Collaborative Research: MRA: Climate legacies and timescales of influence on carbon cycle processes in drylands

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

Earth’s climate is changing, and climate extremes such as droughts and heat waves are becoming more common. Such changes are impacting vegetation productivity, the carbon cycle, and the water cycle, especially in drier regions in the western United States. Studies are showing that not only do extreme climate events affect ecosystems when those events occur, but the effects continue long after the events themselves. This lingering effect of climate extremes, especially drought events, is often referred to as a climate or drought “legacy.” Studies also suggest that past conditions, regardless of whether extreme or not, continue to affect ecosystems after they have occurred, such that ecosystems have “memory” of those past conditions. The importance of such legacies and memory may be critical to understanding how continued climate change will impact Earth’s ecosystems and carbon balance. This project will study the legacies and memory of climate variables — such as precipitation, drought, and temperature — on tree growth, forest productivity, and ecosystem carbon fluxes in the western US. Researchers will analyze a huge volume of data of different types, including annual tree growth, carbon variability, and vegetation production, and will use computer simulations to predict future trends. Results from this work will increase understanding of how plants and ecosystems are impacted by climate variability and extreme climate events, which may be useful for mitigating the impacts of climate change. Post-doctoral researchers, graduate students, and undergraduate trainees will participate in the research. The project will share knowledge gained from this research with local and regional communities via collaborations with professional river guides, state and federal agencies, and scientists and land managers interested in understanding the impacts of drought on vegetation, ecosystems, and the carbon cycle. This study seeks to quantify legacies (prolonged impacts of an extreme event) and memory (timescales of influence, whether extreme or not) of climate-related drivers on key C-cycle components, over a range of spatial and temporal scales across drylands in the western US. This study will (1) quantify the magnitude and duration of climate (e.g., drought) legacies on C fluxes; (2) evaluate climatic memory and the timescales over which climate drivers impact C fluxes; (3) determine how legacy and memory responses vary across drylands in the western US; and (4) evaluate the importance of legacies and memory for the C cycle. To address these, this study will employ modern statistical methods (wavelet analyses, machine learning, Bayesian models) to integrate diverse datasets varying in temporal and spatial coverage and resolution, including multiple tree-ring networks, ground-based flux towers, satellite data products, model-data fusion products, and biospheric model outputs. This study will provide insights into the magnitude and duration of climate-C-cycle legacies, how these legacies vary across space, and the potential mechanisms giving rise to such legacies. The core project team (8 researchers) includes 3 early career scientists, and multiple additional participants (postdocs, PhD students, undergraduates). The project includes a variety of training and outreach activities aimed at the scientific community, land and resource managers, agency stakeholders, and the public. Activities include organizing sessions for scientific meetings, a workshop focused on “Drought Legacies and Terrestrial C-cycling,” facilitating interagency communication via collaborations with the National Integrated Drought Information System, working with professional guide programs in the Colorado Plateau region to disseminate knowledge to the public, and developing hands-on educational materials for the Flagstaff Festival of Science. 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.