Re-establishment of an extinct population of the endangered aquatic plant Potamogeton coloratus

• Potamogeton coloratus is a critically endangered plant of calcareous waters.
• It has vanished in large regions of its range.
• A local soil seed bank was used for its restoration in the Czech Republic.
• Two populations were re-established more than 30 years after its extirpation.
• Restored pools have also been populated by other endangered macrophyte species.

Persistent soil seed banks play a key role in preventing extirpation of plants during periods of temporarily unsuitable conditions. They can serve as effective tools in achieving the goal of restoring wetland vegetation. Potamogeton coloratus, an aquatic plant of shallow, calcareous waters, has become critically endangered or vanished in large regions of its mainly European range. In the Czech Republic, it was observed in 1977 for the last time (prior to our restoration project) and has been classified as an extinct species. We successfully re-established one population of it, and also established a new one, both located in a fen complex from which it has been absent for more than 30 years. One population was restored in a desilted pool in which the species had occurred previously; the other was established in a newly created pool by means of transferring soil, including the seed bank, from a pool in which the species formerly occurred. Monitoring of these sites over subsequent years confirmed establishment and increase of the populations. Along with the target species, other rare, native aquatic plants (e.g. Utricularia vulgaris and Chara hispida) were found growing in the newly created pool. Propagules of these species were also detected in the sediment collected in the old pool prior the desilting and subjected to soil seed bank analysis. Although altogether 26 plant species were identified in the soil seed bank, no propagules of P. coloratus were detected, most likely due to their small number in the sediment analyzed.