Role of Mesoscale Convective Systems in Driving Forest Dynamics in the Amazon


Robinson Negron-Juarez1* (, Jennifer A. Holm1, Yanlei Feng2, Mingjie Shi3, David Urquiza- Muñoz4, Daniel Marra4, David Romps5, Ruby Leung3, William Riley1, Jeffrey Chambers1,5


1Lawrence Berkeley National Laboratory, Berkeley, CA; 2Carnegie Institution for Science, Stanford, CA; 3Pacific Northwest National Laboratory, Richland, WA; 4Max Planck Institute for Biogeochemistry, Jena, Germany; 5University of CaliforniaBerkeley, CA



There is limited knowledge about the recurrent mechanisms driving complex tropical forest dynamics, such as tree mortality, regrowth, and associated ecosystem characteristics and processes in the Amazon. Understanding these mechanisms is critical to comprehending the current stage of forests and how they will change with future variations of forest dynamics in response to disturbance, changing climates, and extremes. The most recurrent modes of tree mortality in the Amazon are uprooted and broken trees, which are largely associated with strong winds produced by severe convective processes. As a result, tree mortality by winds, known as windthrows, is becoming a growing area of research. Using a ModEx approach, researchers found that windthrows have a preferential direction (westward), coincident with the preferential movement of mesoscale convective systems in the Amazon. Intense convection is a predictor of windthrows and winds higher than 12 m/s can produce broken trees. This study also shows that trees are sensitive to an increase in windthrows, with the western Amazon being the most sensitive region. Vegetation regrowth after windthrows is faster in the Western Amazon than in the Central Amazon and windthrows display a spatial pattern of occurrence. Furthermore, windthrows have increased with time and show a shift toward the western Amazon. A work in progress is the nexus between inventory plots that enable in situ measurements of tree mortality and remote sensing data that enable regional assessments of this mortality. However, both study types are concluding similar results, mostly regarding the increase in tree mortality and its shift. Importantly, windthrows as a driver of tree mortality are not currently included in Earth system models. Future work will include development of a wind disturbance and mortality mechanism into FATES and simulations of convective characteristics responsible for windthrows using E3SM.