The most common tool to predict future changes in species range are species distribution models. These models do, however, often underestimate potential future habitat, as they do not account for phenotypic plasticity and local adaptation, although being the most important processes in the response of tree populations to rapid climate change. Here, we quantify the difference in the predictions of future range for Norway spruce, by (i) deriving a classic, occurrence-based species distribution model (OccurrenceSDM), and (ii) analysing the variation in juvenile tree height and translating this to species occurrence (TraitSDM). Making use of 32 site locations of the most comprehensive European trial series that includes 1,100 provenances of Norway spruce originating from its natural and further beyond from its largely extended, artificial distribution, we fit a universal response function to quantify growth as a function of site and provenance climate. Both the OccurrenceSDM and TraitSDM show a substantial retreat towards the northern latitudes and higher elevations (−55 and −43%, respectively, by the 2080s). However, thanks to the species’ particularly high phenotypic plasticity in juvenile height growth, the decline is delayed. The TraitSDM identifies increasing summer heat paired with decreasing water availability as the main climatic variable that restricts growth, while a prolonged frost-free period enables a longer period of active growth and therefore increasing growth potential within the restricted, remaining area. Clear signals of local adaptation to climatic clines spanning the entire range are barely detectable, as they are disguised by a latitudinal cline. This cline strongly reflects population differentiation for the Baltic domain, but fails to capture the high phenotypic variation associated to the geographic heterogeneity in the Central European mountain ranges paired with the species history of postglacial migration. Still the model is used to provide recommendations of optimal provenance choice for future climate conditions. In essence, assisted migration may not decrease the predicted range decline of Norway spruce, but may help to capitalize on potential opportunities for increased growth associated with warmer climates.

In Mitteleuropa werden zukünftig häufigere Trocken- und Hitzeperioden mit wirtschaftlichen Einbußen in der Waldwirtschaft erwartet. Die Douglasie (Pseudotsuga menziesii (Mirb.) Franco) wird als Alternative für die wirtschaftlich bedeutsame, jedoch trockenheitsempfindliche Fichte diskutiert (Picea abies (L.) H.Karst.). Zwei Unterarten, die Küsten- (FDC) und die Inlandsdouglasie (FDI), sind im ausgedehnten natürlichen Verbreitungsgebiet in Nordamerika beheimatet, welches ein großes Potenzial für die Auswahl produktiver und trockenresistenter Herkünfte bietet. Unser Ziel war, die Trockenreaktion verschiedener Douglasienherkünfte unter Verknüpfung morphologischer und physiologischer Parameter und die der Trockenheitsresistenz bzw. -empfindlichkeit zugrundeliegenden Mechanismen zu erforschen. Ein Herkunftsversuch in Südwestdeutschland ermöglichte die Untersuchung 50-jähriger Douglasien verschiedener Herkünfte entlang eines Höhengradienten. Unter kontrollierten Bedingungen simulierten wir die Effekte einer Hitzewelle auf Jungbäume zweier Provenienzen. Wir analysierten die Kohlenstoff- und Sauerstoff-Stabilisotopenzusammensetzung, den Gaswechsel der Blätter, Veränderungen im Stoffwechsel und das Baumwachstum. Unsere Ergebnisse zeigen bei FDC aus humiden Regionen hohe Wachstumseinbußen unter Trockenheit und moderat bis stark verringerte stomatäre Leitfähigkeit, unterstützt durch Photoprotektion. FDC aus Regionen mit starker Sommertrockenheit reagierten kaum mit Stomataschluss und Wachstumseinbußen auf Trockenheit, jedoch mit starker Osmoregulation und Monoterpen-Emissionen, welche zur Trockenresistenz beitragen könnten. FDI aus einer ariden Region zeigten hohe An, geringes Wachstum und stark antioxidative und photoprotektive Mechanismen. Die Herkünfte unterscheiden sich stark in ihrer Trockenreaktion und ihren Schutzmechanismen. Der Anbau trockenresistenter Herkünfte wird an Standorten von Vorteil sein, für die eine Häufung von ariden Sommerperioden vorhergesagt wird. / In Central Europe, more frequent periods of dry and hot weather are expected in the future with economic losses in the forestry sector. Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) is discussed as a timber species alternative to the economically important but drought-sensitive spruce (Picea abies (L.) H. Karst.). Two subspecies, the coastal (FDC) and the interior Douglas-fir (FDI), are native to an extensive natural range in North America, offering a great potential for the selection of productive and drought tolerant provenances. Our goal was to investigate the drought response of different Douglas-fir provenances on the morphological and physiological level, as well as the mechanisms underlying drought resistance or susceptibility. A provenance trial in southwestern Germany established in 1958 allowed the study of 50-year-old Douglas-fir trees of diverse provenances along a height gradient. Under controlled conditions, we simulated the effects of a heat wave on young trees of two provenances. We analyzed carbon and oxygen stable isotopic composition, leaf gas exchange, changes in metabolism and tree growth. FDC from humid regions responded to drought with strong growth decline and a medium to strong stomatal closure, supported by enhanced instantaneous photoprotection. FDC from regions with very dry summer conditions showed a small growth decline and anisohydric regulation of stomatal conductance under drought, supported by high levels of osmotic adjustment. High monoterpene emissions might contribute to the drought resistance. FDI from an arid region showed high assimilation rates, low growth potential and a high antioxidant, photoprotective, drought and heat protective potential. The provenances differ greatly in their dry reaction and their protective mechanisms. The cultivation of drought resistant crops will be beneficial at sites predicted to accumulate arid summer periods.