Problem gatunków inwazyjnych i ekspansywnych w leśnych rezerwatach przyrody Wyżyny Śląsko-Krakowskiej

In the present article a problem of very abundant occurrence of plant species both of native and alien origin with a tendency to fast spread and consequences of this phenomenon was highlighted. The spread of species considered as invasive or expansive is a serious threat to biodiversity of natural plant communities, especially in protected areas e. g. nature reserves. The aim of this work is to qualify a roll of species, expanding their range with fast rate, in forest vegetation of 15 chosen nature reserves of the Silesian-Kraków Upland. In woodland phytocoenoses of the reserves of the Silesian-Kraków Upland 3 expansive and 11 invasive alien plant species were observed. Of native vascular plant the most frequent were: Carex brizoides, Calamagrostis epigeios and Rubus hirtus. Among aliens Impatients parviflora was recorded in all nature reserves expect one. Species which tend to colonize new areas and habitats are characterized by highly specialized mechanisms of growth and seed disperal. Also disturbed ecological balance of forest ecosystems due to various forms of certification of them encourages abundant expansive and invasive species occurrence. In future rate of expansion and invasion probably will intensify