Long‐term ecosystem nitrogen limitation from foliar δ 15 N data and a land surface model
| Autor: | Silvia Caldararu, Lin Yu, Tea Thum, Richard Nair, Melanie Kern, Sönke Zaehle |
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| Rok vydání: | 2021 |
| Předmět: |
0106 biological sciences
Global and Planetary Change 010504 meteorology & atmospheric sciences Ecology Carbon sink chemistry.chemical_element Climate change δ15N 15. Life on land Atmospheric sciences 01 natural sciences Nitrogen Carbon cycle Nutrient Deposition (aerosol physics) chemistry 13. Climate action Environmental Chemistry Environmental science Ecosystem 010606 plant biology & botany 0105 earth and related environmental sciences General Environmental Science |
| Zdroj: | Global Change Biology |
| ISSN: | 1365-2486 1354-1013 |
| Popis: | The effect of nutrient availability on plant growth and the terrestrial carbon sink under climate change and elevated CO2 remains one of the main uncertainties of the terrestrial carbon cycle. This is partially due to the difficulty of assessing nutrient limitation at large scales over long periods of time. Consistent declines in leaf nitrogen (N) content and leaf δ15 N have been used to suggest that nitrogen limitation has increased in recent decades, most likely due to the concurrent increase in atmospheric CO2 . However, such data sets are often not straightforward to interpret due to the complex factors that contribute to the spatial and temporal variation in leaf N and isotope concentration. We use the land surface model (LSM) QUINCY, which has the unique capacity to represent N isotopic processes, in conjunction with two large data sets of foliar N and N isotope content. We run the model with different scenarios to test whether foliar δ15 N isotopic data can be used to infer large-scale N limitation and if the observed trends are caused by increasing atmospheric CO2 , changes in climate or changes in sources and magnitude of anthropogenic N deposition. We show that while the model can capture the observed change in leaf N content and predict widespread increases in N limitation, it does not capture the pronounced, but very spatially heterogeneous, decrease in foliar δ15 N observed in the data across the globe. The addition of an observation-based temporal trend in isotopic composition of N deposition leads to a more pronounced decrease in simulated leaf δ15 N. Our results show that leaf δ15 N observations cannot, on their own, be used to assess global-scale N limitation and that using such a data set in conjunction with an LSM can reveal the drivers behind the observed patterns. |
| Databáze: | OpenAIRE |
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