2024 Abstracts

Regional-Scale, Observation-Informed Tropical Forest Diversity in ELM-FATES


Marcos Longo1* (mlongo@lbl.gov), Lara Kueppers1,2, Charles Koven1, Rosie Fisher3, Gregory Lemieux1, Ryan Knox1, Jessica Needham1, Jennifer Kowalczyk1, Jeffrey Chambers1,2, Polly Thornton2, Helene Muller-Landau4, S. Joseph Wright4, Antonio Antonino5, Damien Bonal6, Paulo Brando7, Benoit Burban8, Géraldine Derroire9, José Silva10, Eduardo Souza10, Maria del Rosario Uribe7


1Lawrence Berkeley National Laboratory, Berkeley, CA; 2University of California–Berkeley, CA; 3CICERO Centre for International Climate Research, Oslo, Norway; 4Smithsonian Tropical Research Institute, Panama City, Panama; 5Universidade Federal de Pernambuco–Recife, PE, Brazil; 6Université de Lorraine, INRAE, AgroParisTech, UMR Silva, Nancy, France; 7Yale School of the Environment, Yale University, Yale, CT; 8INRAE, UMR 0745 EcoFoG, Campus Agronomique, Kourou, French Guiana; 9CIRAD, UMR 0745 EcoFoG, Campus Agronomique, Kourou, French Guiana; 10Universidade Federal Rural de Pernambuco–Serra Talhada, PE, Brazil



Droughts in tropical ecosystems are increasingly hotter and more frequent, with potentially significant impacts on carbon and water cycles throughout the 21st century. The ability to predict how forests will respond to climate change will largely depend on whether terrestrial biosphere models represent the diversity of individual trees’ trade-offs between allocation of resources to growth and drought tolerance. Here, the project presents its approach to define regional-scale plant functional types (PFTs) for the Functionally Assembled Terrestrial Ecosystem Simulator (FATES). The team pooled trait and allometry data from multiple open-source databases (including TRY and Environmental System Science Data Infrastructure for a Virtual Ecosystem) of 34 traits across 2096 tree species in the Neotropics and used an unsupervised clustering approach to identify and implement PFTs along the main observed trade-off axes. This approach generated five tropical PFTs (four evergreen, one drought-deciduous), with the evergreen clusters representing structural growth strategies (maximum height), tolerance to shade, and leaf stoichiometry. The team tested FATES at multiple mature forest sites along a precipitation gradient (500 to 3000 millimeters per year) in the Neotropics. Researchers found that FATES qualitatively represents biomass differences across dry and moist forests but overestimates drought-deciduous abundance and underestimates evergreen PFT fractions under current climate. The project is currently implementing a multisite parameter sensitivity to further constrain the model predictions. Results hitherto indicate a potential for advancing understanding of PFT co-existence across the tropics using observed traits; however, they suggest that additional data and model process development are needed to quantitatively improve the model predictions.