Fig 4. Dependence of growing season mean (A) net ecosystem CO₂ exchange (NEE, μmol m^-2 s^-1), (B) ecosystem respiration (ER, μmol m^-2 s^-1), and (C) gross ecosystem productivity (GEP, μmol m^-2 s^-1) on aboveground biomass (AGB) across treatments in 2012 (solid circles), 2013 (open triangle), and 2014 (open square).

** represents a significant relationship at the P < 0.01 level.