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

Sheppard, L.; Crossley, A.; Leith, I.D.; Hargreaves, K.J.; Carfrae, J.; van Dijk, N.; Cape, J.N.; Sleep, D. ORCID:; Fowler, D.; Raven, J.A.. 2004 An Automated Wet Deposition System to Compare the Effects of Reduced and Oxidised N on Ombrotrophic Bog Species: Practical Considerations. Water, Air and Soil Pollution: Focus, 4 (6). 197-205.

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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

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Programmes pre-2009 publications > Biogeochemistry > BG02 Recovery from acidification and eutrophication
UKCEH and CEH Sections/Science Areas: _ Atmospheric Sciences
_ Environmental Chemistry & Pollution
ISSN: 0049-6979
Additional Keywords: ambient N deposition, automated spray system, lichens, mosses, nutrient levels, oxidised N deposition, reduced N deposition
NORA Subject Terms: Meteorology and Climatology
Ecology and Environment
Atmospheric Sciences
Date made live: 20 May 2009 08:44 +0 (UTC)

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