Lichens and tobacco plants as complementary biomonitors of air pollution in the Grenoble area (Isère, southeast France)

This biomonitoring study was aimed at providing an overall assessment of nitrogen oxides (NOX) and tropospheric ozone (O3) in the Grenoble area (Isère, France). Two bioindicators, lichens and tobacco plants, were used to estimate, respectively, the spatial distribution of NOX and O3. The following methodological approaches were adopted: bioaccumulation of nitrogen in the lichen Physcia adscendens, bioindication of ozone as shown by visible injury to tobacco plants (cv. Bel W3), and biomonitoring at the lichen community level (IAP). Complementary biomonitoring maps, the first based on nitrogen concentrations of lichens and the second based on tobacco leaf injuries, were highly comparable with results obtained from physico-chemical analyses. Multivariate analyses (Canonical Correspondance Analysis) were used to determine the relationships between levels of atmospheric NO2 and O3 and the lichen communities (IAP). A lichen sensitivity scale to NO2 and O3 was attempted for 43 epiphytic species, from which it was possible to define five clusters according to their indifference, sensitivity or resistance to NO2 and O3.