One of the habitat types protected within the framework of the NATURA 2000 network due to the presence of species of European importance are fresh meadows from the Arrhenatherion alliance. The maintenance of their characteristic floristic composition depends on habitat conditions and extensive use, while any changes in this respect trigger succession transformations potentially threatening their nature value.The aim of the study was to conduct nature and habitat valuation of one of the largest meadow complexes in the Wielkopolska region, i.e. Wielki Łęg Obrzański, which will make it possible to describe the preservation status of fresh meadows and their habitats.Based on multifaceted analyses of 535 relevés made using the Braun-Blanquet method in the years 2006-2012 and representing the Arrhenatherion alliance, the phytosociological and botanical structure as well as constancy of species in individual variants (floristic types) were determined. Moreover, their habitat conditions were defined, i.e. soil moisture and nitrogen content using the index method according to Ellenberg, while laboratory methods were used to determine the content of organic matter, soil moisture as well as the contents of potassium, magnesium and phosphorus in soil.Floristic composition of fresh meadows from the Arrhenatherion alliance differs due to high heterogeneity of habitat. The presence of fresh meadow phytocenoses both on dried organic soils (the driest forms of flood meadows) and on mineral soils (oak-hornbeam forests) contributes to differences in the floristic composition both in ryegrass meadows and grass-fescue meadows, mainly due to soil moisture and fertility as well as sward use type. This constituted the basis for the identification of lower syntaxonomic units in the internal structure of the plant associations. Five variants were distinguished in Arrhenatheretum elatioris, while the community of Poa pratensis-Festuca rubra was developed in as many as 8 variants.
Abstract. The floristic composition of anthropogenic meadow communities undergoes transformations dependent on utilisation and habitat conditions. One of their consequences includes encroachment into and maintenance in the sward of some expansive plant species e.g. Taraxacum officinale. The objective of the study was to analyse the impact of the occurrence of Taraxacum officinale on the floristic diversity of meadow-pasture communities at varying levels of utilisation and habitat conditions. The effect of Taraxacum officinale presence on changes in the floristic composition of meadow communities was assessed on the basis of results of geobotanical studies carried out by Braun-Blanquet's method. The studies assumed evaluation of plant species proportions in the sward of meadow communities based on the share of Taraxacum officinale, floristic diversity and the natural value index of the sward. The highest share of analysed plant species was determined in extensively utilised meadows and pastures found on periodically dry habitats. Simultaneously, the high numbers of examined plant species exert a negative influence on the floristic diversity index and the natural value of plant communities.
On the basis of multifaceted investigations of approximately 600 phytosociological surveys of foxtail meadows taken in years 2002-2012 in river valleys with the assistance of the Braun-Blanquet method, the authors carried out evaluation of the floristic composition with respect to phytosociological structure, floristic variability, degree of synanthropisation and life form structures. In addition, they ascertained the dependence of floristic variability of Alopecuretum pratensis phytocenoses on site conditions determined using: the phytoindication method and the laboratory analyses assessed the soil content of available forms of P and K and of Mg. The greatest areas among the recognised syntaxons are taken up by patches of a typical sub-association developed in fresh sites on soils of lightly acid reaction and moderate nitrogen availability. Floristic variability of Alopecuretum pratensis is characterised by: presence in the phytosociological structure of species characteristic for other syntaxons, floristic abundance and botanical structure, domination of species of the 1 st and 2 nd degree of stability, high proportion of synanthropic species, values of the floristic diversity index (H'), natural and fodder score values. Geobotanical variability of foxtail meadows confirms difficulties with unequivocal determination of the systematic position of the Alopecuretum pratensis association.
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