Alien plants on the rise: 30 new taxa and long-term trends in Slovakia

Keeping track of new alien plants getting into the wild or escaping from cultivation is crucial for understanding of biodiversity dynamics and for mitigation of the potential negative impacts that could accompany their further spread.This study focuses on the area of Slovakia, the Central European country where tens of new alien vascular plant taxa have been recorded every decade since 1910.We analyzed how many new neophytes were discovered in the territory of Slovakia in individual decades after 1790, when the first floristic study focused on the area was published.The incidence of first records of new neophytes has recently been increasing, and is expected to reach its new maximum in the current decade (2020-2029).It is assumed that the political regime transformation of Czechoslovakia in 1989 created new connections of the territory of extant Slovakia with many parts of the world, which facilitated the introduction of many new alien taxa.In this context, we aimed to analyze how many new neophytes were discovered in the area of Slovakia after these events (in the period of 1990-2025) and identify the specific localities and habitats where these taxa were most frequently discovered within the country.We also compiled an annotated list of 30 new (previously unpublished) alien vascular plant taxa discovered in Slovakia in 2020-2025.The record analysis of the first occurrence made in the focused time period (1990-2025; n = 231) showed that new neophytes were most frequently discovered in the area of the capital city Bratislava and its immediate surroundings, with several other less significant hotspots.On a finer scale, new alien taxa were recorded in a wide spectrum of habitats, with urban green infrastructure being the most frequent category (20%).The results of this study help to identify the locations and specific habitats that may continue to act as sources of biological invasions in the future and should therefore be monitored with increased caution.