Catalogue and evaluation of aquatic plants in estany de Sils (La Selva, Catalonia)

Abstract

Since the beginning of the eighteenth century, botanists in the southwest of Europe have recognized Estany de Sils (La Selva, Catalonia) as having a unique plant population, especially with regard to aquatic plants. Despite the lake being definitively drained in 1851, there is still today a fairly diverse aquatic flora in the remaining marshes and seasonal ponds. In this work, we present the catalogue of the flora of the aquatic plants in this Mediterranean wetland, compiled from field trips and from consultation of various herbaria and botanical works. Thus, according to our data, in the last 300 years, 37 aquatic plants have populated the lake, 12 of which are currently thought to have become locally extinct (although the presence of three of them is in doubt). The plants that have disappeared include Trapa natans, Marsilea quadrifolia, Najas minor and Rorippa amphibia. In addition, using the catalogue of flora, and following the criteria proposed by researchers of the Real Jardín Botánico de Madrid, we have carried out a botanical evaluation of Estany de Sils as a wetland area (I_H index). Its botanical value has been found to be very high (an I_H of 7.0 in 1850 compared to an I_H of 6.9 in 2014) and the lake can still be considered a wetland of European importance nowadays. It must be noted, that the 30.6% and the 19.4% of the vascular aquatic plants existing in Catalan Countries and Spain, respectively, have been observed in the study area.