Limited effect of increased atmospheric CO2 concentration on ombrotrophic bog vegetation

Boreal and subarctic peatlands contain 20-30% of the world's soil organic c arbon, and if growing, they constitute sinks for atmospheric CO2. We hypoth esized that even in the nutrient-poor bog environment, elevated CO2 would s timulate Sphagnum growth more than vascular plant growth, thereby improving Sphagnum's competitive strength and enhancing carbon (C) sequestration. Free-air carbon dioxide enrichment (FACE) experiments took place on predomi nantly ombrotrophic peatbog-lawns in Finland (FI), Sweden (SW), The Netherl ands (NL), and Switzerland (CH). After 3 yr of treatment, increased CO2 concentration (560 ppm on volume bas is) had no significant effect on Sphagnum or Vascular plant biomass at eith er site. This research suggests that, just as with other nutrient-poor ecosystems, i ncreased atmospheric CO2 concentrations will have a limited effect on bog e cosystems.