Collaborative Research: ORCC: Investigating drought and cold resistance of northeastern US trees to inform ecological modeling and forest management practices

美国东北部的气候趋势和预测包括仲夏干旱频率的增加。尽管森林管理者越来越重视气候适应和协助树木迁徙作为管理目标，但他们的努力受到信息差距的限制，因为干旱对东北部树木的影响以前并不是高度优先的研究重点。此外，树木对干旱的适应方式可能会影响它们对其他压力因素的脆弱性，如极端寒冷和春季霜冻破坏，这些因素将在未来几十年继续成为东北冬季的一部分。这项研究将提高对东北树种如何应对干旱的理解，以及不同的干旱适应能力如何影响它们对其他气候压力的脆弱性。这将通过对美国东北部的许多物种和地点条件进行与干旱有关的植物特性的广泛测量来实现，在阿拉巴马州的一个地点，该地点在目前范围的南端包含类似的物种。将使用一种新方法收集数据，这种方法大大增加了可处理的组织样本的数量。结果将被用来改进一个森林模拟模型，该模型可以帮助森林管理者评估不同管理战略的结果。这项工作将得到一个利益相关者咨询委员会的指导，该委员会由森林管理者、保护组织和其他投资于东北森林未来福祉的人组成。在美国东北部，气候预测包括仲夏干旱的频率增加，以及总体上更温暖的冬季，但周期性的北极空气输入可能导致晚春结冰和破坏性的寒冷压力。预测森林将如何反应的能力受到植物性状种间和种内变异的知识的限制，这些植物性状调节树木对气候胁迫的反应，以及它们反映环境或进化驱动因素的程度。这项研究通过以下方式解决这些不确定性：(1)深入研究膨胀度损失点的变化和驱动因素--树木水平干旱反应的关键决定因素--以及相关的抗寒和抗旱特性；(2)确定所研究个体的抗旱和抗寒之间的关系。这项工作将涉及对叶片渗透势和膨压损失点、相关生理植物性状和生根深度的广泛田间测量，以及对遗传相同个体的操纵实验。将在美国东北部和阿拉巴马州的一个地点进行采样，这些地点在它们活动范围的南端有类似的物种。这项工作将由一个由森林投资人员(例如森林管理者、保护团体和土著社区成员)组成的咨询委员会指导。结果将用于改进一种生态系统模型，该模型模拟一系列气候和森林管理情景下的森林生长。这将使一系列优先考虑气候适应能力和协助树木迁移的管理目标受益。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Climate trends and predictions in the northeastern U.S. include an increase in the frequency of mid-summer droughts. Although forest managers increasingly prioritize climate adaptation and assisted tree migration as management goals, their efforts are limited by information gaps because drought impacts on northeastern trees have not previously been a high research priority. Further, how trees adapt to drought may affect their vulnerability to other stressors such as extreme cold and spring frost damage, factors that will continue to be part of northeastern winters for decades to come. This research will improve understanding of how northeastern tree species respond to drought and how different drought adaptations affect their vulnerability to other climate stressors. This will be achieved by conducting extensive measurements of drought-related plant traits across many species and site conditions in the northeastern U.S. and at a site in Alabama that contains similar species at the southern end of their current range. Data will be collected using a novel method that greatly increases the number of tissue samples that can be processed. Results will be used to improve a forest simulation model that can help forest managers evaluate the outcomes of different management strategies. This work will receive guidance from a stakeholder advisory board consisting of forest managers, conservation groups and others invested in the future well-being of northeastern forests.In the northeastern U.S., climate projections include an increase in the frequency of mid-summer droughts, and winters that are warmer overall, but with periodic infusions of arctic air that can cause late-spring freezes and damaging cold-stress. The ability to predict how forests will respond is limited by knowledge of inter- and intra-specific variation in plant traits that regulate tree responses to climatic stress and the degree to which they reflect environmental or evolutionary drivers. This research addresses these uncertainties by (1) performing an in-depth study of the variation and drivers of turgor loss point—a key determinant of tree-level drought response—as well as associated cold and drought resilience traits and (2) identifying the relationship between drought and cold resilience in the individuals studied. The work will involve extensive field measurements of leaf osmotic potential and turgor loss point, associated physiological plant traits and rooting depth, as well as a manipulative experiment on genetically identical individuals. Sampling will be conducted at sites across the northeastern U.S. and at a site in Alabama with similar species at the southern end of their range. The work will be guided by an advisory board made of people invested in the forest (e.g., forest managers, conservation groups and indigenous community members). Results will be used to improve an ecosystem model that simulates forest growth under a range of climate and forest management scenarios. This will benefit a range of management objectives that prioritize climate resilience and assisted tree migration.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.