Floristic diversity of selected plant communities on extensive and abandoned grasslands in the Nadwieprzański Landscape Park / Zróżnicowanie florystyczne wybranych zbiorowisk roślinnych ekstensywnych użytków zielonych w Nadwieprzańskim Parku Krajobrazowym

Abstract

Abstract The paper presents floristic diversity of some plant communities in the Nadwieprzański Landscape Park (middle part of the Wieprz River valley). Phytosociological relevés were made in the years 2005-2007 with Braun-Blanquet method. Species richness was a base to calculate the Shannon-Wiener diversity index. The Wieprz River valley has the character of a floodplain. In its middle reaches, communities of the Molinio- Arrhenatheretea class accounted for nearly 75% of all plant communities in grasslands. Herbaceous communities were represented by associations from the Filipendulion alliance. The greatest diversity (H’ = 3.4) was characteristic for vegetation of the Valeriano-Filipenduletum association. It formed small patches in abandoned meadows. Small patches of plants from the Lythro-Filipenduletum ulmariae association, having a slightly smaller floristic diversity (H’ = 3.0) were found on abandoned meadows located in highly silted and poor organic soils. Characteristic species of herbaceous communities (Filipendula ulmaria, Valeriana officinalis and Lythrum salicaria) occurred also in the sward of abandoned thistle meadows. Typical thistle meadows (Cirsietum rivularis), with the predominance of Cirsium rivulare developed in land depressions, not far from the Wieprz River, in the vicinity of abandoned drainage ditches and along the edges of the valley. However, the total abandonment of these meadows leads to changes in floristic composition of the sward and to succession towards herbaceous communities.