The Past and Future of NGEE Tropics Measurements and ModEx

Authors

Nate McDowell¹* (nate.mcdowell@pnnl.gov), Jeffrey Warren², Chonggang Xu³, Alistair Rogers⁴, Kolby Jardine⁴, Stuart Davies⁵, Daniel Zuleta⁵, Zachary Robbins³, Cynthia Wright⁶, Rutuja Chitra-Tarak³, Alfonso Zambrano⁵, Bruno Gimenez⁷, Crist Santos⁷, Gustavo Spanner⁷, Regison Oliveira⁷, Niro Higuchi⁷, Robinson Negron-Juarez⁴, Mizanur Rahman¹, Kurt Solander³, Julien Lamour⁸, Joe Wright⁵, Michael Keller⁶, Jeffrey Chambers^4,9, NGEE Tropics team

Institutions

¹Pacific Northwest National Laboratory, Richland, WA; ²Oak Ridge National Laboratory, Oak Ridge, TN; ³Los Alamos National Laboratory, Los Alamos, NM; ⁴Lawrence Berkeley National Laboratory, Berkeley, CA; ⁵Smithsonian Tropical Research Institute, Panama City, Panama; ⁶USDA Forest Service; ⁷National Institute of Amazonian Research, Manaus, Amazonas, Brazil; ⁸French National Centre for Scientific Research, France; ⁹University of California–Berkeley, CA

URLs

https://ngee-tropics.lbl.gov

Abstract

Next-Generation Ecosystem Experiments (NGEE) Tropics has promoted leaps forward in understanding of tropical tree function from root to global scales using deliberate integration of empirical and numerical approaches. The empirical work has tested numerous hypotheses regarding tropical tree function at the site level, the data of which are being employed for model development. Functionally Assembled Terrestrial Ecosystem Simulator (FATES) efforts have simultaneously resulted in large advances in mechanistic representation of forest function. One critical next step is to emphasize efforts on model-experiment (ModEx) hypotheses from tissue to pantropical scales. To test FATES’s capability to simulate physiological and demographic processes, the model will be evaluated at five sites located across Malaysia, Panama, and Brazil, where extensive water- and carbon-related traits and processes are being measured at root to whole-tree scales. These simulations allow rigorous evaluation if the model gets the right answers for the right reasons and simultaneously allows tests of alternative mechanisms underlying variation in carbon and water fluxes and demography. At the pantropical scale, the team is utilizing long-term networks of forest demographics, carbon storage, nutrient availability, and functional traits to provide the basis for empirical and numerical hypotheses. Finally, remotely sensed datasets are being used for model parameterization of biomass, wind disturbance, and land use at large scales. Here, the team summarizes the existing and planned datasets, model developments, and associated ModEx efforts and highlights the key next steps to achieve the goal of generating a process-rich model that accounts for carbon dioxide, climate, and land-use impacts on the pantropical carbon sink.