Blue carbon biomass stocks but not sediment stocks or burial rates exhibit global patterns in re-established mangrove chronosequences: a meta-analysis

Abstract

The re-establishment of mangrove forests is necessary to increase the quantity of sequestered carbon that would help to mitigate climate change. Determining long-term patterns of mangrove chronosequences is needed to develop a predictive capacity of carbon sequestration. We conducted a global meta-analysis of aboveground, belowground, sediment, and total ecosystem organic carbon (CORG) stocks and CORG burial rates (SCBR) in reforested, afforested, and naturally regenerated mangroves. Global patterns were detected for aboveground and belowground biomass CORG and ecosystem CORG stocks but not for sediment CORG stocks or SCBR. Mangrove trees increase carbon storage for up to a century, although they begin to plateau after 30-50 yr. Statistical analyses identified multiple variables as possible drivers and strong relationships between (1) mangrove biomass CORG stocks and forest age, (2) sediment and ecosystem CORG stocks, and (3) dominant mangrove species and environmental variables. Lack of a significant relationship between mangrove biomass and sediment blue carbon may be attributable to differences in environmental timescales and life histories between vegetation, sediment CORG, and subsurface sedimentary deposits. Sediment burial rates were nearly identical between those measured in re-established and natural forests, indicating that re-establishment of mangrove forests is a viable and predictable means of increasing long-term blue carbon sequestration. The global patterns suggest that predictive models can be constructed to improve forecasting of mangrove carbon sequestration, assisting in the sustainable development of mangrove plantations and mitigating climate change through market-based approaches.