Harris Thomson C, Roach W Jean, Miller Erin M, Simard Suzanne W
Faculty of Forestry, Forest Sciences Centre, The University of British Columbia, Vancouver, British Columbia, Canada.
Glob Chang Biol. 2025 Jan;31(1):e70027. doi: 10.1111/gcb.70027.
The future climatic niche of interior Douglas-fir (Pseudotsuga menziesii var. glauca [Mirb.] Franco) is expected to have little spatial overlap with its current range due to climate change. The resulting misalignment of the climatic niche and species distribution is expected to result in many forests becoming maladapted in their current location, thus increasing vulnerability to disturbance and reducing productivity. This novel study examined the individual and interactive effects of climatic transfer distance and silviculture systems on planted 3-year-old Douglas-fir seedlings across the natural range of interior Douglas-fir in British Columbia. Several climatic transfer distance variables were considered, and the silviculture systems tested comprised the following gradients of tree retention: 0% retention (clearcut), 10% dispersed retention (seed-tree), 30% aggregate retention, and 60% aggregate retention with thinning from below. Using linear mixed effect models, we found that survival and height were positively correlated with movements of seedlings to warmer, wetter, and more humid climates. Moisture availability had a stronger influence than temperature, indicating that seedlings transferred to warmer but more arid climates would experience decreased survival and height. Where seedlings were transferred to climates with greater frost frequency or decreased humidity, greater retention of overstory trees improved survival and height. Conversely, movements to more favorable climatic conditions (warmer and wetter) resulted in improved survival and height where overstory retention was low. Our findings suggest that genetic reshuffling of populations through assisted migration could benefit from overstory retention where stressful climatic conditions due to aridity or increased frost frequency occur.
由于气候变化，内陆花旗松（Pseudotsuga menziesii var. glauca [Mirb.] Franco）未来的气候生态位预计与其当前分布范围几乎没有空间重叠。气候生态位与物种分布的这种错位预计将导致许多森林在其当前位置变得适应不良，从而增加对干扰的脆弱性并降低生产力。这项新研究考察了气候转移距离和造林系统对不列颠哥伦比亚省内陆花旗松自然分布范围内种植的3年生花旗松幼苗的个体和交互影响。考虑了几个气候转移距离变量，测试的造林系统包括以下树木保留梯度：0%保留（皆伐）、10%分散保留（母树）、30%聚集保留和60%聚集保留并进行下层疏伐。使用线性混合效应模型，我们发现存活率和树高与幼苗向更温暖、更湿润和更潮湿气候的迁移呈正相关。水分供应比温度的影响更强，这表明转移到更温暖但更干旱气候的幼苗存活率和树高会降低。当幼苗转移到霜冻频率更高或湿度降低的气候时，更多地保留上层树木可提高存活率和树高。相反，当上层保留率较低时，向更有利气候条件（更温暖和更湿润）的迁移会提高存活率和树高。我们的研究结果表明，在因干旱或霜冻频率增加而出现压力气候条件的地方，通过辅助迁移进行种群基因重组可能会受益于上层保留。
