Factors influencing organic carbon accumulation in mangrove ecosystems

Background

Mangrove forest sediments can store a significant amount of organic carbon (900 Mg ha-1). Environmental and anthropogenic impacts, like storms or deforestation, can increase or decrease carbon accumulation rates within mangrove sediments and ecosystems. Therefore, it is important to understand how these impacts affect blue carbon ecosystems’ storage capacity.

Goals and Methods

The authors conducted a literature search of studies with sediment core data from mangroves in human-managed conservation areas, as well as mangroves impacted by degradation and deforestation, storms and natural flooding, and urban effluents and aquaculture. They also examined differences in carbon accumulation from sediments within vegetated mangrove areas, at the mangrove margins, and in mudflats. Statistical analysis examined differences between geographical regions, environmental conditions, mangrove species composition, and sedimentary environments.

Conclusions and Takeaways

Organic carbon accumulation rates in managed conservation areas are fourfold higher than in degraded areas, but they are twofold to threefold lower than accumulation rates for mangroves undergoing environmental or anthropogenic impacts. Environmental impacts, like storms or frequent flooding, increase carbon accumulation rates due to mangrove roots trapping organic debris, especially in more densely vegetated areas. Mangroves affected by anthropogenic impacts, like sewage or aquaculture, have higher organic carbon accumulation and sediment accretion rates, highlighting how mangroves are important for sequestering carbon and nutrients in eutrophic environments. These results show that mangrove forests facing frequent anthropogenic and environmental impacts are still important carbon sinks.