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| Titel |
Spatiotemporal analysis of nitrogen cycling in a mixed coniferous forest of the northern United States |
| VerfasserIn |
I. Howard, K. K. McLauchlan |
| 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 ; 12, no. 13 ; Nr. 12, no. 13 (2015-07-01), S.3941-3952 |
| Datensatznummer |
250118005
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| Publikation (Nr.) |
 copernicus.org/bg-12-3941-2015.pdf |
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| Zusammenfassung |
| Nitrogen (N) is the limiting nutrient to primary productivity in a variety
of temperate forests, and N cycling is undergoing a variety of anthropogenic
changes, notably a doubling of reactive N (Nr) on a global scale. Yet, the magnitude of these changes to N cycling has been difficult to document in terrestrial ecosystems, especially in old-growth forests. To determine the trajectory of N cycling and the potential impacts of anthropogenic influences at local scales, we measured the composition of
stable nitrogen isotopes (δ15N) in wood from living red pine
trees (Pinus resinosa) at a single site in northern Minnesota, USA. A synchronous decline
in wood δ15N values began approximately in the 1920s in 17
individual trees at different topographic positions, indicating a common
driver. The decline in wood δ15N values corresponded with
declines in sedimentary δ15N recorded in lacustrine sediments
of the same catchment. Disturbance regime and species composition began to
change at the turn of the 20th century with park establishment,
providing a likely mechanism of decline in δ15N values toward
present. While other mechanisms of this change are possible, we conclude that while there may be consequences of increased influxes of various forms of anthropogenic Nr into terrestrial ecosystems at the global level, these changes are not being expressed at a local level in this temperate forest ecosystem. |
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