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| Titel |
Species-specific trajectories of nitrogen isotopes in Indiana hardwood forests, USA |
| VerfasserIn |
K. K. McLauchlan, J. M. Craine |
| 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. 2 ; Nr. 9, no. 2 (2012-02-24), S.867-874 |
| Datensatznummer |
250006774
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| Publikation (Nr.) |
 copernicus.org/bg-9-867-2012.pdf |
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| Zusammenfassung |
| Humans have drastically altered the global nitrogen (N) cycle, and these
alterations have begun to affect a variety of ecosystems. In North America,
N deposition rates are highest in the central US, yet there are few
studies that examine whether N availability has been increasing to different
tree species in the forests of the region. To determine the species-specific
trajectories of N availability in secondary temperate forests experiencing
high N deposition, we measured the N concentrations and composition of
stable N isotopes in wood of four tree species from six hardwood forest
remnants in northern Indiana, USA. Annual nitrogen deposition rates
averaged 5.8 kg ha−1 from 2000 to 2008 in this region. On average, wood
δ15N values in Quercus alba have been increasing steadily over the past 100
years. In contrast, wood δ15N values have been declining in
three other hardwood species – Acer saccharum, Carya ovata, and Fagus grandifolia – over the same time period. The
species-specific trends suggest a change in the partitioning of ammonium and
nitrate among species, due to an increase in nitrification rates over time.
With no apparent net change in wood δ15N over the past century
at the stand level, there is currently little evidence for consistent trends
in stand-level N availability over time in the Indiana forests. |
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