Tropical forests take up more carbon (C) from the atmosphere per annum by photosynthesis than any other type of vegetation. Phosphorus (P) limitations to C uptake are paramount for tropical and subtropical forests around the globe. Yet the generality of photosynthesis-P relationships underlying these limitations are in question, and hence are not represented well in terrestrial biosphere models. Here we demonstrate the dependence of photosynthesis and underlying processes on both leaf N and P concentrations. The regulation of photosynthetic capacity by P was similar across four continents. Implementing P constraints in the ORCHIDEE-CNP model, gross photosynthesis was reduced by 36% across the tropics and subtropics relative to traditional N constraints and unlimiting leaf P. Our results provide a quantitative relationship for the P dependence for photosynthesis for the front-end of global terrestrial C models that is consistent with canopy leaf measurements.
Bibliographical noteFunding Information:
This work was supported in part by grants from the Australian Research Council Discovery scheme (grants DP160102452 and DP210100115) and the NSW Research Attraction and Acceleration Program (independent grants to D.S.E. and M.D.K.). D.S.E. also acknowledges research fellowships through the Chinese Academy of Sciences President’s International Fellowship Initiative, Grant No. 2018VBA0015, and the German Academic Exchange program (DAAD). M.D.K. acknowledge support from the Australian Research Council Centre of Excellence for Climate Extremes (CE170100023), the ARC Discovery Grant (DP190101823). I.J.W. acknowledges support by Australian Research Council (DP170103410). Y.S., P.C., D.S.G., L.T.V. and I.A.J. are funded by the “IMBALANCE-P” project of the European Research Council (ERC-2013-SyG-610028). A.P.W. was also supported by the US DOE, Office of Science, Office of Biological and Environmental Research at Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, for the US DOE under contract DE-AC05-00OR22725. J.L.Z. received funding from the National Natural Science Foundation of China (31870385) and the CAS 135 program (2017XTBG-F01). K.J.B., T.F.D., F.Y.I. and P.M. were supported by the UK National Environment Research Council ‘Tropical Biomes in Transition (TROBIT)’ consortium via research grant NE/D01185x/1 to the University of Edinburgh. T.F.D. and S.G. received funds from USAID for funding via the PEER program (grant agreement AID-OAA-A-11-00012). The contribution of P.R. was supported by the U.S. NSF Biological Integration Institutes grant DBI-2021898.
© 2022, The Author(s).