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Volume 20, Issue 1 p. 30-59
Perspectives on the Modern Nitrogen Cycle

Global assessment of nitrogen deposition effects on terrestrial plant diversity: a synthesis

R. Bobbink,

Corresponding Author

R. Bobbink

B-WARE Research Centre, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands

E-mail: r.bobbink@b-ware.euSearch for more papers by this author
K. Hicks,

K. Hicks

Stockholm Environmental Institute, University of York, York YO10 5DD United Kingdom

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J. Galloway,

J. Galloway

Environmental Sciences Department, University of Virginia, Charlottesville, Virginia 22904 USA

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T. Spranger,

T. Spranger

German Federal Environment Agency (UBA), Wörlitzer Platz 1, 06844 Dessau, Germany

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R. Alkemade,

R. Alkemade

Netherlands Environmental Assessment Agency (MNP), P.O. Box 303, 3720 AH Bilthoven, The Netherlands

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M. Ashmore,

M. Ashmore

Environment Department, University of York, Heslington, Yorkshire YO10 5DD United Kingdom

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M. Bustamante,

M. Bustamante

Universidade de Brasilia, Departamento de Ecologia, Campus Universitário Darcy Ribeiro, CEP 70.919-970, Brasilia-DF, Brazil

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S. Cinderby,

S. Cinderby

Stockholm Environmental Institute, University of York, York YO10 5DD United Kingdom

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E. Davidson,

E. Davidson

The Woods Hole Research Center, 149 Woods Hole Road, Falmouth, Massachusetts 02540-1644 USA

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F. Dentener,

F. Dentener

European Commission, Joint Research Centre, Institute for Environment and Sustainability, Ispra (VA), Italy

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B. Emmett,

B. Emmett

Centre for Ecology and Hydrology, Orton Building, Deniol Road, Bangor LL57 2UP United Kingdom

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J-W. Erisman,

J-W. Erisman

Energy Research Centre of the Netherlands, ECN, P.O. Box 1, 1755 ZG Petten, The Netherlands

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M. Fenn,

M. Fenn

U.S. Forest Service, PSW Research Station, 4955 Canyon Crest Drive, Riverside, California 92507 USA

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F. Gilliam,

F. Gilliam

Department of Biological Sciences, Marshall University, Huntington, West Virginia 25701 USA

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A. Nordin,

A. Nordin

Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden

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L. Pardo,

L. Pardo

USDA Forest Service, P.O. Box 968, Burlington, Vermont 05402 USA

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W. De Vries,

W. De Vries

Alterra, Wageningen University and Research Centre, P.O. Box 47, 6700 AA Wageningen, The Netherlands

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First published: 01 January 2010
Citations: 1,644

Corresponding Editor: N. B. Grimm. For reprints of this Invited Feature, see footnote 1, p. 3.

Abstract

Atmospheric nitrogen (N) deposition is a recognized threat to plant diversity in temperate and northern parts of Europe and North America. This paper assesses evidence from field experiments for N deposition effects and thresholds for terrestrial plant diversity protection across a latitudinal range of main categories of ecosystems, from arctic and boreal systems to tropical forests. Current thinking on the mechanisms of N deposition effects on plant diversity, the global distribution of G200 ecoregions, and current and future (2030) estimates of atmospheric N-deposition rates are then used to identify the risks to plant diversity in all major ecosystem types now and in the future.

This synthesis paper clearly shows that N accumulation is the main driver of changes to species composition across the whole range of different ecosystem types by driving the competitive interactions that lead to composition change and/or making conditions unfavorable for some species. Other effects such as direct toxicity of nitrogen gases and aerosols, long-term negative effects of increased ammonium and ammonia availability, soil-mediated effects of acidification, and secondary stress and disturbance are more ecosystem- and site-specific and often play a supporting role. N deposition effects in mediterranean ecosystems have now been identified, leading to a first estimate of an effect threshold. Importantly, ecosystems thought of as not N limited, such as tropical and subtropical systems, may be more vulnerable in the regeneration phase, in situations where heterogeneity in N availability is reduced by atmospheric N deposition, on sandy soils, or in montane areas.

Critical loads are effect thresholds for N deposition, and the critical load concept has helped European governments make progress toward reducing N loads on sensitive ecosystems. More needs to be done in Europe and North America, especially for the more sensitive ecosystem types, including several ecosystems of high conservation importance.

The results of this assessment show that the vulnerable regions outside Europe and North America which have not received enough attention are ecoregions in eastern and southern Asia (China, India), an important part of the mediterranean ecoregion (California, southern Europe), and in the coming decades several subtropical and tropical parts of Latin America and Africa. Reductions in plant diversity by increased atmospheric N deposition may be more widespread than first thought, and more targeted studies are required in low background areas, especially in the G200 ecoregions.