Tree population responses to climatic extremes

背景日益严重的气候事件对森林生态系统产生重大影响。例如，2021年，加拿大西部发生了创纪录的高温干旱事件，导致树木大量死亡，并将影响长期的森林健康。与此同时，暖冬导致树木在春季过早生长，到秋季又过晚，增加了霜冻破坏的风险。然而，树种和种群科普极端条件的能力差异很大，而且由于强大的选择压力，往往受到高度遗传控制。调查对极端气候的遗传适应是预测森林反应和减轻影响的关键。我的研究项目的长期目标是发现和模拟加拿大西部森林中关键树种对极端气候的适应能力。为此，我将建立一支由2名博士生、2名硕士生和4名理学学士生组成的包容性和多元化团队，他们将有公平的培训和研究机会。在5年的时间里，这些HQP将测试广泛分布的针叶树，黑松的树木种群的遗传变异，并进一步研究两个标志性的，共同发生的沿海针叶树-西部红杉和道格拉斯冷杉的树木繁殖种群内的变异。我们将：1）量化生长对热干旱事件的反应的遗传控制; 2）建立与生理学的联系; 3）揭示物候变化背后的遗传结构; 4）创建特定于种群的气候生态位模型，将遗传适应极端气候的新知识纳入其中。这种跨学科的研究涉及跨部门的伙伴关系，提供HQP网络的机会。方法将新的树木表型鉴定方法与成熟的森林遗传学实验相结合。子代和种源试验可用于解码树木种群之间的遗传或遗传变异模式。为了回顾性地评估弹性和推断生理机制，我们将使用树木年轮，功能木材解剖和稳定同位素分析。为了在接近真实的时间内评估树木的反应，我们将从安装在无人机上的传感器的新组合中获得遥感数据，这些传感器以前从未应用于后代试验。这些代理数据将与树叶属性进行地面验证，并进一步与独立的树木年轮数据进行验证。由此产生的数据将指导利基建模。Impact森林遗传学项目为不列颠哥伦比亚省的植树计划提供了大部分材料，每年种植数百万棵树苗。通过与政府合作伙伴的合作，研究结果可以指导这些项目选择具有气候适应特性的树木。种植能够抵御极端气候的树苗将有助于新建立的森林保持长期健康和生产力，以支持一系列生态和经济价值。在该方案中对HQP进行培训将进一步提高应对气候变暖和极端气候影响的能力。

Background Increasingly severe climatic events significantly impact forest ecosystems. In 2021, for example, a record-breaking heat-drought event in western Canada led to significant tree mortality and will impact long-term forest health. At the same time, warmer winters cause trees to grow too early in spring and too late into the fall, increasing risk of frost damage. However, the capacity of tree species and populations to cope with extreme conditions varies widely and is often under high genetic control due to strong selective pressures. Investigating genetic adaptation to climatic extremes is key for predicting forest responses and mitigating impacts. Objectives & HQP The long-term objective of my research program is to discover and model the adaptive capacity of keystone tree species in Canada's western forests to climate extremes. To that end, I will build an inclusive and diverse team of 2 PhD, 2 MSc and 4 BSc students, who will have equitable access to training and research opportunities. Over 5 years, these HQP will test genetic variation across tree populations of a widespread conifer, lodgepole pine, and further examine variation within tree breeding populations for two iconic, co-occurring coastal conifers - western redcedar and Douglas-fir. We will: 1) Quantify genetic control of growth responses to heat-drought events; 2) establish links with physiology; 3) reveal genetic architecture behind changes in phenology; and 4) create population-specific climate niche models that incorporate this new knowledge of genetic adaptation to climatic extremes. This inter-disciplinary research involves partnerships across sectors, offering HQP networking opportunities. Methods New approaches to phenotyping trees will be combined with mature forest genetics experiments. Progeny and provenance trials can be used to decode patterns of inheritance or genetic variation across tree populations. To retrospectively assess resilience and to infer physiological mechanisms, we will use tree-rings, functional wood anatomy and stable isotope analyses. To assess tree responses in near real time, we will obtain remotely-sensed data from a novel assemblage of drone-mounted sensors, never before applied to progeny trials. These proxy data will be ground-truthed with foliar properties and further validated with independent tree-ring data. Resulting data will guide niche modeling. Impact Forest genetics programs supply the majority of material for tree planting initiatives in British Columbia, with millions of seedlings planted annually. By working with government partners, research results can guide these programs to select trees with climate-adaptive traits. Planting seedlings resilient to climate extremes will help newly established forests maintain long-term health and productivity to support a suite of ecological and economic values. Training of HQPs in this program will further increase capacity to address effects of climate warming and extremes.