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| Titel |
Nitrogen deposition: how important is it for global terrestrial carbon uptake? |
| VerfasserIn |
G. Bala, N. Devaraju, R. K. Chaturvedi, K. Caldeira, R. Nemani |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 11 ; Nr. 10, no. 11 (2013-11-11), S.7147-7160 |
| Datensatznummer |
250085405
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| Publikation (Nr.) |
 copernicus.org/bg-10-7147-2013.pdf |
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| Zusammenfassung |
| Global carbon budget studies indicate that the terrestrial ecosystems have
remained a large sink for carbon despite widespread deforestation
activities. CO2 fertilization, N deposition and re-growth of
mid-latitude forests are believed to be key drivers for land carbon uptake.
In this study, we assess the importance of N deposition by performing
idealized near-equilibrium simulations using the Community Land Model 4.0
(CLM4). In our equilibrium simulations, only 12–17% of the deposited
nitrogen is assimilated into the ecosystem and the corresponding carbon
uptake can be inferred from a C : N ratio of 20 : 1. We calculate the
sensitivity of the terrestrial biosphere for CO2 fertilization, climate
warming and N deposition as changes in total ecosystem carbon for unit
changes in global mean atmospheric CO2 concentration, global mean
temperature and Tera grams of nitrogen deposition per year, respectively.
Based on these sensitivities, it is estimated that about 242 PgC could have
been taken up by land due to the CO2 fertilization effect and an
additional 175 PgC taken up as a result of the increased N deposition since
the pre-industrial period. Because of climate warming, the terrestrial ecosystem
could have lost about 152 PgC during the same period. Therefore, since
pre-industrial times terrestrial carbon losses due to warming may have been
more or less compensated by effects of increased N deposition, whereas the
effect of CO2 fertilization is approximately indicative of the current
increase in terrestrial carbon stock. Our simulations also suggest that the
sensitivity of carbon storage to increased N deposition decreases beyond
current levels, indicating that climate warming effects on carbon storage may
overwhelm N deposition effects in the future. |
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