The effect of site conditions on the abundance of populations of I. glandulifera, selected individual features (height and width of stems, number of whorls and side branches, flower production), and floral traits (total length of flowers, length and width of lower sepal, spur length) were investigated in years 2013-14. Observations were conducted on fallow land, at roadsides, along riverbanks and edges of a riparian forest as well as in a willow thicket and a riparian forest inside located in the Vistula River valley in southern Poland. In these stands, taken successively, light availability gradually diminished, while plant canopy height and soil moisture increased. The low abundance of the population on the fallow land may have been caused by low soil humidity triggering seedling mortality, whereas the low abundance in the interior of the riparian forest may have been due to seasonal water stagnation hampering the development of offspring. The increasing values of individual traits from the fallow land to riparian forest edge might be linked to growing lateral shade, whereas the much lower values in the willow thicket and forest interior might be caused by full shade. Individuals growing on the fallow land, at roadsides, and along riverbanksproduced flowers with small total lengths and large lower sepals and spurs, whereas individuals occurring in willow thickets and riparian forests showed opposite tendency. The considerable stem dimensions and substantial production of large flowers may augment chances for successful resource capture and pollinator visits in open sites, while the reduced size of individuals and moderate production of small flowers may be sufficient for the maintenance of populations in closed habitats
In recent years, programmes aimed at improving environmental conditions in river valleys within urban spaces have been initiated in many of the European Community countries. An example is the project “Revitalization of Urban River Spaces – REURIS” which was implemented in 2009-2012. Its main aim was to revitalize a part of the valley of the River Ślepiotka in Katowice. One of the tasks of the project was a comprehensive treatment to combat invasive plant species occurring in this area, carried out by using a combination of chemical and mechanical methods. Chemical treatment involved the application of herbicide mixtures, and mechanical treatment included, among others, mowing and/or removal of the undesirable plants. The work focused primarily on reducing the spread of two species of the Impatiens genus: I. glandulifera and I. parviflora, and the species Padus serotina, Reynoutria japonica and Solidago canadensis. Currently, the maintenance works on this section of the river are performed by the Urban Greenery Department in Katowice, which continues the elimination of invasive plants, according to the objectives of the REURIS program. In 2012 the Department of Botany and Nature Protection at the Faculty of Biology and Environmental Protection started to monitor the implementation and the effects of the implemented actions for elimination and participated in the action of removal of selected invasive plant species: Impatiens parviflora and Reynoutria japonica within specific areas. These actions led to a reduction in the area occupied by invasive plants and a weakening of their growth rate and ability to reproduce.