Echinocystis lobata on Berounka riverbanks

The Berounka River flows from Plzeň to Prague in W and C Bohemia and has a total length of 138.7 km. Occurrence of the invasive annual species Echinocystis lobata was repeatedly investigated along the entire river. Number of its localities (half-kilometre long sections) and length of its stands were recorded. In 1982, the species was not yet registered at all. In 1992, a single locality appeared near Plzeň and E. lobata has been spreading since then. In 2002, it occurred at 189 of a total of 278 investigated sections of the river. An extreme summer flood mid August 2002 caused a moderate decrease in number of localities to 155, which was followed by an increase again. Three years after the flood (in 2005) the number of localities was 195. A less extreme flood in early June 2013 destroyed young plants and caused reduction of the number of localities to 97.