WILL INCREASES IN ATMOSPHERIC CO2 AFFECT REGROWTH FOLLOWING GRAZING IN C-4 GRASSES FROM TROPICAL GRASSLANDS - A TEST WITH SPOROBOLUS-KENTROPHYLLUS

We grew a C-4 grass from the Serengeti ecosystem under ambient (370 pp m) and elevated (700 ppm) CO2, and under clipped and unclipped conditi ons to test whether regrowth following grazing would be affected by el evated CO2. Above-ground productivity was slightly decreased under ele vated CO2, and was similar between clipped and unclipped plants. Regro wth (clipping offtake) following clipping was similar in the two CO2 t reatments, and there was no CO2 by clipping interaction on biomass, pr oductivity, or leaf nutrient concentrations. Based on this evidence, w e suggest that C-4 grasses from the Serengeti will show little direct response to future increases in atmospheric CO2.