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Widespread inhibition of daytime ecosystem respiration


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, it is not possible to measure either at the ecosystem scale during the daytime. Eddy-covariance 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 the light. Yet the extent of inhibition remains debated, and implications for estimates of ecosystem-scale respiration and photosynthesis remain unquantified. Here, we quantify an apparent inhibition of daytime ecosystem respiration across the global FLUXNET eddy-covariance network and identify a pervasive influence that varies by season and ecosystem type. We develop partitioning methods that can detect an apparent ecosystem-scale inhibition of daytime respiration and find that diurnal patterns of ecosystem respiration might be markedly different than previously thought. The results call for the re-evaluation of global terrestrial carbon cycle models and also suggest that current global estimates of photosynthesis and respiration may be biased, some on the order of magnitude of anthropogenic fossil fuel emissions.

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Code availability

Code used in the analysis presented in this paper is available online in two repositories. The first contains the modified REddyProc partitioning algorithms and can be accessed at The second contains the post-partitioning data processing pipeline code and can be accessed at

Data availability

This work used openly available FLUXNET 2015 v3 Tier 1 eddy-covariance data acquired and shared by the FLUXNET community. All related data is publicly available for download at


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T.F.K. was supported by the NASA Terrestrial Ecology Program IDS Award no. NNH17AE86I. D.P. thanks the RINGO project funded by the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement no. 730944. We also acknowledge support from the Director, Office of Science, Office of Biological and Environmental Research of the US Department of Energy under the AmeriFlux Management Project. This work used eddy-covariance data acquired and shared by the FLUXNET community, including these networks: AmeriFlux, AfriFlux, AsiaFlux, CarboAfrica, CarboEuropeIP, CarboItaly, CarboMont, ChinaFlux, Fluxnet-Canada, GreenGrass, ICOS, KoFlux, LBA, NECC, OzFlux-TERN, TCOS-Siberia and USCCC. The ERA-Interim reanalysis data are provided by ECMWF and processed by LSCE. The FLUXNET eddy-covariance data processing and harmonization was carried out by the European Fluxes Database Cluster, AmeriFlux Management Project and Fluxdata project of FLUXNET, with the support of CDIAC and the ICOS Ecosystem Thematic Center, and the OzFlux, ChinaFlux and AsiaFlux offices. We especially acknowledge all the principal investigators who contributed data to the FLUXNET Tier 1 dataset.

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T.F.K. designed and performed the analysis and led the drafting of the manuscript. M.M. and T.W. developed the original REddyProc software and advised on modifications. All authors provided feedback on the analysis and the manuscript.

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Correspondence to Trevor F. Keenan.

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Keenan, T.F., Migliavacca, M., Papale, D. et al. Widespread inhibition of daytime ecosystem respiration. Nat Ecol Evol 3, 407–415 (2019).

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