The southern Baltic region spans a significant part of the European continent with its forests under significant pressure due to climate changes. The implications of these changes are crucial for both native and non-native tree species. Under future climate scenarios, most native conifer populations might lose their climatic optima in the region. In contrast, for non-native Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), climatic conditions are expected to become optimal in the Baltic Sea region. Therefore, understanding the acclimatisation trajectory of Douglas-fir over the last century is essential to assess its potential to supplement retreating species and reduce pressure on local habitats. To study the region-wide acclimatisation in the secondary distribution, we established a network of 27 Douglas-fir tree-ring chronologies along the south Baltic Sea. We determined the spatio-temporal stability of the climate signal in tree rings and the potential coastal effect on the plasticity of the growth response. We found a region-wide trend of climate-growth relationships, with a dominant effect of the early-growth season temperatures being more pronounced for mature than young stands. Sites with higher mean annual temperatures exhibit a stronger positive temperature–growth correlation, demonstrating the sensitivity of Douglas-fir to climate warming. Douglas-fir could serve as a more heat-tolerant alternative to the declining European species of the Pinaceae family and contribute to the preservation of functionally comparable coniferous forest communities. However, forest practitioners should be aware that Douglas-fir may alter habitat conditions affecting microclimate and influencing species diversity.

中文翻译：

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波罗的海南部地区花旗松 （Pseudotsuga menziesii） 气候生长响应时空稳定性的温度驱动变化

波罗的海南部地区横跨欧洲大陆的很大一部分，由于气候变化，其森林承受着巨大的压力。这些变化的影响对本地和非本地树种都至关重要。在未来的气候情景下，大多数本地针叶树种群可能会失去该地区的最佳气候条件。相比之下，对于非本地花旗松 （Pseudotsuga menziesii （Mirb.）Franco） 的气候条件预计将在波罗的海地区变得最佳。因此，了解花旗松在上个世纪的适应轨迹对于评估其补充退缩物种和减轻对当地栖息地压力的潜力至关重要。为了研究次生分布中的区域范围的适应情况，我们建立了一个由波罗的海南部沿线的 27 个花旗松年轮年表组成的网络。我们确定了树木年轮中气候信号的时空稳定性以及沿海对生长响应可塑性的潜在沿海影响。我们发现了气候-生长关系的区域范围趋势，其中早期生长季节温度对成熟林分的影响比对年轻林分更明显。年平均温度较高的地点表现出更强的正温度-生长相关性，证明了花旗松对气候变暖的敏感性。花旗松可以作为松科植物科不断下降的欧洲物种的更耐热的替代品，并有助于保护功能相当的针叶林群落。然而，森林从业者应该意识到，花旗松可能会改变栖息地条件，影响小气候并影响物种多样性。