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| Titel |
Contributions of secondary forest and nitrogen dynamics to terrestrial carbon uptake |
| VerfasserIn |
X. Yang, T. K. Richardson, A. K. Jain |
| 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 ; 7, no. 10 ; Nr. 7, no. 10 (2010-10-08), S.3041-3050 |
| Datensatznummer |
250005007
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| Publikation (Nr.) |
 copernicus.org/bg-7-3041-2010.pdf |
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| Zusammenfassung |
| We use a terrestrial carbon-nitrogen cycle component of the Integrated
Science Assessment Model (ISAM) to investigate the impacts of nitrogen
dynamics on regrowing secondary forests over the 20th century. We
further examine what the impacts of nitrogen deposition and land use change
history are on terrestrial carbon uptake since preindustrial time. Our
results suggest that global total net land use emissions for the 1990s
associated with changes in cropland, pastureland, and wood harvest are 1.22 GtC/yr. Without considering the secondary forest regrowth, the estimated net
global total land use emissions are 1.58 GtC/yr or about 0.36 GtC/yr higher
than if secondary forest regrowth is considered. Results also show that
without considering the nitrogen dynamics and deposition, the estimated
global total secondary forest sink for the 1990s is 0.90 GtC/yr or about
0.54 GtC/yr higher than estimates that include the impacts of nitrogen dynamics
and deposition. Nitrogen deposition alone is responsible for about 0.13 GtC/yr of the total secondary forest sink. While nitrogen is not a limiting
nutrient in the intact primary forests in tropical regions, our study
suggests that nitrogen becomes a limiting nutrient for regrowing secondary
forests of the tropical regions, in particular Latin America and Tropical
Africa. This is because land use change activities, especially wood harvest,
removes large amounts of nitrogen from the system when slash is burnt or
wood is removed for harvest. However, our model results show that carbon
uptake is enhanced in the tropical secondary forests of the Indian region.
We argue that this may be due to enhanced nitrogen mineralization and
increased nitrogen availability following land use change in the Indian
tropical forest ecosystems. Results also demonstrate that there is a
significant amount of carbon accumulating in the Northern Hemisphere where
most land use changes and forest regrowth has occurred in recent decades.
This study indicates the significance of secondary forests to terrestrial
carbon sinks, the importance of nitrogen dynamics to the magnitude of
secondary forests carbon uptake, and therefore the need to include both
primary and secondary forests and nitrogen dynamics in terrestrial ecosystem
models. |
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