The study was conducted in the wetland ecosystems in the Biebrza Valley, on peat soils with a varying degree of peat mineralization. The aim of this work was to assess differences between the content of elements in wetland plants and the effect of these differences on the plant elemental stoichiometry. The content of particular elements in a mass unit and the sum of the content of elements in the unit, i.e. in the biological yield, correspond with the nutrient demand of the plants. The content of N, P, K, Ca, Mg, Na and S in mg kg-1 d.w. was determined in aerial parts of various plant species (including leaves of shrubs), and the sum was calculated of all the concentrations of elements in mmol(+) kg-1. The inter-elemental relationships were determined as: (i) an element: element ratio for each element, in (mmol(+) kg-1), and (ii) the percent contribution of each element to the sum of elements. The values of nutrient demand for the species examined varied from about 1000 mmol(+) kg-1 d.w., to more than 6000 mmol(+) kg-1 d.w. Based on significant differences in the values of the sums of element, the species analyzed were split into five groups: up to 2300 mmol(+) kg-1, 2301-3500 mmol(+) kg-1, 3501-4500 mmol(+) kg-1, 4501-6000 mmol(+) kg-1 and above 6000 mmol(+) kg-1,, respectively. Meanwhile, the stoichiometry presented in the form of either an element: element ratio or the percent contribution of each element to the sum of elements did not differ significantly between plants with various nutrient demands.  

23.3.2018