EGU24-12352, updated on 09 Mar 2024
https://doi.org/10.5194/egusphere-egu24-12352
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Tropical forests: a source of CO!

Hella van Asperen1,2, Thorsten Warneke2, Alessandro Carioca de Araújo3,4, Bruce Forsberg3, Sávio José Filgueiras Ferreira5, Thomas Röckmann6, Carina van der Veen6, Sipko Bulthuis7, Shujiro Komiya1, Sam P Jones1, Santiago Botía8, Leonardo Ramos de Oliveira3, Thiago de Lima Xavier3, Jailson da Mata3, Marta de Oliveira Sá9, Paulo Ricardo Teixeira3, Julie Andrews de França e Silva3, Justus Notholt2, and Susan Trumbore1
Hella van Asperen et al.
  • 1Max Planck Institute for Biogeochemistry (MPI-BGC), Dep. for Biogeochemical Processes, Hans Knöll Strasse 10, 07745, Jena, Germany
  • 2Institute of Environmental Physics (IUP), University of Bremen, Otto-Hahn-Allee 1, Bremen, 28359, Germany
  • 3Programa de Grande Escala da Biosfera-Atmosfera na Amazônia (LBA), Instituto Nacional de Pesquisas da Amazônia (INPA), Av. André Araújo, 2936, Petrópolis, AM 69067-375, Manaus, Brazil
  • 4Brazilian Agricultural Research Corporation (EMBRAPA), Embrapa Amazônia Oriental, Tv. Dr. Enéas Piheiro, s/n, Marco, PA 66095-903, Caixa postal 48, Belém, Brazil
  • 5Coordenação de Dinâmica Ambiental (CODAM), Instituto Nacional de Pesquisas da Amazônia (INPA), Av. André Araújo, 2936, Petrópolis, AM 69067-375, Manaus, Brazil
  • 6Institute for Marine and Atmopsheric Research Utrecht (IMAU), Utrecht University, Princetonplein 5, 3584, Utrecht, Netherlands
  • 7Max Planck Institute for Chemistry (MPI-C), Hahn-Meitner-Weg 1, Mainz, 55128, Germany
  • 8Max Planck Institute for Biogeochemistry (MPI-BGC), Dep. for Biogeochemical Systems, Hans Knöll Strasse 10, 07745, Jena, Germany
  • 9PhD student of Postgraduate Program in Climate and Environment (CLIAMB) - INPA/UEA, Instituto Nacional de Pesquisas da Amazônia (INPA), Av. André Araújo, 2936, Petrópolis, AM 69067-375, Manaus, Brazil

CO is an indirect greenhouse gas because it reacts with OH, therefore increasing the lifetime of methane: its possible indirect radiative forcing has been estimated as larger than that of N2O. Previous studies have indicated that temperate and boreal forests act as a net sink for CO, but the role of tropical rain forest ecosystems has not been investigated. We present the first CO flux measurements from tropical forest and forest soils, and can show that tropical rain forests are a net source of CO to the atmosphere.

During two intensive field campaigns at tropical rain forest fieldsite ZF2 (Manaus, Brazil), soil CO fluxes were determined by use of flux chambers. In addition, nighttime vertical CO concentration profiles were measured and different micro-meteorological techniques were applied to estimate ecosystem CO fluxes. Furthermore, we performed nocturnal CO concentration measurements in a seasonally inundated valley, which was hypothesized as a potential hotspot for ecosystem CO emissions.

Soil CO fluxes ranged from -0.19 (net soil uptake) to 3.36 (net soil emission) nmol m-2 s-1, averaging ∼1 nmol CO m-2 s-1. Fluxes varied with season and topographic location, with highest fluxes measured in the dry season in a seasonally inundated valley. Nocturnal canopy air profiles show consistent decreases in CO mixing ratios with height, which requires positive surface fluxes between 0.3 and 2.0 nmol CO m-2 s-1. Similar fluxes are derived using a canopy layer budget method, which considered the nocturnal increase in CO over time (1.1 to 2.3 nmol CO m-2 s-1). Using wet season concentration profiles of CO, the estimated valley ecosystem CO production exceeded the measured soil valley CO fluxes, indicating a potential contribution of the valley stream to overall CO emissions.

Based on our field observations, we expect that tropical rain forest ecosystems are a net source of CO. Extrapolating our first observation-based tropical rain forest soil emission estimate of ∼1 nmol m-2 s-1, a global tropical rain forest soil emission of ∼16.0 Tg CO yr-1 is suggested. Total ecosystem CO emissions might surpass this estimate, considering that valley streams and inundated areas could serve as local CO emission hotspots. To further improve tropical forest ecosystem CO emission estimates, more in-situ tropical forest soil and ecosystem CO flux measurements are essential.

How to cite: van Asperen, H., Warneke, T., Carioca de Araújo, A., Forsberg, B., José Filgueiras Ferreira, S., Röckmann, T., van der Veen, C., Bulthuis, S., Komiya, S., P Jones, S., Botía, S., Ramos de Oliveira, L., de Lima Xavier, T., da Mata, J., de Oliveira Sá, M., Ricardo Teixeira, P., Andrews de França e Silva, J., Notholt, J., and Trumbore, S.: Tropical forests: a source of CO!, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12352, https://doi.org/10.5194/egusphere-egu24-12352, 2024.