In new research, study authors have shown evidence that far more methane is released by growing trees that grow on floodplains in the Amazon basin than by soil or surface water, and this takes place in both dry and wet conditions.

As specified in a Phys.org report, most methane gas released from Amazon wetlands areas is expelled into the atmosphere through tree root systems, with substantial emissions taking place "even when the ground is not flooded."

In their work, the University of Birmingham researchers specified methane is the most essential greenhouse gas, and much more methane comes from wetlands.

A great deal of research is currently being conducted into how much methane is released through this route, although models usually assume that the gas is only generated when the ground is flooded and underwater.

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(Photo: Krzysztof Golik on Wikimedia Commons)
Flooded trees in Kampong Phlouk, Siem Reap Province, Cambodia

Methane Emission

Essentially, in wetland regions where there are no trees, methane would usually be consumed by the soil on its way to the surface, although in forested wetland areas, the study authors say the tree roots could be functioning as a transport system for the gas, up to the surface where it's escaping into the atmosphere from the tree trunks.

Methane can leak through the said route even when produced in soil and water that is a number of meters underneath the ground level.

Meaning, the present models could substantially underestimate the possible extent of methane releases in wetland regions like the Amazon basin.

The researchers performed measurements across three plots in the three major rivers' floodplains in the central Amazon basin to try the theory.

Global Wetland Methane Emissions Estimated

In the study, Non-flooded riparian Amazon trees are a regionally significant methane source, published in the Philosophical Transactions of the Royal Society A; the same trees were observed at each plot at four-time points within the year to capture their reactions to changing levels of waters with the yearly flood.

Methane discharges were gauged using a portable greenhouse analyzer, and then the approximations were carried out to scale the results across the Amazon basin.

In general, the research team approximated that almost half of worldwide wetland methane emissions  

are channeled out by trees, with the unpredicted outcomes that trees are essential for emissions too, at times when the floodplain water table is sitting underneath the soil's surface.

According to Professor Vincent Gauci, lead author of the School of Geography, Earth and Environmental Sciences at the University of Birmingham, their results have shown that the present global emissions calculations are missing an important piece of the picture.

He added that there is now a need to develop methods and approaches that consider the substantial role of trees in wetland methane emission.

The research team was led by the University of Birmingham and included scientists from Federal of Rio de Janeiro, Lancaster University, the Met Office Hadley Centre, and Linkoping University.

Related information on methane and global warming are shown on SWRM's YouTube video below:

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