Landscaping, 2003 Lichen (Evernia prunastri), Wood, Motor oil (65 cm x 54 cm x 11 cm) SO2 > 70ug/m3, 2003 Lichen (Evernia prunastri), glass Lichen Nugget, 2003 Lichen (Evernia prunastri), bronze Lichen Project Lichen is a fungus which contains algae. Lichen species are sensitive to pollutants such as sulphur dioxide in the air and different species have different tolerance levels. Where I live in the Perthshire countryside, I find an abundance of Evernia prunastri on trees. Evernia prunastri is class 3 out of 4 meaning that the air is clean. I have not yet seen any Evernia prunastri on trees in the city centre of Edinburgh or Glasgow. Its tolerance level of SO2 is about 60-70 ug per cubic metre, above which Evernia prunastri will die. This is featured in SO2 >70ug/m3 where in polluted air, only the lichen inside the glass controlled environment survives. Lichen Nugget is a hand held sample of Evernia prunastri to identify the species which indicates clean air. What looks like a landscaping model of a park, Landscaping is in fact a mapping of Evernia prunastri in the U.K., which reflects poor air quality in urban areas such as Glasgow and the mid-lands where the species cannot be found. <<< Back