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Mycorrhizal fungi reduce the negative effects of nitrogen enrichment on plant community structure in dune grassland

Authors

  • MARCEL G. A. Van Der HEIJDEN,

    1. Faculty of Earth and Life Sciences, Institute of Ecological Science, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands,
    2. Agroscope Reckenholz-Tänikon, Research Station ART, Reckenholzstrasse 191, 8046 Zurich, Switzerland
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    • 1These authors contributed equally to this work.

  • SEBASTIAAN VERKADE,

    1. Faculty of Earth and Life Sciences, Institute of Ecological Science, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands,
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    • 1These authors contributed equally to this work.

  • SUSANNE J. De BRUIN

    1. Faculty of Earth and Life Sciences, Institute of Ecological Science, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands,
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Marcel G. A. van der Heijden, Agroscope Reckenholz-T änikon, Research Station ART, Reckenholzstrasse 191, 8046 Zurich, Switzerland, tel. +41 44 377 7278, fax +41 44 377 7201, e-mail: marcel.vanderheijden@art.admin.ch

Abstract

Nitrogen (N) inputs to ecosystems have increased worldwide, often leading to large changes in plant community structure and reducing plant diversity. Yet, the interaction of increased N availability with other factors that determine plant community composition, are still poorly understood. Here, we test whether the impact of N addition on plant communities depends on the presence of arbuscular mycorrhizal fungi (AMF). AMF are widespread plant symbionts that facilitate growth of many plant species. We hypothesize that AM fungi reduce the negative impact of N addition on plant communities by supporting growth of species that are sensitive to N enrichment.We established experimental grassland microcosms consisting of 18 plant species. These microcosms were subjected to high and low N supply and were inoculated with AMF or remained nonmycorrhizal. Both N addition and AMF had a big impact on plant community composition, but with opposite effects. N addition induced a 2.8-fold increase in grass biomass and reduced legume biomass. Grasses dominated the microcosms at high N supply, especially when AMF were absent. In contrast, AMF enhanced biomass of all legumes species (on average 6.8-fold) and reduced the relative abundance of grasses. The proportion of legume biomass out of total shoot biomass at high N supply was 19% with AMF and only 3% without AMF. Our results show that responses of plant communities to N enrichment depend on AMF and that AMF can reduce the negative impact of increased N availability on plant community structure by reducing grass dominance.

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