Scientific Results

  • ID:
    publications-1813
  • Type:
    Peer reviewed articles
  • Year:
    2022
  • Authors:
    Dong, N, Wright, I. J., Chen, J.M., Luo, X., Wang, H., Keenan, T.F., Smith, N.G. & Prentice, I.C.
  • Title:
    Rising CO2 and warming reduce global canopy deman for nitrogen.
  • Venue/Journal:
    New Phytologist
  • DOI:
    10.1111/nph.18076
  • Research type:
    Hydrological modeling
  • Water System:
    Irrigation Systems
  • Technical Focus:
  • Abstract:
    SummaryNitrogen (N) limitation has been considered as a constraint on terrestrial carbon uptake in response to rising CO2 and climate change. By extension, it has been suggested that declining carboxylation capacity (Vcmax) and leaf N content in enhanced‐CO2 experiments and satellite records signify increasing N limitation of primary production. We predicted Vcmax using the coordination hypothesis and estimated changes in leaf‐level photosynthetic N for 1982–2016 assuming proportionality with leaf‐level Vcmax at 25°C. The whole‐canopy photosynthetic N was derived using satellite‐based leaf area index (LAI) data and an empirical extinction coefficient for Vcmax, and converted to annual N demand using estimated leaf turnover times. The predicted spatial pattern of Vcmax shares key features with an independent reconstruction from remotely sensed leaf chlorophyll content. Predicted leaf photosynthetic N declined by 0.27% yr−1, while observed leaf (total) N declined by 0.2–0.25% yr−1. Predicted global canopy N (and N demand) declined from 1996 onwards, despite increasing LAI. Leaf‐level responses to rising CO2, and to a lesser extent temperature, may have reduced the canopy requirement for N by more than rising LAI has increased it. This finding provides an alternative explanation for declining leaf N that does not depend on increasing N limitation.
  • Link with Projects:
    787203
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