Fig. 2. Photosynthetic acclimation to elevated pCO₂ of P. alpina var. vivipara plants grown at two nutrient regimes: one‐fifth strength (low) or full‐strength (high) Long Ashton nutrient solution. Data are means of six replicates ± s.e. ** Significant difference between nutrient treatment means at the P < 0·01 level determined by Student’s t‐test. An acclimation index < 1 indicates a loss of photosynthetic capacity.