Abundant rainfall, which occurred in Europe in 1997, caused many flash floods. They made considerable devastation particularly in the montane and submontane regions. Valleys of bigger streams, as well as steep, easily eroding slopes underwent the biggest changes. In the Babiogorski National Park, on northern slopes of Babia Gora Mt. (the Western Carpathians, the High Beskid) numerous new initial habitats (slump and gravel heaps) appeared in the stream valleys. Before the flood, the dominant types of the alluvial vegetation were Petasitetum kablikiani and phytocoenoses of alder trees - Alnetum incanae variant with Petasiles kablikianus. Therefore the extensive populations of butterbur (P kablikianus) had the significant importance in plant consolidation of the riverbed. As the effect of geomorphological water action underwent three types of gravel heaps. The object of this study is the investigation the processes and dynamics of overgrowing with plants of recent alluvial habitats, and especially the role of Petasites kablikianus in forming new plant cover. In the Babiogorski National Park, in the Rybny stream valley, where plant cover of the alluvia was extremely natural, there were established three permanent plots on three types of habitats. Each year there are performed observations in the squares (20x20 cm). Floral composition, percentage cover of the species and its life form arc stated for each square. After two years of observations pioneer species, the most abundant species, their frequency on analysed plots and three strategies of territorial occupancy for Petasites kablikianus were ascertained.