Assessing photosynthetic biomarkers in lichen transplants exposed under different light regimes

The present work is a methodological study testing alternative exposure conditions of lichen transplants for biomonitoring studies. We evaluated the effects of different light regime on the vitality of lichen by analysing the photosynthetic efficiency of transplanted thalli of the fruticose species Pseudevernia furfuracea (L.) Zopf. var. furfuracea. In particular, we tested the hypothesis that shading lichen transplants is necessary to ensure sufficient lichen vitality during the exposure time. Thalli of P. furfuracea were exposed in a polluted area within the harbour of Genoa (N-Italy) for 4 weeks under two experimental conditions: 5 thalli were covered with a shade cloth, whereas 5 thalli were kept in the light. We showed that, under the same environmental conditions (i.e., climate and pollution regime), shading the thalli minimised the photoinhibition and prolonged the vitality of the lichen. Thus, we recommend shading lichen transplants during biomonitoring surveys to better detect the effects of pollution on the lichens.