Short-Term Cattle Grazing Effects on Restored Conservation Reserve Program Grasslands Across a Steep Precipitation Gradient

Abstract

Cattle (Bos taurus) 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.