Macrophyte distribution in the River Vils (Oberpfalz, Bavaria)

Abstract

The macrophyte vegetation of the eutrophic River Vils (Oberpfalz, Bavaria) was surveyed and mapped in summer 1999. Regarding carbonate content, the river is of medium to rather hard. The macrophyte diversity is relatively high. In the Vils 26 tracheophytic hydrophytes, 24 tracheophytic amphiphytes and 37 helophytic species were found. The picture is dominated by eutrophent elements like Potamogeton pectinatus, Ceratophyllum demensum, Sparganium emersum and others. Floristic specialities in the Vils are the hybrids Potamogeton x fluitans and Potamogeton x schreberi. The distribution diagram shows patterns for several species in the river course. According to changes in the floristic composition and river-morphological structures, the river could be divided into five reaches (A-E). These reaches were characterized regarding Relative Plant Mass (RPM) and species numbers as well as Mean Mass Index and Relative Range Length. The RPM values in combination with species numbers revealed important new aspects regarding biodiversity and the dominance of macrophyte species. Additionally the macrophyte distribution across the river was described by five transects.