N deposition :: Woolly Hair Moss

Latin name: 
Racomitrium lanuginosum

Impact Type: Deposition of pollutant

Key Concerns:

Montane heaths, which are dominated by Racomitrium lanuginosum, have declined in distribution and health in recent decades (Ratcliffe and Thompson 1988). Both land use changes and atmospheric N deposition have been implicated in the decline (Thompson & Baddeley 1991). The tissue N content of the moss was shown to be least in north-western Scotland and greatest near urban areas of northern England (Pitcairn et al. 1995). The importance of atmospheric N supply in determining the tissue N content of the moss was demonstrated by transplant studies between regions (with different N deposition) and between sites within a mountain system. Increases in tissue N content may affect the N assimilation processes, decomposition and the partitioning of N between the various components of the ecosystem (Baddeley et al. 1994). Increased N content may make the moss more attractive as a food source.

Additional Comments:

There are substantial effects of nitrogen deposition on bryophytes, making it difficult to separate the effects of acidification from those of eutrophication. R. lanuginosum abundance is also effected by climate change (Tallis 1995). Two recent experiments have confirmed the sensitivity of Racomitrium to wet deposited N (Jones et al. 2002, Pearce and van der Wal 2002). 

Critical Load/level: 
Habitat/ Ecosystem Type Eunis Code Critical Load/ Level Status Reliability Indication of exceedance Reference
Moss and lichen dominated mountain summits E4.2

5-10 kg N ha-1 year-1

UNECE 2010 - Noordwijkerhout workshop quite reliable

Effects upon bryophytes or lichens.

472
References: 
Jones, M.L.M.; Oxley, E.R.B.; Ashenden, T.W. 2002 The influence of nitrogen deposition, competition and desiccation on growth and regeneration of Racomitrium lanuginosum (Hedw.) Brid Environmental Pollution 120 371-378
Pearce, I.F.K.; Van der Wal, R. 2002 Effects of nitrogen deposition on growth and survival of montane Racomitrium lanuginosum heath Biological Conservation 104 83-89
Pitcairn, C.E.R.; Fowler, D.; Grace, J. 1995 Deposition of fixed atmospheric nitrogen and foliar nitrogen content of bryophytes and Calluna vulgaris Environmental Pollution 88 193-205
Ratcliffe, D.A.; Thompson, D.B.A.; Usher, (Eds) M.B.; Thompson, (Eds) D.B.A. 1988 Ecological Change in the Uplands 9-36
Soares, A.; Pearson, J. 1997 Short-term physiological responses of mosses to atmospheric ammonium and nitrate. Water, Air and Soil Pollution 93 225-242
Thompson, D.B.A.; Baddeley, J.A.; Woodin, (Eds) S.J.; Farmer, (Eds) A.M. 1991 The effects of acid deposition on nature conservation in Great Britain NCC Focus on Nature Conservation Report 26 17-28

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