Experiments show that elevated atmospheric CO2 (eCO2) often enhances plant photosynthesis and productivity, yet this effect varies substantially and may be climate sensitive. Understanding if, where and how water supply regulates CO2 enhancement is critical for projecting terrestrial responses to increasing atmospheric CO2 and climate change. Here, using data from 14 long-term ecosystem-scale CO2 experiments, we show that the eCO2 enhancement of annual aboveground net primary productivity is sensitive to annual precipitation and that this sensitivity differs between woody and grassland ecosystems. During wetter years, CO2 enhancement increases in woody ecosystems but declines in grass-dominated systems. Consistent with this difference, woody ecosystems can increase leaf area index in wetter years more effectively under eCO2 than can grassland ecosystems. Overall, and across different precipitation regimes, woody systems had markedly stronger CO2 enhancement (24%) than grasslands (13%). We developed an empirical relationship to quantify aboveground net primary productivity enhancement on the basis of changes in leaf area index, providing a new approach for evaluating eCO2 impacts on the productivity of terrestrial ecosystems.
Bibliographical noteFunding Information:
The authors acknowledge the FACE experiments, scientists’ investigations and publications that provide data for this study. Y.P. acknowledges the support of Bullard Fellowship at Harvard University. O.L.P acknowledges support from the Royal Society and the European Research Council ERC (AdG grant 291585). R.S.N. and R.J.N acknowledge support from the US Department of Energy, Office of Science, Biological and Environmental Research Office. R.O. acknowledges support from Jane and Aatos Erkko 375th Anniversary Fund through the University of Helsinki. The contribution of P.B.R. was supported by the US NSF Biological Integration Institutes grant DBI-2021898. The lead author is grateful to J. Morgan and J. Nösberger for valuable comments and insights contributed to earlier drafts of the manuscript. This study was originally inspired by a synthesis study published in 2004 by Nowak et al.16.
© 2022, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.
- Carbon Dioxide
- Water Supply
PubMed: MeSH publication types
- Research Support, Non-U.S. Gov't
- Research Support, U.S. Gov't, Non-P.H.S.
- Journal Article