Nutrient cycling in a natural stand of Typha angustifolia

We studied nutrient cycling within a natural monospecific stand of Typha angustifolia along the shoreline of Lake Teganuma, a shallow eutrophic lake northeast of Tokyo. Seasonal patterns of biomass and nutrient concentrations in the above- and belowground plant parts were observed over a period of two years, and nutrients released from the dead plants into the water environment were estimated at the end of the first year of the study. T. angustifolia shoots accumulated 46.7 g/m(2) N and 4.7 g/m(2) P in 2003 and 56.9 g/m(2) N and 5.9 g/m(2) p in 2004 during the growing season from April to December. At the end of the growing season, as nutrient production and accumulation slowed down, translocation of the nutrients and photoassimilate from leaves to rhizomes started. About 45-48% of the nitrogen and 37-45% of the phosphorus that had accumulated in the shoots were translocated to the rhizomes during the winter. After they died, the shoots released about 4.6 g/m(2) of nitrogen and 0.8 g/m(2) of phosphorus into the water.