The local production of seeds within Germany has the advantage that potential previous local adaptation is transferred to the next generation. In recent times, nearly all Douglas fir seed traded and planted in Germany is produced in domestic approved seed stands and seed orchards (Anonymous 2021). Most of the Douglas fir growing in Germany belongs to the coastal “green” variety, which performed better in European provenance field tests (Kleinschmit and Bastien 1992 Spellmann et al. Today, Douglas fir covers about 2% of the German forest areas and therefore represents the most frequent non-native forest tree species in Germany (Riedel et al. In Germany, Douglas fir is seen as valuable for future cultivation since it represents a high-performing species with good adaptive potential to future climatic conditions and can be integrated into local ecosystems (Spellmann et al. A third intermediate variety the so-called “grey” or Fraser River Douglas fir, has been described but is not commonly accepted (Kleinschmit and Bastien 1992 Spellmann et al. Two different varieties of Douglas fir have been described, the coastal-so-called “green”- variety growing on the North American Pacific Coast, and the inland-so-called “blue”- variety (Lavender and Hermann 2014). Conclusions on the establishment of future seed orchards and regarding areas requiring further research are drawn at the end of the paper.ĭouglas fir ( Pseudotsuga menziesii Franco), a conifer native to western North America, was introduced to Europe about 190 years ago (Lavender and Hermann 2014). Larger numbers, however, might be needed to reliably conserve the entire genetic diversity over succeeding generations. Even with a relatively low number of 40 clones, seed orchard design with randomized and repeated planting of clones led to low selfing rates, and despite uneven parental contributions, the number of successful parents and the level of genetic intermixture were high enough to allow the transfer of an adequate part of the genetic diversity to the next generation. We detected low pollen contamination rates due to high levels of spatial isolation. Here we analyse the transfer of genetic diversity from parent to offspring generation in four older German seed orchards. Local seed production in seed stands and seed orchards may secure that local adaptation is transferred to the next generation, but small population sizes could lower genetic diversity and thus future adaptability. In Germany, Douglas fir ( Pseudotsuga menziesii Franco) is seen as a valuable species for future cultivation in times of climate change.
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