Macrophytes as bioindicators of the physicochemical characteristics of wetlands in lowland and mountain regions of the central Balkan Peninsula

Abstract The simultaneous monitoring of vegetation, water and sediments was conducted in wetlands of the central Balkan Peninsula due to the lack of available knowledge on the univariate response of macrophytes along environmental gradients. The environmental preferences and bioindicator potential of macrophytes were assessed using Huisman-Olff-Fresco (HOF) models. Bolboschoenus maritimus and Scirpus lacustris subsp. tabernaemontani are valuable bioindicators of slightly saline (electroconductivity of 2000–4000 μS cm −1 in the sediment) and alkaline habitats that are rich in SO 4 2− . Their ecological niches are partially overlapped. Bolboschoenus maritimus prefers saltier and more alkaline habitats for optimal development. The salinity and alkalinity of habitats are decisive factors in the ecological diversification of the Boloboschoenus species. Bolboschoenus glaucus is adapted to non-saline (400–900 μS cm −1 ) and slightly alkaline habitats, unlike Bolboschoenus maritimus . Relatively deep, slightly acid waters which are poor in SO 4 2− (0.30 mg/l), and sediments with low values of electroconductivity and K 2 O (6.8 mg/100 g sediment) are preferred by Typha angustifolia, Sparganium erectum and Typha latifolia . The abundance of Phalaris arundinacea , Scirpus lacustris , Carex riparia and Eleocharis palustris increases when there is a decrease in the amount of nutrients (NH 4 + , PO 4 3− and SO 4 2− ) in the water. Phragmites australis has low indicative value and regional bioindicator potential. The data obtained in the study may serve as a basis for adjusting the existing indicator values of these species and extending indicator systems by defining the indicator values of species with respect to environmental variables which have not yet been considered.