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

TY - JOUR

T1 - Global patterns and substrate-based mechanisms of the terrestrial nitrogen cycle

AU - Niu, Shuli

AU - Classen, Aimee Taylor

AU - Dukes, Jeffrey S.

AU - Kardol, Paul

AU - Liu, Lingli

AU - Luo, Yiqi

AU - Rustad, Lindsey

AU - Sun, Jian

AU - Tang, Jianwu

AU - Templer, Pamela H.

AU - Thomas, R. Quinn

AU - Tian, Dashuan

AU - Vicca, Sara

AU - Wang, Ying-Ping

AU - Xia, Jianyang

AU - Zaehle, Sönke

N1 - © 2016 John Wiley & Sons Ltd/CNRS.

PY - 2016/6/1

Y1 - 2016/6/1

N2 - 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.

AB - 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.

KW - Journal Article

KW - Review

U2 - 10.1111/ele.12591

DO - 10.1111/ele.12591

M3 - Review

C2 - 26932540

SN - 1461-023X

VL - 19

SP - 697

EP - 709

JO - Ecology Letters

JF - Ecology Letters

IS - 6

ER -