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的频率增加。尽管森林管理者越来越重视气候适应和帮助树木迁移作为管理目标，但由于干旱对东北树木的影响以前并不是一个高度优先的研究，因此他们的努力受到信息缺口的限制。此外，树木适应干旱的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损害，这些因素将在未来几十年继续成为东北冬季的一部分。这项研究将提高人们对东北树种如何应对干旱的认识，以及不同的干旱适应如何影响它们对其他气候压力的脆弱性。这将通过在美国东北部和阿拉巴马州的一个地点对许多物种和与干旱有关的植物性状进行广泛的测量来实现，该地点在其当前范围的南端包含了类似的物种。数据收集将使用一种新的方法，大大增加了可以处理的组织样本的数量。研究结果将用于改进森林模拟模型，该模型可帮助森林管理者评估不同管理策略的结果。这项工作将得到由森林管理者、保护团体和其他投资于东北森林未来福祉的人组成的利益相关者咨询委员会的指导。在美国东北部，气候预测包括仲夏干旱的频率增加，冬季整体变暖，但北极空气的周期性注入可能导致晚春冻结和破坏性的冷应激。对调节树木对气候胁迫的反应的植物性状的种间和种内变异以及它们反映环境或进化驱动因素的程度的了解，限制了预测森林将如何作出反应的能力。本研究通过(1)深入研究膨胀损失点的变化和驱动因素（树级干旱响应的关键决定因素）以及相关的寒冷和干旱恢复力特征(2)确定所研究个体的干旱和寒冷恢复力之间的关系来解决这些不确定性。这项工作将包括广泛的实地测量叶片渗透势和膨胀损失点，相关的植物生理性状和生根深度，以及对基因相同的个体进行操纵实验。采样将在美国东北部和阿拉巴马州的一个地点进行，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投资于森林的人组成的咨询委员会指导（例如，森林管理者、养护团体和土著社区成员）。研究结果将用于改进模拟一系列气候和森林管理情景下森林生长的生态系统模型。这将有利于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。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.