Long-term changes in the allergenic potential of ruderal vegetation in a Central European urban area

Abstract Allergenic pollen from ruderal vegetation, particularly grasses (Poaceae) and invasive weeds such as Ambrosia artemisiifolia , poses increasing health risks in urban areas. Climate change and urbanisation influence the distribution and allergenic potential of these plant communities. This study analyses long-term changes in allergenic species within ruderal vegetation in Bratislava, Slovakia, and their relationship with meteorological factors, using phytosociological relevés from two periods (1975–1982 and 2011–2017). Changes in the proportion and cover of allergenic species, as well as the allergenic potential of ruderal vegetation, were assessed statistically and correlated with meteorological data. Of the 458 recorded species, 105 were allergenic, contributing 58% of the vegetation cover. Allergenic species richness, cover, and proportion increased significantly, driven primarily by invasive Asteraceae and grasses. Air temperature showed strong positive correlations with these metrics, while precipitation had minimal impact. The highest allergenic potential was recorded in the Stellarietea mediae class. However, the overall allergenic potential of ruderal vegetation over the four decades remained relatively stable, despite the changing species composition: the spread of some invasive species was balanced by the retreat of others.