Schnelle Ausbreitung des invasiven Neophyten Phedimus stoloniferus in der Schweiz

Horticultural trade is a principal pathway for unintentional and intentional introductions of non-native plants. Although the majority of plants imported for horticulture have proven non-invasive, several successful horticultural escapes are causing severe economic and environmental harm. In Switzerland, the two ornamental plant species Phedimus stoloniferus and Phedimus spurius escaped from gardens and are nowadays considered as invasive neophytes in grasslands. We recorded the size and populations of the two plant species in the region of the Emmental (canton Bern) and in the surroundings of Rickenbach (canton Schwyz) both in 2010 and 2012. The findings of the two surveys were compared with published data from 2008. In the Emmental, the number of populations with Ph. stoloniferus increased from 39 in 2008 to 80 in 2010 and 106 in 2012. Similarly, in Rickenbach the number of localities increased from 14 in 2008 to 25 in 2010 and 39 in 2012. In contrast, only three localities with Ph. spurium were detected in both regions. Processes and conditions which may explain differences in the distribution and spread of the two species are discussed.