The introduction of the aquatic carnivorous plant Aldrovanda vesiculosa to new potential sites in the Czech Republic:: A five-year investigation

Five microsites in shallow dystrophic waters were selected for the introduction of a critically endangered aquatic carnivorous plant Aldrovanda vesiculosa in the Trebon region in S Bohemia, the Czech Republic. The selected sites were fen pools close to two hypertrophic fishponds, Ptaci blato (four microsites) and Domaninsky tone microsite). In June 1995, 30 plants from an allochthonous population in E Poland were introduced in each of the microsites. Water chemistry and plant growth dynamics were investigated at the microsites throughout the 1995-1996 seasons, and the maximum size of the subpopulations were estimated during the 1997-1999 seasons. The selected waters may be characterized as oligo-mesotrophic. The warm and dry 1995 season resulted in a low water level (ca. 10 cm below average) and plant propagation was poor at all but one microsite. However, the rainy and colder 1996 season resulted in a high water level, and thus rapid plant propagation occurred at all four microsites at the Ptaci blato fishpond and between 841 and 2669 turions were formed. Here, the doubling time of the apices was between 13.5-19.3 days in the summer. At the Domaninsky fishpond, however, the growth was relatively poor in 1996. The overwintering rate of turions (19-100%) was found as being high enough to keep the introduced plant populations stable. At each of the four microsites at Ptaci blato, the maximum numbers of shoot apices were estimated to be between 1,000-20,000 in the 1997-1999 seasons. Depth of free water appears to be the crucial factor for the rapid growth of Aldrovanda at some selected sites; water depth below 5 cm is unfavourable. Overall, Aldrovanda was successfully established in an intensively agricultural landscape in the Trebon region.