Die Uferflora der Weser / Friedrich Wilhelm Oppermann
The riparian flora of the river Weser between Münden and Bremerhaven was documented. 89 representative test areas were selected each 5 km in distance from each other. In addition random sampling along the river banks was carried out to provide a complete record of species present. Altogether 315 vascular plant species were found. The frequency distributions of 231 species are shown in the tables 4a to 4i. The formal structuring of the investigated river section into upper reaches (Oberweser), middle reaches (Mittelweser) and lower reaches (Unterweser) is reflected by the composition of the riparian flora. The frequencies of the different species for each of the three reaches of the river are reported. Calculated species frequencies revealed floristic differences for the different reaches. This is particularly the case for "index-species" whose occurrence is mainly limited to one specific reach of the river. There were 42 neophytes found along the banks of the investigated river section, but only four species were found in more than 25 % of the test areas: Bidens frondosa, Atriplex sagittata, Impatiens glandulifera und Xanthium albinum. Only Bidens frondosa is a very frequent species along the Oberweser as well as along the Mittelweser. The other three neophytic species have a selective occurrence in only one of the Weser parts.