Nitrogen

Main results for nitrogen are:

  • The total nitrogen concentration in mosses can potentially be used as an indicator of total atmospheric nitrogen deposition. However, the relationship between nitrogen deposition and its concentration in mosses might be affected by environmental factors such as local climate and the form of nitrogen deposition. This requires further investigation.  (Nitrogen moss report)
  • The total nitrogen concentration in mosses is moderately correlated with modelled atmospheric deposition and concentrations in air or precipitation of various nitrogen forms. Multivariate analysis identified the concentration of reduced nitrogen in air to be statistically the most significant factor, followed by the concentration of oxidised nitrogen in air. (Annual report 2008/9)
  • Analysis of herbarium moss samples from selected European countries revealed no change in the nitrogen concentration in mosses between ca. 1860 and 1960, but generally an increase after 1960.  (Annual report 2005/6)
  • A preliminary exercise to develop a likelihood-based approach to assess empirical critical load exceedances across Europe showed that ‘Alpine and sub-alpine grasslands’ and ‘Arctic, alpine and sub-alpine scrub habitats’ are most at risk from adverse affects of atmospheric nitrogen pollution.  (N impacts report)
  • In field surveys, the impacts of atmospheric nitrogen deposition on vegetation are difficult to separate from other environmental factors.However, some surveys indicate increases in nitrogen-liking species or a reduction in species richness with increasing nitrogen deposition.  (eg Countryside Survey UK)

 

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