Collaborative Research: Understanding the impacts of an ongoing megadrought: Synthesizing the role of soil moisture in driving ecosystem fluxes from site to regional scales

美国西部的旱地目前处于长达23年的“大干旱”时期，构成了过去1200年来最干旱的时期。这场巨灾是一场持续的气候危机，正在严重影响自然生态系统、受管理的森林、农业系统和人类水资源。尽管造成了如此严重的后果，但我们对巨型地震的了解相当有限。具体地说，研究界缺乏对特大干旱如何影响土壤水分的全面了解，特别是对植被健康至关重要的深层水分池。对于碳和水循环在过去23年中是如何变化的，人们的理解也很有限；这是调节全球气候反馈的生态系统功能的重要指标。这项研究加强了我们对旱地如何受到特大干旱影响的生态学理解，这为更具预测性地了解未来气候变化的影响奠定了基础。这一知识可转移到其他旱地和非旱地生物群，因为预计在未来几十年，这种特大干旱在全球范围内的频率和严重性将会增加。为了实现这些目标，这项研究结合了数百个长期运行的土壤水分深度剖面与对浅层土壤水分、深水可获得性和地下水的遥感估计。这些数据使我们能够评估特大干旱对植物可用水的影响，并作为这些用于干旱监测的遥感产品的关键验证。来自21个涡旋协方差塔的数据与一个新的经验式生态系统通量网格数据集配对，以揭示旱地生态系统功能的驱动因素，并在高空间和时间分辨率上量化大尺度变化对碳-水通量的影响。通过综合这些数据源，它们的独特优势得到了利用；利用现场数据解决详细的机械问题，并使用建模和遥感数据研究碳水循环的广泛趋势。该项目由生态系统科学和既定的激励竞争研究计划(EPSCoR)共同资助。该奖项反映了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。

Drylands in the American West are currently in the grips of a 23-year long ‘megadrought’, constituting the driest period of the last 1,200 years. This megadrought is an ongoing climate crisis that is severely impacting natural ecosystems, managed forests, agricultural systems, and human water resources. Despite such serious consequences, our understanding of the megadrought is quite limited. Specifically, the research community lacks a comprehensive understanding of how the megadrought has impacted soil moisture, particularly the deeper moisture pools that are critical for vegetation health. There is also a limited understanding of how carbon and water cycling have changed over the last 23 years; an important indicator of ecosystem function that mediates global climate feedbacks. This research enhances our ecological understanding of how drylands have been impacted by the megadrought, which sets the stage for a more predictive understanding of future climate change impacts. This knowledge is transferable to other dryland and non-dryland biomes, as such megadroughts are projected to increase in frequency and severity globally in the coming decades. To accomplish these aims, the research combines hundreds of long-running soil moisture depth profiles with remotely-sensed estimates of shallow soil moisture, deep water availability, and groundwater. These data allow us to assess the impacts of the megadrought on plant-available water, and serve as a crucial validation of these remotely-sensed products for drought monitoring. Data from 21 eddy covariance towers are paired with a new gridded dataset of empirically-modeled ecosystem fluxes to uncover the drivers of dryland ecosystem function, and quantify the impact of the megadrought on carbon-water fluxes at high spatial and temporal resolutions. By synthesizing these data sources their unique strengths are leveraged; addressing detailed mechanistic questions with in situ data, and examining broad trends in carbon-water cycling using modeled and remotely-sensed data. This project is jointly funded by Ecosystem Science and the Established Program to Stimulate Competitive Research (EPSCoR).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.