Recovery of Soil Processes in Replanted Mangroves: Implications for Soil Functions

Abstract

Mangrove revegetation is a vital strategy to recover ecosystem services (e.g., climate regulation and pollutants retention) provided by these ecosystems. Although soils are directly or indirectly responsible for diverse ecosystem services in mangrove ecosystems, few studies have focused on the recovery of soil functions (e.g., carbon sequestration) after mangrove replanting. This study aimed to evaluate the recovery of soil processes associated with Fe, S, and C dynamics and its implications for the restoration of soil functions. Two mangrove sites under replanting initiatives were studied along the Brazilian coast (i.e., NE and SE). The study was conducted in 3- and 7-year-old replanted mangrove forests, and a comparison was made with degraded and mature mangroves. Particle size, soil C stocks, Fe forms, total Fe and S contents, degrees of pyritization of Fe, and mineralogical assemblages were assessed. Seven years after replanting, soil C stocks increased by 42% and 29% in mangrove soils from the NE and SE sites, respectively. In addition, significant increases were observed in fine particles, reactive Fe, and pyrite contents in replanted plots. These new conditions promoted organic matter accumulation, stabilization, and potential metal retention. Our findings highlight the potential of revegetation programs for recovering soil processes and essential soil functions.