and decades grazing can alter fuel characteristics of ecosystems. On a yearly basis, grazing can reduce the amount and alter the continuity of fine fuels, potentially changing wildlife fire spread and intensity. However, how grazing-induced fuel alterations affect wildland fire depends on weather conditions and plant community characteristics. As weather conditions become extreme, the influence of grazing on fire behavior is limited, especially in communities dominated by woody plants.
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This review of the literature found that in general long-term rest and modern properly managed grazing produce few significant differences. However, some topic areas have not been adequately studied to accurately predict the influence of long-term rest compared to managed grazing. In some situations, not grazing can cause an accumulation of fine fuels that increase fire risk and severity and, subsequently, the probability of sagebrush steppe rangelands converting to exotic annual grasslands. Shifts in plant communities (i.e., exotic annual grass invasion and western juniper encroachment), caused in part from historical improper grazing, cannot be reversed by long-term rest.
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This study found that growth rate of cheatgrass increased in both warming and snowmelt treatments. Largest increases occurred in warming plots during the wettest year, indicating that the magnitude of response to warming depends on moisture availability. Results indicate that increasing temperature will exacerbate cheatgrass impacts, especially where warming causes large reductions in the depth and duration of snow cover.
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This review examines the effects of disturbances, such as grazing, and changes in climate on resilience and resistance of cold desert shrublands that span temperature and precipitation gradients across the western United States. It demonstrates how to use information about cold desert resilience and resistance to help manage this ecosystem and describes the benefits of using protection, prevention, restoration, and monitoring strategies to determine priority management areas and appropriate management actions.
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This brief evaluates the potential effects of Diorhabda herbivory on tamarisk fire behavior at Great Basin and a Mojave Desert sites.
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This study investigated factors controlling cheatgrass invasions in sagebrush systems, including the influence of livestock grazing. It found that cheatgrass invasion was limited where few and small gaps existed between bunchgrass and where biological soil crusts were present to stabilize soil and limit cheatgrass establishment. Results also suggest that grazing reduces invasion resistance by decreasing bunchgrass abundance and trampling biological soil crusts. Managing grazing to ensure abundance and variety of bunchgrasses and to preserve biological soil crusts could help restore sagebrush ecosystems.
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In this review of recent literature and meta-analysis of seeding after wildfires, the authors found that seeding has little effect on erosion during the first year after fire and is highly dependent upon initial establishment and coverage of species in successive years. Older seedings were more likely to show reductions in invasives than younger seedings. Seedings with high plant establishment were more likely to reduce invasives than those with low establishment.
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This purpose of this article is to outline how weather and climate information can be used to facilitate Ecologically-Based Invasive Plant Management (EBIPM) and adaptive management planning. The discussion follows the eight steps to adaptive management outlined in EBIPM planning guides.
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This study evaluated restoration efforts applied to grasslands dominated by an invasive plant, sulfur cinquefoil, 6 yr after treatments. Of the five herbicides evaluated, picloram continued to provide the best control of sulfur cinquefoil over 6 yr. Plots with picloram applied in the fall had greater native forb cover. Seeding resulted in a 20% decrease in exotic grass cover. Successful establishment of native perennial grasses was not apparent until 6 yr after seeding. Our study found integrating herbicide application and the addition of native grass seed to be an effective grassland restoration strategy, at least in the case where livestock are excluded.
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The results of this study suggest that mowing, as a standalone
treatment, does not restore the herbaceous understory in degraded Wyoming big sagebrush plant communities. Mowing should not be applied in Wyoming big sagebrush plant communities with degraded understories without additional treatments to limit exotic annuals and promote perennial herbaceous vegetation.