Tapping the Power of Mangroves

Scientists have long known that mangroves—woody trees and shrubs that grow in coastal waters—hold a hidden superpower: They are highly efficient at storing carbon, offering an intriguing solution to mitigate climate change.

In fact, researchers estimate that mangrove ecosystems can store up to 10 times more carbon than rainforests.

But fully tapping mangroves’ potential is a challenge. These tropical plants face numerous threats, including sea level rise, deforestation and changing land use. And, in individual countries, a lack of country-level data makes it difficult to assess how much carbon their mangroves are absorbing.

In Belize and Panama, nations with extensive mangrove ecosystems, Smithsonian scientists are working to gather data on mangrove carbon stocks and build local capacity for conservation.

Data from these projects—led by national governments in collaboration with the Smithsonian, nongovernmental organizations, universities and local scientists—will be critical to help Belize and Panama update their plans (or nationally determined contributions) every five years to meet the U.N. Paris Agreement targets for reducing carbon emissions.

Belize Estimates Blue Carbon

In April 2023, researchers with the Smithsonian Environmental Research Center and collaborating partners published a study in the journal Science of the Total Environment introducing the first national estimate of mangrove carbon stocks in Belize.

The two-year study found that Belize’s 58,000 hectares (about 14,300 acres) of mangroves hold 25.7 million metric tons of carbon—roughly equivalent to the mass of 14 million cars. The total varied greatly from estimates drawn from global or regional averages, highlighting the need for country-specific studies.

Scientists measure mangrove carbon in two ways: through biomass (the content of plants themselves) and sediment (below ground). For biomass carbon, measurements such as the width of tree trunks and the height of trees are recorded. For sediment, physical samples are taken from a core that extends three meters in depth.

Science-to-Policy Step

Study findings represent the first data released from the Belize Blue Carbon project, led by a group of Belizean and international scientists. Measuring blue carbon—or carbon stored in marine and coastal ecosystems, including mangroves and seagrass—is an important science-

to-policy step for Belize in meeting its commitments under the Paris Agreement.

The government of Belize has set goals of protecting an additional 12,000 hectares and restoring 4,000 hectares of mangroves by 2030.

Hannah Morrissette, Ph.D., coastal wetland biogeochemist at the Smithsonian Environmental Research Center, said the Belize project can serve as a model for other countries.

“A collaborative project of this magnitude and unique holistic nature has set the baseline for future blue carbon research,” Morrissette said. “The results show how different mangrove ecosystems can be from one another in a relatively small area and highlight their importance to national climate change mitigation goals.”

Results from the Belize study are available as part of the Coastal Carbon Atlas, a free global blue carbon data clearinghouse managed by the Smithsonian Environmental Research Center.

Panama Study Set for 2023 

Panama is next in line to develop its own mangrove dataset; an 18-month study along the Pacific coast is set to begin in summer 2023. Led by the government of Panama, scientists from the Smithsonian Environmental Research Center, Smithsonian Tropical Research Institute (Panama) and partner organizations will aggregate and analyze data to shape national policy on wetlands and climate change.

Training is also a priority. Smithsonian scientists will help train local community members, students, protected area managers, and government and nongovernmental organization staff to identify mangrove species, assess health conditions and estimate carbon content in biomass and soil.

“Training is important to help Panama implement plans and policies to expand mangrove conservation in the long term,” said Tania Romero, laboratory manager, Naos Marine Lab, Smithsonian Tropical Research Institute. “In addition, it is an investment in local efforts for conservation and in building research capacity across the country.”

The Pew Charitable Trusts provided support for blue carbon/mangroves research in Belize and Panama. 

Learn more: serc.si.edu/labs/marine-conservation

Published Summer 2023 in IMPACT Vol. 9. No 2

Click here to read more about the Smithsonian's work to build, maintain and protect resilient ecosystems.