Seasonal patterns of global change effects on C fluxes.

Cumulative effects of global changes on gross ecosystem production (P_eco; g m⁻² yr⁻¹) and ecosystem respiration (R_eco; g m⁻² yr⁻¹) in 2007–2010 at the Prairie Heating and CO₂ Enrichment Experiment (PHACE) in Cheyenne, WY USA. Treatment effects are differences from ambient values for each year of the experiment with increases in fluxes expressed as “stimulation” and decreases in fluxes expressed as “suppression.” Data are expressed as cumulative across the growing season with the CO₂ effect in blue, warming effect in red, CO₂×warming interactive effect in purple, and irrigation effect in green. Daily precipitation amounts are depicted in the bottom panel. Both annual and growing season precipitation totals (in parentheses) are included for each year.