Species Composition of Tree Vegetation in the City of Sofia

The article examines the diversity of tree species in part of Sofia, Bulgaria, spanning approximately 60 km². A total of 91 species from 53 genera and 25 families were identified. Dominating in the area is Fraxinus excelsior, which constitutes 494 individuals, representing 12.7% of the total number of trees. The genus Fraxinus is the most abundant, with five species accounting for 22.21% of all trees observed. Although these proportions marginally surpass the thresholds outlined by the 10/20/30% rule, they do not yet indicate significant concern. Nonetheless, the high prevalence of Fraxinus excelsior and its genus raises alarms about potential increased risks of disease and environmental stress. Other frequently encountered species include Prunus cerasifera, Quercus robur, Aesculus hippocastanum, Juglans regia, Fraxinus oxycarpa and Tilia cordata. Two invasive species were found in notable quantities: Robinia pseudoacacia (163 individuals) and Ailanthus altissima (88 individuals).