STRATEGIES OF NITROGEN CYCLING OF PHRAGMITES-AUSTRALIS AT 2 SITES DIFFERING IN NUTRIENT AVAILABILITY

Below-ground biomass and nitrogen content were determined at two genet ically homogenous Phragmites stands differing in morphology, in produc tivity, and in nutrient supply. Comparable ration between above-ground standing crop and rhizome biomass were found at both sites, whereas t he root biomass/above standing crop ratio was significantly higher at the nutrient poor site. Investigations on the dynamics of nitrogen con tent revealed distinct differences in nitrogen translocation to the rh izomes between the investigated clones indicating two ecophysiological strategies in shortage behaviour. These two strategies could be attac hed to the ''assimilation type'' and to the ''translocation type'', re spectively. A modified definition of both types is presented.