INFLUENCE OF IRON AND MANGANESE CONTENTS IN GROUND WATER OUTFLOWS ON VEGETATION DIVERSITY IN SPRING ECOSYSTEMS OF THE MIDDLE POMERANIA

摘要

Floristic, phytosociological and hydrochemical investigations were performed in 16 spring complexes of the Pomeranian rivers (northern Poland) in years 2006-2007. The aim of the study was to reveal the level of iron and manganese ion concentrations in ground water outflows and to assess their influence on vegetation diversity. Spring waters contained low concentrations of Fe and Mn. Iron content in 73 cases was below 1 mg dm~(-3). In 26 cases it exceeded 1 mg dm~(-3) and ranged from 1.007 to 9.540 mg dm~(-3). The average iron content amounted to 1.262 mg dm~(-3). The concentration of Mn in 59 cases was lower than 0.1 mg dm~(-3). Higher manganese content was observed at 34 sites and it ranged from 0.104 do 0.954 mg dm~(-3). In 7 cases the obtained Mn concentration exceeded 1 mg dm~(-3) (1.131 -5.150 mg dm~(-3)). The average manganese content was at the level of 0.302 mg dm~(-3). On the basis of 100 phytosociological pictures we distinguished 8 spring communities of Mon-tio-Cardaminetea class, 2 spring moss communities of Fon-tinaletea antipyreticae class and 5 flowing-waters phyto-coenoses of Phragmitetea class. The observed vegetation contained 89 plants species, including 66 vascular plants, 14 moss species and 6 hepatic species. Redundancy analysis (RDA) revealed, that Glyceria nemoralis and Carex remota tolerated high concentrations of iron and manganese. Brachythecium rivulare preferred lower, but also relatively high Fe and Mn contents. Agrostis stolonifera turned out to prefer higher concentration of iron than manganese, opposite to Palustriella commutata. Hepatic species Pel-lia endiviifolia was abundant at low contents of the analysed ions. Relatively low Fe and Mn concentrations were preferred by Cardamine amara and Cratoneuron filicinum. RDA analysis of plant communities indicated that Glyc-erietum nemoralis-plicatae and Agrostis stolonifera occurred under high contents of iron and manganese. Relatively high Fe concentration favoured communities Carda-mino-Beruletum erecti and Porella platyphylla. In turn, communities Pellia endiviifolia and Palustriella commutata were abundant at low contents of the studied ions. The remaining plant species and communities preferred moderate levels of Fe and Mn concentrations.