Targeted cattle grazing for shrub control in woody-encroached oak savannas

Woody encroachment threatens savanna ecosystems around the world. In the midwestern United States, remnant oak savannas persist in a woody-encroached state due to the removal of grazing and fire disturbances from the landscape. Primary oak savanna restoration methods, such as thinning and fire, can promote a dense shrub layer. Therefore, it is necessary to explore other tools to control woody species, such as targeted grazing. We conducted an experiment to evaluate the effectiveness of targeted cattle grazing as a shrub control method and its impacts on the herbaceous community. We used high-density, short-duration grazing to target shrubs and minimize negative non-target impacts. We found that this type of cattle management reduced shrub density over the short term, but there was substantial resprout after 1 year of no grazing. Targeted grazing lowered herbaceous cover and shifted species composition but did not affect herbaceous species richness or diversity. We saw no increase in non-native cover during the study, though we documented isolated occurrences of new non-native species in the grazing paddocks. Overall, our study points to the potential of targeted cattle grazing as a viable tool to help restore the understory of woody-encroached ecosystems. Successfully meeting vegetation objectives requires a grazing manager with knowledge of the site, the target species, and livestock care and nutrition, as well as a commitment to adaptive management.