Figure 2.

The effect of long-term (lifetime or >3 years) growth at elevated [CO₂] in the field on leaf respiration. The data points show mean leaf respiratory O₂ uptake (±90% confidence intervals) on an area and mass basis for leaves grown at elevated [CO₂] relative to controls grown at current ambient [CO₂]. The points are means for seven species (Table I) weighted for replication and variance using meta-analytical statistical methods.