Will increases in atmospheric CO2 affect regrowth following grazing in C4 grasses from tropical grasslands? A test with Sporobolus kentrophyllus.

We grew a C4 grass from the Serengeti ecosystem under ambient (370 ppm) and elevated (700 ppm) CO2, and under clipped and unclipped conditions to test whether regrowth following grazing would be affected by elevated CO2. Above-ground productivity was slightly decreased under elevated CO2, and was similar between clipped and unclipped plants. Regrowth (clipping offtake) following clipping was similar in the two CO2 treatments, and there was no CO2 by clipping interaction on biomass, productivity, or leaf nutrient concentrations. Based on this evidence, we suggest that C4 grasses from the Serengeti will show little direct response to future increases in atmospheric CO2.