Swiss Federal Research Institute for Forest, Snow and Landscape Research (WSL), Zürcherstrasse 111, 8903, Birmensdorf, Switzerland,
Oecologia. 2013 Dec;173(4):1587-600. doi: 10.1007/s00442-013-2696-6. Epub 2013 Jun 15.
Environment and genetics combine to influence tree growth and should therefore be jointly considered when evaluating forest responses in a warming climate. Here, we combine dendroclimatology and population genetic approaches with the aim of attributing climatic influences on growth of European larch (Larix decidua) and Norway spruce (Picea abies). Increment cores and genomic DNA samples were collected from populations along a ~900-m elevational transect where the air temperature gradient encompasses a ~4 °C temperature difference. We found that low genetic differentiation among populations indicates gene flow is high, suggesting that migration rate is high enough to counteract the selective pressures of local environmental variation. We observed lower growth rates towards higher elevations and a transition from negative to positive correlations with growing season temperature upward along the elevational transect. With increasing elevation there was also a clear increase in the explained variance of growth due to summer temperatures. Comparisons between climate sensitivity patterns observed along this elevational transect with those from Larix and Picea sites distributed across the Alps reveal good agreement, and suggest that tree-ring width (TRW) variations are more climate-driven than genetics-driven at regional and larger scales. We conclude that elevational transects are an extremely valuable platform for understanding climatic-driven changes over time and can be especially powerful when working within an assessed genetic framework.
环境和遗传因素共同影响树木的生长，因此在评估气候变暖对森林的影响时，应将两者结合起来考虑。在这里，我们结合树木年代学和种群遗传学方法，旨在确定气候对欧洲落叶松（Larix decidua）和挪威云杉（Picea abies）生长的影响。我们从海拔约 900 米的海拔梯度上的种群中采集了增量芯和基因组 DNA 样本，该梯度的空气温度梯度涵盖了约 4°C 的温差。我们发现，种群之间的低遗传分化表明基因流动很高，这表明迁移率足够高，可以抵消局部环境变化的选择压力。我们观察到，随着海拔的升高，生长速度会降低，并且沿着海拔梯度，生长季节温度与生长之间的相关性从负相关转变为正相关。随着海拔的升高，由于夏季温度而导致生长的解释方差明显增加。沿着这条海拔梯度观察到的气候敏感性模式与分布在阿尔卑斯山脉的落叶松和云杉地点的模式进行比较，结果表明，在区域和更大范围内，树木年轮宽度（TRW）的变化更多是由气候驱动的，而不是由遗传驱动的。我们得出结论，海拔梯度是一个非常有价值的平台，可以随着时间的推移了解气候驱动的变化，并且在评估遗传框架内工作时特别有效。
