Exotic annual grass invasion and dominance of rangelands is a concern across western North America and other semiarid and arid ecosystems around the world. Postfire invasion and dominance by exotic annual grasses in sagebrush communities is especially problematic as there are no cost-effective control strategies available for the vast acreages already invaded. However, fall-winter grazing by cattle has been suggested as a potential tool to decrease exotic annual grasses and encourage native perennial vegetation, but to date its efficacy has not been tested. We evaluated fall-winter grazing over 4 yr after wildfire in Wyoming big sagebrush (Artemisia tridentata Nutt. subsp. wyomingensis Beetle & Young) steppe invaded by exotic annual grasses. Fall-winter grazing reduced exotic annual grass and annual forb cover and density and increased the native perennial bunchgrass, Sandberg bluegrass (Poa secunda L.). Exotic annual grass cover and density were 1.5 × greater in ungrazed compared with fall-winter grazed areas after 4 yr. At this time, Sandberg bluegrass density and cover were 1.6 × and 2.3 × greater in fall-winter grazed compared with ungrazed areas. Large perennial bunchgrasses and perennial forbs did not increase with fall-winter grazing because either grazing did not facilitate their increase or they were slow to respond to decreases in exotic annuals. Fall-winter grazing likely decreased exotic annual grass by defoliating it during its early growth in the fall and late winter and by reducing ground cover that facilitates exotic annual grass emergence and growth. Fall-winter grazing clearly reduced exotic annual grasses, but its effects on native perennial vegetation were not conclusive. Careful application of fall-winter grazing appears to be a valuable tool for managing exotic annual grass cover and abundance, but longer-term research is necessary to determine if it can facilitate the return of native perennial dominance.

每年北美北部西部以及世界其他半干旱和干旱的生态系统都对外来年草入侵和牧场的优势地位感到担忧。鼠尾草群落中的异国一年生禾草在大火后的入侵和控制方面尤其成问题，因为对于已经入侵的大面积土地没有可用的成本有效的控制策略。然而，已提出用牛秋冬放牧作为减少异国一年生禾本科植物和鼓励当地多年生植被的潜在工具，但迄今为止尚未对其功效进行测试。我们评估了秋冬季放牧在怀俄明州大山艾树（野火后超过4年蒿三齿纳特。亚种。wyomingensis甲虫（Young Beetle＆Young）草原受到一年生异国草种的入侵。秋冬放牧减少了每年异国情调的草丛和一年生的Forb覆盖物和密度，并增加了本地多年生的束草，Sandberg bluegrass（Poa secundaL.）。4年后，未除草的外来年草覆盖度和密度比秋冬放牧的地区大1.5倍。这时，放牧的秋冬桑德伯格草丛的密度和覆盖度分别比未草木化的地区高1.6倍和2.3倍。随着秋冬放牧，大型多年生束草和多年生草没有增加，因为要么放牧不促进它们的生长，要么它们对异国一年生植物的减少反应迟钝。秋冬放牧可能会通过在秋季和冬季末的早期生长期间使它脱落并减少地面覆盖物，从而减少异国一年生禾草的生长，从而减少异国一年生禾草的生长和生长。秋冬放牧明显减少了一年生异国草种，但其对当地多年生植物的影响尚无定论。