Spreading of alien plant species along tourist tracks in Karkonosze Mts.

Investigations of plants growing along rarely frequented paths in the region of Mumlawski Wierch (1219 m a.s.l.) and a busy tourist track leading onto Szrenica Mt. (1362 m a.s.l.) were performed. An analysis was made of a distance to which the species brought by tourists may invade spruce forest communities. It was found that number of non-indigenous species ( phytocenotically foreign to the natural forest communities of Karkonosze Mts.) depends primarily on intensity of tourist traffic. In the region of Mumlawski Wierch waysides were not colonised by the non-native species, whereas along the way to Szrenica Mt. a lot of alien species were recorder. These were mostly synanthropic species as well as species typical of meadows and grasslands, and all of them belonged exclusively to apophytes. Furthermore, it has been revealed that possibilities of those plants to grow along waysides; a distance of their penetration into communities of spruce forests depends on the degree of tree cover destruction.