Erechtites hieracifolia -an invasive plant species in peatlands habitats of south-eastern Poland (Central Europe)

Agata Stadnicka-Futoma^1*Małgorzata Jaźwa^2*Konrad Kata³Ewelina Klichowska⁴

• ¹University of Rzeszow, Rzeszów, Poland
• ²Opole University, Opole, Opole, Poland
• ³Independent researcher, Rzeszow, Poland
• ⁴Jagiellonian University, Kraków, Lesser Poland, Poland

Erechtites hieracifolia is an invasive plant species increasingly colonizing peatland communities in Central Europe. Invasive plants pose a growing global threat by spreading into diverse habitats and contributing to biodiversity loss, a process intensified by human activity and climate change. Peatlands are particularly vulnerable due to their sensitivity to groundwater fluctuations and habitat degradation. This study aimed to analyze the floristic composition of peatland plant communities with the presence of E. hieracifolia, assess potential differences between invaded and non-invaded plots, and evaluate changes in species cover over a three-year period. Additionally, new localities of E. hieracifolia in Poland were documented. In 2019, a total of 60 phytosociological relevés were collected from 12 peatland patches (6 with E. hieracifolia, 6 without). The same sites were revisited in 2022. Syntaxonomic classification of vegetation types was conducted, and differences in species composition were analyzed using PERMANOVA. Shannon-Wiener and Simpson indices were calculated to compare biodiversity between the two groups. E. hieracifolia was most frequently found in degraded raised bogs with low groundwater levels, particularly in the Sphagno recurvi–Eriophoretum vaginati association. The highest species cover (25%) was observed in patch 11. Over the study period, the number of colonized patches increased from 6 to 8, often accompanied by an increase in cover and range, indicating ongoing expansion. The species was strongly associated with patches dominated by Eriophorum vaginatum, which may provide favorable microhabitat conditions. Statistical analyses revealed significant floristic differences between invaded and non-invaded groups. Biodiversity indices were slightly lower in communities with E. hieracifolia, suggesting that habitat degradation, particularly peatland drying, facilitates invasion. Given that E. hieracifolia is spreading in habitats protected under the EU Habitats Directive, long-term monitoring is warranted. Remedial actions may be needed to prevent further expansion, especially in ecologically valuable and sensitive areas.