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| Titel |
The role of phosphorus dynamics in tropical forests – a modeling study using CLM-CNP |
| VerfasserIn |
X. Yang, P. E. Thornton, D. M. Ricciuto, W. M. Post |
| 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 ; 11, no. 6 ; Nr. 11, no. 6 (2014-03-28), S.1667-1681 |
| Datensatznummer |
250117312
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| Publikation (Nr.) |
 copernicus.org/bg-11-1667-2014.pdf |
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| Zusammenfassung |
| Tropical forests play a significant role in the global carbon cycle and
global climate.
However, tropical carbon cycling and the feedbacks from tropical ecosystems
to the climate system remain critical uncertainties in the current generation
of carbon–climate models. One of the major uncertainties comes from the lack of
representation of phosphorus (P), currently believed to be the most limiting
nutrient in tropical regions. Here we introduce P dynamics and C–N–P
interactions into the CLM4-CN (Community Land Model version 4 with prognostic Carbon and Nitrogen)
model and investigate the role of P cycling in
controlling the productivity of tropical ecosystems. The newly developed
CLM-CNP model includes all major biological and geochemical processes
controlling P availability in soils and the interactions between C, N, and P
cycles. Model simulations at sites along a Hawaiian soil chronosequence
indicate that the introduction of P limitation greatly improved the model
performance at the P-limited site. The model is also able to capture the
shift in nutrient limitation along this chronosequence (from N limited to P
limited), as shown in the comparison of model-simulated plant responses to
fertilization with the observed data. Model simulations at Amazonian forest
sites show that CLM-CNP is capable of capturing the overall trend in NPP (net primary production)
along the P availability gradient. This comparison also suggests a
significant interaction between nutrient limitation and land use history.
Model experiments under elevated atmospheric CO2 ([CO2]) conditions
suggest that tropical forest responses to increasing [CO2] will interact
strongly with changes in the P cycle. We highlight the importance of two
feedback pathways (biochemical mineralization and desorption of secondary
mineral P) that can significantly affect P availability and determine the
extent of P limitation in tropical forests under elevated [CO2]. Field
experiments with elevated CO2 are therefore needed to help quantify
these important feedbacks. CO2 doubling model experiments show that
tropical forest response to elevated [CO2] can only be predicted if the
interactions between C cycle and nutrient dynamics are well understood and
represented in models. Predictive modeling of C–nutrient interactions will
have important implications for the prediction of future carbon uptake and
storage in tropical ecosystems and global climate change. |
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