Convergence of potential net ecosystem production among contrasting C₃grasslands

Abstract Metabolic theory and body size constraints on biomass production and decomposition suggest that differences in the intrinsic potential net ecosystem production ( NEP POT ) should be small among contrasting C 3 grasslands and therefore unable to explain the wide range in the annual apparent net ecosystem production ( NEP APP ) reported by previous studies. We estimated NEP POT for nine C 3 grasslands under contrasting climate and management regimes using multiyear eddy covariance data. NEP POT converged within a narrow range, suggesting little difference in the net carbon dioxide uptake capacity among C 3 grasslands. Our results indicate a unique feature of C 3 grasslands compared with other terrestrial ecosystems and suggest a state of stability in NEP POT due to tightly coupled production and respiration processes. Consequently, the annual NEP APP of C 3 grasslands is primarily a function of seasonal and short‐term environmental and management constraints, and therefore especially susceptible to changes in future climate patterns and associated adaptation of management practices.