SO2 :: Usnea species
Impact Type: Direct exposure to pollutant
Key Concerns:
Usnea spp. are highly sensitive to SO2, and are also believed to be sensitive to acidic deposition (Seaward & Hitch 1982). Hawksworth & Rose (1970a) suggest that some species can tolerate up to 40 µg m-3 SO2 (U. subfloridana), U. ceratina and rubiginea can tolerate up to 35 µg m-3 SO2, and that U. florida under 30 µg m-3 SO2, with U. artculata and filpendula only found in area with pure air.