Biodiversity of epiphytic lichens and heavy metal contents of Flavoparmelia caperata thalli as indicators of temporal variations of air pollution in the town of Montecatini Terme (central Italy)

Abstract

The results of a biomonitoring survey carried out in the town of Montecatini Terme (central Italy) in the period 1993-2000 using the biodiversity of epiphytic lichens and the accumulation of heavy metals in thalli of Flavoparmelia caperata as indicators of air pollution are reported. From 1993 to 2000, the mean ILD value for the whole study area increased from 18+/-18 to 42+/-22, the lowest ILD value increased from 0 to 11 and the highest ILD value increased from 67 to 84. A 'lichen desert' was found only in 1993 and stations classified as 'natural' were lacking only in 1993 and 1996. Concentrations of all heavy metals decreased from 1993 to 1999. It is concluded that vehicular traffic is the main source of atmospheric pollution in the study area. The most likely changes that may have caused lichen communities to improve and heavy metals to drop is conversion of heating systems to methane (abatement of SO2) and the use of unleaded gasoline (reduction of Pb). The present results showed that despite their slow growth rate, lichens respond rapidly to decreasing concentrations of air pollutants, allowing annual changes to be detected.