Charalambos Neophytou1, Elisabeth Pötzelsberger1, Marcela van Loo1,2 and Hubert Hasenauer1
1Institute of Silviculture, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences (BOKU), Peter-Jordan-Str. 82, 1190 Vienna, Austria
2Department of Botany and Biodiversity Research, Faculty of Life Sciences, University of Vienna, Rennweg 14, 1030 Vienna, Austria
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Non-native tree species play an important role in European forestry. Here, we explore the origin and genetic variation in space and time, observed in introduced populations of such species. Our first study species is Douglas-fir (Pseudotsuga menziesii), which has a prominent position in Central European forestry. Results show that a relatively small part of the native range served as seed source for most ofh 67 genotyped Douglas-fir stands spread across Germany and Austria. Hence, this part of the native range includes provenances with superior performance in Europe. Despite a high genetic diversity among adult trees, we observed a significant reduction of genetic diversity in the natural regeneration which we attribute to a limited number of reproducing adult trees. In the case of the tree of heaven (Ailanthus altissima), our second study species, we observed signatures of repeated founder effects in Eastern Austria, an area of early introduction. Additionally, In spite of a single maternal lineage characterizing all ten study stands, we observed a significant genetic structure among the populations. Our results support that genetic drift led to genetic differentiation, given that the effective population size was locally very small. Third, we present current results on the origin and genetic variation of the Northern red oak (Quercus rubra) introduced to European populations. We conclude that genetic drift is a major factor shaping the genetic variation in the introduced range. Since introduced populations constitute an important seed source, special caution should be exercised when establishing seed stands and seed orchards, but also during seed harvesting, in order to avoid genetic erosion after species introduction.