Mires and Peat (Jul 2014)
The exposure of British peatlands to nitrogen deposition, 1900–2030
Abstract
Nitrogen (N) pollution from industry and intensive agriculture is one of the greatest threats to ecosystems globally. Peatland ecosystems are particularly sensitive to atmospheric pollution and Great Britain has both extensive peatlands and high levels of nitrogen deposition. This study combines data from national pollutant deposition models, hind-casting factors and projections of future deposition with survey-based mire vegetation data to quantify the nitrogen deposition exposure of different vegetation communities and how this has changed over time. By sub-dividing a wide range of diverse peatland habitats the results give a more nuanced picture of N deposition to peatlands than has previously been possible. Grid cells containing mire vegetation receive an average of 14.1 kg N ha-1 yr-1 (decade to 2010) and have received an average cumulative deposition of 1312 kg N ha-1 since 1900. The lower limit of the critical load range is exceeded for 69.6 % of cells, but deposition levels and potential for consequent harm vary widely across Britain and between vegetation types. Nitrogen deposition to peatlands is currently falling and is projected to continue to fall until 2020 but with relatively little further change by 2030. N is likely to continue to accumulate in British peats for at least the first three decades of the 21st Century. It is clear that N deposition is currently a serious threat to British peatlands and is likely to remain so for some time to come.
