Successional dynamics of Cynosurus pasture after abandonment in Podkrkonoší

Between 1996-2002, successional dynamics on an abandoned pasture in Přední Ždírnice (lat. 50°32'N, long. 15°40'E) was examined. A 7-year study was performed on the abandoned mesotrophic pasture classified as Cynosurion Tüxen 1947 at the start of the study. Two permanent plots (100 m2) were established and sampled three times a year; changes in plant species composition (species cover) and plant species diversity (species number) were studied. Species assemblages of the Cynosurus pasture were described, E1 (herb layer) and E2 (shrub layer) covers were calculated and a secondary succession in the plant community was evaluated. Abandonment caused the decrease in the cover of the species sensitive to shading - e.g. Taraxacum sect. Ruderalia, Trifolium repens, Lathyrus pratensis, Plantago major, Stellaria graminea, Vicia cracca. Contrary to this, the cover of Calamagrostis epigejos, Rubus sp., Galium album, Galium verum, Knautia arvensis, Veronica chamaedrys increased, probably due to their ability to spread by clonal growth and as a result of the competitive relationships in the plant community. A big production of Calamagrostis epigejos litter may be the outcome of a significant decrease (by 9%) in E1 cover (P = 0.04). Although the grassland was invaded by ruderal and weedy species (Apera spica-venti, Myosotis arvensis, Veronica arvensis) and by shrubs Crataegus sp. and Rosa sp. (an increase by 16%), an increase in species number was not significant. Phytosociologically, the Cynosurion Tüxen 1947 community came closer to the Arrhenatherion Koch 1926 alliance.