Patterns of traffic polycyclic aromatic hydrocarbon pollution in mountain areas can be revealed by lichen biomonitoring: A case study in the Dolomites (Eastern Italian Alps)

•Road traffic is among the main sources of impact in high elevation ecosystems.•Lichens were used to detect road traffic pollution in the Dolomites.•Lichens of Dolomite passes have higher pollution than those in remote sites.•Pollution in the lichens decreases with increasing distance from the road.

In mountain areas of touristic interest the evaluation of the impact of human activities is crucial for ensuring long-term conservation of ecosystem biodiversity, functions and services. This study aimed at verifying the biological impact of polycyclic aromatic hydrocarbon (PAH) emissions due to traffic along the roads leading to seven passes of the Dolomites (SE Alps), which were recently declared a UNESCO World Heritage Site. Thalli of the epiphytic lichen Pseudevernia furfuracea, collected at increasing distances from the roads, were used as biomonitors. Our study revealed a gradient of decreasing PAH pollution within 300 m from the roads. Differences among passes were evident mainly for samples collected nearest to the roads, but PAH concentrations at 300 m were almost always higher than those of undisturbed reference sites, indicating that traffic PAH pollution may impact natural ecosystems and lichen diversity at relatively long distances from the emission source.