Historical land use changes lead to massive loss of soil carbon stocks in a recovering, semiarid mangrove

Land use changes lead to substantial releases of carbon from the soil into the atmosphere. In carbon-rich ecosystems, like mangrove forests, this carbon loss may be more intense. This study evaluated soil carbon stocks in a mangrove area historically impacted by salt farming, which is under ecosystem recovery, in the semiarid coast of Northeastern Brazil. The neotropical mangrove sites in the Pacoti River showed marked spatial variability in soil density, texture, organic carbon concentration, nitrogen, and stable isotope signatures (delta C-13 and delta N-15) among sampled sites. Carbon stocks in the top meter layer ranged from only 12 Mg C ha(-1) (degraded area) to 283 Mg C ha(-1) (preserved Rhizophora mangle stands). The carbon stocks in the well-preserved sites are close to the national and global average, highlighting the importance of semiarid mangroves as efficient carbon sinks and emphasizing the urgency for protection and restoration in light of the ongoing climate emergency.