Verbreitung und Bestandsdynamik von Ambrosia artemisiifolia in zwei Regionen in Baden-Wurttemberg und Einfluss der Vorkommen auf die Pollenkonzentration: Ergebnisse einer dreijahrigen Studie

摘要

Between 2006 and 2009 stands of common ragweed (Ambrosia artemisiifolia) were mapped in two areas in Baden-Wuerttemberg (Waghausel and Bad Waldsee Reute) and the species' pathways of introduction, spreading, and population dynamics were examined. At Waghausel the number of ragweed stands and individual plants were substantially higher than at Bad Waldsee-Reute. During the time of investigation new introductions mainly by bird seeds were registered at both study sites. While a weak spreading of ragweed was observed at Bad Waldsee-Reute in only one case, spreading was noticed at Waghausel in different places. In one case it was severe. Without intensified control measures a further spreading of the species is probable at Waghausel. In both areas relatively small amounts of ragweed pollen were measured. Despite the large distinction in population size, pollen concentrations were nearly similar in both study sites. Nevertheless pollen measurements at Waghausel in 2007 done by the German Meteorological Service resulted in different high pollen values depending on the size and the position of ragweed stands regarding the pollen trap, flight obstacles as well as the wind and precipitation conditions.