Grass forage quality and quantity in savannas: Will elevated atmospheric CO2 concentration induced increases in water use efficiency compromise C4 grass soil nitrogen acquisition?

Photosynthesis (Amax), stomatal conductance (gs), water use efficiency (WUE), nutrient gain and biomass of six grass species under direct, indirect (mass-flow), and no nutrient supply (control). Leaf vein density, specific leaf area and stomata density of the same species measured on well fertilized plants.