Do grazers alter nitrogen dynamics on grazing lawns in a South African savannah?

The presence of grazers on grazing lawns in East Africa and North America often alters nitrogen cycling and availability. Grazing lawns can be defined as areas where grasses are kept in a short, actively growing, palatable state by the action of grazers. Our aim was to test whether lawns have enhanced leaf nitrogen (N) concentrations, total soil N and δ 15 N when compared to tall grass areas in a South African savannah. Previous studies have used ecosystem δ 15 N as a proxy of N availability, and enriched δ 15 N values have been suggested to indicate higher N availability or higher N transformation rates. Across all sites, foliar N concentrations (but not soil N) were higher when compared to tall grass areas, and evidence of enriched foliar and soil δ 15 N values was found on the lawns. These results suggest that grazers may be involved in altering the rates of N transformations directly on grazing lawns. Regardless of whether these N transformations included increased net N mineralization, higher N concentrations in above‐ground foliage attract grazers back to the lawns, encouraging their maintenance.