Zacharias Melanie, Pampuch Timo, Heer Katrin, Avanzi Camilla, Würth David G, Trouillier Mario, Bog Manuela, Wilmking Martin, Schnittler Martin
Institute of Botany und Landscape Ecology, University of Greifswald, Soldmannstr. 15, 17487 Greifswald, Germany.
Conservation Biology, University of Marburg, Karl-von-Frisch-Strasse 8, 35043 Marburg, Germany.
Sci Total Environ. 2021 Dec 1;798:149267. doi: 10.1016/j.scitotenv.2021.149267. Epub 2021 Jul 26.
Knowledge on the adaptation of trees to rapid environmental changes is essential to preserve forests and their ecosystem services under climate change. Treeline populations are particularly suitable for studying adaptation processes in trees, as environmental stress together with reduced gene flow can enhance local adaptation. We investigated white spruce (Picea glauca) populations in Alaska on one moisture-limited and two cold-limited treeline sites with a paired plot design of one forest and one treeline population each, resulting in six plots. Additionally, one forest plot in the middle of the distribution range complements the study design. We combined spatial, climatic and dendrochronological data with neutral genetic marker of 2203 trees to investigate population genetic structure and drivers of tree growth. We used several individual-based approaches including random slope mixed-effects models to test the influence of genetic similarity and microenvironment on growth performance. A high degree of genetic diversity was found within each of the seven plots associated with high rates of gene flow. We discovered a low genetic differentiation between the three sites which was better explained by geographic distances than by environmental differences, indicating genetic drift as the main driver of population differentiation. Our findings indicated that microenvironmental features had an overall larger influence on growth performances than genetic similarity among individuals. The effects of climate on growth differed between sites but were smaller than the effect of tree size. Overall, our results suggest that the high genetic diversity of white spruce may result in a wider range of phenotypes which enhances the efficiency of selection when the species is facing rapid climatic changes. In addition, the large intra-individual variability in growth responses may indicate the high phenotypic plasticity of white spruce which can buffer short-term environmental changes and, thus, allow enduring the present changing climate conditions.
了解树木如何适应快速的环境变化对于在气候变化背景下保护森林及其生态系统服务至关重要。林线种群特别适合用于研究树木的适应过程，因为环境压力与基因流减少相结合可以增强局部适应性。我们在阿拉斯加的一个水分受限和两个寒冷受限的林线地点对白云杉（Picea glauca）种群进行了调查，采用配对样地设计，每个地点设置一个森林种群和一个林线种群，共六个样地。此外，在分布范围中部的一个森林样地补充了研究设计。我们将空间、气候和树木年代学数据与2203棵树的中性遗传标记相结合，以研究种群遗传结构和树木生长的驱动因素。我们使用了几种基于个体的方法，包括随机斜率混合效应模型，来测试遗传相似性和微环境对生长性能的影响。在与高基因流率相关的七个样地中，每个样地都发现了高度的遗传多样性。我们发现三个地点之间的遗传分化较低，用地理距离比用环境差异能更好地解释这种分化，这表明遗传漂变是种群分化的主要驱动因素。我们的研究结果表明，微环境特征对生长性能的总体影响大于个体间的遗传相似性。气候对生长的影响在不同地点有所不同，但小于树木大小的影响。总体而言，我们的结果表明，白云杉的高遗传多样性可能导致更广泛的表型范围，这在物种面临快速气候变化时提高了选择效率。此外，个体生长反应的巨大变异性可能表明白云杉具有高表型可塑性，能够缓冲短期环境变化，从而使其能够承受当前不断变化的气候条件。
