The present monitoring study was undertaken to analyze the impact of atmospheric pollution on the lichens found near a power station in northern Spain. Data from 565 relevés gathered on 113 sites were analyzed. In areas near the power station the lichen species belong to the Xanthorion community. In areas away from the power station and that are not under the influence of dominant winds, the lichenic diversity increases and the species present belong to the Parmelion community. In intermediate areas between the two, there is a great increase in lichen diversity, in these areas there is a replacement of the species that typically belong to the Xanthorion community, by species typical of the Parmelion community. Because of this we propose the analysis of the number of lichen species together with the distribution of bioindicator taxa as a complement to lichen diversity analysis in biomonitoring studies.