Differences in morphology and C/N-balance between clones ofPhragmites australis within a plantation at a degraded fen

The morphology, productivity and C/N-balance of 9 different clones ofPhragmites australis planted in 1997 in a degraded fen area of 40,000 m² was investigated in order to estimate the degree of variation between the genotypes. The planted reed clones showed significant differences in morphology, standing crop and stand structure at the same site. The above-ground biomass of some reed clones was due to high culms and large leaf areas, while among others it was due to high shoot densities and small culms. The productivity of the individual clones also differed. At the end of the 1998 growing season the standing crop of the clones ranged from about 700 to 2,000 g of dry matter per m². Differences were found in the C/N-dynamics as in the standing stock of total nitrogen in the above-ground biomass (ranging from 15 to 50 g N/m²) and the relative nitrogen content of the shoots. Furthermore, seasonal changes in the amount of free amino acids and carbohydrates in the basal internodes of the different clones were compared. The patterns are discussed with respect to the nutritional status of the reed plants. In conclusion, the results suggest high genotypic variation despite the comparable site conditions and thus a strong influence of genetically determined differences in growth and resource exploitation on the characteristics of reed clones.