Impact Type: Direct exposure to pollutant
The Orange-fruited elm-lichen (Caloplaca luteoalba) used to be relatively widespread in the UK, but has suffered a severe decline in the last century. It is now largely confined to the dry bark of mature elm trees (Biodiversity Steering Group 1995). It is probably sensitive to SO2, however there is no published research as to the effects of air pollution on this species.
|Habitat/ Ecosystem Type||Critical Load/ Level||Status||Reliability||Indication of exceedance||Reference|
|Forests and semi-natural vegetation||
20 µg SO2 m-3 annual mean and half-year(Oct-March) mean
|UNECE, 2004||quite reliable i.e. the results of some studies are comparable||
Low temperature appears to enhance the negative effects of SO2, and the lower critical level of 15 µg SO2 m-3 is used where the effective temperature sum (ETS) (i.e. the sum of temperatures) above 5oC is below 1000 degree days (d.d) (Ashmore et al., 1994).