Foliar and soil δ15N values reveal increased nitrogen partitioning among species in diverse grassland communities

Authors

  • MARLÉN GUBSCH,

    Corresponding author
    1. Institute of Plant, Animal and Agroecosystem Sciences, ETH Zurich, Universitaetsstrasse 2, CH-8092 Zurich, Switzerland
      M. Gubsch. e-mail: mgubsch@gmail.com
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  • CHRISTIANE ROSCHER,

    1. Max Planck Institute for Biogeochemistry, POB 100164, D-07701 Jena, Germany
    2. UFZ, Helmholtz Centre for Environmental Research, Department of Community Ecology, Theodor-Lieser-Strasse 4, D-06120 Halle, Germany
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  • GERD GLEIXNER,

    1. Max Planck Institute for Biogeochemistry, POB 100164, D-07701 Jena, Germany
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  • MAIKE HABEKOST,

    1. Max Planck Institute for Biogeochemistry, POB 100164, D-07701 Jena, Germany
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  • ANNETT LIPOWSKY,

    1. Max Planck Institute for Biogeochemistry, POB 100164, D-07701 Jena, Germany
    2. Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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  • BERNHARD SCHMID,

    1. Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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  • ERNST-DETLEF SCHULZE,

    1. Max Planck Institute for Biogeochemistry, POB 100164, D-07701 Jena, Germany
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  • SIBYLLE STEINBEISS,

    1. Max Planck Institute for Biogeochemistry, POB 100164, D-07701 Jena, Germany
    2. Institute of Groundwater Ecology, Helmholtz Zentrum Munchen, German Research Centre for Environmental Health GmbH, Ingolstaedter Landstrasse 1, D-85764 Neuherberg, Germany
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  • NINA BUCHMANN

    1. Institute of Plant, Animal and Agroecosystem Sciences, ETH Zurich, Universitaetsstrasse 2, CH-8092 Zurich, Switzerland
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M. Gubsch. e-mail: mgubsch@gmail.com

ABSTRACT

Plant and soil nitrogen isotope ratios (δ15N) were studied in experimental grassland plots of varying species richness. We hypothesized that partitioning of different sources of soil nitrogen among four plant functional groups (legumes, grasses, small herbs, tall herbs) should increase with diversity. Four years after sowing, all soils were depleted in 15N in the top 5 cm whereas in non-legume plots soils were enriched in 15N at 5–25 cm depth. Decreasing foliar δ15N and Δδ15N (= foliar δ15N − soil δ15N) values in legumes indicated increasing symbiotic N2 fixation with increasing diversity. In grasses, foliar Δδ15N also decreased with increasing diversity suggesting enhanced uptake of N depleted in 15N. Foliar Δδ15N values of small and tall herbs were unaffected by diversity. Foliar Δδ15N values of grasses were also reduced in plots containing legumes, indicating direct use of legume-derived N depleted in 15N. Increased foliar N concentrations of tall and small herbs in plots containing legumes without reduced foliar δ15N indicated that these species obtained additional mineral soil N that was not consumed by legumes. These functional group and species specific shifts in the uptake of different N sources with increasing diversity indicate complementary resource use in diverse communities.

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