What have we learned from 15 years of free‐air CO 2 enrichment (FACE)? A meta‐analytic review of the responses of photosynthesis, canopy properties and plant production to rising CO 2

Summary Free‐air CO 2 enrichment (FACE) experiments allow study of the effects of elevated [CO 2 ] on plants and ecosystems grown under natural conditions without enclosure. Data from 120 primary, peer‐reviewed articles describing physiology and production in the 12 large‐scale FACE experiments (475–600 ppm) were collected and summarized using meta‐analytic techniques. The results confirm some results from previous chamber experiments: light‐saturated carbon uptake, diurnal C assimilation, growth and above‐ground production increased, while specific leaf area and stomatal conductance decreased in elevated [CO 2 ]. There were differences in FACE. Trees were more responsive than herbaceous species to elevated…

• NS
  National Science Foundation
• AV
  Alexander von Humboldt-Stiftung