The future of tropical forests matter to future climate.
NGEE-Tropics is advancing model predictions of tropical forest carbon cycle responses to a changing climate over the 21st Century.
Our Research
Current Earth system models poorly represent the processes controlling tropical forest carbon cycling, contributing to large uncertainties in climate projections. To address this challenge, NGEE–Tropics research focuses on state-of-the-science model development and measurements that are most critical for projecting tropical forest carbon cycling and associated energy and water fluxes. We have developed and are continuing to improve a new hierarchical, modular modeling platform, called E3SM-FATES (Energy Exascale Earth System Model)-Functionally Assembled Terrestrial Ecosystem Simulator), that integrates crucial processes of plant demography, ecophysiology, below-ground biogeochemistry, and aquifer-to-canopy hydrology. E3SM-FATES will enable an improved understanding of how diversity in plant functional traits ... Read More
To improve tropical forest representation in Earth system models (ESMs), NGEE-Tropics is carrying out field and lab studies to generate key data. We are also integrating diverse existing and new data into data products valuable for model development, parameterization, and testing. The NGEE-Tropics Data Synthesis and Management Framework includes infrastructure for archiving project data collections, and for defining and building data synthesis and analysis products needed as model parameters and benchmarks. The data team is also developing a portal that provides access to project data and relevant community data repositories, enabling broad usage consistent with data use agreements. The data portal is intended to ... Read More
Earth system model (ESM) representations of tropical forests currently rely on very limited datasets and understanding of these highly diverse and dynamic ecosystems. NGEE-Tropics is prioritizing field observations that are most critical to improving parameterizations in existing models, such as ACME-FATES, developing robust new process representations, and evaluating model simulations. While Phase 1 focuses on synthesis of existing data and uncertainty assessments to prioritize new field efforts for Phase 2, Phase 1 also includes an initial set of field activities organized around known model needs in collaboration with key field science partners. Field Pilot Studies We have initiated three Integrated ... Read More
Why is Drought Important? Drought has had major impacts on tropical forests over the last two decades and is expected to occur more frequently and with greater intensity in the coming decades. Intense drought can affect carbon uptake and release, increase tree mortality and alter water and energy exchange with the atmosphere. However, current Earth system model representation of forest response to drought is underdeveloped and poorly tested pantropically. Key aspects of drought impacts that are high priority for research include the mechanisms by which variation in local to regional soil hydrology affect plant hydraulics and forest water and carbon ... Read More
Why are CO2 and Temperature Important? Tropical forests exchange approximately 41 petagrams of carbon per year with the atmosphere – the largest carbon flux of any ecosystem on the planet. Global increases in CO2 concentrations and associated changes in temperature can have both direct and indirect effects on this exchange, and on the amount of carbon allocated to forest growth. To reliably project future climate, Earth system models (ESMs) must accurately represent these huge CO2 fluxes and effects of rising CO2 and temperature on tropical forests. Despite the importance of tropical forests in the global carbon cycle, their response to ... Read More
Why is Natural Disturbance Important? The structure of tropical forests is influenced by the growth and death of individual trees, and by forest disturbance events at local, landscape, and regional scales. Natural disturbances include wind, storms, fire, drought, floods, and outbreaks of insects and disease, and can vary in frequency and intensity. Disturbance and subsequent forest recovery are essential to forest functioning, and some disturbance processes are expected to increase in intensity and frequency with climate warming affecting forest carbon, water and energy fluxes. Key processes for understanding how tropical forests are dynamically structured through disturbance and subsequent recovery include plant recruitment, ... Read More
Why is Anthropogenic Disturbance Important? Anthropogenic, or direct human disturbance of tropical forests includes deforestation, as well as forest degradation through activities such as selective logging and understory fires. Deforestation and degradation fragment forests and alter their functioning. These activities are estimated to release about 2.9 petagrams C per year, increasing atmospheric CO2 concentrations. About 30% of tropical forests are recovering from deforestation, representing a major global carbon sink of about 1.6 petagrams C per year, or roughly half of the total C released from deforestation and fire in the tropics. Anthropogenic disturbances, especially degradation, and subsequent recovery are minimally represented in current models. ... Read More
Why is Hydrology Important? Water is essential for tree growth and survival. Water is also tightly coupled to forest energy and nutrient budgets. In many tropical forests, trees obtain their water from surface soil that is highly weathered and interspersed with macropores that quickly move rainwater from the surface into stream channels. Where the water table is shallow or if trees have deep roots, groundwater can also be an important source. Understanding and modeling how surface and subsurface plant water availability varies across the landscape and through time are essential for predicting how tropical forests will respond to hydroclimate change, ... Read More
Why are Nutrient Constraints Important? Mineral nutrients, such as nitrogen and phosphorus, are essential for plant growth in tropical forests, which primarily grow on highly weathered soils. Nutrient deficiencies can constrain photosynthesis and growth, and may limit how much forests can benefit from rising CO2 or how fast they recover following anthropogenic disturbance. Nutrient uptake by plants is associated with how their roots are distributed and function, as well as interactions between roots and soil microbes. Phosphorus (P) is considered to be the limiting nutrient in many tropical lowland forests. Co-limitation by nitrogen (N) can also play a large role ... Read More
Recent News
The Science This paper showed an increasingly stronger impact on terrestrial gross primary production (GPP) by extreme droughts than by
Below versus above Ground Plant Sources of Abscisic Acid (ABA) at the Heart of Tropical Forest Response to Warming Abscisic
Climate Sensitive Size-dependent Survival in Tropical Trees Survival of trees in the tropics can be grouped into four types and
