Moths, lichens and air pollution along a transect from Manchester to north Wales.
The light reflectance, type of epiphyte cover, and lichen flora of samples of oak trees at fifty-three sites along the transect were recorded. The correlation coefficients of two biological methods based mainly on plant indicators with measured levels of pollution were 0.635 and 0.670 respectively, but there is sometimes poor correspondence between different readings for the same site. There is a clear decline in air pollution along the transect. Values for winter fall from 170 to 40 mu g/m3 SO2, 100 to 10 mu g/m3 smoke. 93% of the variation in frequency of carbonaria in Biston betularia is accounted for by number of lichen taxa, grid reference, and cover by crustose lichen, but a correlation is also obtained when the grid reference is omitted. The results show some similarity with those obtained by Lees et al. (1973) for sites elsewhere; those for Gonodontis bidentata resemble those they obtained for Phigalia pedaria.