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Water, Air, & Soil Pollution: Focus

, Volume 4, Issue 6, pp 197–205 | Cite as

An Automated Wet Deposition System to Compare the Effects of Reduced and Oxidised N on Ombrotrophic Bog Species: Practical Considerations

  • L. J. SheppardEmail author
  • A. Crossley
  • I. D. Leith
  • K. J. Hargreaves
  • J. A. Carfrae
  • N. van Dijk
  • J. N. Cape
  • D. Sleep
  • D. Fowler
  • J. A. Raven
Article

Abstract

Critical N loads for ombrotrophic bogs, which often contain rare and N-sensitive plants (especially those in lower plant groups: lichens, mosses and liverworts), are based on very few experimental data from measured, low background N deposition areas. Additionally the relative effects of reduced versus oxidised N are largely unknown. This paper describes an automated field exposure system (30 km S. of Edinburgh, Scotland) for treating ombrotrophic bog vegetation with fine droplets of oxidised N (NaNO3) and reduced N (NH4Cl). Whim Moss exists in an area of low ambient N deposition (ca. 8 kg N ha−1 y−1), the sources and quantification of which are described. The wet N treatment system is run continuously, and is controlled/activated by wind speed and rainfall to provide a unique simulation of “real worl” treatment patterns (no rain=no treatment). Simulated precipitation is supplied at ionic concentrations below 4 mM in rainwater collected on site. Treatments provide a replicated dose response to 16, 32 and 64 kg N ha−1 y−1 adjusted for ambient deposition (8 kg N ha−1 y−1). The 16 and 64 kg N ha−1 y−1 are duplicated with a P+K supplement. Baseline soil chemistry and foliar nutrient status was established for all 44 plots for Calluna vulgaris, Sphagnum capillifolium, Hypnum jutlandicum and Cladonia portentosa.

Keywords

ambient N deposition automated spray system lichens mosses nutrient levels oxidised N deposition reduced N deposition 

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Copyright information

© Kluwer Academic Publishers 2004

Authors and Affiliations

  • L. J. Sheppard
    • 1
    Email author
  • A. Crossley
    • 1
  • I. D. Leith
    • 1
  • K. J. Hargreaves
    • 1
  • J. A. Carfrae
    • 1
    • 2
  • N. van Dijk
    • 1
  • J. N. Cape
    • 1
  • D. Sleep
    • 3
  • D. Fowler
    • 1
  • J. A. Raven
    • 2
  1. 1.C.E.H. EdinburghPenicuikScotland
  2. 2.Division of Environmental and Life SciencesDundee UniversityDundeeScotland
  3. 3.CEH LancasterLancasterUK

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