The global land surface absorbs about a third of anthropogenic emissions each year, due to the difference between two key processes: ecosystem photosynthesis and respiration. Despite the importance of these two processes, direct observations of either are lacking. Eddy-covariance (EC) measurements are widely used as the closest ‘quasi-direct’ ecosystem-scale observation from which to estimate ecosystem photosynthesis and respiration. Recent research, however, suggests that current estimates may be biased by up to 25%, due to a previously unaccounted-for process: the inhibition of leaf respiration in light. Yet the extent of inhibition at the ecosystem scale remains debated, and impacts on global estimates of photosynthesis and respiration unquantified.
Results/Conclusions
Here, we quantify the extent of inhibition of ecosystem respiration across the global FLUXNET EC network, and identify a pervasive influence that varies by season and ecosystem type. We develop partitioning methods that account for inhibition, and find that diurnal patterns of ecosystem respiration might be markedly different than previously thought. The results call for the reevaluation of global terrestrial carbon cycle models, and also suggest that current global budgets of photosynthesis and respiration may be biased on the order of magnitude of anthropogenic fossil fuel emissions.