Mangrove restoration to meet the climate challenge in Southeast Asia

In  a recent study  researchers from the French research institute CIRAD, Srinakharinwirot University and the Joint Graduate School of Energy and Environment (JGSEE), both in Thailand, analysed 32 years of satellite data and field measurements across 24 study plots in South East Asia, examining species diversity and mangrove structure along a gradient from the sea to inland areas. The findings show that natural mangroves have significantly higher above-ground biomass than those that have been restored or have regenerated spontaneously.

“This is mainly due to restoration practices that often involve mono-specific plantations, in other words they consist of a single species”, say Valéry Gond and Camille Piponiot, scientists at CIRAD and co-authors of the study.

In natural mangroves, above-ground biomass can reach up to 536 tonnes of carbon per hectare, compared with just 99 tonnes per hectare in restored plantations, which is five times less.

According to Asamaporn Sitthi of Srinakharinwirot University and lead author of the study, these findings highlight the complexity of mangrove restoration. To ensure restoration efforts are effective, it is essential to consider species diversity, the conditions of the site, the density of plants and the way in which they are planted.

Towards more diverse, locally adapted approaches

A more diverse, tailored approach is therefore needed to maximise the impact of restoration projects, an approach now being driven by several regional initiatives, including the RESCuE project (Monitoring and REstoration for Sustainable Coastal Ecosystems).

Now in its second phase, the RESCuE project is working to develop mangrove restoration strategies in partnership with local stakeholders and communities in Thailand, Cambodia and Malaysia, and soon in in the Mekong Delta in Vietnam.

Reducing pressure on mangroves through improved aquaculture practices

These findings offer new opportunities for Vietnam, which has vast mangrove areas and has succeeded in restoring some of the mangroves lost over recent decades. The mangroves form narrow strips along the coast or estuarine rivers. Much of this mangrove area is not protected and is used for integrated aquaculture to support the livelihoods of local communities.

According to authorised management plans, 60 per cent of the total area must be maintained as mangrove, which can be harvested every 15 years. This allows for carbon storage and carbon credit trading, and it generates environmental benefits.

However, because fish, shrimp and crab yields are low in the remaining 40 per cent of aquaculture areas, encroachment on mangroves is often observed. Improving incomes and resilience in these aquaculture zones could significantly reduce the pressure on mangroves and their associated biodiversity.

"Diverse aquaculture practices, a balanced nutrient supply and multiple integration systems can greatly increase incomes and resilience within the production system, while reducing or preventing encroachment,” says Kazi Ahmed Kabir, a researcher at CIRAD specialising in sustainable aquaculture systems and coastal ecosystem restoration.

These systems include agroforestry, which combines mangroves with horticultural crops, as well as integrated multi-trophic aquaculture (IMTA), combining the production of shrimp, crabs, fish and seaweed.

The study was published in Nature last March ahead of the UN One Ocean Science Congress that took place in Nice, France, in June.

(CIRAD/wi)

Reference:

Sitthi, A., Pimple, U., Piponiot, C. et al. Assessing the effectiveness of mangrove rehabilitation using above-ground biomass and structural diversity. Sci Rep 15, 7839 (2025). https://doi.org/10.1038/s41598-025-92514-7  

More information:

The RESCuE-2 - Monitoring and REstoration for Sustainable Coastal Ecosystems