The aim of this study was to determine the presence, distribution and abundance of alien invasive plants in the riparian zone along the right bank of the river Sotla. Of interest were also the effects of environmental factorson the occurence of invasive species. In the 2008 growing season water course was divided into 86 sections of 100 m length. The condition of riparian zone and hinterland was estimated, the invasive species along the river Sotla were surveyed, their phenological phases were identified and their phytosociological classes and occurence in diferent parts of the water course were determined. In august 2012 the inventory on 17 random selected sites was repeated, this time, only the occurence, frequency and distribution of alien invasive plants. In most of the sections the condition of riparian zone and hinterland was good. Poor condition was recorded in the middle and lower river course, which is a result of land use patterns beyond riparian zone and width of riparian vegetation. The state of some individual sections was deemed as very good, where no major changes were recorded in river channel and riparian vegetation. 13 alien invasive species were identified. The most frequent species indentified were Echinocystis lobata, Solidago gigantea, Robinia pseudacacia, Helianthus tuberosus and Impatiens glandulifera. Variability among invader groups can in most cases be explained by the height of riparian vegetation. Also, significant share of variability can be explained by stream depth, changes in channel structure and land-use pattern beyond the riparian zone. Comparison of selected sections between the years 2008 and 2012 showed that the occurence of alien invasive plants was higher in 2012, even two new alien invasive species - Spiraea japonica and Ailanthus altissima were found and indentified.
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