Abstract
The aluminium smelter in Žiar nad Hronom has operated since 1953. As a result, the surrounding area is now one of the most polluted regions in Slovakia. Since the implementation of new production and filtration technologies in 1996, the amount of emissions has significantly decreased. Our aim was to evaluate the long-term restoration of an environment that has been damaged by fluorine-based air pollutants. We analysed the contamination of forest ecosystems in three beech stands at various distances from the emission source (2, 7, and 18 km). Signs of restoration in adult beech trees were observed through a decrease in defoliation and a reduction in the necrotic disease of the bark in tree crowns. However, the impacts of air pollution on ectomycorrhizal associations persist. In the reduced number of ectomycorrhizal fungal species (16 species in the polluted stand compared to 38 species in the control stand), the low representation of sensitive fungal orders (Cantharellales, Gomphales, and Boletales), and the indices of species richness and heterogeneity (Hill, Margalef, Simpson, and Shannon–Weaver). In some respects, the findings indicate that the beech ecosystem is capable of revitalization within 25 years after a reduction in air pollution. However, much more sensitive indicators of successful restoration, compared to the characteristics of the trees, are the communities of macromycetes.