Reynoutria x bohemica (Polygonaceae): modeling potential changes in its secondary range in Ukraine

Reynoutria × bohemica Chrtek et Chrtková (Polygonaceae) is one of the most aggressive invasive plant species in Europe, posing significant ecological risks to native ecosystems. In Ukraine, there is currently a more active spread of the species than of one of its parent forms (R. japonica Hout). In this study, species distribution modelling (SDM) was applied for the territory of Ukraine using climatic variables across three temporal projections (2025, 2021–2040, 2041–2060). Principal component analysis (PCA) and clustering of variables identified the key environmental factors shaping the species’ potential distribution. The highest contribution to the models was associated with precipitation seasonality (bio_14), minimum temperature of the coldest month (bio_6), and temperature seasonality (bio_4), reflecting the species’ sensitivity to the interaction between moisture availability and temperature extremes. Heat maps of percent contribution (PC) and permutation importance (PI) revealed temporal shifts in variable relevance: while precipitation-related parameters remained consistently important, temperature-related predictors gained greater influence under future climate scenarios. The results indicate that the northern and north-eastern regions of Ukraine are the most vulnerable to further invasion. The findings provide a robust methodological basis for predicting invasion risks and justify the need for regionally differentiated monitoring and biosecurity strategies.