Restoration of Cnidion dubii meadows on Warsaw cross-section of the Middle Vistula Valley

The studies were carried out as the part of flooded meadows’ restoration on the Warsaw cross-section of Natura 2000 site Middle Vistula Valley. They concerned determination the possibility of restoration and improvement of species composition plant communities of meadows in river valleys by limitation growth of the invasive alien species and introducing diasporas of plant species from natural meadows. Seeding material for restoration was taken from well preserved natural Cnidion dubii meadows lying in Lower Pilica Valley in the neighborhood of Warsaw. Seeding material contained 26 native species including representative species for Cnidion dubii meadows: Cnidium dubium , Allium angulosum , Sanguisorba officinalis and Galium boreale . Three levels of seedbed preparation intensity were checked: low cutting of old vegetation; ploughing on depth about 20 cm and rototilling, removing of sward and upper soil layer thick 30 cm. Two ways of seeding material placement were also tested: sowing + rolling + mulching (covering with straw); sowing + rolling (without mulching). The applied methods of seedbed preparation and used seeding material allowed introducing of 17 plant species. Removing of topsoil was the most effective in limitation of invasive alien species occurrence and favored emergence and initial growth of Sanguisorba officinalis , Allium angulosum and Galium boreale . Ploughing and rototilling of topsoil layer effectively limited of Acer negundo occurrence and favored the growth of Cnidium dubium .