Cattle grazing is often excluded from restored grasslands due to potential risks to grassland recovery. This restriction has often been applied to the 5.6 million acres of Conservation Reserve Program (CRP) plantings designed to restore native grassland plant communities on former cropland. Because large herbivores historically played a key role in maintaining these grassland systems, excluding such grazers may hamper recovery of plant compositional and structural heterogeneity important to wildlife. We conducted a grazing experiment on 108 CRP sites in Kansas, quantifying the effects of periodic cattle grazing on plant communities restored via two CRP conservation practices (CP2, Establishment of Permanent Native Grasses and CP25, Rare and Declining Habitat) across a broad precipitation gradient. Cattle grazing was implemented during the growing season on 53 of the 108 sites in 2017−2018 with rest from grazing in 2019. Grazing reduced vegetation biomass and increased vegetation structural heterogeneity in 2017 and 2018. Grazing effects on plant community composition, specifically shifts in dominant grass abundances, were observed in 2018 but not 2017 or 2019. These effects were subtle and did not result in consistent changes to plant species richness, non-native abundance, or floristic quality. The effects of conservation practice were independent of grazing but strongly dependent on mean annual precipitation. Plant community composition differed significantly between CP2 and CP25 in the western (drier) and eastern (wetter) regions, but no differences were detected in the central region. Forb cover increased with precipitation at a greater rate on CP25 than CP2, indicating greater forb establishment in the eastern region. These results indicate that moderate, short-term grazing can enhance habitat structural heterogeneity that may be beneficial for wildlife while causing minimal plant community changes.

中文翻译：

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短期放牛对陡降水梯度恢复保护区计划草原的影响

由于草原恢复存在潜在风险，恢复的草原通常不包括放牧牛群。这一限制通常适用于 560 万英亩的保护保护区计划 (CRP) 种植园，旨在恢复以前农田上的原生草原植物群落。由于大型食草动物历史上在维持这些草原系统方面发挥着关键作用，因此排除此类食草动物可能会阻碍对野生动物重要的植物组成和结构异质性的恢复。我们在堪萨斯州的 108 个 CRP 地点进行了放牧实验，量化了定期放牧牛对在广泛的降水梯度范围内通过两种 CRP 保护实践（CP2，建立永久原生草和 CP25，稀有和下降的栖息地）恢复的植物群落的影响。 2017-2018 年，108 个地点中的 53 个在生长季节实施了牛放牧，2019 年停止放牧。2017 年和 2018 年放牧减少了植被生物量，增加了植被结构异质性。放牧对植物群落组成的影响，特别是优势植物群落的变化2018 年观察到草丰富度，但 2017 年或 2019 年没有观察到。这些影响很微妙，并没有导致植物物种丰富度、非本地丰富度或植物区系质量的一致变化。保护措施的效果与放牧无关，但很大程度上取决于年平均降水量。 CP2和CP25在西部（较干燥）和东部（较湿润）地区的植物群落组成存在显着差异，但在中部地区没有检测到差异。 CP25 上的杂草覆盖率随着降水量的增加而增加，其速率高于 CP2，这表明东部地区的杂草建立量更大。这些结果表明，适度、短期的放牧可以增强栖息地结构异质性，这可能对野生动物有益，同时造成植物群落变化最小。