NSFDEB-NERC: Understanding drought and post-drought legacy effects in tropical forest

从单个树木到森林生态系统的水平，该项目解决了在理解热带森林如何应对干旱方面的一个重大空白。这项研究将利用一种新型雷达传感器在巴西热带亚马逊森林进行大规模干旱试验。研究结果将有助于进一步了解干旱的影响，特别是在树木和森林尺度上。塔式雷达传感器以比卫星雷达传感器高得多的分辨率探测植被含水量的变化。研究人员将把这种森林尺度的雷达信号与详细的植物生理数据结合起来。该小组还将把干旱实验与干旱后的测量结果进行比较，以研究长期干旱对森林恢复的影响。这项研究是与英国自然环境研究委员会（NERC）合作资助的，是美国和英国实验室之间的国际合作。这项研究还将支持培训一名博士后研究员和两个“科学与影响”讲习班。这项在亚马逊雨林进行大规模森林生态系统实验和多尺度测量的研究有几个目标。该项目将创造新的能力，通过使用高分辨率塔式雷达含水量信号来监测干旱对热带森林的影响。基于塔的传感器数据将与植物组织水势测量和叶片（/冠层）或木质（/茎）组织的水分释放进行比较和校准。通过测量树木和土壤的水分利用（蒸腾）和水力导度，将进一步利用植物和雷达的干旱应激反应数据来推断干旱期间树木和森林尺度上整体功能的变化。该项目还将进行一项测试，以确定在实验干旱消除后，雷达-植物水势关系是否可以为科学理解植物状态指标（含水量和水势）以及树木和森林整体功能容量（蒸腾、水力导度）的恢复速度提供信息。这将决定森林从干旱中恢复的速度，是否存在干旱后的遗留影响，以及森林在未来干旱下是否仍有功能失效的风险。最后，将结果与来自现有和新出现的卫星雷达数据流的卫星信号进行比较和综合。这些关系将用于开发动态绘制和预测热带森林干旱风险的潜力，并改进从空间探测生物量变化的能力。除了在一个国际合作项目中培训一名博士后研究员外，研究人员还将在项目开始和结束时通过两次科学与影响讲习班与利益攸关方（陆地表面建模人员和土地利用/气候缓解规划者）接触，以确定在监测和基于模型的陆地-大气相互作用预测方面的改进，以及用于土地利用规划的森林干旱风险早期预警。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。

This project addresses a significant gap in understanding of how tropical forests respond to drought, from the level of individual trees to that of the forest ecosystem. The research will leverage a large-scale drought experiment in a tropical Amazon forest in Brazil with the use of a new radar sensor. The results will provide advances in understanding the effects of drought, particularly at tree and forest scales. The tower-based radar sensor detects changes in vegetation water content at much higher resolution than is possible using satellite radar sensors. Researchers will integrate this forest-scale radar signal with detailed plant physiology data. The team will also compare the drought experiment with post-drought measurements to study the effects of long-term drought on forest recovery. The research is funded in partnership with the UK's Natural Environment Research Council (NERC) as an international collaboration between U.S. and U.K. laboratories. This study will also support the training of a postdoctoral researcher and two "Science and and Impact" workshops.This study of large-scale forest ecosystem experimentation and multi-scale measurements in the Amazonian rain forest has several objectives. The project will create new capacity to monitor the effects of drought on tropical forests by using high-resolution tower-based radar water-content signal. The tower-based sensor data will be compared and calibrated with plant tissue water potential measurements and moisture release from leaf (/canopy) or woody (/stem) tissue. The plant and radar drought-stress response data will be further used to infer altered overall function during drought at tree and forest scales, using measurements of water use (transpiration) and hydraulic conductance in trees and soil. The project will also perform a test of whether, after the experimental drought has been removed, the radar-plant water potential relationship can inform scientific understanding of the rate of recovery in plant status metrics (water content and water potential), and in overall tree and forest functional capacity (transpiration, hydraulic conductance). This will determine how quickly the forest is able to recover from the drought, whether there are post-drought legacy effects, and whether the forest remains at risk of functional failure under future drought. Finally, the results will be compared and integrated with satellite-based signals from both existing and emerging satellite-radar data-streams. The relationships will be used to develop the potential to dynamically map and predict drought risk in tropical forests, and to improve the detection of biomass change from space. In addition to training a postdoctoral researcher in an international collaborative project, the investigators will engage stakeholders (land surface modellers; and land use/climate mitigation planners) through two Science & Impact workshops at the start and end of the project to identify improvements in monitoring and model-based prediction of land-atmosphere interactions, and early warning of drought risk to forests for use in land-use planning.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.