Changes in nutrient limitation of spring fen vegetation along environmental gradients in the West Carpathians

Question: How does nutrient limitation vary along major environmental gradients in fens and wet meadows? Location: West Carpathians ( Czech Republic, Slovakia). Methods: We recorded total plant species composition in 83 plots of 9 m(2). Living above-ground biomass of total vegetation was sampled. Concentrations of Ca, Fe, N, P, K were determined. Obtained data were analysed by various univariate and multivariate statistical techniques. Results: Major environmental gradients correspond to the poor-rich vegetation gradient, from poor Sphagnum-fens to calcareous fens, and the fen-meadow gradient from sedgemoss fens to forb-rich wet meadows. Ca-concentration in above-ground biomass was strongly positively correlated with the poor-rich gradient, while Fe- and N-concentrations had an opposite trend. Poor-fen vegetation contained little calcium and much iron. The lowest P-concentrations were found in calcareous tufa-forming fens. Variation in N: K ratio indicated a slight decrease of K-availability towards poor fens. Along the fen-meadow gradient, vegetation uptake of P, K and Ca increases and the uptake of Fe decreases. Conclusions: Our results suggest that variation in the type of nutrient limitation is not a dominant cause of the poor-rich gradient in fens due to the important role of calcium and iron. Nevertheless, species distribution along the poor-rich gradient is influenced by phosphorus shortage in tufa-forming fens and relatively high N-uptake and low K-availability in poor fens. Additional P- and K-supply to Ca-rich fens can alter species composition towards forb-rich meadows.