Considerable area of riparian forests in the middle valley of the Warta River (nearby Radzewo village) was transformed to meadows and pastures. Some tree species, connected with those sites, i.e. black and white poplars, were cut off, died or are dying. The key conditions responsible for natural regeneration of this two species undergo rapid changes as a result of disturbances in flooding water flow related to establishment (in 1986) of retention reservoir in Jeziorsko and artificial draining of this area. The ecological niche, previously suitably for poplars is filled up by invasive North American species of Acer negundo (boxelder or ashleaf maple). The seeds of this maple were probably brought with floods from nearby places. Mass appearance of young generations of Acer negundo is a result of easy generative propagation of this species. The last living female trees of black poplar are now under threat and only protection ex situ of seeds (stored in traditional way or in liquid nitrogen) will make possible to regenerate this population in the future.

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