The aim of this study was to determine the link between the elements of a riverbed system (river length, longitudinal profile, bottom width, river bed depth, bank slope, bank protection, bottom substrate, and level of silt build-up), modified by regulatory and maintenance work, the number of aquatic vascular plant species, and their evenness present in both small and medium lowland streams in Poland.
100 study sections were analysed in 29 watercourses. Due to their geological, hydromorphological, and climate settings, the examined watercourses are representative of the central European plains, of which 65 sections are located in regulated and maintained watercourses and 35 are in unmodified streams. The Shapley value regression method was used to establish the influence of the stream features on aquatic plants.
Results identified 27 different macrophyte taxa, where the most frequently occurring were Sparganium emersum Rehmann, Phalaris arundinacea L., and Lemna minor L. The results found that aquatic plant communities were influenced by the analysed factors, regardless of whether a watercourse was shaped by technical means or not. The most influential parameters were the level of silt build-up and bottom width. Furthermore, results brought to evidence that watercourses are complex systems where elements are linked by a series of relationships and that single correlations among environmental elements, anthropogenic interactions, and aquatic plants are very rare.