Rising CO2 and warming lead to declining global canopy demand for nitrogen
- 1Imperial College London, Department of Life Sciences, Silwood Park Campus, Ascot , UK
- 2Department of Biological Sciences, Macquarie University, Ryde, Australia
- 3Ministry of Education Key Laboratory for Earth System Modelling, Department of Earth System Science, Tsinghua University, Beijing, China.
- 4Department of Geography, National University of Singapore, Singapore, Singapore
- 5Department of Biological Sciences, Texas Tech University, Lubbock, USA
Nitrogen (N) limitation constrains the magnitude of terrestrial carbon uptake in response to CO2 fertilization and climate change. However, the trajectory of N demand, and how it is influenced by continuing changes in CO2 and climate, is incompletely understood. We estimate recent changes in global canopy N demand based on a well-tested optimality hypothesis for the control of photosynthetic capacity (Vcmax). The predicted global pattern of optimal leaf-level Vcmax is similar to the pattern derived from remotely sensed chlorophyll retrievals. Over the period from 1982 to 2015, rising CO2 and warming both contributed to decreasing leaf-level N demand. Widespread increases in green vegetation cover over the same period (especially in high latitudes) imply increasing total canopy N demand. The net global trend is, nonetheless, a decrease in total canopy N demand. This work provides a new perspective on the past, present and future of the global terrestrial N cycle.
How to cite: Dong, N., Prentice, I. C., Wright, I., Luo, X., and Smith, N.: Rising CO2 and warming lead to declining global canopy demand for nitrogen, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10540, https://doi.org/10.5194/egusphere-egu21-10540, 2021.
