The AmazonFACE program addresses the overarching question: "How will climate change affect the Amazon forest, the biodiversity it harbors, and the ecosystem services it provides to humanity?" The central feature of the program is a field experiment of unprecedented scope that will expose an old-growth Amazon forest to the CO2 concentration of the future in an research station near Manaus, Brazil using Free-Air CO2 Enrichment (FACE) technology. An increased knowledge on the functioning of the world's largest tropical forest in light of climate change and the usage of this knowledge for steering regional policies on climate change mitigation and adaptations are part of the legacy the program attempts to establish.

FACE Technology

FACE technology has proven to be a valuable method to determine long-term, ecosystem-scale responses of forests to elevated CO2 in temperate regions. Although the scientific and logistical challenges of implementing a FACE experiment in a tall, highly diverse, and relatively remote forest are substantial, we have identified an implementation pathway that makes strong use of existing resources, infrastructure, and knowledge bases. Each of our FACE ring is composed by 16 towers disposed in circular fashion and linked to a liquid CO2 storage tank encompassing an area of forest of 30m diameter and 35m height. Target atmospheric CO2 concentration inside this forest area is 50% above current CO2 concentrations (~400+200 parts per million of volume). Computer sensors control the release of CO2-enriched air according to wind speed and direction. Each of these FACE plots have to be densely monitored and surveilled to capture ecosystem's response to the CO2 stimulus.

Experimental Site

Location of the eight experimental forest plots:

Project Phasing

The Program is now approaching the end of Phase 1, which focus on (1) baseline integrated ecological characterization of the experimental site prior to the CO2 enrichment; (2) elaboration of formal engineering plans for the experimental infrastructure and (3) assessment of the potential socio-economic impacts of an Amazon forest dieback and AmazonFACE linkages with policies.

Click here for a summary of Phase 1 Results.

Program Tasks

Task 1 - Aboveground Ecological Processes

The aboveground component of AmazonFACE focus on measuring the growth and structure of the trees, the carbon they absorb from the air during photosynthesis and release back to the air during respiration, and the water they use to maintain their metabolism. We need to know how the balance of gains and losses occur under different climate conditions. We also need to know how the uniquely high species diversity here affects these processes. We can then monitor how they change when we simulate the effects of a future atmosphere by exposing the forest to an elevated atmospheric CO2 concentration. We may get more carbon gains, but also more carbon losses. And different species will be favored or disadvantaged. Will the carbon sink of Amazonia continue? Or will it turn into a carbon source? Will there be more evaporative cooling, or less? Perhaps the biomass of the forest will change, with fewer species dominating? We need to know these answers to understand and predict the future well-being of the South American tropics, and the global atmosphere.

Task 2 - Belowground Ecological Processes

The availability of nutrients, especially phosphorus, may limit the extent to which carbon storage increases in Amazon forest in response to elevated atmospheric CO2 . However, trees may be able to alleviate this limitation by investing some of the additional carbon fixed under elevated CO2 to nutrient acquisition. In addition, greater water-use efficiency in the forest canopy may result in more water remaining in the soils which could increase resistance to drought. The below-ground measurements in AmazonFACE aim to investigate these fundamental issues: can trees gain greater access to limiting nutrients under elevated CO2 and does soil water availability increase. The measurements will determine how CO2 fumigation affects carbon allocation to roots using a combination of ingrowth cores, mini-rhizotron cameras, and the partitioning of below-ground respiration into the activity of roots, mycorrhizal fungi and soil microbes. Changes in rates of nutrient cycling and uptake will be determined through assays of root and microbial enzyme activities, determinations of stocks and availabilities of different soil nutrients using established extraction and fractionation schemes, as well as measurements of root nutrient contents to contribute to calculation of nutrient uptake. Finally, soil moisture and water movements are being monitored continuously down to a depth of 2 metres.

Task 3 - Ecosystem Modeling

The modeling component of AmazonFACE aims to integrate the knowledge we gain from both the experimental and the ecosystem modeling community in order to make more informed decisions for the experiment and maximize the scientific outcome on both fronts. Among this task activities are a model inter-comparison project with a number of state-of-the-art ecosystem models, the development of new ways to model the highly-diverse tropical forests (e.g. trait-based models), and the work with conceptual models to further explore underlying assumptions in ecosystem models. Ultimate goal is to up-scale the results (ecological process functioning) from the field experiment to the entire Amazon basin and other tropical forests. For the moment, the model inter-comparison activity is delivering hypotheses for the CO2 response of the forest that can directly be tested during the experiment. It will further identify key model deficiencies by confronting model results with experimental data from the AmazonFACE.

Task 4 - Meteorology and Engineering

The AmazonFACE experiment will be the first to use FACE technology in a tall tropical forest. AmazonFACE will also be established in the most remote location ever attempted for FACE research. Technical challenges include providing reliable road access, electric power, communications, CO2 supply and access to the forest canopy. We have identified 8 research plots with appropriate tree size and stand density for a FACE experiment. Two of these plots have been selected for use in the prototype, proof of concept phase of this research. They are currently undergoing intensive surveys and characterization to document conditions prior to beginning CO2 enrichment.

We have installed towers in these two plots, with instruments at multiple levels to provide the local meteorological data needed to design the CO2 delivery systems and estimate seasonal, maximum and annual CO2 needs for proposed enrichment scenarios. These towers also provide convenient access to the forest canopy for biological studies.

Task 5 - Socio-political- economic impacts

If the Amazon forest dieback or any similar large-scale climate-driven degradation of the Amazon forest indeed occurs, this would represent a significant threat to the region's economy via changes in the regional and global rainfall patterns, agricultural losses and impairment of hydropower supply. This task follows the principle that anticipating socio-economic impacts can better prepare us, in terms of policies, to cope with future climatic adversities. In that sense it investigates the impacts of this climate-forest degradation on several sectors of the Amazonian socio-economy, namely agriculture, fisheries, energy, transport, cities, migration, health and ecosystem services. In its current stage researchers in task are also carrying out a systematic identification of existing public policies that could benefit from the AmazonFACE experiment results.

Integration and Synthesis

This task aims to answer crosslinking questions such as changes in net primary productivity and to assure data flow between the project partners. Sharing of standardized data among project participants is important for advancing the science product in a consistent way, most efficiently moving data to models, and avoiding both redundant and missing measurements.


The AmazonFACE program seeks innovative ways to make its scientific outputs reach decision makers, students and the general public. In that context it offers periodically training courses, is now touring with a science-art interface exhibition in the USA and Brazil and has prepared a non-scientific language Fotobook about the program.