The nutrient nitrogen critical load for raised and blanket bog, as set under the UNECE Convention on Long Range Transboundary Air Pollution, is 5-10 kgN/ha/yr. The range reflects "real intra-ecosystem variation between different regions where the ecosystem has been studied (Bobbink & Hettelingh, 2011).
It is recommended that the minimum of the critical load range (5 kg N/ha/yr) continues to be used for screening assessment.
Guidance is available for the detailed assessment stage for determining the appropriate value with the critical load range for an individual bog site/habitat. The third step of this guidance is to consider the precipitation modifier, using the approach developed by the UK NFC (Hall et al, 2011).
This tool has been developed to help to identify the relevant rainfall band for a specified location and hence the relevant part of the critical load range."
Bobbink, R. & Hettelingh, J.P. (eds). (2011). Review and revision of empirical critical loads and dose-response relationships. Proceedings of an expert workshop, Noordwijkerhout, 23-25 June 2010. Published by RIVM. http://www.rivm.nl/bibliotheek/rapporten/680359002.pdf
Hall, J., Emmett, B., Garbutt, A., Jones, L., Rowe, E., Sheppard, L., Vanguelova, E., Pitman, R., Britton, A., Hester, A., Ashmore, A., Power, S., Caporn, S. (2011). UK Status Report July 2011: Update to empirical critical loads of nitrogen Report to Defra under contract AQ801 Critical Loads and Dynamic Modelling. http://cldm.defra.gov.uk/PDFs/UK_status_report_2011_finalversion_July2011_v2.pdf
|Rainfall range (mm)||Median CLnutN (kg N ha-1 year-1)|
|548 - 758||8|
|759 – 1285||9|
This tool below can be used to show the likely critical load for Bogs at any location in the UK based on the rainfall ranges above. Simply add in your grid reference and submit.