Carbon uptake by mature Amazon forests has mitigated Amazon nations' carbon emissions

Background: Several independent lines of evidence suggest that Amazon forests have provided a significant carbon

sink service, and also that the Amazon carbon sink in intact, mature forests may now be threatened as a result of

different processes. There has however been no work done to quantify non-land-use-change forest carbon fluxes on

a national basis within Amazonia, or to place these national fluxes and their possible changes in the context of the

major anthropogenic carbon fluxes in the region. Here we present a first attempt to interpret results from groundbased

monitoring of mature forest carbon fluxes in a biogeographically, politically, and temporally differentiated way.

Specifically, using results from a large long-term network of forest plots, we estimate the Amazon biomass carbon balance

over the last three decades for the different regions and nine nations of Amazonia, and evaluate the magnitude

and trajectory of these differentiated balances in relation to major national anthropogenic carbon emissions.

Results: The sink of carbon into mature forests has been remarkably geographically ubiquitous across Amazonia,

being substantial and persistent in each of the five biogeographic regions within Amazonia. Between 1980 and 2010,

it has more than mitigated the fossil fuel emissions of every single national economy, except that of Venezuela. For

most nations (Bolivia, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname) the sink has probably additionally

mitigated all anthropogenic carbon emissions due to Amazon deforestation and other land use change. While the

sink has weakened in some regions since 2000, our analysis suggests that Amazon nations which are able to conserve

large areas of natural and semi-natural landscape still contribute globally-significant carbon sequestration.

Conclusions: Mature forests across all of Amazonia have contributed significantly to mitigating climate change for

decades. Yet Amazon nations have not directly benefited from providing this global scale ecosystem service. We suggest

that better monitoring and reporting of the carbon fluxes within mature forests, and understanding the drivers

of changes in their balance, must become national, as well as international, priorities.