Next-Generation Ecosystem Experiments–Tropics

NGEE-Tropics is a DOE-funded, multi-institutional project led by Berkeley Lab, focused on how tropical forests interact with Earth’s climate. Tropical forests cycle more CO2 and water than any other ecosystem, and play critical roles in determining Earth’s energy balance. Intact tropical forests are also estimated to be Earth’s largest carbon sink, yet the stability of this sink is susceptible to a warming climate and disturbance processes. Understanding of carbon and related water and energy exchanges between tropical forests and the atmosphere lags that of other ecosystems, and poor model representation of these processes is the most significant source of terrestrial uncertainty in projections of Earth’s future climate.

NGEE-Tropics: Dawn breaking over Manaus fieldsite, photo

Photo courtesy of Jeff Chambers

The 10-year vision for NGEE-Tropics is dramatically reduced uncertainty in Earth System Model (ESM) projections, and increased scientific understanding of how tropical forest ecosystems will respond to climate and atmospheric change. An overall critical question is whether these forests will continue to offset a large fraction of anthropogenic carbon emissions in the 21st century or become carbon sources from vegetation die-back under a warming climate.  The overarching goal of NGEE-Tropics is to develop a predictive understanding of how tropical forest carbon balance and climate system feedbacks will respond to changing environmental drivers over the 21st Century. Global environmental drivers of change include higher temperatures, shifting precipitation patterns, rising concentrations of atmospheric greenhouse gases, and altered disturbance regimes including changing land-use patterns.

Three overarching questions will guide our research:

Q1. How do tropical forest ecosystems respond to changing temperature, precipitation, and atmospheric CO2 concentration?

Q2. How do disturbance and land-use change in tropical forests affect carbon, water and energy fluxes?

Q3. How will the response of tropical forests to climate change be mediated by spatial and temporal heterogeneity in belowground processes?

All NGEE-Tropics research activities will be tightly coupled and anchored by a transformational model framework that will enable us to rigorously address high-priority tractable science questions that fall under these larger overarching questions.

The grand deliverable of NGEE-Tropics is the development of a representative, process-rich tropical forest ecosystem model, extending from bedrock to the top of the vegetative canopy, in which the evolution and feedbacks of tropical ecosystems in a changing climate can be modeled at the scale/resolution of a next generation ESM grid cell (i.e., expected to be at least 10 x 10 km grid size). To achieve this goal, we will develop a new hierarchical, modular modeling platform that integrates crucial processes needed to represent tropical forest ecosystem responses to global changes, including belowground biogeochemistry, plant demography and ecophysiology, plant functional traits, and aquifer-to-canopy hydrology.

Model advances will be directly enabled by pantropical syntheses of existing data, and investments in high priority observations and experiments that enhance process representation, support model parameterization and provide critical model benchmarks. These model functionalities have never been brought together into a single platform or rigorously evaluated against observations at a pantropical scale. Thus, NGEE-Tropics will enable cutting-edge research advances toward addressing tropical forest response to a changing atmosphere and warming climate.

Led by Berkeley Lab’s Earth and Environmental Sciences Area, NGEE-Tropics also includes partnerships with four national laboratories and a number of other institutions: Brookhaven National Laboratory, Los Alamos National Laboratory, Oak Ridge National Laboratory, Pacific Northwest National Laboratory, Smithsonian Tropical Research Institute, U.S. Department of Agriculture’s Forest Service, National Center for Atmospheric Research, National Aeronautics and Space Administration, and a number of universities and other state and federal agencies.  NGEE-Tropics also greatly benefits from international collaborative relationships, such as with Brazil’s National Institute of Amazonian Research (Instituto Nacional de Pesquisas da Amazônia – INPA), and anticipates expansion of this collaborative network of tropical Earth system scientists to realize our goals.