Soil greenhouse gas emissions from dead and natural mangrove forests in Southeastern Brazil

Mangroves forests may be important sinks of carbon in coastal areas but upon their death, these forests may become net sources of carbon dioxide (CO₂) and methane (CH₄) to the atmosphere. Here we assessed the spatial and temporal variability in soil CO₂ and CH₄ fluxes from dead mangrove forests and paired intact sites in SE-Brazil. Our findings demonstrated that during warmer and drier conditions, CO₂ soil flux was 183 % higher in live mangrove forests when compared to the dead mangrove forests. Soil CH₄ emissions in live forests were > 1.4-fold higher than the global mangrove average. During the wet season, soil GHG emissions dropped significantly at all sites. During warmer conditions, mangroves were net sources of GHG, with a potential warming effect (GWP100) of 32.9 ± 10.2 (±SE) Mg CO₂e ha^-1 y^-1. Overall, we found that dead mangroves did not release great amounts of GHG after three years of forest loss.