EN
Las Osobowicki forest is a remnant riparian woodland of the Odra valley, although its site conditions have been anthropogenically disturbed. To assess species richness of the drained forest, floristic data were collected from circular plots with a radius of 5.64 m. Plots were systematically distributed in forest communities. In total, 87 species were identified in the study area, with a mean of 14 species per plot. The share of alien species was minor. Flood prevention caused site drying and, as a result, decrease in species richness of the riparian forest. However, spatial distribution of species number values proves the sustained influence of the moisture factor on the vegetation. Connection of species richness and hydrological conditions is supported by positive correlation between species richness and Ellenberg moisture index.