The spread of non-native species is a rising problem. The distribution of invasive alien species has increased, especially during the last decades, which is a threat to native flora. These specific plant species can severely affect the flora of an area, because they can repress native species and thereby reduce the biodiversity. However, the vegetation of riparian habitats is particularly affected by the immigration of non-native species as they spread rapidly along river systems. Additionally, due to fluctuating water levels ruderal sites are created which are colonized rapidly by invasive alien plants. This thesis deals with the vegetation of the restored section „Mitte West” of the Traisen river in Lower Austria. The LIFE+ Project schedules an improvement of the river structure between Traismauer and Zwentendorf. As a result of the renaturation, a new, natural river channel has developed. To analyze the seed bank, soil samples were taken in the new river bed and examined for the occurrence of invasive alien plants. The received data was compared with previous studies from 2011 and 2014. In addition, the data from the seed bank analysis was compared with the results from a vegetation mapping of the same year. The seed bank was tested for seeds of Acer negundo, Bunias orientalis, Impatiens glandulifera, Impatiens parviflora, Robinia pseudoacacia and Solidago gigantea. The analysis has shown that the number of seeds of invasive alien plants has significantly decreased in the study years 2011 2014 and 2015. In 2015, no seeds of non-native plants were found. Nevertheless, individuals appeared on the surface due to seed dispersal by wind from neighboring habitats, as well as the transport of seeds through flood events. For this reason, it is recommendable to continue observing the presence of invasive alien species in the project area and a further monitoring of these species is advisable.