Strategies of nitrogen cycling of Phragmites australis at two sites differing in nutrient availability

Below-ground biomass and nitrogen content were determined at two genetically homogenous Phragmites stands differing in morphology, in productivity, and in nutrient supply. Comparable ration between above-ground standing crop and rhizome biomass were found at both sites, whereas the root biomass/above standing crop ratio was significantly higher at the nutrient poor site. Investigations on the dynamics of nitrogen content revealed distinct differences in nitrogen translocation to the rhizomes between the investigated clones indicating two ecophysiological strategies in shortage behaviour. These two strategies could be attached to the ''assimilation type'' and to the ''translocation type'', respectively. A modified definition of both types is presented.