Title
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Global patterns and substrate-based mechanisms of the terrestrial nitrogen cycle
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Author
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Abstract
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Nitrogen (N) deposition is impacting the services that ecosystems provide to humanity. However, the mechanisms determining impacts on the N cycle are not fully understood. To explore the mechanistic underpinnings of N impacts on N cycle processes, we reviewed and synthesised recent progress in ecosystem N research through empirical studies, conceptual analysis and model simulations. Experimental and observational studies have revealed that the stimulation of plant N uptake and soil retention generally diminishes as N loading increases, while dissolved and gaseous losses of N occur at low N availability but increase exponentially and become the dominant fate of N at high loading rates. The original N saturation hypothesis emphasises sequential N saturation from plant uptake to soil retention before N losses occur. However, biogeochemical models that simulate simultaneous competition for soil N substrates by multiple processes match the observed patterns of N losses better than models based on sequential competition. To enable better prediction of terrestrial N cycle responses to N loading, we recommend that future research identifies the response functions of different N processes to substrate availability using manipulative experiments, and incorporates the measured N saturation response functions into conceptual, theoretical and quantitative analyses. |
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Language
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English
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Source (journal)
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Ecology letters. - Oxford, 1998, currens
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Publication
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Oxford
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2016
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ISSN
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1461-023X
[print]
1461-0248
[online]
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DOI
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10.1111/ELE.12591
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Volume/pages
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(2016)
, p. 1-13
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ISI
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000375752400011
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Full text (Publisher's DOI)
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Full text (open access)
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