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| Titel |
Seasonal variation in nitrogen pools and 15N/13C natural abundances in different tissues of grassland plants |
| VerfasserIn |
L. Wang, J. K. Schjoerring |
| 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 ; 9, no. 5 ; Nr. 9, no. 5 (2012-05-02), S.1583-1595 |
| Datensatznummer |
250007017
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| Publikation (Nr.) |
 copernicus.org/bg-9-1583-2012.pdf |
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| Zusammenfassung |
| Seasonal changes in nitrogen (N) pools, carbon (C) content and natural abundance of
13C and 15N in different tissues of ryegrass plants were
investigated in two intensively managed grassland fields in order to address
their ammonia (NH3) exchange potential. Green leaves generally had the
largest total N concentration followed by stems and inflorescences.
Senescent leaves had the lowest N concentration, indicating N re-allocation.
The seasonal pattern of the Γ value, i.e. the ratio between
NH4+ and H+ concentrations, was similar for the various
tissues of the ryegrass plants but the magnitude of Γ differed
considerably among the different tissues. Green leaves and stems generally
had substantially lower Γ values than senescent leaves and litter.
Substantial peaks in Γ were observed during spring and summer in
response to fertilization and grazing. These peaks were associated with high
NH4+ rather than with low H+ concentrations. Peaks in Γ
also appeared during the winter, coinciding with increasing δ15N
values, indicating absorption of N derived from mineralization of
soil organic matter. At the same time, δ13C values were
declining, suggesting reduced photosynthesis and capacity for N
assimilation. δ15N and δ13C values were more
influenced by mean monthly temperature than by the accumulated monthly
precipitation. In conclusion, ryegrass plants showed a clear seasonal
pattern in N pools. Green leaves and stems of ryegrass plants generally seem
to constitute a sink for NH3, while senescent leaves have a large
potential for NH3 emission. However, management events such as
fertilisation and grazing may create a high NH3 emission potential even
in green plant parts. The obtained results provide input for future
modelling of plant-atmosphere NH3 exchange. |
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