Mangroves provide societies with food, fiber, fuel and protection from storms. More recently, studies conducted by the Forest Service have shown that intact mangrove forests store more carbon than any other tropical or temperate forested ecosystem. This suggests that these highly productive ecosystems can offset greenhouse gas emissions through their ability to remove carbon dioxide from the atmosphere and sequester it belowground.
Despite the many ecosystem services mangroves provide, they have been seriously degraded from intensive socio-economic development. Up to half of the world’s mangroves have been lost in the last 40 years to coastal development or deforestation for charcoal production or aquaculture. In an attempt to offset these losses, government and non-governmental organizations have been working to create manmade mangrove plantations. But do they work as well as intact mangroves when it comes to sequestering carbon?
Scientists with the Forest Service’s Pacific Southwest Research Station, in collaboration with the Forest Service’s International Programs division and the University of Hawaii at Manoa, have been working on a U.S. Agency for International Development project called SWAMP (Sustainable Wetland Adaptation and Mitigation Program). Scientists recently completed a long-term study comparing carbon stocks between restored and intact mangroves in Cambodia and the Philippines. Within 10 years of replanting, mangrove plantations stored as much carbon below ground as intact forests. Within 20–25 years, both below- and above-ground carbon storage were within the same levels of intact mangroves.
Results suggest that mangrove restoration through plantations can be an effective mitigation tool for removing and storing significant amounts of carbon from the atmosphere. Additional studies are underway in Indonesia and Vietnam investigating fish assemblages and water quality within restored mangroves.