Regional dynamics of Calamagrostis pseudophragmites on riverbanks in the NP Gesäuse inferred from AFLPs

Calamagrostis pseudophragmites (Poaceae) is a pioneer equestrian grass that grows on the banks of the Alpine rivers and is one of the endangered species in Austria due to the increasing river regulations and the increasing number of hydropower plants. The population of C. pseudophragmites in Gesäuse National Park was studied to assess the clonal structure and role of clonal migration along the Enns, as well as to determine the genetic structure, differentiation and mode of regional dynamics within the population. The present study suggests that sexual reproduction is predominant in the C. pseudophragmites population and that vegetative reproduction is important at the subpopulative level. The overall genetic differentiation between subpopulations is moderate, but both Haslau subpopulations are very different from other eastern subpopulations. Thus, there is a remarkable gene flow within the population mainly due to pollen flight. The distribution of seeds takes place between all population groups. The population of C. pseudophragmites in the Gesäuse provides evidence for metapopulation dynamics in terms of extinction and (re)population processes, especially in the few years since the Kammerer study (2003). As long as the regeneration of the population is possible and the population has not experienced major setbacks, no specific genetic threat to the survival of this species in Gesäuse is known. Further, constant monitoring and increased protection of the sensitive habitat of C. pseudophragmites is proposed.