RAPID: Mapping drought stress and hydraulic refugia with repeat hyperspectral data

与气候变化有关的日益严重的干旱和热浪正在危害世界各地的生态系统和经济。该项目利用美国国家航空航天局（NASA）制作的独特时间序列遥感图像和南加州持续干旱的情况，开发测绘和监测植物干旱压力的新技术。植物干旱胁迫、植物水分利用和植物水源（如表土或地下水）的详细测量将与植物水分含量的遥感测量相联系，以开发远程监测干旱胁迫的方法。这些方法将用于确定在持续干旱期间景观上抗旱能力和抗旱脆弱性的地区，并将利用不久的将来发射的卫星促进全球对农业、林业和水资源管理的干旱监测。该项目还将培训研究生和本科生，并为加州大学圣巴巴拉分校新的实地本科课程奠定基础。该项目旨在以前所未有的时空粒度了解干旱胁迫的空间变化。该项目利用了NASA表面生物和地质高频时间序列探路者任务的独特重复机载高光谱图像，该任务于2022年3月至6月进行，恰逢南加州持续的长期干旱。拟议的研究框架将解决围绕干旱引起的树木死亡、地下水获取和物种内抗逆性变化的一些关键突出问题。对两种橡树在不同地形和土壤梯度上的水分有效性进行详细的生理测量，将与植物冠层含水量和叶片含水量的遥感指标联系起来，以跟踪春季干旱期间景观中数千棵树木的干旱胁迫发展。这将增加对水资源压力如何在空间上发展的理解，并确定景观特征，如地形脆弱的地点和可能获得岩石水的水力避难所。将地面生理应力测量与高时间分辨率的高光谱航空图像严格联系起来，将为了解植物干旱胁迫的地形、地貌和生态水文控制提供工具，并开发利用即将到来的高光谱卫星任务进行全球干旱监测的方法。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。

Increasing droughts accompanied by heat waves that are associated with climate change are harming ecosystems and economies worldwide. This project takes advantage of a unique time series of remote sensing images being produced by NASA and an ongoing drought in southern California to develop new techniques for mapping and monitoring plant drought stress. Detailed measurements of plant drought stress, plant water use and plant water source (e.g. surface soil or groundwater) will be linked to remotely sensed measurements of plant water content to develop methods for remotely monitoring drought stress. These methods will be used to identify areas of drought resilience and drought vulnerability on the landscape during the ongoing drought, and will facilitate global drought monitoring for agriculture, forestry and water resource management using satellites being launched in the near future. This project will also train graduate and undergraduate students and provide the foundation for new field-based undergraduate courses at the University of California, Santa Barbara. This project seeks to understand spatial variation in drought stress with unprecedented spatial and temporal granularity. The project takes advantage of unique repeat airborne hyperspectral imagery from the NASA Surface Biology and Geology High Frequency Timeseries Pathfinder mission March-June of 2022 that coincides with an ongoing prolonged drought in southern California. The proposed research framework will tackle some of the key outstanding questions surrounding drought-induced tree mortality, subsurface water access, and variations in stress resistance within a species. Detailed physiological measurements on two species of oak trees across topographic and edaphic gradients in water availability will be linked to remotely sensed metrics of plant canopy water content and leaf water content to follow the development of drought stress in thousands of trees across the landscape during the spring dry down. This will increase understanding of how water stress develops spatially and identify landscape features such as topo-edaphically vulnerable sites and hydraulic refugia that likely have access to rock water. Rigorously linking ground-based measurements of physiological stress to hyperspectral airborne imagery at high temporal resolutions will provide the tools to understand topographic, geomorphic, and ecohydrological controls on plant drought stress, and develop methods for global drought monitoring using upcoming hyperspectral satellite missions.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.