Assessing intraspecific variation in frost tolerance of northern tree species: implications for assisted migration and climate change

评估北方树种抗冻性的种内变异：对辅助迁徙和气候变化的影响

• 批准号: RGPIN-2022-04093
• 负责人: Caspersen, John
• 金额: $ 2.4万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=743833
• 关键词: Assessing; intraspecific; variation; frost; tolerance

Ironically, assessing whether trees are frost tolerant is critical for helping managed forests adapt to global warming, because one of the most promising adaptation strategies, within-range assisted migration, relies on planting native species using seeds or seedlings that have been imported from warmer climates. This strategy not only assumes that southern transplants will be better adapted to rising temperatures than local trees, but also that they are tolerant of current conditions, particularly growing-season frost. While transplant experiments show that this is true of some species, it is not true of all the species that have been studied, and too few species have been studied to fully assess both the promise and risks of within-range assisted migration. Assessing the frost tolerance of naturally established trees is also critical because global warming will advance the onset of spring growth while also amplifying temperature swings, making trees more vulnerable to frost damage, regardless of whether they are transplants or not. Trees may be particularly vulnerable if they initiate growth at the very beginning of the growing season, as a necessary, but risky adaptation to short growing seasons near the northern limit of a species' range. However, it remains uncertain whether peripheral northern populations are generally more vulnerable to frost than lower-latitude populations, highlighting the need to study naturally established trees as well as transplants. Clearly, predicting and mitigating the impact of climate change requires a better understanding of how frost influences the growth and survival of trees. Toward this end, the proposed research will assess the frost tolerance of transplants and naturally established trees. The three main objectives of the research are: 1) to assess the survival, growth and frost tolerance of transplanted hardwoods, using new transplant experiments; 2) to assess the impact of frost on the long-term growth of a transplanted conifer, using an existing transplant experiment; 3) to assess the impact of frost on naturally established trees, using a national tree-ring database. The proposed research will be of broad interest to scientists studying climate change adaptation because it will test fundamental assumptions about assisted migration. The results will also be valuable to society at large, including natural resource managers and policy makers who need to know how climate change and assisted migration will impact forests. Finally, the results of the new transplant experiments will be of economic interest to the forest sector, whose silvicultural strategies must adjust to the impacts of global warming.

具有讽刺意味的是，评估树木是否抗冻对于帮助管理的森林适应全球变暖至关重要，因为最有希望的适应战略之一，范围内协助迁移，依赖于使用从温暖气候进口的种子或幼苗种植本地物种。这一策略不仅假设南方移植的树木比当地树木更能适应气温上升，而且还假设它们能耐受当前的条件，特别是生长季节的霜冻。虽然移植实验表明，这是真实的一些物种，这是不是所有的物种已经研究，太少的物种已经研究，以充分评估的承诺和风险的范围内协助迁移。 评估自然生长的树木的耐霜冻性也至关重要，因为全球变暖将提前春季生长的开始，同时也会放大温度波动，使树木更容易受到霜冻的损害，无论它们是否是移植的。如果树木在生长季节一开始就开始生长，这是一种必要的适应，但在靠近物种分布范围的北方界限的短生长季节，这种适应是有风险的。然而，它仍然不确定周边北方人口是否一般更容易受到霜冻比低纬度人口，突出需要研究自然建立的树木以及移植。显然，预测和减轻气候变化的影响需要更好地了解霜冻如何影响树木的生长和生存。为此，拟议的研究将评估移植和自然建立的树木的抗冻性。该研究的三个主要目标是：1）使用新的移植实验评估移植硬木的生存，生长和抗冻性; 2）使用现有的移植实验评估霜冻对移植针叶树长期生长的影响; 3）使用国家树木年轮数据库评估霜冻对自然建立的树木的影响。这项拟议的研究将对研究气候变化适应的科学家产生广泛的兴趣，因为它将测试有关协助移民的基本假设。研究结果对整个社会也很有价值，包括自然资源管理人员和决策者，他们需要了解气候变化和协助移徙将如何影响森林。最后，新移植试验的结果将对林业部门产生经济利益，因为林业部门的造林战略必须适应全球变暖的影响。