Zmiany w runie żyznej buczyny niżowej Galio odorati-Fagetum w rezerwacie Wronie w latach 1967-2005

The Wronie nature reserve was established in 1978 for conservation of Pomeranian fertile beech forest Galio odorati−Fagetum (=Melico−Fagetum) outside of the natural range of European beech Fagus sylvatica. Reserve is located in Golub−Dobrzyń Forest District (53°18'39.52"N; 18°54'3.89"E; N Poland). The aim of our study was to determine the influence of passive protection for beech forest herb layer biodiversity. For our research, we used four series of phytosociological relevés made in 1967, 1984, 1995 and 2005. To investigate changes in habitat conditions we used Ellenberg indicator values. Differences between years were analysed with ANOVA and Tukey test. In subsequent years, the frequency and cover of non−forest species, mainly from Epilobietea, Artemisietea, Trifolio−Geranietea and Molinio−Arrhenatheretea classes increased. This is caused by the increase in light availability, as result of disturbances in the tree stands (windthrow, oak decline, insect gradation). Light is the only Ellenberg coefficient that has significantly changed during 38 years (fig., tab. 2). Increase of light availability had no effect on biodiversity of forest herb species from Querco−Fagetea class. In comparison, with other studies in similar forest communities, our results suggests that passive protection might give different effects on biodiversity in similar forest communities, depending on tree stand dynamics.