Amazonian vegetated estuarine ecosystem as a global hotspot in carbon sequestration

Abstract

Mangroves provide a vital role in mitigating climate change through sequestering large amounts of carbon. Brazil contains the second largest extent of mangroves in the world, with 77% of this adjacent to the Amazon estuary, a largely understudied region, due to its extent and inaccessibility. To address this, this study analysed rates of carbon sequestration in the mangroves and várzea of the Amazon estuary. Observed rates of carbon sequestration varied between 111-3,487 gC m2 year-1, with a regional average of 1,718 gC m2 year-1. This compares very favourably with previously reported global averages of 134-226 gC m2 year-1, suggesting that these sites sequester an order of magnitude more carbon than global averages. This is likely due to the large volume of organic material provided by the Amazon and Tocantins Rivers, as well as from inputs along the coast from the Bragança Mangrove, the second largest continuous mangrove in the world.

Comparison of Carbon Storage in Forested and Non-Forested Soils in Tropical Wetlands of Caimanera, Colombia, and Llano, Mexico

“…This accumulation of peat has also been observed in some mangroves in Micronesia, where it was attributed to the rise in sea levels [60]. Regarding the sediment, it sequesters carbon according to its texture, which can be silty, clayey, or sandy, each with different sequestering capacities; for instance, silty sediments tend to sequester more carbon if found in greater proportions than others [61]. It is important to highlight that despite the results obtained, the heterogeneity of mangrove ecosystems poses a challenge for making solid and definitive comparisons regarding carbon storage, as it depends on multiple hydrogeomorphological variables [53].…”