title: Phenological Variation in Ambrosia artemisiifolia L. Facilitates Near Future Establishment at Northern Latitudes.
abstract: The invasive weed Ambrosia artemisiifolia (common ragweed) constitutes a great threat to public health and agriculture in large areas of the globe. Climate change, characterized by higher temperatures and prolonged vegetation periods, could increase the risk of establishment in northern Europe in the future. However, as the species is a short-day plant that requires long nights to induce bloom formation, it might still fail to produce mature seeds before the onset of winter in areas at northern latitudes characterized by short summer nights. To survey the genetic variation in flowering time and study the effect of latitudinal origin on this trait, a reciprocal common garden experiment, including eleven populations of A. artemisiifolia from Europe and North America, was conducted. The experiment was conducted both outside the range limit of the species, in Sweden and within its invaded range, in Croatia. Our main hypothesis was that the photoperiodic-thermal requirements of A. artemisiifolia constitute a barrier for reproduction at northern latitudes and, thus, halts the northern range shift despite expected climate change. Results revealed the presence of a north-south gradient in flowering time at both garden sites, indicating that certain European populations are pre-adapted to photoperiodic and thermal conditions at latitudes up to, at least, 60° N. This was confirmed by phenological recordings performed in a region close to the northern range limit, the north of Germany. Thus, we conclude that there exists a high risk for establishment and spread of A. artemisiifolia in FennoScandinavia in the near future. The range shift might occur independently of climate change, but would be accelerated by it.
authors.affiliation: Swedish University of Agricultural Sciences, Department of Crop Production Ecology, Uppsala, Sweden.
authors.forename: Romain
authors.initials: R
authors.lastname: Scalone
authors.affiliation: Technische Universität Berlin, Department of Ecology, Plant Ecology and Ecosystem Science, Berlin, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Lemke
authors.affiliation: University of Josip Juraj Strossmayer, Faculty of Agriculture, Osijek, Croatia.
authors.forename: Edita
authors.initials: E
authors.lastname: Štefanić
authors.affiliation: Swedish University of Agricultural Sciences, Department of Crop Production Ecology, Uppsala, Sweden.
authors.forename: Anna-Karin
authors.initials: AK
authors.lastname: Kolseth
authors.affiliation: University of Josip Juraj Strossmayer, Faculty of Agriculture, Osijek, Croatia.
authors.forename: Sanda
authors.initials: S
authors.lastname: Rašić
authors.affiliation: Swedish University of Agricultural Sciences, Department of Crop Production Ecology, Uppsala, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Andersson
mesh_terms: D000383:Agriculture; D031164:Ambrosia / Q000502:physiology*; D057231:Climate Change; D017753:Ecosystem; D005060:Europe; D005544:Forecasting; D010641:Phenotype; D017440:Photoperiod; D063148:Plant Dispersal / Q000502:physiology*; D057685:Plant Weeds / Q000502:physiology*; D012098:Reproduction / Q000502:physiology; D012621:Seasons; D012639:Seeds / Q000502:physiology*