The Increasing in the Floristic Diversity of the Abandoned Arrhenatherion Elatioris Meadows by Dicotyledonous Species Oversowing

The paper presents the research on the increasing in the floristic diversity of abandoned Arrhenatherion elatioris meadows through the introduction of three dicotyledonous species: Achillea millefolium, Daucus carota and Leucanthemum vulgare and the re-management. They were carried out in the meadows of the landscape reserve The Ursynow Escarpment (Skarpa Ursynowska) in 2016-2018. The studies were aimed at restoring natural values of these meadows, especially their landscape and aesthetic functions. The experiment was designed in the community of Arrhenatherum elatius - Bromus inermis, as a randomised complete block, with eight replications, on the plots of 2 m(2). In each plot the diaspores (collected in The Lower Pilica Valley) were sown close to the centre of the plot, within an area of 0.5x0.5 m. In the sowing year two top-cuttings and one productive one were made. In the following years the meadows were mowed once or twice. The following features were estimated: the abundance of sown species populations, the seedling density, the heights of the sown species, the height of the resident vegetation, the total ground cover, the species composition of the sward and the species richness. The improvement of the landscape and aesthetic functions of the reserve due to increasing in the species richness from 10 to 38 species and significant decreasing in Urtica dioica share was achieved. The species diversity, described with the Shannon-Wiener index, enlarged of 53% in the first year after oversowing. The introduced species decided also about the improvement of the total ground cover. Fast and lasting effect was obtained especially on the area over-sown with L. vulgare. The good effects in the first two years were obtained also in the plots with D. carota (biennial species). A. millefolium was characterised by significantly fewer number of seedlings but its population abundance was increasing gradually during the following years. The impact of high grasses (A. elatius, B. inermis) on the soil coverage by the plants of sown species and their heights was shown. The studies also proved that in the conditions of summer drought the resident vegetation may protect the seedlings against the temperature and evapotranspiration.