Abstract
Secondary succession of abandoned agricultural land is a long-term process, shaped by numerous biotic and abiotic factors. One stage in this process is the encroachment of pioneer tree species, among which the black cherry Padus serotina is increasingly common. This invasive species is widespread in temperate forests in Europe and is beginning to colonize open habitats, including fallow lands. In this study, we evaluated the effects of P. serotina on floristic composition, vegetation, and species diversity. Ten fallows in Lower Silesia (SW Poland) were selected. Within each field, five study plots invaded by P. serotina and five without this species were established. Botanical composition and area covered by individual plant species were determined in total of 100 plots. Our results indicate that the P. serotina seedlings and saplings have the strongest impact on species composition. The increase in P. serotina cover in the herb layer is accompanied by a reduction in the spread of expansive species such as Calamagrostis epigejos and Solidago gigantea. The low thickets formed by P. serotina provide perching sites for birds and facilitate seed dispersal, which promotes the development of multispecies shrub communities and enhances species diversity in study fallows at the current stage of succession.