Rising CO2 and warming reduce global canopy demand for nitrogen
In: New Phytologist, Jg. 235 (2022-09-01), Heft 5
academicJournal
- 1692 - 1700
Zugriff:
Nitrogen (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.
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Rising CO2 and warming reduce global canopy demand for nitrogen
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Autor/in / Beteiligte Person: | Dong, Ning ; Wright, Ian J ; Chen, Jing M ; Luo, Xiangzhong ; Wang, Han ; Keenan, Trevor F ; Smith, Nicholas G ; Prentice, Iain Colin |
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Zeitschrift: | New Phytologist, Jg. 235 (2022-09-01), Heft 5 |
Veröffentlichung: | eScholarship, University of California, 2022 |
Medientyp: | academicJournal |
Umfang: | 1692 - 1700 |
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