EGU2020-18290, updated on 10 Jan 2024
EGU General Assembly 2020
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

AmazonFACE – Assessing the response of Amazon rainforest functioning to elevated atmospheric carbon dioxide concentrations

Anja Rammig1, Katrin Fleischer1, Sabrina Garcia2, Nathielly Martins2, Juliane Menezes2, Lucia Fuchslueger3, Karst Schaap2, Iokanam Pereira2, Bruno Takeshi2, Carlos Quesada2, Bart Kruijt4, Richard Norby5, Alessandro Araujo6, Tomas Domingues7, Thorsten Grams1, Iain Hartley8, Martin De Kauwe9, Florian Hofhansl10, and David Lapola11
Anja Rammig et al.
  • 1Technische Universität München, TUM School of Life Sciences, Freising, Germany
  • 2National Institute of Amazonian Research (INPA), Manaus, Brazil
  • 3Centre for Microbiology and Environmental Systems Science, University of Vienna, Austria
  • 4Alterra Wageningen, Wageningen, The Netherlands
  • 5Oak Ridge National Laboratory, Oak Ridge, TN, USA
  • 6Brazilian Agricultural Research Corporation (EMBRAPA), Belém, Brazil
  • 7FFCLRP, Department of Biology, University of São Paulo, Ribeirão Preto, Brazil
  • 8Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK,
  • 9Climate Change Research Centre, University of New South Wales, Sydney, New South Wales, Australia
  • 10International Institute for Applied Systems Analysis, Laxenburg, Austria
  • 11Center for Meteorological and Climatic Research Applied to Agriculture, University of Campinas, Campinas, Brazil

The rapid rise in atmospheric CO2 concentration over the past century is unprecedented. It has unambiguously influenced Earth’s climate system and terrestrial ecosystems. Elevated atmospheric CO2 concentrations (eCO2) have induced an increase in biomass and thus, a carbon sink in forests worldwide. It is assumed that eCO2 stimulates photosynthesis and plant productivity and enhances water-use efficiency – the so-called CO2-fertilization effect, which may provide an important buffering effect for plants during adverse climate conditions. For these reasons, current global climate simulations consistently predict that tropical forests will continue to sequester more carbon in aboveground biomass, partially compensating human emissions and decelerating climate change by acting as a carbon sink. In contrast to model simulations, several lines of evidence point towards a decreasing carbon sink strength of the Amazon rainforest. Reliable predictions of eCO2 effects in the Amazon rainforest are hindered by a lack of process-based information gained from ecosystem scale eCO2 experiments. Here we report on baseline measurements from the Amazon Free Air CO2 Enrichment (AmazonFACE) experiment and preliminary results from open-top chamber (OTC) experiments with eCO2. After three months of eCO2, we find that understory saplings increased carbon assimilation by 17% (under light saturated conditions) and water use efficiency by 39% in the OTC experiment. We present our main hypotheses for the FACE experiment, and discuss our expectations on the potential driving processes for limiting or stimulating the Amazon rainforest carbon sink under eCO2. We focus on possible effects of eCO2 on carbon uptake and allocation, nutrient cycling, water-use and plant-herbivore interactions, which need to be implemented in dynamic vegetation models to estimate future changes of the Amazon carbon sink.

How to cite: Rammig, A., Fleischer, K., Garcia, S., Martins, N., Menezes, J., Fuchslueger, L., Schaap, K., Pereira, I., Takeshi, B., Quesada, C., Kruijt, B., Norby, R., Araujo, A., Domingues, T., Grams, T., Hartley, I., De Kauwe, M., Hofhansl, F., and Lapola, D.: AmazonFACE – Assessing the response of Amazon rainforest functioning to elevated atmospheric carbon dioxide concentrations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18290,, 2020.