Abundance of Coleanthus subtilis in relation to nutrient concentrations in pond soils - A case study of localities in Poland

- Habitat conditions were characterized by measurement of environmental variables instead use of Ellenberg Indicator Values.
- Biomass of C. subtilis was higher on soils rich in N, K, Mg and Na yet poor in P.
- Pond soils rich in nutrients also favoured the abundance of C. subtilis.
- Coleanthus subtilis can cope with relatively wide range of pH values and nutrient concentrations.
- Study revealed that C. subtilis tolerates relatively high concentrations of Ca.

Coleanthus subtilis is a rare ephemeral plant species that grows on exposed river banks or pond bottoms. Its natural European localities are considered to be historical ones; however, new localities in man-made habitats have been increasingly reported. Although C. subtilis is protected under international agreements, little is known about the influence of soil chemistry on this species, thus we ask the following questions: i) what is the range of basic soil chemistry parameters for sites colonised by C. subtilis in Poland; ii) how does the soil chemistry influence population density and biomass production of the species; and iii) what is the influence of the soil chemistry on the species composition of plant communities with C. subtilis. We analysed the chemistry of the bottom sediments (pH and concentrations of N, P, K, Ca, Mg, Na, Mn, Fe, Cd, Co, Cr, Cu, Ni and Pb) of 11 fishponds; population density and biomass production were analysed on 47 plots, from which the species composition was determined on 24 samples. The chemistry of the bottom sediments significantly influenced the population density and biomass production of C. subtilis. It was restricted to acidic and neutral substrates and preferred soils rich in N, K, Ca, Mg and Na but poor in P. In such habitats higher biomass production was obtained by C. subtilis, but none of the factors significantly influenced the species composition in its communities.