Senecionetum fluviatilis in Poland from a European perspective – diversity, distribution and threats

Abstract

Senecio sarracenicus is a rare river corridor plant, featured on Red Data Lists of threatened flora in several European countries. The habitat typical for this species is protected in the European Union. The species constitutes its own association Senecionetum fluviatilis, but syntaxonomic separateness of this community was rejected by some authors who assigned it to the Convolvulo sepium-Cuscutetum europaeae. Comprehensive analysis of phytosociological material from different European countries was conducted using classification and ordination methods, and both associations from Poland were compared. The study showed a clear separation between both associations in terms of species composition and community structure as well as microhabitats they occupy in river valleys. The species composition of the Senecionetum fluviatilis is similar within Europe regardless of sample location. In Poland, Solidago gigantea is the most frequent neophyte among alien species penetrating the association under study. Although S. gigantea does not affect the diversity and total species richness, it does reduce the native species cover; when its coverage is large (>25%), it may in addition reduce the number of native species. This means that S. gigantea has a substitutive relation to native components of the association Senecionetum fluviatilis, particularly with respect to Senecio sarracenicus.