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Abstract Betula pendula Roth. is considered a pioneering plant species important for urban ecosystems. Based on the sequencing of fungal ITS, we characterized the ectomycorrhizal (ECM) communities of twenty silver birch trees growing in a contaminated, highly anthropo-pressured urban environment and in a natural reserve site. We analysed chemical properties of each tree soil samples, focusing on effects of anthropogenic transformation. Three effects of urbanization: high heavy metal content, increased salinity and soil alkalinity, were highly correlated. The examined trees were divided into two forest and two urban clusters according to the level of anthropogenic soil change. The effect of soil transformation on the ECM communities was studied, with the assumption that stronger urban transformation leads to lower ECM vitality and diversity. The results of the study did not confirm the above hypothesis. The ECM colonization was above 80% in all clusters, but the forest clusters had significantly higher share of vital non-ECM root tips than the urban ones. Eleven mycorrhizal fungal species were identified varying from seven to nine and with seven species observed in the most contaminated urban plot. However, the lowest Shannon species diversity index was found in the most natural forest cluster. In conclusion, our findings demonstrate no significant negative effect of the urban stresses on the ECM communities of silver birch suggesting that both forest and urban trees have the potential to generate a similar set of ECM taxa.

Abstract This article is a study of risk assessment of trees with hollows, cavities and fruiting bodies for the improvement of the management and protection of urban trees growing along pedestrian routes. 317 trees were examined using TRAQ risk classes, VTA and ISA BMP methodology, Roloff's vitality classification, and sonic tomography (SoT) during the spring and summer of 2021. The collected data was analysed using the Kruskal–Wallis H-test, the Dunn multiple comparison test, the pairwise comparison of proportions with Holm correction, the U-Manna-Whitney test, and the Fisher exact test. The analysed trees grow alongside public footpaths and footways in central Zakopane, Poland. The study results indicate that tree trunk hollows are judged to have no adverse effects on a tree’s vitality when assessed using visual methods and are deemed to have a limited effect on vitality estimated with SoT. Though most high and moderate-risk trees, according to SoT (88% and 80%, respectively), had hollows, such trees were a small fraction of all 171 trees with hollows, cavities and/or fruiting bodies, 2.3% and 8.8%, respectively. Therefore, the decision to remove a tree should be based on advice from a professional arborist, supported by sonic tomography (SoT) or similar objective methods.