Effects of agriculture on epiphytic lichen vegetation in central Italy

The influence of agriculture, i.e., of fertilizers and ammonia emissions from crops and sheep grazing, on epiphytic lichen vegetation, and the use of nitrophytic lichen species in bioindication of air pollution were investigated in a geothermal area in central Italy. Floristic analysis showed that the lichen vegetation is only slightly influenced by agriculture. Analysis of the lichen data and chemico-physical parameters of tree bark supporting lichen growth failed to demonstrate marked differences between agricultural and non-agricultural sites, the higher total frequency of nitrophytic species in agricultural sites being the only parameter discriminating between the two site types. Bark nitrogen and pH were not discriminant. Factors determining the higher total frequency of nitrophytic species in agricultural sites may include dust impregnation of bark and the drier microclimate of trees in these sites. It is concluded that nitrophytic lichens can be included in the calculation of the Index of Atmospheric Purity in the study area.