Large methane emissions from Amazonian floodplain trees

A recent study led by Sunitha Pangala presented the discovery and showed the importance of a previously unknown conduit of methane from floodplains to the atmosphere in the Amazon. The conduit are trees. To demonstrate the importance of this conduit two approaches have been pursued. On the one hand methane flux from tree stems has been measured in floodplain trees of many river stems of the Amazon and for a large number of trees. This data was up-scaled using area estimates of seasonally flooded floodplains.

Sampling set-up for methane from tree stems. Photo Credit: Sunitha Panagala

Setting up of methane tree sampling equipment. Photo credit: Sunitha Pangala

Aircraft were used to regularly (bi-weekly) take vertical profile samples of the lower troposphere methane concentration field. These data together with a back-trajectory based atmospheric inverse transport model were used to estimate the total Amazon basin methane balance. This tropospheric methane sampling program is being led by Luciana Gatti at INPE in Sao Jose dos Campos, Brazil.

While there is disagreement between upscaling of previously known methane flux processes and the aircraft based methane balance, inclusion of the discovered additional flux path leads to good agreement between the two approaches. The discovery of the tree conduit is important because the Amazon contributes a substantial fraction of methane emissions from wetlands globally. This contribution is approximately 8-10% of all contemporary methane emissions to the atmosphere.

While Sunitha Pangala and Luciana Gatti were the main researchers on this study, scientists from several other institutions were involved including the  Open University, NOAA, ESRL and University of Leeds.

The full article is available here:

Large emissions from floodplain trees close the Amazon methane budget, Sunitha R. Pangala, Alex Enrich-Prast, Luana S. Basso, Roberta Bittencourt Peixoto, David Bastviken, Edward Hornibrook, Luciana V. Gatti, Humberto Marotta Ribeiro, Wanderley Rodrigues Bastos, Olaf Malm, Emanuel Gloor, John Miller, Vincent Gauci (2017) Nature, 552, 230–234, doi:10.

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