A new approach to environmental monitoring is presented in this work, related to the use of a biophotonic instrument to support evaluation of lichens stress status. Lichens are widely used as bioindicators, that is organisms able to indicate the presence and amount of atmospheric pollutants. The proposed approach requires the measure of lichens fluorescence response by means of a self-developed biophotonic instrument, in order to obtain an objective evaluation of lichens stress status. The lichens rise fluorescence response was measured, following the OJIP procedure, a standardized laboratory method for plants health analysis. The experimental validation of this approach was done in two steps. Firstly, lichens of "Physcia Adscendens" species were collected on poplar trees, in tree areas: the first and the second areas near an industrial zone, direction of the prevailing winds, the third at a distance of about ten kilometers. Then the changes in fluorescence activity were evaluated, placing near an industrial area several samples of "Flavoparmelia Caperata (L.) Hale" lichens, collected in a non-polluted area. A fluorescence response modification was observed, demonstrating that changes in atmospheric pollution could be monitored by means of differential measurements on suitable samples. To validate the obtained results, the pollution degree was estimated using also a widely accepted method, which is the evaluation of lichen biodiversity. Lichen vegetation of the poplar trees was surveyed using a sampling grid of ten units. The Lichen Biodiversity Index (LBI) was calculated as the sum of the frequencies of all species within the grid. As a result of the comparison between fluorescence response shape and LBI evaluation, a real correlation was found, demonstrating the proposed approach effectiveness.
