White-tailed deer (Odocoileus virginianus) are now the dominant large herbivores in tallgrass prairie ecosystems of the U.S. Midwest and have unique ecological impacts compared to the historically dominant bison (Bison bison) and elk (Cervus elaphus) that were extirpated from this region. While most of our knowledge of white-tailed deer impacts on plant communities and ecosystem processes comes from forested habitats, relatively little research has focused on deer effects in prairies. In this review, we discuss the ecological impacts of white-tailed deer in North American tallgrass prairies, potential deer management strategies, and areas of future research.
Unlike bison and elk, deer are selective grazers that preferentially eat nutrient-rich forbs. At high deer densities, this consumption of forbs can have negative effects on prairie biodiversity and alter nutrient cycling. Deer can decrease plant diversity by reducing the abundance and reproductive success of their preferred plant species, shifting the plant community to one dominated by species avoided by deer or tolerant of herbivory.
At lower densities, deer may maintain biodiversity in accordance with the intermediate disturbance hypothesis. Deer are able to maintain a balance between deer-avoided and deer-preferred species abundance by giving unpreferred or herbivory-tolerant species an advantage, but not completely suppressing herbivory-sensitive species. Nonconsumptive deer impacts also influence prairies through transporting invasive species, trampling on deer trails, and redistributing nutrients in fecal pellets and carcasses. Management strategies such as hunting, use of fences, and patch-burning can alleviate the pressures of overabundant deer populations, while maintaining their ability to promote heterogeneity.