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

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.