Synantropizacja flory roślin naczyniowych rezerwatu Wieliszewskie Łęgi (środkowa Polska)

Understanding human influence on vegetation dynamics is important from both conservation and human management perspectives. The Wieliszewskie Łęgi Reserve, located in central Poland, is a young forest area that was cut off from the flood waters of the Narew river in 1963, but since then has been constantly and intensively supplied with water from overflows under the dike. On the southern side, adjacent to the reserve, there are patches of valuable meadows, rushes and scrub communities. The aim of this study was to determine the degree of synanthropization of the flora in the Wieliszewskie Łęgi reserve and to assess changes occurring in its vegetation. The vascular plant flora of the reserve and its southern vicinity was surveyed in 2017 and the plant communities within the study area were mapped. In the area of the reserve, we observed a total of 264 vascular plant species, whereas for the entire area under study, 314 species were recorded. Of these, 14 were classified as valuable. The high species richness was mainly due to the presence of a large number of apophytes – native species quickly colonizing sites transformed by man. Therefore the degree of naturalness of the reserve’s flora was relatively low, which is most likely due to the lack of refugia for typical forest species. A number of plant communities of non-forest, scrub and forest character, typical for swampy, wet, semixeric as well as dry habitats were recorded. Succession, manifested by the disappearance of non-forest and scrub communities and progression of forest communities, is superimposed on the processes of transformation into semixeric oak-hornbeam communities in the highest areas and carr communities in the lowest areas. A low proportion of kenophytes (16 species) and a zero value of the index of fluctuation changes indicate a relative resistance of the reserve to invasion by alien species.