Global patterns and substrate-based mechanisms of the terrestrial nitrogen cycle

Shuli Niu, Aimée T. Classen, Jeffrey S. Dukes, Paul Kardol, Lingli Liu, Yiqi Luo, Lindsey Rustad, Jian Sun, Jianwu Tang, Pamela H. Templer, R. Quinn Thomas, Dashuan Tian, Sara Vicca, Ying Ping Wang, Jianyang Xia, Sönke Zaehle

Research output: Contribution to journalReview articlepeer-review

144 Scopus citations

Abstract

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. Copyright

Original languageEnglish (US)
Pages (from-to)697-709
Number of pages13
JournalEcology Letters
Volume19
Issue number6
DOIs
StatePublished - Jun 1 2016
Externally publishedYes

Keywords

  • Leaching
  • Mineralisation
  • Nitrification
  • Nitrogen deposition
  • Nitrogen loss
  • Plant N uptake
  • Saturation
  • Soil N retention
  • Threshold

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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