Rapid: Assessing Temporal Dynamics of Disturbance Interactions as a Driver of a Novel Forest Mortality Event

在世界上许多森林地区，引进的害虫和病原体造成的干扰，加上气候条件的变化，对森林健康造成了影响。随着这些类型的干扰变得更加频繁，它们之间的相互作用可以大大扩大对森林健康和可持续性的影响。这个项目将研究一个前所未有的、持续的森林死亡事件，它影响了新英格兰南部以橡树为主的森林。树木死亡率似乎与干旱和非本地舞毒蛾毛虫的多次冠层落叶的相互作用有关。该项目将评估这些干扰的时间和相互作用对森林健康的影响。这项研究将评估树木死亡率较高的地区是那些经历了最严重的最初干旱的地区，还是那些在干旱发生前经历了落叶的地区。该项目的结果将对森林利益相关者非常有价值，帮助他们了解树木死亡事件的根本原因，并有可能预测未来的影响。调查人员与区域森林管理界密切接触，该项目的结果将用于规划森林管理战略，包括与这一死亡事件有关的树木砍伐。该项目非常重要，因为它将传达对木制品市场、林业和树木栽培实践以及公众一般森林利用的潜在影响。气候介导的干扰（如干旱）和生物干扰（如落叶害虫）之间的相互作用正日益推动大陆尺度森林的结构和功能。然而，与干旱对生物干扰的影响相关的时间滞后尚未得到很好的理解，并且缺乏解决这一问题的经验数据。本研究的核心假设是，干旱和落叶干扰的相互作用将通过干扰与初始干旱严重程度之间的时间接近来调节。该项目将结合高时空分辨率遥感分析和树木年代学重建森林生长模式，以评估相互作用干扰的时间和严重程度如何影响温带森林生态系统的干扰抵抗模式、森林生产力和树木死亡率。这项研究将在一个通过遥感分析确定的林分网络中进行，该网络将在与最初干旱干扰有关的落叶时间的各个类别之间复制。该项目的结果将为未来的实验和建模研究提供假设生成、模型参数化和一般概念框架，以评估陆地生态系统中干扰相互作用的机制基础和后果。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。

In many forested regions of the world, disturbances caused by introduced pests and pathogens, along with changing climatic conditions, has resulted in forest health impacts. As these types of disturbances become more frequent, the interactions between them can greatly amplify the impacts on forest health and sustainability. This project will study an unprecedented, ongoing forest mortality event that affects oak-dominated forests in southern New England. Tree mortaility appears to be related to the interaction of both drought and multiple canopy defoliations by non-native Gypsy Moth caterpillars. This project will evaluate how the timing and interactions of those disturbances matters in forest health. The research will assess if areas that have greater tree mortality are those that experienced the most intense initial drought or if they underwent defoliation closer in time to the drought. The results of the project will be very valuable to forest stakeholders, helping them understand the underlying causes of the tree mortality event and potentially allowing prediction of future impacts. The investigators are highly engaged with the regional forest management community and the results of the project will be used in planning forest management strategies including tree removals related to this mortality event. The project is important as it will communicate the potential ramifications for wood products markets, forestry and arboriculture practices, and general forest use by the public. Interactions between climate-mediated disturbances, such as droughts, and biotic disturbances, such as defoliating insect pests, are increasingly driving continental-scale forest structure and function. However, the temporal lags associated with drought effects on biotic disturbance are not well understood and empirical data to address this topic are lacking. The central hypothesis of this project is that the effect of interacting drought and defoliation disturbance will be mediated by temporal proximity between disturbances and initial drought severity. The project will combine high temporal and spatial resolution remote sensing analysis with dendrochronological reconstruction of forest growth patterns to assess how the timing and severity of interacting disturbances affects patterns of disturbance resistance, forest productivity, and tree mortality in temperate forest ecosystems. The study will be conducted in a network of forest stands, identified through the remote sensing analysis, which will be replicated across categories of defoliation timing in relation to the initial drought disturbance. The results of the project will support hypothesis generation, model parameterization, and general conceptual frameworks for future experimental and modeling studies that can evaluate the mechanistic basis for, and consequences of, disturbance interactions in terrestrial ecosystems.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.