The Effect of Drainage and Management on Peat Chemistry and Nutrient Deficiency in the Former Jegrznia-Floodplain (Ne-Poland)

The Jegrznia floodplain has been deprived of flooding since the late 19th century. Human influence has been limited to haymaking and cattle grazing without land reclamation. Therefore, the present vegetation reflects the impact of hydrological changes, without being much disturbed by changes in other factors. A drainage gradient on the former floodplain was examined for nutrient deficiencies and compared with an intact floodplain. For this purpose we analyzed nutrient concentrations in above ground biomass, we measured redox potentials and peat variables for a rich fen vegetation, a well-developed fen meadow as well as an impoverished fen meadow vegetation. According to P:N-ratios in above ground biomass, all vegetation types appear to be limited by phosphorus, whereas the impoverished fen meadow is also limited by potassium. These results are supported by the chemical composition of the peat, redox characteristics and the physical changes in the peat induced by drainage. It is concluded that hydrological changes in combination with an annual mowing regime resulted in a shift from no nutrient limitation to P- and/or K-limitation in the former Jegrznia floodplain. Changes in hydrology at Jegrznia stopped the input of nutrients, increased the leaching of K and turned P into unavailable Al and Fe-complexes. Continued mowing increased P- and K-deficiency.