Nitrogen, Phosphorus, and Potassium resorption efficiency and proficiency of four emergent macrophytes from nutrient-rich wetlands

This study examined the nutrient dynamics of nitrogen (N), phosphorus (P), and potassium (K) resorption from senescing leaves in four hydrophytes. Differences in N, P, and K concentrations of green leaves during the vegetation season were studied to test the influence of plant strategy on nutrient resorption efficiency. Live leaves were tagged at defined canopy heights and collected in the period from March to August. Senescent leaves were collected in September. All tissue samples were analyzed for N, P, and K concentrations. Significant differences in N resorption and N utilization among the four macrophytes were observed. Particularly high values of N concentrations were detected in Phragmites australis in comparison with other species. However, these differences were not observed with respect to P and K resorption efficiencies and proficiencies. Nitrogen and phosphorus resorption efficiency was lowest in Glyceria maxima (22.0%) and highest in Phragmites australis (49.9%), indicating that minor proportions of these nutrients were translocated to the rhizomes during senescence. The analyses of changes in nutrient concentrations in green leaves during the vegetation season suggest that wetland species with different nutrient strategy uptakes can show similar final nutrient concentrations in plant tissue. In the present study, macrophytes were characterized by high leaf N concentrations, higher litter N concentrations, and lower values of NRE, which documents the high productivity of these plants and their importance in primary production in wetlands.