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This article in JEQ

  1. Vol. 41 No. 6, p. 2033-2045
     
    Received: Feb 10, 2012
    Published: October 18, 2012


    * Corresponding author(s): joerg.luster@wsl.ch
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doi:10.2134/jeq2012.0059

Soil Nitrogen Dynamics in a River Floodplain Mosaic

  1. J. Shresthaac,
  2. P.A. Niklausb,
  3. E. Frossardc,
  4. E. Samaritanid,
  5. B. Hubera,
  6. R. L. Barnarde,
  7. P. Schleppia,
  8. K. Tocknerf and
  9. J. Luster *a
  1. a Swiss Federal Institute for Forest, Snow, and Landscape Research, Zürcherstrasse 111, CH-8903 Birmensdorf, Switzerland
    c Institute of Agricultural Sciences, ETH Zurich, Eschikon 33, 8315 Lindau, Switzerland
    b Institute of Evolutionary Biology and Environmental Studies, Univ. of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
    d Institute of Biology, Univ. of Neuchatel, Rue Emile Argand 11, CH-2000 Neuchatel, Switzerland
    e Dep. of Agroecology, INRA Dijon, 17 rue Sully, BP 86510, Dijon, France
    f Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), and Institute of Biology, Freie Universität Berlin, Müggelseedamm 310, D-12587, Berlin, Germany. Assigned to Associate Editor Jake Beaulieu

Abstract

In their natural state, river floodplains are heterogeneous and dynamic ecosystems that may retain and remove large quantities of nitrogen from surface waters. We compared the soil nitrogen dynamics in different types of habitat patches in a restored and a channelized section of a Thur River floodplain (northeast Switzerland). Our objective was to relate the spatiotemporal variability of selected nitrogen pools (ammonium, nitrate, microbial nitrogen), nitrogen transformations (mineralization, nitrification, denitrification), and gaseous nitrogen emission (N2O) to soil properties and hydrological processes. Our study showed that soil water content and carbon availability, which depend on sedimentation and inundation dynamics, were the key factors controlling nitrogen pools and processes. High nitrogen turnover rates were measured on gravel bars, characterized by both frequent inundation and high sediment deposition rates, as well as in low-lying alluvial forest patches with a fine-textured, nutrient-rich soil where anaerobic microsites probably facilitated coupled nitrification–denitrification. In contrast, soils of the embankment in the channelized section had comparatively small inorganic nitrogen pools and low transformation rates, particularly those related to nitrate production. Environmental heterogeneity, characteristic of the restored section, favors nitrogen removal by creating sites of high sedimentation and denitrification. Of concern, however, are the locally high N2O efflux and the possibility that nitrate could leach from nitrification hotspots.

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Copyright © 2012. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.