Amazonian floodplains are a major global carbon sink

Abstract:

Terrestrial vegetation with high photosynthetic capacities, such as tropical forests, are regarded as a natural sinks for atmospheric carbon. Indeed, tropical forests play an important role in atmospheric carbon (CO₂) assimilation, as these systems contain about half of the global terrestrial carbon biomass. The Amazon Basin covers an area of approximately 8 million km². The Amazon Forest is one of the major global atmospheric carbon (C) sinks, however this sink has been shown to be partly offset by CO₂ and CH₄ aquatic emissions and via particulate or dissolved organic carbon transported to the ocean. This is primarily because that within the Amazon forest are vast wetlands that are composed of anoxic sediments located within the lakes and inundated forests. Here, we show that Amazonian floodplains, that cover an area of ~785,000 km², i.e. 10% of the basin, are a major and unaccounted global C sink. The results here suggest that the Amazon inundated forests carbon burial rate is two orders of magnitude greater than any terrestrial forest and similar to the carbon burial rates estimated for global mangrove forests. Our first order estimates indicate that the Amazon floodplain forests are on an aerial basis as one of the most efficient carbon sinks on the globe. As a result, the findings outlined in this research may contribute in the protection of these global significant carbon sinks as mitigation strategies to reduce atmospheric greenhouse gasses and a negative feedback to anthropogenic climate change.