NH3 :: Sphagnum moss

Latin name: 
Sphagnum spp.

Impact Type: Direct exposure to pollutant

Key Concerns:

Enhanced ammonia concentrations (e.g. in the vicinity of intensive poultry farms) have been shown to have negative effects on bryophyte diversity (Pitcairn 1998). Although not studied the known sensitivity of Sphagnum to nitrogen deposition (Gunnarsson & Rydin 2000, Williams et al. 1999, Baxter1992) suggests that this genus will also be affected in such situations.

Additional Comments:

A critical level for NH3 exposure has been set (Ashmore & Wilson 1994) although Burkhardt et al. (1998) have shown that in general critical loads for nitrogen deposition are already exceeded at NH3 concentrations less then the critical level. Another factor which can influence the impact of NH3 deposition is drainage. Williams et al (1999) showed that drainage of peatlands can reduce the capture by Sphagna of inorganic nitrogen. A new field study (Sheppard pers comm.) is examining the impact of NH3 along a transect for a range of sphagnum species. Bleaching has been observed in S. papillosum, but so far the long term implications remain to be seen. Effects are likely to be strongly linked to the critical level

Critical Load/level: 
Habitat/ Ecosystem Type Critical Load/ Level Status Indication of exceedance Reference
Higher plants

3 µg NH3 m-3 annual mean (uncertainty of 2-4 µg NH3 m-3)

UNECE, 2007

Direct visible injury; species composition changes. Ecosystems where sensitive lichens and bryophytes are an important part of the ecosystem integrity, the critical level is set at 1 µg NH3 m-3.

Ashmore, M.R.; Wilson, [Eds.] R.B. 1994 Critical levels of air pollutants for Europe Report of the Egham workshop
Burkhardt, J.; Sutton, M.A.; Milford, C.; Storeton-West, R.L.; Fowler, D. 1998 Ammonia concentrations at a site in southern Scotland from 2 yr of continuous measurements Atmospheric Environment 32 325-331
Gunnarsson, U.; Rydin, H. 2000 Nitrogen fertilization reduces Sphagnum production in bog communities New Phytologist 147 527-537
Pitcairn, C.E.R.; Leith, I.D.; Sheppard, L.J.; Sutton, M.A.; Fowler, D.; Munro, R.C.; Tang, S.; Wilson, D. 1998 The relationship between nitrogen deposition, species composition and foliar nitrogen concentrations in woodland flora in the vicinity of livestock farms. Environmental Pollution 102 41-48
Williams, B.L.; Buttler, A.; Grosvernier, P.; Francez, A.J.; Gilbert, D.; Ilomets, M.; Jauhiainen, J.; Matthey, Y.; Silcock, D.J. 1999 The fate of NH4NO3 added to Sphagnum magellanicum carpets at five European mire sites Biogeochemistry 45 73-93

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