2024 Abstracts

Ecosystems Under Stress: Knowledge Gaps and Approaches Using MOFLUX as a Testbed


Jeffrey D. Wood1* (woodjd@missouri.gov), Emma G. Cochran1, Lianhong Gu2, Melanie Mayes2, Christian Salvador2, Hunter A. Seubert1, Paul J. Hanson2, Daniel Ricciuto2


1University of Missouri, Columbia, MO; 2Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN



Drought and heat are important stressors that influence forest ecosystem processes and biosphere-atmosphere gas exchange. The Missouri Ozark AmeriFlux (MOFLUX) site, situated in the central U.S. forest-grassland transitional zone, experiences frequent droughts and heat stress episodes. Indeed, drought plays a key role in shaping temporal variations of gas exchange within and across years, as well as stand composition through pulses of drought-induced tree mortality. Here, researchers synthesize new research aimed at broadly answering the question: how does drought and/or heat stress influence the spatiotemporal variations of the forest carbon cycle? Specific questions include: (1) how does drought and temperature influence the spatial variation of soil respiration?; (2) how do drought and heat stress influence the surface energy imbalance?; and (3) how does heat stress influence isoprene production and atmospheric chemistry? To address these questions, the team leveraged the long-term data record that was started in 2004, as well as opportunistic volatile organic compound (VOC) measurements made during the 2023 growing season using proton transfer reaction–time of flight–mass spectrometry (PTR- TOF-MS). VOC emissions are important plant stress responses and are associated with the protection of sensitive plant tissues when energy supply overwhelms energy demand during drought and heatwaves. Answering these intersecting questions will help guide future monitoring efforts to ensure that spatiotemporal variations are adequately characterized and enhance integrated scientific understanding of how temperate broadleaf forests dynamically respond to drought and heat stress.