O3 :: Woolly Hair Moss

Latin name: 
Racomitrium lanuginosum

Impact Type: Direct exposure to pollutant

Key Concerns:

The magnitude of O3 impacts on bryophytes in the UK is currently very uncertain. The largest O3 concentrations occur at high altitude sites, and the most severe bryophyte impacts are therefore expected for species at Scottish mountain sites. However, with the exception of the experimental studies of Potter et al. (1996a,b) and others, there has been little demonstration of actual species responses in the field.

Lee et al. (1998) suggest that Racomitrium lanuginosum is sensitive to acute ozone if exposure is continued for more than two days.

Additional Comments:


Critical Load/level: 
Habitat/ Ecosystem Type Critical Load/ Level Status Reliability Indication of exceedance Reference
Semi-natural vegetation

AOT40 3000ppb hours over 3 months or AOT40 5000ppb over 6 months

UNECE, 2010 expert judgement i.e. only limited or no data are avaliable for this type of receptor

AOT40 is the Accumulated concentration Over a Threshold of 40 ppb. If an hourly average ozone concentration exceeds 40 ppb the difference between the concentration and 40 ppb is added to a running total. The units are therefore ppb multiplied by hours. For natural vegetation, the AOT40 is summed for the daylight hours for a period of three months. Daylight hours are defined as when solar radiation exceeds 50 W m-2. The daylight hours are when plant stomata are normally open.

Flux-based critical levels, based on biomass reduction, are also available for local and regional assessment but are not yet incorporated into APIS. See critical levels chapter of the UNECE Mapping Manual.

Lee, J.A.; Woodin, (Eds) S.J.; Farmer, (Eds) M. 1991 The effects of acid deposition on nature conservation in Great Britain NCC Focus on Nature Conservation Report 26 12-16
Potter, L.; Foot, J.P.; Caporn, S.J.M.; Lee, J.A. 1996 Responses of four Sphagnum species to acute ozone fumigation Journal Bryology 19 19-32

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