Biogeochemistry

, Volume 76, Issue 3, pp 453–475

Flow of Deposited Inorganic N in Two Gleysol-dominated Mountain Catchments Traced with 15NO3 and 15NH4+

  • Isabelle Providoli
  • Harald Bugmann
  • Rolf Siegwolf
  • Nina Buchmann
  • Patrick Schleppi
Article

DOI: 10.1007/s10533-005-8124-1

Cite this article as:
Providoli, I., Bugmann, H., Siegwolf, R. et al. Biogeochemistry (2005) 76: 453. doi:10.1007/s10533-005-8124-1
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Abstract.

In two mountain ecosystems at the Alptal research site in central Switzerland, pulses of 15NO3 and 15NH4 were separately applied to trace deposited inorganic N. One forested and one litter meadow catchment, each approximately 1600 m2, were delimited by trenches in the Gleysols. K15NO3 was applied weekly or fortnightly over one year with a backpack sprayer, thus labelling the atmospheric nitrate deposition. After the sampling and a one-year break, 15NH4Cl was applied as a second one-year pulse, followed by a second sampling campaign. Trees (needles, branches and bole wood), ground vegetation, litter layer and soil (LF, A and B horizon) were sampled at the end of each labelling period. Extractable inorganic N, microbial N, and immobilised soil N were analysed in the LF and A horizons. During the whole labelling period, the runoff water was sampled as well. Most of the added tracer remained in both ecosystems. More NO3 than NH4+ tracer was retained, especially in the forest. The highest recovery was in the soil, mainly in the organic horizon, and in the ground vegetation, especially in the mosses. Event-based runoff analyses showed an immediate response of 15NO3 in runoff, with sharp 15N peaks corresponding to discharge peaks. NO3 leaching showed a clear seasonal pattern, being highest in spring during snowmelt. The high capacity of N retention in these ecosystems leads to the assumption that deposited N accumulates in the soil organic matter, causing a progressive decline of its C:N ratio.

Keywords

15N tracerMountain forestMountain meadowNitrate leachingNitrogen deposition

Copyright information

© Springer 2005

Authors and Affiliations

  • Isabelle Providoli
    • 1
  • Harald Bugmann
    • 2
  • Rolf Siegwolf
    • 3
  • Nina Buchmann
    • 4
  • Patrick Schleppi
    • 1
  1. 1.Snow and Landscape Research (WSL)Swiss Federal Institute for ForestBirmensdorfSwitzerland
  2. 2.Forest EcologySwiss Fed. Inst. of Technology, ETH-ZentrumZurich Switzerland
  3. 3.Laboratory of Atmospheric ChemistryPaul Scherrer InstituteVilligen-PSISwitzerland
  4. 4.Institute of Plant SciencesSwiss Fed. Inst. of Technology, ETH ZentrumZurichSwitzerland