Impact Type: Direct exposure to pollutant
Scots pine is known to be sensitive to SO2 at concentrations which occurred in or downwind of large urban conurbations in the 1960s and 1970s. The poor performance of Scots pine in certain trials in the Pennines was attributed to high mean winter concentrations of SO2 and similar results were obtained from the Ruhr area in Germany (Farrar et al. 1977, Knabe 1970). Current concentrations of SO2 in the UK are unlikely to affect growth of Scots pine except in the immediate vicinity of point sources. Recent studies from Finland suggest that Scots pine may take up SO2 from the atmosphere more rapidly than Norway spruce (Manninen & Huttunen, 2000), and that the Critical Level under Finnish conditions may need to be smaller than that currently used by UNECE (Manninen et al., 1996).
Emissions of heavy metals and sulphur from such a point source, a non-ferrous smelter in the Kola Peninsula have reduced tree and needle growth causing canopy loss in surrounding forests of Scots pine (Nojd & Reames 1996). Older trees were found to be more susceptible than younger ones with growth reductions occurring further away from the pollution source. The lipid composition of roots is also influenced by industrial pollution, possibly related to SO2 exposure (Pukacki & Kaminska-Rozek, 2002).
Mixtures of pollutants such as SO2, NO2 and ozone may have contributed to growth reductions.
|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).