Convergence in phosphorus constraints to photosynthesis in forests around the world
David S. Ellsworth, Kristine Y. Crous, Martin G. De Kauwe, Lore T. Verryckt, Daniel S. Goll, Sönke Zaehle, Keith J. Bloomfield, Philippe Ciais, Lucas A. Cernusak, Tomas F. Domingues, Mirindi Eric Dusenge, Sabrina García, Rossella Guerrieri, F. Yoko Ishida, Ivan A. Janssens, Tanaka Kenzo, Tomoaki Ichie, Belinda E. Medlyn, Patrick Meir, Richard J. Norby, Peter B. Reich, Lucy Rowland, Louis S. Santiago, Yan Sun, Johan Uddling, Anthony P. Walker, K. W. L. K. Weerasinghe, Martine J. van de Weg, Yun‐Bing Zhang, Jiao‐Lin Zhang, Ian J. Wright
Abstract
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.